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Title: The Life of Sir Humphrey Davy, Bart. LL.D., Volume 2 (of 2)
Author: Paris, John Ayrton
Language: English
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THE LIFE
OF
SIR HUMPHRY DAVY,
BART. LL.D.
LATE PRESIDENT OF THE ROYAL SOCIETY, FOREIGN ASSOCIATE
OF THE ROYAL INSTITUTE OF FRANCE,
&c. &c. &c.
BY
JOHN AYRTON PARIS, M.D. CANTAB. F.R.S. &c.
FELLOW OF THE ROYAL COLLEGE OF PHYSICIANS.
IN TWO VOLUMES.
VOL. II.
LONDON:
HENRY COLBURN AND RICHARD BENTLEY,
NEW BURLINGTON STREET.
M DCCC XXXI.
CONTENTS.
CHAPTER X.
Mr. Faraday's introduction to Sir H. Davy.--A renewed correspondence
on the subject of the Gunpowder Manufactory.--Davy
obtains permission from Napoleon to visit the Continent.--He embarks
in a Cartel from Plymouth.--Is arrested at Morlaix.--Arrives
at Paris.--Visits the Louvre.--His extraordinary conduct
upon that occasion.--Inspects the Colossal Elephant, and is introduced
to M. Alavair, its architect.--The discovery of the dungeons
of the Bastile.--Davy's interesting letter to M. Alavair.--He attends
a meeting of the Institute.--Is visited by all the principal savans
of Paris.--The adventure which befell Lady Davy in the Thuilleries'
Garden.--Anniversary dinner of the Philomatic Society.--The
junior Chemists of France invite Davy to a splendid entertainment.--How
far Davy is entitled to be considered the discoverer
of the true nature of Iodine.--Napoleon's unlucky experiment
with the Voltaic battery.--Davy is presented to the Empress
Josephine.--An account of the Court ceremony at Malmaison.--Remarks
on the conduct of Davy during his visit to Paris.--He quits the
capital of France, and proceeds by way of Lyons, to Montpellier.--Is
assisted in experiments on sea-weed by M. Berard.--Crosses
the Alps.--Arrives at Genoa.--Institutes experiments on
the Torpedo.--Visits Florence, and accomplishes the combustion
of the diamond, by the great lens in the cabinet of Natural
History.--Experiments on Iodine.--He examines the colours used by
the Ancients.--Visits all the celebrated Philosophers of Italy and
Switzerland, with whom he works in their laboratories.--Returns
to England 1
CHAPTER XI.
Collieries of the North of England.--Fire-damp.--The dreadful
explosion at Felling Colliery described.--Letters from the Bishop
of Bristol to the Author.--A Society is established at Bishop-Wearmouth
for preventing accidents in coal mines.--Various projects
for ensuring the miner's safety.--The Reverend Dr. Gray, the present
Bishop of Bristol, addresses a letter to Sir H. Davy, and
invites his attention to the subject.--Sir H. Davy's reply.--Farther
Correspondence upon the possibility of devising means of security.--Sir
H. Davy proposes four different kinds of lamp for the purpose.--The
Safe-lamp--The Blowing-lamp--The Piston-lamp--The
Charcoal-lamp.--His investigation of the properties of fire-damp
leads to the discovery of a new principle of safety.--His
views developed in a paper read before the Royal Society on the
9th of November 1815.--The first Safety-lamp.--Safety-tubes superseded
by Safety-canals.--Flame Sieves.--Wire-gauze lamp.--The
phenomenon of slow combustion, and its curious application.--The
invention of the Safety-lamp claimed by a Mr. Stephenson.--A
deputation of Coal-owners wait upon Sir H. Davy, in order to
express to him the thanks of the Proprietors for his discovery.--Mr.
Buddle announces to Dr. Gray (now Bishop of Bristol) the intention
of the Coal-trade to present him with a service of plate.--The
Resolutions are opposed, and the claims of Stephenson urged,
by Mr. W. Brandling.--A dinner is given to Sir Humphry, at which
the plate is presented to him.--The President and Council of the Royal
Society protest against the claims still urged by Mr. Stephenson's
friends.--Mr. Buddle's letter in answer to several queries
submitted to him by the Author.--Davy's Researches on Flame.--He
receives from the Royal Society the Rumford Medals.--Is
created a Baronet.--Some observations on the apathy of the State
in rewarding scientific merit.--The Geological Society of Cornwall
receives the patronage and support of Sir Humphry 58
CHAPTER XII.
Sir Humphry Davy suggests a chemical method for unrolling
the ancient Papyri.--He is encouraged by the Government to
proceed to Naples for that purpose.--He embarks at Dover.--His
experiments on the Rhine, the Danube, the Raab, the Save, the
Ironzo, the Po, and the Tiber, in order to explain the formation of
mists on rivers and lakes.--His arrival and reception at Naples.--He
visits the excavations at Herculaneum.--He concludes that it
was overwhelmed by sand and ashes, but had never been exposed
to burning matter.--He commences his attempt of unrolling the
Papyri.--His failure.--He complains of the persons at the head of
the department in the Museum.--He analyses the waters of the
Baths of Lucca.--His return to England.--Death of Sir Joseph
Banks.--He is elected President of the Royal Society.--Some
remarks on that event.--He visits Penzance.--Is honoured by a
public dinner.--Electro-magnetic discoveries of Oersted extended
by Davy.--He examines Electrical Phenomena in vacuo.--The
results of his experiments questioned.--He enquires into the state
of the water, and aëriform matter in the cavities of crystals.--The
interesting results of his enquiry confirm the views of the
Plutonists 160
CHAPTER XIII.
The Liquefaction of Chlorine Gas first effected by Mr. Faraday,
and witnessed by the Author.--Sir H. Davy continues the
investigation.--His paper on the application of Liquefiable Gases as
mechanical agents.--Other probable uses of these bodies.--He
proposes several methods to prevent the fumes which arise from
Smelting-furnaces.--Importance of the subject.--His Letters to
Mr. Vivian.--The Government solicit the advice of the Royal Society
on the subject of protecting the Copper Sheathing of Ships
from the action of sea-water.--Sir H. Davy charges himself with
this enquiry.--He proposes a plan of protection founded on Voltaic
principles.--His numerous experiments.--He embarks on board
the Comet steam-vessel bound to Heligoland, in order to try his
plan on a vessel in motion.--He arrives at Mandal, lands, and
fishes in the lakes.--The Protectors washed away.--He teaches
the inhabitants of Christiansand to crimp fish.--He remains a few
days at Arendal.--A Norwegian dinner.--The Protectors are examined
and weighed.--Results of the experiment.--The steam-vessel
proceeds up the Glommen.--He visits the great waterfall.--Passes
into Sweden.--Has an interview with the Crown Prince of
Denmark, and afterwards with Prince Christian at Copenhagen.--He
visits Professor Oersted.--He proceeds to Bremen to see Dr.
Olbers.--Returns to England.--His third paper read before the Royal
Society.--Voltaic influence of patches of rust.--A small quantity
of fluid sufficient to complete the circuit.--He receives from the
Royal Society the Royal Medal.--The Progress of Voltaic discovery
reviewed.--The principle is of extensive application.--The
Author's researches into the cause of the solution of Lead in spring
water.--An account of the numerous trials of Protectors.--Failure
of the plan.--Report of the French on the state of the protected
frigate, La Constance.--Dr. Revere's new plan of Protection 208
CHAPTER XIV.
The failure of the Ship protectors a source of great vexation to
Davy.--His Letters to Mr. Poole.--He becomes unwell.--He
publishes his Discourses before the Royal Society.--Critical Remarks
and Quotations.--He goes abroad in search of health.--His
Letter to Mr. Poole from Ravenna.--He resigns the Presidency
of the Royal Society.--Mr. Gilbert elected _pro tempore_.--Davy
returns to England, and visits his friend Mr. Poole.--Salmonia, or
Days of Fly-fishing.--An Analysis of the Work, with various
extracts to illustrate its character 283
CHAPTER XV.
Sir H. Davy's Paper on the Phenomena of Volcanoes.--His
experiments on Vesuvius.--Theory of Volcanic action.--His reception
abroad.--Anecdotes.--His last Letter to Mr. Poole from
Rome.--His paper on the Electricity of the Torpedo.--Consolations
in Travel, or the Last Days of a Philosopher.--Analysis of the
work.--Reflections suggested by its style and composition.--Davy
and Wollaston compared.--His last illness.--Arrival at Geneva.--His
Death 341
A GENERAL REVIEW OF THE HISTORY OF CHEMICAL SCIENCE,
AND OF THE REVOLUTIONS PRODUCED IN ITS DOCTRINES BY
THE DISCOVERIES OF SIR HUMPHRY DAVY 415
APPENDIX--Will of Sir Humphry Davy 457
THE LIFE
OF
SIR HUMPHRY DAVY,
BART. &c. &c.
CHAPTER X.
Mr. Faraday's introduction to Sir H. Davy.--A renewed
correspondence on the subject of the Gunpowder
Manufactory.--Davy obtains permission from Napoleon
to visit the Continent.--He embarks in a Cartel from
Plymouth.--Is arrested at Morlaix.--Arrives at Paris.--Visits
the Louvre.--His extraordinary conduct upon that
occasion.--Inspects the Colossal Elephant, and is introduced
to M. Alavair, its architect.--The discovery of the dungeons
of the Bastile.--Davy's interesting letter to M. Alavair.--He
attends a meeting of the Institute.--Is visited by all the
principal _savans_ of Paris.--The adventure which befell
Lady Davy in the Thuilleries' Garden.--Anniversary dinner
of the Philomatic Society.--The junior Chemists of France
invite Davy to a splendid entertainment.--How far Davy is
entitled to be considered the discoverer of the true nature
of Iodine.--Napoleon's unlucky experiment with the Voltaic
battery.--Davy is presented to the Empress Josephine.--An
account of the Court ceremony at Malmaison.--Remarks on
the conduct of Davy during his visit to Paris.--He quits
the capital of France, and proceeds, by way of Lyons, to
Montpellier.--Is assisted in experiments on sea-weed by M.
Berard.--Crosses the Alps.--Arrives at Genoa.--Institutes
experiments on the Torpedo.--Visits Florence, and accomplishes
the combustion of the diamond, by the great lens in the cabinet
of Natural History.--Experiments on Iodine.--He examines the
colours used by the Ancients.--Visits all the celebrated
Philosophers of Italy and Switzerland, with whom he works in
their laboratories.--Returns to England.
It is said of Bergman, that he considered the greatest of his
discoveries to have been the discovery of Scheele.[1] Amongst the
numerous services conferred upon Science by Sir Humphry Davy, we
must not pass unnoticed that kind and generous patronage which
first raised Mr. Faraday from obscurity, and gave to the chemical
world a philosopher capable of pursuing that brilliant path of
enquiry which the genius of his master had so successfully explored.
[1] See Note at page 42, vol. i.
The circumstances which first led Mr. Faraday to the study of
chemistry, and by which he became connected with the Royal
Institution, were communicated to me, by himself, in the following
letter.
TO J. A. PARIS, M.D.
MY DEAR SIR, Royal Institution, Dec. 23, 1829.
You asked me to give you an account of my first introduction
to Sir H. Davy, which I am very happy to do, as I think the
circumstances will bear testimony to his goodness of heart.
When I was a bookseller's apprentice, I was very fond of
experiment, and very averse to trade. It happened that a
gentleman, a member of the Royal Institution, took me to hear
some of Sir H. Davy's last lectures in Albemarle Street. I took
notes, and afterwards wrote them out more fairly in a quarto
volume.
My desire to escape from trade, which I thought vicious and
selfish, and to enter into the service of Science, which I
imagined made its pursuers amiable and liberal, induced me at
last to take the bold and simple step of writing to Sir H.
Davy, expressing my wishes, and a hope that, if an opportunity
came in his way, he would favour my views; at the same time I
sent the notes I had taken at his lectures.
The answer, which makes all the point of my communication, I
send you in the original, requesting you to take great care of
it, and to let me have it back, for you may imagine how much I
value it.
You will observe that this took place at the end of the year
1812, and early in 1813 he requested to see me, and told me
of the situation of assistant in the Laboratory of the Royal
Institution, then just vacant.
At the same time that he thus gratified my desires as to
scientific employment, he still advised me not to give up
the prospects I had before me, telling me that Science was
a harsh mistress; and, in a pecuniary point of view, but
poorly rewarding those who devoted themselves to her service.
He smiled at my notion of the superior moral feelings of
philosophic men, and said he would leave me to the experience
of a few years to set me right on that matter.
Finally, through his good efforts I went to the Royal
Institution early in March of 1813, as assistant in the
Laboratory; and in October of the same year, went with him
abroad as his assistant in experiments and in writing. I
returned with him in April 1815, resumed my station in the
Royal Institution, and have, as you know, ever since remained
there.
I am, dear Sir, very truly yours,
M. FARADAY.
The following is a note of Sir H. Davy, alluded to in Mr. Faraday's
letter:
TO MR. FARADAY.
SIR, December 24, 1812.
I am far from displeased with the proof you have given me
of your confidence, and which displays great zeal, power of
memory, and attention. I am obliged to go out of town, and
shall not be settled in town till the end of January: I will
then see you at any time you wish.
It would gratify me to be of any service to you. I wish it may
be in my power.
I am, Sir, your obedient humble servant,
H. DAVY.
I must now recall the reader's attention to the affair of the
gunpowder manufactory, to which some allusion has been already
made. It is far from my wish to intrude upon the public any account
of a private transaction; but the circumstances to which I must
refer are already well known, and I believe, moreover, that they
have been the subject of misrepresentation.
The letters I shall introduce appear to me highly interesting; and
by the warmth of feeling with which they repel the bare suspicion
of his prostituting science to the acquisition of wealth, to
develope a feature in his character too important to be omitted in
a memoir of his life.
From the following letter, it would appear that Davy's alarms, with
respect to his responsibilities, were first awakened by a sight of
the labels, in which his name was introduced.[2]
[2] I am here bound to state, from a careful examination of all
the original documents, that his name was introduced in the very
words which he suggested, and which I have at this moment before
me in his own handwriting:--so differently, however, does the
same sentence strike the eye in print and in manuscript, that an
author frequently does not recognise his own composition.
TO JOHN GEORGE CHILDREN, ESQ.
MY DEAR CHILDREN, Rokeby, July -- 1813.
I am very sorry you did not come to Cobham, as the party was
very pleasant.
Your apparatus was magnificent, worthy an Imperial Institute:
there were some swine however for the pearls; at least, there
was one,--you cannot suppose I mean any other than----.
I have been much disturbed and vexed by enquiries respecting
the price of _my_ gunpowder, which from the labels I find is
supposed to be _sold_ by me. These labels must be altered, so
as to put in a clear point my relations to the manufacture;
and it must be understood by the public that I have given my
gratuitous assistance and advice only.
I have written to Mr. Burton by post, giving two forms. I shall
do you more good if these are adopted than I can now; and I
wish them to be adopted speedily, as it may otherwise get
abroad that I have nothing to do with the powder, and that my
name is used in a manner which does not meet my approbation.
In the labels in the windows, it should not be _under my
directions_, for this implies that I am a superintendent
in the manufactory; but it should be--"RAMHURST GUNPOWDER,
manufactured by Messrs. B. C. and Co. In the composition of
this powder, the proprietors have been assisted by the advice
and assistance of Sir H. Davy."
A fair statement will do the manufacture good. Misapprehension
will do it much harm.
I am now at Rokeby; we shall be in a few days at Braham Castle,
Lord Mackenzie's, near Dingwall, where we shall stay for a
week. After that we shall go to the Marquis of Stafford's,
Dunrobin, near Goldspie.
I am, my dear Children,
Very truly and affectionately yours,
H. DAVY.
TO THE SAME.
MY DEAR CHILDREN, Edinburgh, July 22.
I wrote to you from Rokeby. I expressed my feelings respecting
the gunpowder. I have been in extreme harass and anxiety from
the idea of the use of my name, without the proper explanation,
and I certainly expected that no use would have been made
of it without my sanction. I never saw the label for the
canister till it came to me upon one of them, and I immediately
expressed that I was not satisfied with it.
I told Mr. Burton expressly, that in all cases in which my name
was used it must be in my own way. He is now at the head of
your firm; but it is to _you_, and not to _him_, that I have
given, and shall give my assistance.
Every feeling of friendship and affection prompts my wishes to
be useful to you; I have not the same relations to Mr. Burton.
I am very sorry to give you any trouble on this business, but I
am sure you cannot wish me to remain in a state of anxiety; and
all the friends with whom I have consulted think it absolutely
necessary for my reputation, that, when my name is used, a
clear statement should be given of the true nature of the
connexion.
I think it will be more useful to you, and increase your
influence and power in the partnership, if my assistance is
stated as given to you, and to you only--in this way: "RAMHURST
GUNPOWDER, manufactured by Messrs. Burton, Children, and
Co. after an improved process, founded upon experiments and
investigations made by Sir H. Davy, and communicated by him to
Mr. J. G. Children, under whose immediate superintendence the
gunpowder is made."
I have fully made up my mind on this matter: and if you approve
of the above form, I will state it to be the only one to which
I will consent.
If the gunpowder is called Sir H. Davy's powder, it must be
stated in all cases where my name is used, that it is so called
in honour of my discoveries in chemistry, and because I have
given my gratuitous assistance in making the experiments and
investigations on which the process is founded.
I have resolved to make no profit of any thing connected with
science. I devote my life to the public in future, and I must
have it clearly understood, that I have no views of profit in
any thing I do. I am, my dear Children,
Very affectionately yours,
H. DAVY.
In subsequent letters, which it is not necessary to publish,
Davy dwells upon the necessity of his engagements as a partner
being legally cancelled, as he cannot endure the idea of his
philosophical repose and usefulness being disturbed by the
cares of business, or the trouble of litigation.
It is scarcely necessary to add, that all the parties concerned
in this transaction most readily and cheerfully met Davy's
wishes, all erroneous impressions were effaced, and the affair
was adjusted amicably and satisfactorily; and he prepared
to quit England with a mind relieved from all the fears and
anxieties which had so unfortunately oppressed it.
* * * * *
After the Emperor of the French had sternly refused his
passport to several of the most illustrious noblemen of
England, it was scarcely to be expected that Sir H. Davy would
have been allowed to travel through France, in order to visit
the extinct volcanoes in Auvergne, and afterwards to examine
that which was in a state of activity at Naples.
No sooner, however, had the discovery of the decomposition of
the alkalies and earths, and its probable bearings upon the
philosophy of volcanic action, been represented by the Imperial
Institute to Napoleon, than, with a liberality worthy of the
liberator of Dolomieu, and consistent with his well-known
patronage of science, he immediately and unconditionally
extended the required indulgence.
In consequence of this permission, Sir Humphry and Lady Davy,
the former accompanied by Mr. Faraday as secretary and chemical
assistant, and the latter by her own waiting-maid, quitted
London on the 13th of October 1813, and proceeded to Plymouth;
at which port they immediately embarked in a cartel for Morlaix
in Brittany.
On landing in France, they were instantly arrested by the
local authorities of the town, who very reasonably questioned
the authenticity of their passports, believing it impossible
that a party of English should, under any circumstances, have
obtained permission to travel over the Continent, at a time
when the only English in France were detained as prisoners.
They were accordingly compelled to remain during a period of
six or seven days at the town of Morlaix, until the necessary
instructions could be received from Paris. As soon, however, as
a satisfactory answer was returned, they were set at liberty;
and they reached the French capital on the evening of the 27th
of the same month.
Shortly after his arrival, Davy called upon his old friend and
associate Mr. Underwood, who, although one of the _détenus_,
had during the whole war enjoyed the indulgence of residing in
the capital.
The expected arrival of Davy had been a subject of conversation
with the French _savans_ for more than a month. Amongst those
who were loudest in his praises, was M. Ampère, who had for
several years frequently expressed his opinion that Davy was
the greatest chemist that had ever appeared. Whether this
flattering circumstance had been communicated to the English
philosopher I have no means of ascertaining; but Mr. Underwood
informs me that the very first wish that Davy expressed was
to be introduced to this gentleman, whom he considered as the
only chemist in Paris who had duly appreciated the value of
his discoveries; an opinion which he afterwards took no care
to conceal, and which occasioned amongst the _savans_ much
surprise, and some dissatisfaction. M. Ampère, at the time of
Davy's arrival, was spending the summer at a place a few miles
from Paris, in consequence of which the introduction so much
desired was necessarily delayed.
On the 30th he was conducted by Mr. Underwood to the Louvre.
The English philosopher walked with a rapid step along the
gallery, and, to the great astonishment and mortification of
his friend and _cicerone_, did not direct his attention to a
single painting; the only exclamation of surprise that escaped
him was--"What an extraordinary collection of fine frames!"--On
arriving opposite to Raphael's picture of the Transfiguration,
Mr. Underwood could no longer suppress his surprise, and in a
tone of enthusiasm he directed the attention of the philosopher
to that most sublime production of art, and the chef d'oeuvre
of the collection. Davy's reply was as laconic as it was
chilling--"Indeed, I am glad I have seen it;" and then hurried
forward, as if he were desirous of escaping from any critical
remarks upon its excellencies.
They afterwards descended to view the statues in the lower
apartments: here he displayed the same frigid indifference
towards the higher works of art. A spectator of the scene might
have well imagined that some mighty spell was in operation, by
which the order of nature had been reversed:--while the marble
glowed with more than human passion, the living man was colder
than stone! The apathy, the total want of feeling he betrayed
on having his attention directed to the Apollo Belvidere, the
Laocoon, and the Venus de Medicis, was as inexplicable as it
was provoking; but an exclamation of the most vivid surprise
escaped him at the sight of an Antinous, treated in the
Egyptian style, and sculptured in _Alabaster_.[3]--"Gracious
powers," said he, "what a beautiful stalactite!"
[3] The celebrated Italian antiquary Visconti has so denominated
it.
What a strange--what a discordant anomaly in the construction of
the human mind do these anecdotes unfold! We have here presented
to us a philosopher, who, with the glowing fancy of a poet, is
insensible to the divine beauties of the sister arts! Let the
metaphysician, if he can, unravel the mystery,--the biographer has
only to observe that the Muses could never have danced in chorus at
his birth.
On the following morning, Mr. Underwood accompanied him to the
Jardin des Plantes, and presented him to the venerable Vauquelin,
who was the first scientific man he had seen in Paris. On their
return they inspected the colossal Elephant which was intended
to form a part of the fountain then erecting on the site of the
Bastile. Davy appeared to be more delighted with this stupendous
work than with any object he saw in Paris: to its architect, M.
Alavair, he formed an immediate attachment. It has been observed
that, during his residence in this city, his likes and dislikes to
particular persons were violent, and that they were, apparently,
not directed by any principle, but were the effect of sudden
impulse.
In the course of removing the foundations, and in digging the
canal, the subterranean dungeons of the Bastile were discovered;
they were eight in number, and were called _Les Oubliettes_. As
they were under the level of the ditch of the fortress, any attempt
to escape from them by piercing the wall, must have inevitably
drowned the unhappy prisoner together with all those who inhabited
the contiguous cells; one of which was discovered with the entrance
walled up. Upon demolishing this wall there appeared the skeleton
of the last wretched person who had been thus entombed. In all
these discoveries Davy took the warmest interest.
Upon the construction of the Elephant, he wrote a letter to M.
Alavair, to which I am desirous of directing the attention of my
scientific readers. It derives its peculiar interest from the
opinion which he at that period entertained upon the subject of the
excitement of Voltaic action by the contact of different metals.
TO M. ANTOINE ALAVAIR.
SIR, November 1813.
It will give me much pleasure if I can repay your civility to
me by offering any hints that may be useful in the execution of
the magnificent work constructing under your directions.
Ten parts of copper to one of tin is an excellent composition
for a work upon a great scale, nor do I believe any proportions
can be better.
There is no fear of any decay in the armatures, if they can be
preserved from the contact of moisture; but if exposed to air
and moisture, the presence of the bronze will materially assist
their decay. Wherever the iron is exposed to air, it should, if
possible, be covered with a thin layer of bronze. When the iron
touches the foundation of _lead_, it should in like manner be
covered either by lead or bronze. A contact between metals has
no effect of corrosion, unless a Voltaic circle is formed with
moisture, and then the most oxidable metal corrodes; and iron
corrodes rapidly both with lead and bronze.
The cement which will probably be found the most durable will
be lime, fine sand, and scoria of iron. The materials should be
very fine and intimately mixed. The ancients always made their
cements for great works some months before they were used. I
have the honour to be, Sir, with much consideration,
Your obedient humble servant,
H. DAVY.
Davy took up his abode at the Hotel des Princes, Rue Richelieu;
whither the principal _savans_ of Paris hastened to pay their
respects; which they did with an alacrity and cheerfulness equalled
only by the courtesy of manner with which they expressed their
congratulations.
On the 2nd of November, Davy attended the First Class of the
Institute, and was placed on the right hand of the President, who
on taking the chair announced to the meeting that it was honoured
by the presence of "Le Chevalier Davy."
While Davy was at the meeting of the Institute, a curious adventure
occurred to Lady Davy, the relation of which, by showing the state
of surveillance in which the citizens of Paris were held at that
period, will enable us to appreciate the extent of the obligation
conferred upon Sir Humphry by the Emperor.
Her Ladyship, attended by her maid, had walked into the
Thuilleries' Garden. She wore a very small hat, of a simple
cockle-shell form, such as was fashionable at that time in
London; while the Parisian ladies wore bonnets of most voluminous
dimensions. It happened to be a saint's day, on which, the shops
being closed, the citizens repaired in crowds to the garden. On
seeing the diminutive bonnet of Lady Davy, the Parisians felt
little less surprise than did the inhabitants of Brobdignag
on beholding the hat of Gulliver; and a crowd of persons soon
assembled around the unknown exotic; in consequence of which, one
of the inspectors of the garden immediately presented himself, and
informed her Ladyship that no cause of '_rassemblement_' could be
suffered, and therefore requested her to retire. Some officers of
the Imperial Guard, to whom she appealed, replied, that, however
much they might regret the circumstance, they were unable to afford
her any redress, as the order was peremptory. She then requested
that they would conduct her to her carriage; an officer immediately
offered his arm, but the crowd had by this time so greatly
increased, that it became necessary to send for a corporal's guard;
and the party quitted the garden, surrounded by fixed bayonets.
November 3rd, Humboldt and Gay-Lussac paid their first visit of
compliment to Davy.
5th.--M. Ampère, who came to Paris expressly for the occasion,
was introduced to Davy by Mr. Underwood, and the two philosophers
appeared equally delighted with each other. Some years afterwards,
however, this feeling of friendly regard, on the part of Davy, was
turned into one of bitter aversion, in consequence, as it has been
supposed, of certain perfidious insinuations, by which some of the
_savans_, instigated by feelings of jealousy, had contrived to
prejudice his mind; and which even led him to exert all his efforts
to oppose the election of Ampère as a foreign member of the Royal
Society.
After Ampère's visit, Mr. Underwood accompanied Sir H. and his
lady to the Imperial Library in the Rue Richelieu, and afterwards
to the Cathedral of Notre Dame, where they inspected the crown
and imperial regalia. The splendour of the coronation mantle
of Napoleon may be imagined, when it is stated that its weight
exceeded eighty pounds, and that it was lined with the skins of six
thousand ermines.
6th.--They visited the Museum of French Monuments, in the Rue
des Petits Augustines, which contained the tombs and sculptured
ornaments preserved from the churches that were demolished during
the Revolution. This interesting collection, shortly after the
restoration of the Bourbons, was dispersed. It is a singular fact,
that Davy expressed more admiration at this inferior exhibition
of art, than he did at that of the Greek and Roman statues in
the Museum of the Louvre. Whether his taste had been vitiated by
the inspection of less perfect models in his earlier days, is a
question which I shall leave more competent judges to decide.
10th.--They dined with Count Rumford at Auteuil, who showed his
laboratory to Davy: this was exactly eight months before the poor
brokenhearted Count sank into the grave, the victim of domestic
torment, and of the persecutions of the French _savans_, instigated
by his wife, the widow of the celebrated Lavoisier.
13th.--The anniversary dinner of the Philomatic Society took place
on this day, at a restaurateur's in the Rue St. Honoré; M. Dumeril
in the chair. Although it was very unusual to invite any stranger
upon this occasion, Sir H. Davy and his English friend were
requested to favour the company by their presence. Thirty-three
members were in attendance, amongst whom were Ampère, Brogniart,
Cuvier, Chevreuil, Dulong, Gay-Lussac, Humboldt, Thénard, &c.
At this dinner various complimentary toasts were proposed: and
first, the Royal Society of London, for which Davy having returned
thanks, gave the Imperial Institute. The Linnæan Society of London,
and the Royal Society of Berlin, were given in succession. But
the circumstance which evinced the greatest feeling and delicacy
towards their English guest, was the company's declining to drink
the health of the Emperor. It placed their personal safety even in
some jeopardy; and not a little apprehension was afterwards felt
as to how far Napoleon might resent such a mark of disrespect, for
seven-eighths of the members present were placemen.
November 17th.--Mr. Underwood states that on this day he met
Humboldt at dinner at Davy's hotel; and he adds--"I do not know
whether you are aware that Sir Humphry had a superstitious dislike
at seeing a knife and fork placed crosswise on a plate at dinner,
or upon any other occasion; but I can assure you that such was the
fact; and when it occurred in the company of his intimate friends,
he always requested that they might be displaced; whenever this
could not be done, he was evidently very uncomfortable."[4]
[4] I repeat this as I received it: from my own personal
knowledge I can neither confirm nor refute it; although I
am inclined to believe that Davy was tinged with a degree
of superstitious feeling, or a certain undefined species
of credulity, which shelters itself under the acknowledged
inadequacy of human reason to connect causes with effects.
At about this period, but I am unable to ascertain the particular
day, the junior Chemists, with Thénard as their leader, gave Davy
a sumptuous dinner at one of the most celebrated restaurateurs in
Paris. The following persons formed a committee for that purpose:
Gay-Lussac, Thénard, Dulong, Chevreul, Laugier, Robiquet, and
Clement. As it was by the chemists only that this dinner was given,
neither Arago nor Ampère was included; but Berthollet, Chaptal, and
Vauquelin were invited.
On the morning of the 23rd of November,[5] M. Ampère called upon
Davy, and placed in his hands a small portion of a substance which
he had received from M. Clement; and, although it had been in the
possession of the French chemists for more than twelve months, so
entirely ignorant were they of its true nature and composition,
that it was constantly spoken of amongst themselves as X, the
_unknown_ body.
[5] The date of this event is important; and Mr. Faraday, in
referring to his Journal, finds it to be correctly stated.
How far the suggestions of Davy led to the discovery of the
chemical nature of this interesting substance, which has been
since distinguished by the name of _Iodine_, is a question which
has given rise to much discussion on the Continent. It has been
moreover questioned, how far the love of science, and the fervour
of emulation, can justify the interference which Davy is said to
have displayed upon the occasion. He is accused of having unfairly
taken the subject out of the hands of those who were engaged in its
investigation, and to have anticipated their results.
As his biographer, I feel that it is not only due to the character
of Davy, but essential to the history of Science, that these
questions should be impartially examined; and I have spared no
pains in collecting facts for their elucidation. Mr. Underwood, who
was in the constant habit of associating with the parties concerned
in the enquiry, has furnished me with some important particulars,
and his testimony is fortified by published documents.
The substance under dispute was accidentally discovered by M.
Courtois, a manufacturer of saltpetre at Paris, but kept secret by
him for several years; at length, however, he communicated it to
M. Clement, who made several experiments on it, but without any
favourable result. On the 23rd of August 1813, Clement exhibited
to Mr. Underwood the beautiful experiment of raising it into a
violet-coloured vapour, and that gentleman assures me that this was
the only peculiar property which had at that time been recognised
as distinguishing it. A few days previous to this event, M. Ampère
had received a specimen of the substance, which he had carefully
folded up in paper, and deposited in his pocket, but on arriving
at home, and opening the packet, he was surprised to find that his
treasure had vanished. Clement, however, furnished him with another
supply, and it was this parcel that Ampère transferred into the
hands of Davy; and "for which," says Mr. Underwood, "he told me a
few days ago, that Thénard and Gay-Lussac were extremely angry with
him."
The first opinion which the French chemists entertained respecting
the nature of Iodine, was that it was either a compound of muriatic
acid, or of chlorine, since it formed with silver what appeared
to be a muriate, or a chloride of that metal; but Davy at once
observed that the substance so produced blackened too quickly in
the sun to justify that opinion. He, however, determined to submit
it to a more rigorous examination; and during the latter part of
November he worked upon it at his hotel with his own apparatus,
and on the 3rd of December in the laboratory of M. Chevreul, at
the Jardin des Plantes, with whom, it may be stated in passing,
he perhaps formed a stricter intimacy than with any other chemist
during his sojourn in Paris. Chevreul, however, be it known, was a
brother of the angle; and I understand that he still preserves, as
sacred trophies, some artificial flies with which Davy had supplied
him.
Having pointed out the channel through which Iodine first fell into
the hands of Davy, let us pursue its history. The first public
notice of its existence was read by Clement at the Institute, on
the 29th of November 1813. At the meeting of the 6th of December,
Gay-Lussac, who had only received some 'X' a few days previous to
this date, presented a short note, in which he gave the name of
_Iode_ to the body, and threw out a hint as to its great analogy to
chlorine, while he stated that two hypotheses might be formed as
to its nature, that it might be considered as a simple substance,
or as a compound of oxygen. On the 13th of the same month, a
letter addressed to M. le Chevalier Cuvier, and dated December
11th, was read from Davy to the Institute, in which he offered
a general view of its chemical nature and relations;[6] and on
the 20th of January 1814, he communicated to the Royal Society
of London, a long and elaborate paper, dated Paris, December 10,
1813, and entitled, "Some Experiments and Observations on a new
Substance, which becomes a violet-coloured gas by Heat." In this
paper, while the author assigned to Gay-Lussac all the credit to
which his communication of the 6th of December may be supposed to
entitle him, he evidently felt that some explanation was due to the
chemical world for his having pursued the enquiry. "M. Gay-Lussac,"
he observes, "is still engaged in experiments on this subject,
and from his activity and great sagacity, a complete chemical
history of it may be anticipated. But as the mode of procuring the
substance is now known to the chemical world in general, and as
the combinations and agencies of it offer an extensive field for
enquiry, and will probably occupy the attention of many persons;
and as the investigation of it is not pursued by the discoverer
himself, nor particularly by the gentlemen to whom it was first
communicated, I shall not hesitate to lay before the Royal Society
an account of the investigations I have made upon it; and I do
this with the less scruple, as my particular manner of viewing
the phenomena has led me to some new results, which probably will
not be considered by the Society as without interest in their
relation to the general theory of chemistry, and in their possible
application to some of the useful arts."
[6] See _Annales de Chimie_, tome 88, p. 322. It appears from Mr.
Faraday's Journal, that he worked upon Iodine with a borrowed
Voltaic pile, at his hotel, on the morning of the 11th; and the
results of his experiments are described at the conclusion of the
above letter.
It was not until August 1814, that Gay-Lussac read his paper on
the subject, which was subsequently published in the _Annales de
Chimie_.
After the above short, but I trust honest statement, can any
reasonable doubt exist, that, if Davy had not visited Paris, Iodine
would have remained at the end of the year 1814, as it had been for
two preceding years--the unknown X?
In a communication published in the first volume of the Royal
Institution Journal, Davy offers the following observations upon
this subject: "With regard to Iodine, the first I had of it was
from M. Ampère, who, before I had seen the substance, supposed that
it might contain a new supporter of combustion.
"Who had most share in developing the chemical history of that
body, must be determined by a review of the papers that have been
published upon it, and by an examination of their respective
dates. When M. Clement showed Iodine to me, he believed that the
hydriodic acid was muriatic acid; and M. Gay-Lussac, after his
early experiments, made originally with M. Clement, formed the
same opinion, and _maintained_ it, when I _first_ stated to him my
belief that it was a new and peculiar acid, and that Iodine was a
substance analogous in its chemical relations to Chlorine."
I was very desirous of ascertaining the feeling which at present
prevails amongst the French chemists upon this subject; and I
therefore requested Mr. Underwood to make such enquiries as might
elicit the required information. In a letter from that gentleman,
dated "Paris, August 22, 1830," he says, "Though Thénard and
Gay-Lussac retain great bitterness of feeling towards Davy, on
account of the affair of Iodine, Chevreul and Ampère are still, as
they ever were, of opinion, that such a feeling has its origin in
a misconception; that what Davy did, was from the honest desire of
promoting science, and not from any wish to detract from the merit
of the French chemists."
During his visit to Paris, Davy was not introduced to the Emperor.
Lady Davy observed to me, that, although Sir Humphry felt justly
grateful for the indulgence granted to him as a Philosopher, he
never, for a moment, forgot the duty he owed his country as a
Patriot; and that he objected to attend the levee of her bitterest
enemy. On the other hand, it is said that Napoleon never expressed
any wish to receive the English chemist; and those who seek in the
depths for that which floats upon the surface, have racked their
imaginations in order to discover the source of this mysterious
indifference; but I apprehend that we have only to revert to the
political state of Europe in the year 1813, and the problem will be
solved.
Amongst the reasons for supposing that the Emperor must have felt
ill disposed towards the English philosopher, the following story
has been told; which, as an anecdote, is sufficiently amusing;
and I can state upon the highest authority, that it is moreover
perfectly true.
It is well known that Bonaparte, during his whole career, was in
the habit of personal intercourse with the _savans_ of Paris, and
that he not unfrequently attended the sittings of the Institute.
Upon being informed of the decomposition of the alkalies, he
asked, with some impetuosity, how it happened that the discovery
had not been made in France?--"We have never constructed a Voltaic
battery of sufficient power," was the answer. "Then," exclaimed
Bonaparte, "let one be instantly formed, without any regard to cost
or labour."
The command of the Emperor was of course obeyed; and, on being
informed that it was in full action, he repaired to the laboratory
to witness its powers; on his alluding to the taste produced by
the contact of two metals, with that rapidity which characterised
all his motions, and before the attendants could interpose any
precaution, he thrust the extreme wires of the battery under
his tongue, and received a shock which nearly deprived him of
sensation. After recovering from its effects, he quitted the
laboratory without making any remark, and was never afterwards
heard to refer to the subject.
It is only an act of justice to state that Davy, during his
residence in the French capital, so far from truckling to French
politics, never lost an opportunity of vindicating with temper
the cause of his own country. At the Théâtre de la Porte Saint
Martin, a melodrame was got up, with the avowed intention of
exposing the English character to the execration of the audience.
Lord Cornwallis was represented as the merciless assassin of the
children of Tippoo Saib. Davy was highly incensed at the injustice
of the representation, and abruptly quitted the theatre in a state
of great indignation.
Whatever objections might have existed in his mind, as to his
attending a levee of the Emperor, they did not operate in
preventing his being presented to the Empress at Malmaison; but he
could not be prevailed upon to appear upon that occasion, in any
other than a morning dress; and it was not until after repeated
entreaty, and the assurance that he would not be admitted into
the _Salle de reception_, that he consented to exchange a pair of
half-boots that laced in front, and came over the lower part of his
pantaloons, for black silk stockings and shoes. His constant answer
to the remonstrances of his friends was, "I shall go in the same
dress to Malmaison as that in which I called upon the Prince Regent
at Carlton House."
The introduction of Sir Humphry and Lady Davy to the Empress
Josephine, took place at Malmaison on the 30th of November. The
only English present were, the Earl of Beverley, a _détenue_;
General Sir Edward Paget, a prisoner of war, taken in Spain,
and Mr. Underwood; and it was the first levee at which any of
our countrymen had been introduced, with the exception of Mr.
Underwood, who had been frequently in the habit of paying his court
to the Empress, and to whom, indeed, he was indebted for those
indulgences which have been already mentioned.
The persons present having arranged themselves in a semicircle, the
Empress entered the _Salle de reception_, and in her usual gracious
manner addressed each individual. After this court ceremony, her
Majesty retired, having previously signified to a select few, her
desire that they should follow her into the private apartment.
In the Boudoir, the conversation became general, and turned upon
certain works of art; and upon Lady Davy expressing, in very florid
terms, her admiration of some beautifully embellished cups of
Porcelain, which were stationed on the mantelpiece, her Majesty,
with that good-nature which ever distinguished her, immediately
presented her with a specimen.
The Empress then proposed that Lady Davy should on this occasion
visit her conservatories, upon which it is well known she had
lavished large sums, and was ambitious to be thought to possess
all that was rare and curious. Lady Davy having expressed some
apprehensions as to the coldness of the day, and appearing to
be but thinly clad, one of the Dames du Palais was commanded
to provide cloaks; and in a short time, Mr. Underwood says, a
_mountain_ of the most costly and magnificent furs, that probably
ever appeared even in a Regal Palace, were displayed before her;
the splendid trophies, we may conclude, of the Royal conciliation
at Tilsit.
It was on the 13th of December 1813, that Davy was elected a
corresponding member of the First Class of the Imperial Institute;
there were forty-eight members present, and he had forty-seven
votes: Guyton de Morveau being the only person who opposed his
election.
Nothing ever exceeded the liberality and unaffected kindness and
attention with which the _savans_ of France had received and
caressed the English philosopher. Their conduct was the triumph
of Science over national animosity,--a homage to genius, alike
honourable to those who bestowed, and to him who received it;
and it would be an act of ingratitude, a violation of historical
justice, on the part of the English biographer, did he omit to
express the pride and admiration with which every philosopher in
his country continues to regard it. It would have been fortunate
for the cause of Science, and fortunate for the historian, could he
have terminated the subject with these remarks; but the biographer
has an act of justice to perform, which he must not suffer his
friendship to evade, nor his partialities to compromise.[7]
[7] In offering these observations, the reader may readily
suppose it has not been without much pain that I have made this
sacrifice of personal feeling to principle. I am, however, bound
to observe, that Sir Humphry's sentiments towards France for the
liberal indulgence granted to him were both grateful and kindly;
and so strongly does Lady Davy participate in that feeling, that
I perhaps owe it to her to state that neither her Ladyship's
journals or information have been used upon this occasion.
It would be an act of literary dishonesty to assert that Sir H.
Davy returned the kindness of the _savans_ of France, in a manner
which the friends of Science could have expected and desired. There
was a flippancy in his manner, a superciliousness and hauteur in
his deportment, which surprised as much as they offended. Whatever
opinions he might have formed as to the talents of the leading
chemists, it was weakness to betray, and arrogance to avow them.
He had, by a single blow, fatally mutilated the system which was
the pride and glory of their nation: it was ungenerous to remind
them of his triumph. It required but little tact to have reconciled
the French philosophers to the revolution he had effected; but,
unfortunately, that cannot be said of Davy, which was so wittily
observed of Voltaire,--that if he trod upon the toes of their
prejudices, he touched his hat at the same time: even the affair
of Iodine, had it been skilfully managed, would never have left an
angry feeling. It was not his success, but the manner in which he
spoke of it, that rendered it so offensive. He should have acted
according to the judicious advice given to a member of the clerical
profession, upon his consulting a friend as to the propriety of
continuing his field-sports, should he become a dignitary of the
Church--"You may hunt, but you must not holla."
It may be supposed that the unguarded conduct of Davy reached the
ear of the Emperor; for in a conversation with one of the leading
members of the Institute, Napoleon took occasion to observe, that
he understood the young English chemist held them all in low
estimation.
Having thus candidly avowed the errors of Davy, I may be justified
in claiming from the reader his confidence in the sincerity with
which I shall attempt to palliate them. From my personal knowledge
of his character, I am inclined to refer much of that unfortunate
manner, which has been considered as the expression of a haughty
consciousness of superiority, to the desire of concealing a
_mauvaise honte_ and _gaucherie_--an ungraceful timidity, which
he could never conquer. The bashful man, if he possess strong
passions, will frequently force himself into a state of effrontery,
by a violence of effort which passes amongst ordinary observers
for the sallies of pride, or the ebullitions of temper; whereas
if, on the contrary, his temperament be cold and passionless, he
will exhibit traits of the most painful reserve. This proposition
cannot, perhaps, be more forcibly illustrated than by a comparison
of the manners of Davy and Cavendish, whose temperaments were
certainly as much opposed to each other as fire is to ice: the
latter, however, was shy and bashful, to a degree bordering upon
disease; and nothing so much distressed him as an introduction to
strangers, or as his being pointed out as a person distinguished
in science. On one of the Sunday evening _soirées_ of Sir Joseph
Banks, he happened to be conversing with his friend Mr. Hatchett,
when Dr. Ingenhouz, who was rather remarkable for pomposity of
manner, approached him with an Austrian gentleman in his hand, and
introduced him formally to Mr. Cavendish. He recounted the titles
and qualifications of his foreign friend at great length, and
concluded by saying, that he had been particularly anxious to be
introduced to a philosopher so universally celebrated throughout
Europe as Mr. Cavendish. As soon as Dr. Ingenhouz had finished, the
Austrian gentleman began; he assured Mr. Cavendish that one of his
principal inducements in coming to London, was to see and converse
with one whom he considered the most distinguished chemist of the
age. To all these high-flown addresses, Mr. Cavendish answered not
a single word, but stood with his eyes cast down upon the floor,
in a state of the most painful confusion. At length, espying an
opening in the crowd, he darted through it with all the speed he
could command, and never stopped until he reached his carriage,
which immediately drove him home.
From the same cause, probably, arose Davy's inattention and
carelessness in those little observances of etiquette, which many
may treat as empty and unmeaning ceremonials, but which the members
of a polished community regard as the delicate expressions of
feeling, and the language of sentiment.
It is said, that on conversing in the chamber of the Institute, he
received one of its most distinguished and venerable members, who
approached him with the air of salutation, without rising from his
seat; a circumstance perhaps in itself of very trifling importance,
but it was considered as a mark of disrespect, which is not readily
forgiven, when a spirit of rivalry may be supposed to sharpen the
affront. It will be remembered that Cæsar might date his loss of
popularity to the fact of his having received the Senate while
sitting in the porch of the temple of Venus, and that it formed
one of the chief pretences of those who organised the conspiracy
against his person.
There were, besides, other sources of unpopularity, which we are
bound in fairness and candour to impute to the excellencies,
rather than to the defects, of his character. If we believe with
Johnson, that men have sometimes gained reputation from their
foibles, we may certainly admit the converse of the proposition,
that they have occasionally lost it from their virtues. Davy, as
we have seen, possessed from his earliest years a frankness of
disposition which endeared him to all his friends, but in after
life it unquestionably exposed him to various annoyances, which
by a little reserve he would have certainly escaped. It is quite
surprising how much a little mystery, judiciously managed, will
achieve. Seven veils converted the fragment of a tile, ploughed
up in the neighbourhood of Florence, into an object of awful
devotion.[8]
[8] Gray's Letters.
Although it must be admitted that our philosopher lost some
popularity during his visit to the French metropolis, the _savans_
did not the less respect his talents, or admire his discoveries.
They appear to have been impressed with the same sentiment as that
which animated Voltaire, when he asked whether the discovery of
Racine's weakness made the part of Phædra less admirable.
M. Dumas, who is certainly by no means distinguished for the
readiness with which he is disposed to pay homage to British
talent, has declared that Davy was the greatest chemical genius
that ever appeared.
In fact, the more the researches of this great experimentalist are
studied, the more they must be admired: every attempt to depreciate
their intrinsic importance will only serve to display their exalted
merits; every attempt to falsify their results will only tend to
demonstrate their accuracy. It is by an elaborate examination
only, that the full evidence of their truth can be displayed;
there are points which the keen eye of genius will discern, that
are invisible to a grosser sense: the coldness of criticism then
will only make them glow the brighter; like his own potassium, the
contact even of ice, so far from extinguishing, will light them up
in splendour.
Sir Humphry left Paris on the morning of the 29th of December, and
proceeded by the way of Lyons to Montpellier, where he remained
for a month, and became acquainted with M. BERARD, who afterwards
filled the chemical chair in that university, and in whose
laboratory he worked upon the subject of Iodine, and examined many
of the marine productions of the Mediterranean, with the view of
determining whether they contained that body. M. Berard directed
a considerable quantity of the species of _Ulva_, which abounds
on the coast of Languedoc, to be burnt for him; and although the
ashes consisted for the most part of common salt, he obtained
traces of Iodine in the lixivium. From the general results of
his experiments, however, he concludes, that the ashes of the
_fuci_ and _ulvæ_ of the Mediterranean afford it in much smaller
quantities than the sea-weed, from which soda is procured; and it
was only in a very few instances that he could derive any evidence
of its existence. In the ashes of the corallines and sponges, he
could not obtain the slightest indication of its presence. During
this period he also extended his enquiries respecting the chemical
agencies of Iodine, and the properties of several of its compounds,
especially of those in which he believed it to exist in triple
combination with alkalies and oxygen, and for which he proposed the
name of _Oxy-iodes_.[9]
[9] These are the _Iodates_ of the present day; but Davy, it
would seem, resisted the conviction of Iodic acid being an
_oxy-acid_, upon the same grounds that he opposed the views of M.
Gay-Lussac with regard to the nature of Chloric acid.
While at Montpellier, Davy witnessed the procession of the Pope
on his return to Rome. His Holiness appeared in a state of great
humiliation, and, on being supplicated by a poor woman to cure her
child, he replied, that she must propitiate Heaven by her prayers,
for that he was himself a mere mortal, without power to heal or to
save.
He quitted Montpellier on the 7th of February, and, accompanied
by M. Berard, visited the fountain of Vaucluse; he afterwards
continued his route to Nice, crossed the Col de Tende, to Turin,
and arrived at Genoa on the 25th of February; from which place the
following letter is dated.
TO MR. UNDERWOOD.
MY DEAR UNDERWOOD, Genoa, March 4.
I have not received the letter you announced to me in the
street, concerning Ampère's note, nor any others since I left
Paris. The note came to me through the Prefect of Nice, with an
indorsement by M. Degerand.
I crossed the Alps by the Col de Tende, stayed at Turin three
days, and came here through snow and ice, over the Bochetta,
where I have been waiting for a fair wind for Tuscany. We have
had no impediments except from the snow and the east winds.
If you can hear any thing of the destination of the letters
I have twice missed, I shall thank you to let me know by
addressing me at Rome at the _Posta_. I shall be most happy
to hear some news of you here, and shall always feel a lively
interest in your plans, and in your welfare.
I have been making some experiments here on the Torpedo, but
without any decisive results; the coldness of the weather
renders the powers of the animal feeble; I hope, however, to
resume them at Naples.
Tell M. Ampère, I hope he will not give up the subject of the
laws of the combination of gaseous bodies, which is so worthy
of being illustrated by his talents, and which offers such
ample scope for his mathematical powers, united as they are
with chemical knowledge:--tell him also that I hope he will
sometimes write to me, and that I shall always remember with
pleasure the hours I have passed in his society.
Pray tell me that you are well; and remember me to all that are
interested in me. My wife desires her kind remembrances. I am,
my dear Underwood,
Your very sincere friend,
H. DAVY.
Besides researches on the Torpedo, Davy made farther experiments on
the ashes of Sea-weed, which were collected for him by Professor
VIVIANI, of Genoa.
He left Genoa by water on the 13th, and arrived at Florence on the
16th of March. Here he worked in the laboratory of the Academia
del Cimento, on Iodine; but more particularly on the combustion of
the Diamond. The experiments on this latter body were performed by
means of the great lens in the cabinet of Natural History; the same
instrument as that employed in the first trials on the action of
the solar heat on the diamond, instituted by Cosmo III. Grand Duke
of Tuscany: upon this occasion, he was assisted by COUNT BARDI,
the Director, and SIGNIOR GAZZARI, the Professor of Chemistry at
the Florentine Museum.
I have been informed that the hasty, and apparently careless manner
in which he conducted his experiments, and which has been already
noticed[10] as being characteristic of his style of manipulation,
greatly astonished the philosophers of Florence, and even excited
their alarm for the safety of the lens, which on all occasions had
been used by them with such fastidious caution and delicacy.
[10] Vol. i. p. 144.
In the very first trials on the combustion of the diamond, he
ascertained a very curious circumstance that had not been before
noticed; namely, that the diamond, when strongly ignited by the
lens in a thin capsule of platinum, perforated with many orifices,
so as to admit a free circulation of air, will continue to burn
in oxygen gas after being withdrawn from the focus. The knowledge
of this circumstance enabled him to adopt a very simple apparatus
and mode of operation in his researches, and to complete in a few
minutes experiments which had been supposed to require the presence
of a bright sunshine for many hours.
The new facts obtained by the experiments on Iodine, which he had
commenced at Montpellier and carried on at Florence, he embodied
in a memoir, which was read before the Royal Society on the
16th of June 1814. It treated more particularly of the triple
compounds containing iodine and oxygen,--of the hydrionic acid,
and of the compounds procured by means of it,--of the combinations
of iodine and chlorine,--of the action of some compound gases
on iodine,[11]--and, lastly, of the mode of detecting iodine in
combinations. "If iodine," he says, "exists in sea water, which
there is every reason to believe must be the case, though in
extremely minute quantities, it is probably in triple union with
oxygen and sodium, and in this case it must separate with the first
crystals of common salt."
[11] The compounds which he supposed to be thus produced are of
a very questionable nature; with respect to that formed with the
Olefiant gas, he was evidently in error.
He quitted Florence on the 3rd, and having visited Sienna,
entered Rome on the 6th of April. The Continent having now become
accessible, he met with many of his English friends: but neither
the extended society by which he was surrounded, nor the classical
attractions of the city of the Cæsars, allured him from the
pursuits of Science. We find that, shortly after his arrival,
he renewed his researches on the combustion of different kinds
of charcoal, in the laboratory of the Academia del Lyncei, in
which he was assisted by SIG. MORRICHINI and BARLOCCI, Professors
of the College Sapienza at Rome. Having arranged the results
of this investigation, together with those relating to the
combustion of the diamond, which he had previously obtained at
Florence, he transmitted a paper to the Royal Society, entitled
"Some Experiments on the Combustion of the Diamond, and other
carbonaceous substances;" which was read on the 23rd of June, and
published in the Second Part of the Philosophical Transactions for
the year 1814.
No sooner had it been established by various accurate experiments,
that the diamond and common charcoal consumed nearly the same
quantity of oxygen in combustion, and produced a gas having the
same obvious qualities, than various conjectures were formed to
explain the remarkable differences in the sensible qualities of
these bodies, by supposing some minute difference in their chemical
composition. MM. Biot and Arrago, from the high refractive power
of the diamond, suspected that it might contain hydrogen. Guyton
Morveau inferred from his experiments that it was pure carbon, and
that charcoal was an oxide of carbon; whereas Davy was inclined
to believe, from the circumstance of the non-conducting power of
the diamond, as well as from the action of potassium upon it, that
a minute portion of oxygen might enter its composition, although
such a supposition would be at variance with the doctrine of
definite proportions; but more lately, in his account of some new
experiments on the fluoric compounds, he hazarded the idea that
it might be the carbonaceous principle combined with some new and
subtile element, belonging to the same class as oxygen, chlorine,
and fluorine, which has hitherto escaped detection, but which may
be expelled, or newly combined, during its combustion in oxygen.
"That some chemical difference," says Davy, "must exist between
the hardest and most beautiful of the gems and charcoal, between
a nonconductor and a conductor of electricity, it is scarcely
possible, notwithstanding the elaborate experiments that have
been made on the subject, to doubt: and it seems reasonable to
expect, that a very refined or perfect chemistry will confirm the
analogies of Nature, and show that bodies cannot be exactly the
same in composition or chemical nature, and yet totally different
in all their physical properties."
With these impressions, we may readily imagine the ardour with
which he availed himself of the use of the great lens at Florence.
He had in various ways frequently attempted to fuse charcoal,[12]
but without success. In a letter addressed to Mr. Children is the
following passage: "The great result to be hoped for is the fusion
of carbon; and then you may use diamond in the manufacture of
gunpowder."
[12] The supposed fusion of charcoal by Professor Silliman, by
means of Dr. Hare's galvanic deflagrator, was a fallacy arising
from the earthy impurities of the substance. See _American
Journal of Science_, vol. v. p. 108, and 361.
He tells us that he had long felt a desire to make some new
experiments on the combustion of the diamond and other carbonaceous
substances; and that this desire was increased by the new fact
ascertained with respect to iodine, which by uniting to hydrogen,
affords an acid so analogous to muriatic acid, that it was for
some time confounded with that body. His object in these new
experiments, was to examine minutely whether any peculiar matter
was separated from the diamond during its combustion, and to
determine whether the gas, formed in this process, was precisely
the same in its minute chemical nature, as that formed in the
combustion of common charcoal. By his experiments at Florence, he
satisfactorily accomplished his wishes, and established beyond a
question the important fact, that "the diamond affords no other
substance by its combustion than pure carbonic acid gas; and that
the process is merely a solution of diamond in oxygen, without any
change in the volume of the gas."
As one of the principal objects in these researches was to
ascertain whether water was formed during the combustion of the
diamond, with a view to decide the question of the presence of
hydrogen, every possible source of fallacy was excluded. In one
experiment there was an evident deposition of moisture, but it was
immediately discovered to have been owing to the production of
vapour from a cork connected with a part of the apparatus, during
the combustion.
In the progress of this research, he ascertained a fact, the
knowledge of which must not only be considered as important to the
present enquiry, but as highly valuable in excluding error from our
reasonings upon the delicate results of analysis[13]--I allude to
the extremely minute quantity of water which becomes perceptible
by deposition on a polished glass surface. He introduced a piece
of paper weighing a grain into a tube of about the capacity of
four cubical inches, the exterior of which was gently heated by a
candle; immediately a slight but perceptible dew appeared in the
interior of the upper part of the tube; the paper taken out and
directly weighed in a balance, sensible to 1-100th of a grain, had
not suffered any appreciable diminution. If, then, on burning 1·84
grains of diamond in oxygen gas, not even a barely perceptible
dew was produced, we may consider it as fully proved that this
gem cannot contain hydrogen in its composition: but to render the
demonstration, if possible, still more complete, he kept a small
diamond, weighing ·45 of a grain, in a state of intense ignition
by the great lens of the Florentine Museum, for more than half an
hour, in chlorine; but the gas suffered no change, and the diamond
underwent no alteration either in weight or appearance: now had
the smallest portion of hydrogen been developed, white fumes of
muriatic acid would have been visible, and a certain condensation
of the gas must have taken place.
[13] It has a more especial bearing upon that experimental
research by which the nature of chlorine was established, as
described at page 337, vol. i. to which I beg to refer the
chemical reader.
The general tenor of his results was equally opposed to the idea of
the diamond containing oxygen; for, in such a case, the quantity of
carbonic acid generated by the combustion, would, on comparison,
have indicated that fact. By combining the carbonic acid with lime,
and then recovering the gas from the precipitate by muriatic acid,
he found its proportion to be exactly that which was furnished by
an equal weight of Carrara marble similarly treated.
The enquiry next proceeds to the examination of other forms of
carbonaceous matter, such as plumbago, charcoal formed by the
action of sulphuric acid on oil of turpentine, and that produced
during the formation of sulphuric ether; and lastly, the common
charcoal of oak.
In all these bodies, he detected the presence of hydrogen, both by
the water generated during their combustion, and by the production
of muriatic acid, when ignited in chlorine. The chemical
difference then between the diamond and the purest charcoal, would
appear to consist in the latter containing hydrogen; but Davy very
justly asks whether a quantity of an element, less in some cases
than 1-5000th part of the weight of the substance, can occasion
so great a difference in physical and chemical characters? "It
is certainly possible," says he, "yet it is contrary to analogy,
and I am more inclined to adopt the opinion of Mr. Tennant,
that the difference depends upon crystallization." In support
of such an opinion, he farther adduces the fact, that charcoal
after being intensely ignited in chlorine, is not altered in its
conducting power or colour: in which case the carbon is freed from
the hydrogen, and yet undergoes no alteration in its physical
properties.
One distinction supposed to exist between the diamond and common
carbonaceous substance, the researches of Davy have certainly
removed, viz. its relative inflammability; for he has shown that
the former will burn in oxygen with as much facility as plumbago.
The experiments, then, which Davy conducted at Florence and Rome,
have removed several important errors with regard to the nature
of carbonaceous substances; and though they may not encourage the
labours of those speculative chemists who still hope to illustrate
the old proverb,[14] by manufacturing diamonds out of charcoal,
they certainty show that they are less chimerical than those of the
wild visionaries who sought to convert the baser metals into gold.
[14] "Carbonem pro Thesauro."
While at Rome, Davy was engaged for several successive days in
the house of Morrichini, for the purpose of repeating with that
philosopher his curious experiments on _magnetisation_. Mr. Faraday
was charged with the performance of the experiments, but never
could obtain any results.
On the 8th of May he entered Naples, and remained there for three
weeks, during which period he visited Mount Vesuvius, and the
volcanic country surrounding it. He describes the crater, at this
time, as presenting the appearance of an immense funnel, closed
at the bottom, with many small apertures emitting steam; while on
the side towards Torre del Greco, there was a large aperture from
which flame issued to a height of at least sixty yards, producing a
most violent hissing noise. He was unable to approach sufficiently
near the flame to ascertain the results of the combustion; but
a considerable quantity of steam ascended from it; and he says,
that when the wind blew the vapours upon him, there was a distinct
smell both of sulphurous and muriatic acids, but there was no
indication of carbonaceous matter from the colour of the smoke;
nor was any deposited upon the yellow and white saline matter
which surrounded the crater, and which he found to be principally
sulphate and muriate of soda, and in some specimens there was also
a considerable quantity of muriate of iron. At this period, when
the volcano was comparatively tranquil, he observed the solfaterra
to be in a very active state, throwing up large quantities of
steam, and some sulphuretted hydrogen.
At several subsequent periods he revisited Vesuvius; and I shall
hereafter take occasion to relate all the principal observations he
made, and the conclusions at which he arrived, with respect to this
the most interesting of all the phenomena of mineral nature.
He also took great interest in the excavations at that time going
on at Pompeii, under the direction of Murat, then King of Naples,
who placed at his disposal several specimens of art, which Davy
received with a view to investigate the chemical composition of the
colours used by the Ancients.
On the 25th of May he returned to Rome, and again quitted it on the
2nd of June.
I regret to say that the information I have received, as to the
future continental travels of our philosopher, is extremely meagre,
and will consist of little more than names and dates. Of this,
however, the reader may be assured, that nothing which relates to
his scientific researches has been omitted.
From Rome he proceeded to Terni, and thence to Bologna, where he
remained for three days; then to Mantua, Verona, and Milan. Whether
at this or at some subsequent period he went to Pavia, in order to
pay his homage to the illustrious Volta, I entertain some doubt;
but the time is immaterial to the point of the anecdote I am about
to relate.
Davy had sent a letter to Pavia to announce his intended visit;
and on the appointed day and hour, Volta, in full dress, anxiously
awaited his arrival. On the entrance of the great English
philosopher into the apartment, not only in _déshabille_, but in a
dress of which an English artisan would have been ashamed, Volta
started back in astonishment, and such was the effect of his
surprise, that he was for some time unable to address him.
From Milan, which he left on the 22nd of June, he went to Como,
Domo D'Ossola, and then over the Simplon, to Geneva, where he
arrived on the 25th of that month, and remained until the 18th of
September. During this visit he made various experiments on Iodine,
at the house of De Saussure, which was situated near the edge of
the Lake, and about three miles from Geneva. He also worked at M.
Pictet's house, on the subject of the heat in the solar spectrum.
Here also he met with a number of celebrated persons, whose society
he greatly enjoyed; amongst whom were Madame de Stael, Benjamin
Constant, Necker, and Talma. Lausanne, Vevay, Payerne, Berne,
Zurich, Schaffhausen, and Munich, were successively visited by
him. His route was then continued through Tyrol, Inspruck, Calmar,
Bolsenna, Trent, Bassano, Vicenza, Padua, to Venice; where having
remained two days, he returned to Padua on the 16th of October, and
then proceeded to Ferrara, Bologna, and Pietra-Mala; near which
latter place, in the Apennines, he examined a fire produced by
gaseous matter constantly disengaged from a schist stratum, and
from the results of its combustion, he concluded it to be pure
fire-damp. On again reaching Florence, he found that the Professors
had been dismissed, but he nevertheless resumed his researches,
first at home, and afterwards in the laboratory of the Grand Duke,
where he submitted to analysis some gas which had been collected
by his attendant Mr. Faraday, from a cavity in the earth, about a
mile from Pietra-Mala, then filled with water, and which from the
quantity of gas disengaged is called _Aqua Buja_. It was found to
be pure light carburetted hydrogen, requiring two volumes of oxygen
for its combustion, and producing a volume of carbonic acid gas.
"It is very probable," says he, "that these gases were disengaged
from coal strata beneath the surface, or from bituminous schist
above coal; and at some future period new sources of wealth may be
opened to Tuscany from this invaluable mineral treasure."
On the 29th he left Florence, and passing through Levano, Tortona,
and Terni, arrived again at Rome, on the 2nd of November, where he
remained till the 1st of March 1815.
During this winter he was engaged in an elaborate enquiry into
the composition of ancient colours; and also in experiments upon
certain compounds of iodine and of chlorine. Upon which subjects
he transmitted to the Royal Society three memoirs, viz. one
entitled, "Some Experiments and Observations on the Colours used in
Painting by the Ancients," which was read on the 23rd of February;
a second, "On a solid compound of Iodine and Oxygen," read April
10; and a third, "On the action of Acids on the Salts usually
called Hyper-oxymuriates, and on the Gases produced from them,"
read May 4, 1815; all of which were published in the Philosophical
Transactions for that year.
Although the paintings of the great masters of Greece have been
entirely destroyed, either by accident, by time, or by the
barbarian conquerors at the period of the decline and fall of
the Roman Empire, yet there is sufficient proof that this art
attained a very high degree of excellence amongst a people to whom
genius and taste were a kind of birthright, and who possessed a
perception, which seemed almost instinctive, of the dignified, the
beautiful, and the sublime.
Our philosopher observes, that the subjects of many of those
pictures are described in ancient authors, and that some idea of
the manner and style of the Greek artists may be gained from the
designs on the vases improperly called "Etruscan," which were
executed by artists of Magna Græcia, and many of which are probably
copies from celebrated works: of their execution and colouring,
some faint notion may be gained from the paintings in fresco found
at Rome, Herculaneum, and Pompeii; for, although these paintings
are not properly Grecian, yet at the period when Rome was the
metropolis of the world, the fine arts were cultivated in that city
exclusively by Greek artists, or by artists of the Greek school;
while it is evident, on comparing the descriptions of Vitruvius
and Pliny with those of Theophrastus, that the same materials for
colouring were employed at Rome and at Athens.
With regard to the nature of these pigments, we may obtain some
information from the works of Theophrastus, Dioscorides, Vitruvius,
and Pliny; but until the present memoir by Sir H. Davy, no
experimental attempt had been made to identify them, or to imitate
such of them as are peculiar.
His experiments, he informs us, were made upon colours found in the
Baths of Titus, and the ruins called the Baths of Livia, and in the
remains of other palaces and baths of ancient Rome, and in the
ruins of Pompeii.
By the kindness of his friend Canova, who was charged with the care
of the works connected with ancient art in Rome, he was enabled to
select, with his own hands, specimens of the different pigments
that were found in vases discovered in the excavations made beneath
the ruins of the palace of Titus, and to compare them with the
colours fixed on the walls, or detached in fragments of stucco;
and Signor Nelli, the proprietor of the "Nozze Aldobrandine,"[15]
permitted him to make such experiments upon the colours of that
celebrated picture, as was necessary to determine their nature.
[15] The most celebrated picture of antiquity rescued from the
ruins of Herculaneum. It represents a virgin on her marriage
night, with her female attendants. An engraving of it is to be
seen in Sir William Hamilton's work on Herculaneum.
Without entering into the chemical details of the subject, I shall
offer a general history of the nature of the colours he examined.
Of the red colours, he distinguished four distinct kinds, viz.--one
bright and approaching to orange, which he found to be _Minium_,
or the red oxide of lead; a second, dull red, which he ascertained
to be an iron ochre; a third, a purplish red, which was likewise
an ochre, but of a different tint; and a fourth, a brighter red
than the first, which was _Vermilion_ or _Cinnabar_, a sulphuret
of mercury. On examining the fresco paintings in the Baths of
Titus, he found that all the three first colours had been used, the
ochres particularly, in the shades of the figures, and the minium
in the ornaments on the borders. The fourth red had been employed
in various apartments, and formed the basis of the colouring of
the niche, and of other parts of the chamber in which the Laocoon
is said to have been found in the time of Raphael; a circumstance
which Davy considers as being favourable to the belief that such
apartments were intended for Imperial use, since vermilion, amongst
the Romans, was a colour held in the highest esteem, and was always
one of great costliness.
Of the yellows, the more inferior were mixtures of ochre and
different quantities of chalk; the richer varieties were ochres
mixed with the red oxide of lead.
The ancients had also two other colours, which were orange, or
yellow; the auripigmentum, or [Greek: arsenikon], said to approach
to gold in the brilliancy of its tint, and which is described by
Vitruvius as being found native in Pontus, and which Davy says was
evidently sulphuret of arsenic;--and a pale sandarach, said by
Pliny to have been found in gold and silver mines, and which was
imitated at Rome by a partial calcination of cerusse. He conceives
that this must have been _Massicot_, or the yellow oxide of lead
mixed with minium; I suspect, however, that Davy was mistaken in
supposing that the ancients always applied the term Sandarach
to minium; the [Greek: Sandarakê] of Aristotle was evidently an
arsenical sulphuret.
In his examination of the ancient Frescoes, he could not detect the
use of orpiment; but a deep yellow, approaching to orange, which
covered a piece of stucco in the ruins near the monument of Caius
Cestius, proved to be oxide of lead, and consisted of massicot
and minium. He considers it probable that the ancients used many
colours from lead of different tints, between the "_usta_" of
Pliny, which was our minium, and imperfectly decomposed cerusse, or
pale massicot.
The differently shaded blues, by the action of acids, uniformly
assumed the same tint; from which he concluded that the effect of
the base was varied by different proportions of chalk. This base
he ascertained to be a _frit_, made by means of soda and sand, and
coloured by oxide of copper.
The greens were, in general, combinations of copper; and it seemed
probable, that although they appeared in the state of carbonate,
they might originally have been laid on in that of acetate. The
purple of the ancients, the [Greek: porphora] of the Greeks, and
the _Ostrum_ of the Romans, was regarded as their most beautiful
colour, and was obtained from shell-fish. Vitruvius states that it
was prepared by beating the fish with instruments of iron, freeing
the purple liquor from the shell containing it, and then mixing it
with a little honey. Pliny says that, for the use of the painters,
_argentine creta_, (probably a clay used for polishing silver,)
was dyed with it, and both Vitruvius and Pliny state that it was
adulterated, or imitations of it made by tinging _creta_ with
madder; whence it would appear, that the ancients were acquainted
with the art of making a lake colour from that plant, similar to
the one used by modern painters.
Pliny informs us, that the finest purple had a tint like a
deep-coloured rose. In the Baths of Titus, there was found a
broken vase of earthenware, which contained a pale rose colour;
and Davy selected it as an appropriate subject for his analytical
experiments.
Where this colour had been exposed to the action of the air, its
tint had faded into a cream colour, but the interior parts retained
a lustre approaching to that of carmine. A diluted acid was found
to dissolve out of it a considerable quantity of carbonate of lime,
with which the colouring principle must have been mixed, as a
substance of a bright rose colour remained after the process. This
colouring ingredient was proved to contain siliceous, aluminous,
and calcareous earths, without any sensible trace of metallic
matter, except oxide of iron. Upon heating the substance, first in
oxygen, and then with hyper-oxymuriate of potash, Davy was induced
to consider the colouring matter itself as either of vegetable or
animal origin; the results, however, were so equivocal, that he
renounced the hope of determining its nature from the products of
its decomposition. If it be of animal origin, he thinks it is most
probably the Tyrian or marine purple, as it is likely that the
most expensive colour would have been employed in ornamenting the
Imperial baths.
He had not observed any colour of the same tint as this ancient
lake in the fresco paintings; the purplish reds in the Baths of
Titus he ascertained to be mixtures of red ochres and the blues of
copper.
The blacks and browns were mixtures of carbonaceous matter,
with the ores of iron or manganese. The black from the Baths of
Titus, as well as that from some ruins near the Porta del Popolo,
deflagrated with nitre, and presented all the character of
carbon. This fact agrees with the statements of all the ancient
authors who have described the artificial Greek and Roman black as
consisting of carbonaceous matter, either prepared from the powder
of charcoal, from the decomposition of resin, (a species of lamp
black,) from that of the lees of wine, or from the common soot of
wood fires. Pliny also mentions the inks of the cuttle-fish, but
adds, "_Ex his non fit._"
Davy informs us, that, some years before, he had examined the black
matter of the cuttle-fish, and had found it to be a carbonaceous
substance mixed with gelatine.[16]
[16] I find from a note addressed by Davy to Mr. Underwood, that
he was engaged in these experiments in October 1801.
Pliny, moreover, speaks of ivory black invented by Apelles; of a
natural fossil black; and of a black prepared from an earth of
the colour of sulphur. Davy is of opinion, that both these latter
pigments were ores of iron and manganese; and he observes that the
analysis of some purple glass satisfied him that the ancients were
well acquainted with the ores of manganese.
The _whites_ which he examined from the Baths of Titus, as well as
those from other ruins, were either chalk, or fine aluminous clay;
and he states that, amongst all his researches, he never once met
with cerusse.
This interesting account of the colours used by the ancients is
followed by observations on the manner in which they were applied;
and the paper is concluded with some general remarks of much
practical importance.
The azure, he says, of which the excellence is sufficiently proved
by its duration for 1700 years, may be easily and cheaply imitated:
he found, for instance, that fifteen parts of carbonate of soda,
twenty parts of opaque flint powdered, and three parts of copper
filings, by weight, when strongly heated together for two hours,
yielded a compound substance of exactly the same tint, and of
nearly the same degree of fusibility; and which, when powdered,
produced a fine deep sky-blue.
The azure, the red and yellow ochres, and the blacks, appear to
have been the only pigments which have not undergone any change in
the fresco paintings. The vermilion presents a darker hue than that
of recently made Dutch cinnabar; and the red lead is inferior in
tint to that sold in the shops. The greens are generally dull.
The blue frit above mentioned, he considers as a colour composed
upon the truest principles; and he thinks there is reason to
believe, that it is the colour described by Theophrastus as the one
manufactured at Alexandria. "It embodies," says he, "the colour in
a composition like stone, so as to prevent the escape of elastic
matter from it, or the decomposing action of the elements upon it."
He suggests the possibility of making other _frits_, and thinks it
would be worth while to try whether the beautiful purple given by
oxide of gold could not be made useful in a deeply tinted glass.
Where _frit_ cannot be employed, he observes that metallic
combinations which are insoluble in water, and which are saturated
with oxygen or some acid matter, have been proved by the testimony
of seventeen centuries to be the best pigments. In the red ochres,
for example, the oxide of iron is fully combined with oxygen and
carbonic acid; and the colours composed of them have never changed.
The carbonates of copper, which consist of an oxide and an acid,
have suffered but little alteration. Massicot and orpiment, he
considers as those which have been the least permanent amongst all
the mineral colours.
He next takes a view of the colours which owe their origin to the
improvements of modern chemistry. He considers the _patent yellow_
to be more permanent, and the chromate of lead more beautiful,
than any yellow possessed by the Greeks or Romans. He pronounces
_Scheele's green_ (arsenite of copper), and the insoluble muriatic
combinations of copper, to be more unalterable than the ancient
greens; and he thinks that the sulphate of baryta offers a white
far superior to any pigment possessed by the ancients.
In examining the colours used in the celebrated Nozze Aldobrandine,
he recognised all the compounds which his analytical enquiries had
established: viz. the reds and yellows were all ochres; the blues,
the Alexandrian frit; the greens, copper; the purple, especially
that in the garment of the Pronuba, appeared to be a compound
colour of red ochre and copper; the browns and blacks were mixtures
of ochres and carbon; while the whites were carbonate of lime.
"The great Greek painters," he adds, "like the most illustrious
artists of the Roman and Venetian school, were probably sparing in
the use of the more florid tints in historical and moral painting,
and produced their effects rather by the contrasts of colouring in
those parts of the picture where a deep and uniform tint might be
used, than by brilliant drapery.
"If red and yellow ochres, blacks and whites, were the pigments
most employed by Protogenes and Apelles, so they are likewise
the colours most employed by Raphael and Titian in their best
style. The St. John and the Venus, in the tribune of the Gallery
at Florence, offer striking examples of pictures in which all the
deeper tints are evidently produced by red and yellow ochres, and
carbonaceous substances.
"As far as colours are concerned, these works are prepared for that
immortality which they deserve; but unfortunately, the oil and the
canvass are vegetable materials, and liable to decomposition, and
the last is even less durable than the wood on which the Greek
artists painted their celebrated pictures.
"It is unfortunate that the materials for receiving those works
which are worthy of passing down to posterity as eternal monuments
of genius, taste, and industry, are not imperishable marble or
stone:[17] and that _frit_, or unalterable metallic combinations
have not been the only pigments employed by great artists; and that
their varnishes have not been sought for amongst the transparent
compounds[18] unalterable in the atmosphere."
[17] Copper, it is evident from the specimens in the ruins of
Pompeii, is a very perishable material; but modern science might
suggest some voltaic protection.
[18] Davy thinks that the artificial hydrat of alumina will
probably be found to be a substance of this kind; and that,
possibly, the solution of boracic acid in alcohol will form a
varnish. He also thinks, that the solution of sulphur in alcohol
is worthy of an experiment.
In his memoir "On a solid compound of Iodine and Oxygen," he
enumerates, amongst the agencies of that body, its singular
property of forming crystalline combinations with all the fluid
or solid acids. It will be unnecessary to follow him through this
investigation, since its results have been found to be erroneous.
M. Serullas[19] has lately shown that the crystalline bodies of
Davy are nothing more than the iodic acid, which being insoluble in
acids, is necessarily precipitated by them.
[19] Annales de Chimie, t. 43. p. 216.
His paper "On the action of Acids on Salts usually called
Hyper-oxymuriates," announced the important fact of chlorine
forming with oxygen a compound, in which the latter element exists
in a still greater proportion than in the body previously described
by him under the name of _Euchlorine_.[20]
[20] See page 330. vol. i.
Before finally quitting Italy, he spent three weeks at Naples,
during which period he experimented on iodine and fluorine in the
house of Sementini; he also paid several visits to Vesuvius, and
found the appearances of the crater to be entirely different from
those which it presented in the preceding year:[21] there was,
for instance, no aperture in it; it was often quiet for minutes
together, and then burst out into explosions with considerable
violence, sending fluid lava, and ignited stones and ashes, to a
height of many hundred feet in the air.
[21] See page 42. vol. ii.
"These eruptions," says he, "were preceded by subterraneous
thunder, which appeared to come from a great distance, and which
sometimes lasted for a minute. During the four times that I was
upon the crater, in the month of March, I had at last learnt to
estimate the violence of the eruption from the nature of the
sound: loud and long-continued subterraneous thunder indicated a
considerable explosion. Before the eruption, the crater appeared
perfectly tranquil; and the bottom, apparently without an aperture,
was covered with ashes. Soon, indistinct rumbling sounds were
heard, as if at a great distance; gradually, the sound approached
nearer, and was like the noise of artillery fired under our feet.
The ashes then began to rise and to be thrown out with smoke from
the bottom of the crater; and lastly, the lava and ignited matter
was ejected with a most violent explosion. I need not say, that
when I was standing on the edge of the crater, witnessing this
phenomenon, the wind was blowing strongly from me; without this
circumstance, it would have been dangerous to have remained in such
a situation; and whenever from the loudness of the thunder the
eruption promised to be violent, I always ran as far as possible
from the seat of danger.
"As soon as the eruption had taken place, the ashes and stones
which rolled down the crater seemed to fill up the aperture,
so that it appeared as if the ignited and elastic matter were
discharged laterally; and the interior of the crater assumed the
same appearance as before."
On the 21st of March, he quitted Naples, and
returned to England by the following route:
Rome--Narni--Nocere--Fessombone--Imola--Mantua--(March 30,)
Verona--Pero--Trente--Botzen--Brennah--Inspruck--Zirl--(April
4,) Reuti-Menningen--Ulm--(April 6,)
Stutgard--Heidelburg--Mayence--Boppert--Coblentz--Cologne--(April
14,) Leuch--Brussels--Ostend--Dover--London, April 23, 1815.
CHAPTER XI.
Collieries of the North of England.--Fire-damp.--The dreadful
explosion at Felling Colliery described.--Letters from the
Bishop of Bristol to the Author.--A Society is established
at Bishop-Wearmouth for preventing accidents in coal
mines.--Various projects for ensuring the miner's safety.--The
Reverend Dr. Gray, the present Bishop of Bristol, addresses
a letter to Sir H. Davy, and invites his attention to the
subject.--Sir H. Davy's reply.--Farther correspondence
upon the possibility of devising means of security.--Sir
H. Davy proposes four different kinds of lamp for the
purpose.--The Safe-lamp--The Blowing-lamp--The Piston-lamp--The
Charcoal-lamp.--His investigation of the properties of
fire-damp leads to the discovery of a new principle of
safety.--His views developed in a paper read before the
Royal Society on the 9th of November 1815.--The first
Safety-lamp.--Safety-tubes superseded by Safety-canals.--Flame
Sieves.--Wire-gauze lamp.--The phenomenon of slow Combustion,
and its curious application.--The invention of the Safety-lamp
claimed by a Mr. Stephenson.--A deputation of Coal-owners
wait upon Sir H. Davy, in order to express to him the thanks
of the Proprietors for his discovery.--Mr. Buddle announces
to Dr. Gray (now Bishop of Bristol) the intention of the Coal
trade to present him with a service of plate.--The Resolutions
are opposed, and the claims of Stephenson urged, by Mr. W.
Brandling.--A dinner is given to Sir Humphry, at which the
plate is presented to him.--The President and Council of
the Royal Society protest against the claims still urged by
Mr. Stephenson's friends.--Mr. Buddle's letter in answer
to several queries submitted to him by the Author.--Davy's
Researches on Flame.--He receives from the Royal Society the
Rumford Medals.--Is created a Baronet.--Some observations on
the apathy of the State in rewarding scientific merit.--The
Geological Society of Cornwall receives the patronage and
support of Sir Humphry.
A few months after the return of Sir Humphry Davy to England, his
talents were put in requisition to discover some remedy for an evil
which had hitherto defied the skill of the best practical engineers
and mechanics of the kingdom, and which continued to scatter misery
and death amidst an important and laborious class of our countrymen.
To collect and publish a detailed account of the numerous and
awful accidents which have occurred within the last few years,
from the explosion of inflammable air, or _fire-damp_, in the coal
mines of the North of England, would present a picture of the most
appalling nature. It appears from a statement by Dr. Clanny, in the
year 1813,[22] that, in the space of seven years, upwards of three
hundred pitmen had been suddenly deprived of their lives, besides
a considerable number who had been severely wounded; and that more
than three hundred women and children had been left in a state of
the greatest distress and poverty; since which period the mines
have increased in depth, and until the happy discovery of Davy, the
accidents continued to increase in number.
[22] Phil. Transact. 1813.
It may well be asked how it can possibly have happened that, in
a country so enlightened by science and so distinguished for
humanity, an evil of such fearful magnitude, and of such frequent
recurrence, should for so long a period have excited but little
sympathy, beyond the immediate scene of the catastrophe. It would
seem that a certain degree of doubt and mystery, or novelty, is
essentially necessary to create that species of dramatic interest
by which the passions are excited through the medium of the
imagination: it is thus that the philanthropist penetrates unknown
regions, in search of objects for his compassion, while he passes
unheeded the miserable groups who crowd his threshold; it is
thus that the statesman pleads the injuries of the Negro with an
eloquence that shakes the thrones of kings, while he bestows not a
thought upon the intrepid labourers in his own country, who for a
miserable pittance pass their days in the caverns of the earth, to
procure for him the means of defying the severity of winter, and of
chasing away the gloom of his climate by an artificial sunshine.
That the benefits conferred upon mankind by the labours of Sir H.
Davy may be properly appreciated, it is necessary to describe the
magnitude of the evil which his genius has removed, as well as the
numerous difficulties which opposed his efforts and counteracted
his designs.
The great coal field,[23] the scene of those awful accidents which
will be hereafter described, extends over a considerable part of
the counties of Northumberland and Durham. The whole surface has
been calculated at a hundred and eighty square miles, and the
number of different beds of coal has been stated to exceed forty;
many of which, however, are insignificant in point of dimensions.
The two most important are about six feet in thickness, and are
distinguished by the names of _High main_, and _Low main_, the
former being about sixty fathoms above the latter.
[23] Dr. Thomson has calculated that the quantity of coal
exported yearly from this formation exceeds two millions of
chaldrons; and he thinks it may be fairly stated, in round
numbers, that, at the present rate of waste, it will continue
to supply coal for a thousand years! Mr. Phillips, however, is
inclined to deduct a century or two from this calculation.
From this statement, some idea may be formed of the great extent of
the excavations, and of the consequent difficulty of successfully
ventilating the mines. In some collieries, they are continued for
many miles, forming numerous windings and turnings, along which
the pitmen have frequently to walk for forty or fifty minutes,
before they arrive at the workings; during which time, as well as
when at work, they have no direct communication with the surface
of the earth. The most ingenious machinery, however, has been
contrived for conducting pure air through every part of the mine,
and for even ventilating the old excavations, which are technically
called _Wastes_; and unless some obstruction occur, the plan[24]
so far answers, as to furnish wholesome air to the pitmen, and to
diminish, although, for reasons to be hereafter stated, it can
never wholly prevent, the dangers of _fire-damp_; the nature of
which it will be necessary to consider.
[24] In all large collieries, the air is accelerated through
the workings by placing furnaces, sometimes at the bottom, and
sometimes at the top of the up-cast shaft; in aid of which, at
Wall's-end Colliery, a powerful air-pump worked by a steam-engine
is employed to quicken the draft: this alone draws out of the
mines a thousand hogsheads of air every minute. Stoppings and
trapdoors are also interposed in various parts of the workings,
in order to give a direction to the draft.
The coal appears to part with a portion of _carburetted hydrogen_,
when newly exposed to the atmosphere; a fact which explains
the well-known circumstance of the coal being more inflammable
when fresh from the pit, than after long exposure to the air.
We are informed by the Rev. Mr. Hodgson, that, on pounding some
common Newcastle coal fresh from the mine, in a cask furnished
with a small aperture, he found the gas which issued from it to
be inflammable; and Davy, on breaking some lumps of coal under
water, also ascertained that they gave off inflammable gas. The
supposition that the coal strata have been formed under a pressure
greater than that of the atmosphere, may furnish a clue to the
comprehension of this phenomenon.
On some occasions the pitmen have opened with their picks crevices,
or fissures, in the coal or shale, which have emitted as much
as seven hundred hogsheads of _fire-damp_ in a minute. These
_Blowers_, as they are technically termed, have been known to
continue in a state of activity for many months, or even years
together;[25] a phenomenon which clearly shows that the carburetted
hydrogen must have existed in the cavities of the strata in a very
highly compressed, if not actually in a liquid state, and which, on
the diminution of pressure, has resumed its elastic form.
[25] Sir James Lowther found a uniform current of this
description produced in one of his mines for the space of two
years and nine months. Phil. Trans, vol. 38. p. 112.
All the sources of carburetted hydrogen would appear to unite in
the deep and valuable collieries situated between the great North
road and the sea. Their air courses are thirty or forty miles
in length; and here, as might be expected, the most tremendous
explosions have happened. Old workings, likewise, upon being broken
into, have not unfrequently been found filled with this gas, and
which, by mingling itself with the common air, has converted the
whole atmosphere of the mine into a magazine of _fire-damp_.
On the approach of a candle, it is in an instant kindled: the
expanding fluid drives before it a roaring whirlwind of flaming
air, which tears up every thing in its progress, scorching some of
the miners to a cinder, and burying others under enormous ruins
shaken from the roof; when thundering to the shafts, it converts
the mine, as it were, into an enormous piece of artillery, and
wastes its fury in a discharge of thick clouds of coal-dust,
stones, and timber, together with the limbs and mangled bodies of
men and horses.
But this first, though apparently the most appalling, is not the
most destructive effect of these subterraneous combustions. All
the _stoppings_ and trapdoors of the mine being blown down by the
violence of the concussion, and the atmospheric current entirely
excluded from the workings, such of the miners as may have survived
the discharge are doomed to the more painful and lingering death of
suffocation from the _after-damp_, or _stythe_, as it is termed,
which immediately results from the combustion, and occupies the
vacuum necessarily produced by it.
As the phenomena accompanying these explosions are always of the
same description, to relate the numerous recorded histories of such
accidents would be only to multiply pictures of death and human
suffering, without an adequate object: it is, however, essential
to the just comprehension of the subject, that the reader should
receive at least one well-authenticated account, in all its
terrific details; and I have accordingly selected that which was
originally drawn up with much accuracy and feeling by the Reverend
John Hodgson, and which is prefixed to the funeral sermon preached
on the occasion, and subsequently published by that gentleman.
The accident occurred at Felling Colliery, near Sunderland, on the
25th of May, in the year 1812. This mine was considered by the
workmen as a model of perfection, both with regard to the purity of
its air, and the arrangements of its machinery. The concern was in
the highest degree prosperous; and no accident, except a trifling
explosion which slightly scorched two or three pitmen, had ever
occurred.
Two _shifts_, or sets of men, were constantly employed, the first
of which entered the mine at four, and were relieved at their
working posts by the next set at eleven o'clock in the morning; but
such was the confidence of the pitmen in the safety of this mine,
that the second shift of men were often at their posts before the
first set had left them; and such happened to be the case on the
following unhappy occasion.
About half past eleven, on the morning of the 25th of May, the
neighbouring villages were alarmed by a tremendous explosion. The
subterraneous fire broke forth with two heavy discharges from the
shaft called the '_John Pit_,' which was one hundred and two
fathoms deep, and were almost immediately followed by one from
that termed the '_William pit_,' A slight trembling, as if from an
earthquake, was felt for about half a mile around the workings; and
the noise of the explosion, though dull, was heard to the distance
of three or four miles, and greatly resembled an unsteady fire of
infantry.
Immense quantities of dust and small coal accompanied these blasts,
and rose high into the air, in the form of an inverted cone. The
heaviest part of the ejected matter, such as masses of timber, and
fragments of coal, fell near the pit, but the dust, borne away by a
strong west wind, fell in a continued shower to the distance of a
mile and a half; and in the village of Heworth, it caused a gloom,
like that of early twilight, and so covered the roads that the
footsteps of passengers were strongly imprinted on them.
As soon as the explosion had been heard, the wives and children
of the pitmen rushed to the working pit. Wildness and terror were
pictured in every countenance. The crowd thickened from every side,
and in a very short period several hundred persons had collected
together; and the air resounded with exclamations of despair for
the fate of husbands, parents, and children.
The machinery having been rendered useless by the eruption, the
rope of the _gin_ was sent down the shaft with all possible
expedition. In the absence of horses, a number of men, who seemed
to acquire strength as the necessity for it increased, applied
their shoulders to the _starts_, or shafts of the gin, and worked
it with astonishing expedition.
By twelve o'clock, thirty-two persons, all that survived this
dreadful catastrophe, had been brought to daylight, but of these
three boys lived only a few hours. The dead bodies of two boys,
miserably scorched and shattered, were also brought up at the
same time. Twenty-nine persons, then, were all who were left to
relate what they had observed of the appearances and effect of
the explosion. One hundred and twenty-one were in the mine when
it happened, eighty-seven of whom remained in the workings. Eight
persons had fortunately come up a short time before the accident.
Those who had their friends restored, hastened with them from
the scene of destruction, and for a while appeared to suffer as
much from an excess of joy, as they had a short time before from
the depth of despair; while those who were yet in the agony of
suspense, filled the air with shrieks and howlings, and ran about
wringing their hands and throwing their bodies into the most
frantic and extravagant gestures.
As not one of the pitmen had escaped from the mine by the only
avenue open to them, the apprehension for their safety momentarily
increased, and at a quarter after twelve o'clock, nine persons
descended the John pit, with the faint hope that some might still
survive.
As the fire-damp would have been instantly ignited by candles,
they lighted their way by _steel-mills_;[26] and knowing that
a great number of the miners must have been at the crane when
the explosion happened, they at once attempted to reach that
spot: their progress, however, was very soon intercepted by the
prevalence of _choak damp_, and the sparks from their steel-mill
fell into it like dark drops of blood: deprived therefore of light,
and nearly suffocated by the noxious atmosphere, they retraced
their steps towards the shaft, but they were shortly stopped by
a thick smoke which stood like a wall before them. Here their
steel-mills became entirely useless, and the chance of their ever
finding any of their companions alive entirely hopeless; to which
should also be added the horror arising from the conviction of
the mine being on fire, and the probability of a second explosion
occurring at the next moment, and of their being buried in the
ruins it would occasion.
[26] Steel-mills are small machines, which give light by turning
a cylinder of steel against a piece of flint. Sir James Lowther
had observed early in the last century, that the fire-damp in its
usual form was not inflammable by sparks from flint and steel;
and it appears that a person in his employment invented the
machine in question.
At two o'clock, five of the intrepid persons who had thus nobly
volunteered their assistance, ascended; two were still in the
shaft, and the other two remained below, when a second explosion,
much less severe, however, than the first, excited amongst the
relatives of those entombed in the mine still more frightful
expressions of grief and despair. The persons in the shaft
experienced but little inconvenience from this fresh eruption,
while those below, on hearing the distant growlings, immediately
threw themselves flat on their faces, and in this posture, by
keeping a firm hold on a strong wooden prop, they felt no other
annoyance from the blast than that of having their bodies tossed
in various directions, in the manner that a buoy is heaved by the
waves of the sea. As soon as the atmospheric current returned down
the shaft, they were safely drawn to the light.
As each came up, he was surrounded by a group of anxious enquirers;
but not a ray of hope could be elicited; and the second explosion
so strongly corroborated their account of the impure state of
the mine, that their assertions for the present seemed to obtain
credit. This impression, however, was but of short duration,--hope
still lingered; they recollected that persons had survived similar
accidents, and that, upon opening the mine, they had been found
alive after considerable intervals. Three miners, for instance,
had been shut up for forty days in a pit near Byker, and during
the whole of that period had subsisted on candles and horse-beans.
Persons too were not wanting to agitate the minds of the relatives
with disbelief in the report of the pitmen who had lately descended
to explore the mine. It was suggested to them, that want of
courage, or bribery, might have induced them to magnify the danger,
and to represent the impossibility of reaching the bodies of the
unfortunate sufferers. By this species of wicked industry, the
grief of the neighbourhood began to change its gloomy, for an
irritable aspect. The proposition to exclude the atmospheric air
from the mine, in order to extinguish the fire, was received with
the cries of _Murder!_--and with the determination to oppose such a
proceeding by violence.
Many of the widows lingered about the mouth of the pit during the
whole of the night with the hope of hearing the cries of a husband
or a son.
On Tuesday the 26th, that natural propensity in the human mind to
derive gratification from spectacles of horror, was exemplified in
a very striking manner. An immense crowd of colliers from various
parts, but more especially from the banks of the river Wear,
assembled around the pit, and were clamorous in their reproaches of
the persons concerned in the management of the mine, accusing them
of want of perseverance in their attempts to rescue the unhappy
sufferers. Every one had some successful adventure to relate; all
were liberal in their professions of readiness to give assistance;
but not one was found hardy enough to enter the jaws of the burning
cavern.
The leaders of this outcry, however, who had been led into error
by an impulse which did honour to their hearts, were soon brought
to listen with patience to a relation of all the circumstances
of the explosion, and of the reasons for concluding that the
mine was then actually on fire, and the persons enclosed in it
beyond the hope of recovery. They very candidly allowed, after
this explanation, the impracticability of any attempt to reach
the bodies of the sufferers, until the fire was extinguished; and
they accordingly urged the propriety of excluding from the mine
the access of air, as the only means of accomplishing the object.
At the same time, the proprietors gave the strongest assurances
to the multitude, that if any project could be devised for the
recovery of their friends, no cost or labour should be spared in
executing it; that, if any person could be found willing to enter
the mine, every facility and assistance should be afforded him;
but, as they were assured by the most eminent Viewers that the
workings were inaccessible, they would not hold out any reward for
the attempt,--they would not be accessary to the death of any one,
either by persuasion or bribery.
At the clamorous solicitation, however, of the populace, two
persons again descended the shaft, and very nearly lost their
lives in the attempt. The report of these last adventurers, in a
great measure, convinced the people of the impossibility of their
friends' survival in so deadly an atmosphere, and reconciled them
to the plan of excluding the air. The operation was accordingly
commenced, and it proceeded without interruption; but from various
accidents, more than a month elapsed before the mine was in a
state to admit of examination; and during this interval, numerous
were the idle tales which had been circulated throughout the
country. Several of the sufferers, it was said, had found their
way to the shafts, and been recovered. Their number even had been
circumstantially told--how they had subsisted on candles, oats, and
beans, and how they had heard the different persons who explored
the mine in the hope of rescuing them.
Some conjuror too, it was said, had set his spells and divinations
to work, and had penetrated all the secrets of the mine. He had
discovered one famishing group receiving drops of water from the
roof, another eating their shoes and clothes, and many other
similar pictures of horror. These inventions were carefully related
to the widows, and they produced the effect of daily harrowing up
afresh their sorrows; indeed, it seemed the chief employment of
some to indulge in a kind of insane sport with their own and their
neighbours' calamity.
The morning of Wednesday the 8th of July having been appointed
for exploring the workings, the distress of the neighbourhood
was again renewed at an early hour: a great concourse of people
assembled; some, out of curiosity, to witness the commencement of
an undertaking full of sadness and danger,--some to excite the
revenge, or to aggravate the sorrows, of the relatives by calumnies
and reproaches, for the sole purpose of mischief; but the greater
part came with broken hearts and streaming eyes, in expectation of
seeing the mangled corpse of a father, brother, husband, or son.
The _shifts_ of men employed in this doleful and unwholesome work
were generally about eight in number. They were four hours in, and
eight hours out of the mine; so that each individual wrought two
shifts every twenty-four hours.
When the first shift of men came up, a message was dispatched for
a number of coffins to be in readiness at the mouth of the pit.
Ninety-two had been prepared, and they had to pass by the village
of Low Felling, in their way to the mine. As soon as a cart-load of
them was seen, the howling of the women, who, hitherto secluded in
their dwellings, had now begun to assemble about their doors, came
on the breeze in slow fitful gusts, which presaged a scene of the
greatest distress and confusion.
The bodies were found under various circumstances: one miner, from
his position, must have been sleeping when the explosion happened,
and had never opened his eyes. In one spot were found twenty-one
bodies in ghastly confusion,--some like mummies, scorched as dry as
if they had been baked; one wanted its head, another an arm--the
scene was most terrific: the power of the fire was visible upon
all, but its effects were very various; while some were almost torn
to pieces, there were others who appeared as if they had sunk down
overpowered by sleep.
Every family had made arrangements for receiving the dead bodies of
their kindred; but Dr. Ramsay having given his opinion, that such a
proceeding might spread a putrid fever through the neighbourhood,
and the first body when exposed to observation having presented
a most horrid and corrupt appearance, the people very properly
consented to have each body interred as soon as it was discovered,
on condition that the hearse, in its way to the chapel-yard, should
pass by the door of the deceased.
From the 8th of July to the 19th of September, the heart-rending
scene of mothers and widows examining the putrid bodies of their
sons and husbands, for marks by which to identify them, was daily
renewed; but very few of them were recognised by any personal
mark--they were too much mangled and scorched to retain any of
their features: their clothes, tobacco-boxes, and shoes, were
therefore the only indications by which they could be identified.
The total loss from this terrible accident was ninety-two pitmen;
while forty widows, sixty girls, and twenty-six boys, comprising
in all one hundred and twenty six persons, were thrown upon the
benevolence of the public.
It was impossible that an event of such awful magnitude should not
have deeply affected every humane person resident in the district.
Nothing, in short, could exceed the anxiety which was manifested on
the occasion; but, most unfortunately, there existed an invincible
prejudice against every proposition that could be offered, from a
general impression as to the utter hopelessness of any attempt to
discover a remedy. A few philosophic individuals, however, did form
themselves, as we shall presently learn, into an association for
the laudable purpose of inviting the attention of scientific men to
the subject, and of obtaining from them any suggestions which might
lead to a more secure method of lighting the mines.
To the Reverend Dr. Gray, the present Lord Bishop of Bristol,
who, at the period to which I allude, was the Rector of
Bishop-Wearmouth, and one of the most zealous and intelligent members
of the association, I beg to offer my public acknowledgments
and thanks for the several highly interesting communications
and letters with which his Lordship has obliged me, and
by means of which I have been enabled to present to the
scientific world a complete history of those proceedings which have
so happily led to a discovery, of which it is not too much to say
that it is, at once, the pride of science, the triumph of humanity,
and the glory of the age in which we live.
In a letter I had lately the honour of receiving from that learned
prelate, his Lordship says, "It was at a time when all relief was
deemed hopeless, that Mr. Wilkinson, a barrister in London, and
a gentleman distinguished for the humanity of his disposition,
suggested the expediency of establishing a society for the purpose
of enquiring whether any, and what, methods of security might
be adopted for the prevention of those accidents so frequently
occurring in the collieries of Northumberland and Durham.
"In consequence of this benevolent suggestion, a society was
established at Bishop-Wearmouth, on the 1st of October 1813, by Sir
Ralph Milbanke, afterwards Sir Ralph Noel, Dr. Gray, Dr. Pemberton,
Mr. Robinson, Mr. Stephenson, and several other gentlemen. It was
entitled, 'A Society for preventing Accidents in Coal-Mines;' and
it immediately obtained the patronage of the Bishop of Durham, the
Duke of Northumberland, and other noblemen and gentlemen.
"A very few days before the first meeting, twenty-seven persons
had been killed in a colliery in which Sir Ralph Milbanke had
an interest, and he was called upon at the meeting to state the
particulars of the accident. At that time there was such little
expectation that any means could be devised to prevent the
occurrence of these explosions, that the object of the gentlemen
who convened the meeting, however humane in principle, was
considered by the persons present as chimerical and visionary.
The Society, however, amidst many difficulties and considerable
discouragement, and a perpetual harass by the offer of impracticable
schemes from every quarter, nevertheless persevered in their
meetings, and succeeded in establishing a communication and
correspondence with other Societies in different parts of the
kingdom."[27]
[27] It is unnecessary to enumerate the various schemes that
have been proposed to prevent accidents from fire-damp. Some
were unquestionably of value, and might, by their adoption, have
diminished the frequency of explosions; others were visionary,
or wholly impracticable. It was proposed, for instance, to fill
the mine with an atmosphere of chlorine, which by entering into
chemical union with the carburetted hydrogen, might disarm it of
its power. Dr. Murray, in a paper published in the Transactions
of the Royal Society of Edinburgh, suggests the use of a lamp
that shall be supplied with air from the ground of the pit, by
means of a long flexible tube, upon the false assumption that
the fire-damp alone occupies the higher parts of the mine. Mr.
W. Brandling also constructed a Safe-lamp, which, like that of
Dr. Murray, was fed by air introduced through a long flexible
tube reaching to the floor of the mine. In addition to which, he
attached to the top of the lantern a pair of double bellows, by
the aid of which he at the same time drew out the contaminated
air from the interior of the lamp, and sucked in, through the
flexible tube, a fresh portion to supply its place. To say
nothing of the inefficacy and inconvenience of the long tube, the
bellows possessed the additional objection of frequently puffing
out the light.
One of the most active and intelligent members of the "Society
for preventing accidents in Coal Mines," Dr. Clanny, had for some
time paid particular attention to the object in contemplation.
He first suggested the idea of an insulated lamp, of which an
account appeared in the Philosophical Transactions for 1813.
In 1815, he invented a steam safety-lamp, constructed of the
strongest tinned iron, with thick flint glass in front. In this
machine, the air of the coal mine passes in a current through
a tube, and mixing with the steam, before it can arrive at the
light, burns steadily in the wick of the lamp alone. This lamp
has the valuable property of remaining cool. It has been much
used in the Herrington Mill pit, the Whitefield pit, and the
Engine pit.
"One of the projects offered was, that electrical machines
should be employed, with ramifications to extend through all the
departments of the collieries, and which were to be excited in
discharging their fluid in constant succession, in order gradually
to destroy the inflammable air. Many other suggestions were
proposed, the principal of which were formed with the intention of
purifying the air of the pits by chemical processes, or by forcing
in large quantities of atmospheric air, through pipes and tunnels,
&c.
"The Society, although it received some distinguished patronage,
was not furnished with means sufficiently ample for exciting
emulation by premiums, or even for defraying the expenses of
intelligent artisans; and it unfortunately lost a considerable
portion of its funds by the failure of the Wear Bank.
"Amongst the applications which more particularly excited the
attention of the Society, was that of Mr. Ryan of Donegal, who
objected to the principle upon which the working of collieries was
carried on. He conceived that they should be originally constructed
at the commencement of the working, with a view to admit the
escape of the hydrogen gas to the highest parts of the colliery.
He proposed to ventilate even the foulest pits, and the attention
of the gentlemen proprietors, or occupiers of collieries, in the
neighbourhood of Newcastle, was called upon at public meetings,
and an enquiry set on foot with respect to the validity of his
pretensions. Some gentlemen were even deputed to proceed into
Staffordshire to ascertain the nature and extent of his services
in that county, where he had been for some time employed. An offer
was also made to place under his management the Hecton pit, at
Hepburn, which was particularly foul; but a difference of opinion
having arisen as to the efficacy of his plan, he did not consider
himself sufficiently encouraged to proceed, and he left the country
dissatisfied. He afterwards received the gold medal from the
Society for promoting the Arts and Sciences."
The Society having as yet effected but little towards the great
object of their deliberations, the chairman of the committee, Dr.
Gray, who was generally acquainted with Sir Humphry Davy, judged it
expedient to direct his attention to a subject, upon which, of all
men of science, he appeared to be the best calculated to bring his
extensive stores of chemical knowledge to a practical bearing.
As the life of this valuable man is now closed, and as every
incident in it is interesting as connected with the advancement of
philosophical knowledge, and especially of chemical discoveries
important to the welfare of mankind, it may be worth while to enter
into a review of the proceedings which were adopted upon this
occasion, in order to trace the progress of the discoveries which
were made, and the methods by which he arrived at his conclusions.
Dr. Gray, the chairman of the committee, having addressed to him a
letter with a view to engage him in an investigation so important
to society, received from him the following answer.
TO THE REVEREND DR. GRAY.
SIR,
August 3, 1815.
I had the honour of receiving the letter which you addressed to
me in London, at this place, and I am much obliged to you for
calling my attention to so important a subject.
It will give me great satisfaction if my chemical knowledge can
be of any use in an enquiry so interesting to humanity, and I
beg you will assure the Committee of my readiness to co-operate
with them in any experiments or investigations on the subject.
If you think my visiting the mines can be of any use, I will
cheerfully do so.
There appears to me to be several modes of destroying the
fire-damp without danger; but the difficulty is to ascertain
when it is present, without introducing lights which may
inflame it. I have thought of two species of lights which
have no power of inflaming the gas which is the cause of the
fire-damp, but I have not here the means of ascertaining
whether they will be sufficiently luminous to enable the
workmen to carry on their business. They can be easily
procured, and at a cheaper rate than candles.
I do not recollect any thing of Mr. Ryan's plan: it is possible
that it has been mentioned to me in general conversation, and
that I have forgotten it. If it has been communicated to me in
any other way, it has made no impression on my memory.
I shall be here for ten days longer, and on my return South,
will visit any place you will be kind enough to point out to
me, where I may be able to acquire information on the subject
of the coal gas.
Should the Bishop of Durham be at Auckland, I shall pay my
respects to his Lordship on my return.
I have the honour to be, dear Sir, with much respect, your
obedient humble servant,
H. DAVY.
At Lord Somerville's, near Melrose, N. B.
TO THE SAME.
SIR, Melrose, August 18, 1815.
I received your letter, which followed me to the Moors, where I
have been shooting with Lord Somerville. I should have replied
to it before this time, but we were in a part of the Highlands
where there was no post. I am very grateful to you for the
obliging invitation it contains.
I propose to leave the Tweed side on Tuesday or Wednesday, so
that I shall be at Newcastle either on Wednesday or Thursday.
If you will have the kindness to inform me by a letter,
addressed at the Post Office, where I can find the gentleman
you mention, I will call upon him, and do any thing in my power
to assist the investigation in that neighbourhood.
I regret that I cannot say positively whether I shall be at
Newcastle on Wednesday or Thursday; for I have some business at
Kelso which may detain me for a night, or it may be finished
immediately.
I am travelling as a bachelor, and will do myself the honour of
paying my respects to you at Bishop-Wearmouth towards the end
of the week.
I am, Sir, with much respect,
Your obedient humble servant,
H. DAVY.
The gentleman alluded to in the preceding letter, and to whom
Dr. Gray wished Sir H. Davy to apply, was Mr. Buddle, a person
whose extensive practical knowledge has justly entitled him to be
considered as the highest authority on all subjects connected with
the art of mining, and who has conferred inestimable benefits on
the mining interests by the introduction of successful methods
of ventilation. The account of his interview with Sir H. Davy is
communicated in the following letter.
MR. BUDDLE TO DR. GRAY.
Wall's-end Colliery, August 24, 1815.
SIR,
Permit me to offer my best acknowledgments for the opportunity
which your attention to the cause of humanity has afforded me
of being introduced to Sir Humphry Davy.
I was this morning favoured with a call from him, and he
was accompanied by the Rev. Mr. Hodgson. He made particular
enquiries into the nature of the danger arising from the
discharge of the inflammable gas in our mines. I shall supply
him with a quantity of the gas to analyze; and he has given me
reason to expect that a substitute may be found for the steel
mill, which will not fire the gas. He seems also to think it
possible to generate a gas, at a moderate expense, which, by
mixing with the atmospheric current, will so far neutralize the
inflammable air, as to prevent it firing at the candles of the
workmen.
If he should be so fortunate as to succeed in either the one or
the other of these points, he will render the most essential
benefit to the mining interest of this country, and to the
cause of humanity in particular.
I have little doubt but it will be gratifying to you to be
informed, that progress is making towards the establishment of
a permanent fund for the relief of sufferers by accident and
sickness in the collieries of this district.
I have the pleasure to remain, with great respect, Sir, your
most obedient, humble servant,
John Buddle.
Sir H. Davy on his return to London, having been supplied by Mr.
Buddle with various specimens of _fire-damp_, proceeded, in the
first instance, to submit to a minute chemical examination the
substance with which he had to contend.
In less than a fortnight, he informed Dr. Gray by letter, that he
had discovered some new and unexpected properties in the gas, which
had led to no less than four different plans for lighting the mines
with safety.
TO THE REVEREND DR. GRAY.
Royal Institution, Oct. 30.
MY DEAR SIR,
As it was the consequence of your invitation that I endeavoured
to investigate the nature of the fire-damp, I owe to you the
first notice of the progress of my experiments.
My results have been successful far beyond my expectations.
I shall enclose a little sketch of my views on the subject;
and I hope in a few days to be able to send a paper with the
apparatus for the committee.
I trust the _Safe lamp_ will answer all the objects of the
collier.
I consider this at present as a _private_ communication. I wish
you to examine the lamps I have had constructed, before you
give any account of my labours to the committee.
I have never received so much pleasure from the result of any
of my chemical labours; for I trust the cause of humanity will
gain something by it.
I beg of you to present my best respects to Mrs. Gray, and to
remember me to your son.
I am, my dear Sir, with many thanks for your hospitality and
kindness when I was at Sunderland, your obliged servant,
H. DAVY.
TO THE SAME.
London, October 31, 1815.
MY DEAR SIR,
I sent yesterday a sketch of my results on the fire-damp.
We have lately heard so much of East[28] Shields, that by a
strange accident I confounded it with Bishop-Wearmouth, and
addressed your letter to East Shields.
I could not find any body to frank it, and you will find it a
heavy packet; however, I could not lose a moment in giving you
an account of results which I hope may be useful to humanity.
If my letter has not reached you, it will be found at the Post
Office, East Shields.
With respects to Mrs. Gray, I am, my dear Sir, very sincerely
yours,
H. DAVY.
[28] _Quere_--South Shields.
The sketch alluded to in the foregoing letter, has been kindly
placed in my hands by the Bishop of Bristol; it possesses
considerable interest as an original document, displaying his
earliest views, and tending to illustrate the history of their
progress.
"The fire-damp I find, by chemical analysis, to be (as it
has been always supposed) a hydro-carbonate. It is a chemical
combination of hydrogen gas and carbon, in the proportion of 4 by
weight of hydrogen gas, and 11-1/2 of charcoal.
"I find it will not explode, if mixed with less than six times,
or more than fourteen times its volume of atmospheric air. Air,
when rendered impure by the combustion of a candle, but in which
the candle will still burn, will not explode the gas from the
mines; and when a lamp or candle is made to burn in a close vessel
having apertures only above and below, an _explosive mixture_
of gas admitted _merely enlarges_ the light, and then gradually
extinguishes it without explosion. Again,--the gas mixed in any
proportion with common air, I have discovered, _will not explode_
in a _small tube_, the diameter of which is less than 1/8th of an
inch, or even a larger tube, if there is a mechanical force urging
the gas through this tube.
"Explosive mixtures of this gas with air require much stronger heat
for their explosion than mixtures of common inflammable gas.[29]
Red-hot charcoal, made so as not to flame, if blown up by a
mixture of the mine gas and common air, does not explode it, but
gives light in it; and iron, to cause the explosion of mixtures of
this gas with air, must be made _white_-hot.
"The discovery of these curious and unexpected properties of the
gas, leads to several practical methods of lighting the mines
without any danger of explosion.
"The first and simplest is what I shall call the _Safe lamp_, in
which a candle or a lamp burns in a safe lantern which is air-tight
in the sides, which has tubes below for admitting air, a chamber
above, and a chimney for the foul air to pass through; and this
is as portable as a common lantern, and not much more expensive.
In this, the light never burns in its full quantity of air, and
therefore is more feeble than that of the common candle.
"The second is the _Blowing lamp_. In this, the candle or lamp
burns in a close lantern, having a tube below of small diameter
for admitting air, which is thrown in by a small pair of bellows,
and a tube above of the same diameter, furnished with a cup filled
with oil. This burns brighter than the simple safe lamp, and is
extinguished by explosive mixtures of the fire-damp. In this
apparatus the candle may be made to burn as bright as in the air;
and supposing an explosion to be made in it, it cannot reach to the
external air.
"The third is the _Piston lamp_, in which the candle is made
to burn in a small glass lantern furnished with a piston, so
constructed as to admit of air being supplied and thrown into it
without any communication between the burner and the external air:
this apparatus is not larger than the steel-mill, but it is more
expensive than the other, costing from twenty-two to twenty-four
shillings.
"These lamps are all extinguished when the air becomes so polluted
with fire-damp as to be explosive.
"There is a fourth lamp, by means of which any _blowers_ may be
examined in air in which respiration cannot be carried on: that is,
the _Charcoal lamp_. This consists of a small iron cage on a stand,
containing small pieces of _very well burnt_ charcoal blown up to
a red heat. This light will not inflame any mixtures of air with
fire-damp.[30]
"Of these inventions, the _Safe lamp_, which is the simplest, is
likewise the one which affords the most perfect security, and
requires no more care or attention than the common candle, and
when the air in mines becomes improper for respiration, it is
extinguished, and the workmen ought immediately to leave the place
till a proper quantity of atmospheric air can be supplied by
ventilation.
"I have made many experiments on these lamps with the genuine
fire-damp taken from a blower in the Hepburn Colliery, collected
under the inspection of Mr. Dunn, and sent to me by the Reverend
Mr. Hodgson. My results have been always unequivocal.
"I shall immediately send models of the different lamps to such of
the mines as are exposed to danger from explosion; and it will be
the highest gratification to me to have assisted by my efforts a
cause so interesting to humanity."
[29] _Olefiant_ gas, when mixed with such proportions of common
air as to render it explosive, is fired both by charcoal and
iron heated to a dull-red heat. _Gaseous oxide of carbon_,
which explodes when mixed with two parts of air, is likewise
inflammable by red-hot iron, and charcoal. The case is the same
with _sulphuretted hydrogen_.
[30] "In addition to these four lamps, we learn from an Appendix
to his Paper in the Philosophical Transactions, that in the
beginning of his enquiries, he constructed a close lantern, which
he called the _Fire-valve lantern_; in which the candle or lamp
burnt with its full quantity of air, admitted from an aperture
below, till the air began to be mixed with fire-damp, when, as
the fire-damp increased the flame, a thermometrical spring at the
top of the lantern, made of brass and steel, riveted together,
and in a curved form, expanded, moved a valve in the chimney,
diminished the circulation of air, and extinguished the flame. He
did not, however, pursue this invention, after he had discovered
the properties of the fire-damp, on which his Safety-lamp is
founded."
Contrary to the wish expressed by Sir Humphry Davy, the foregoing
communication was inadvertently read at a public meeting of the
Coal-trade, which was held at Newcastle on the 3rd of November:
a circumstance which occasioned some embarrassment at the time,
but is satisfactorily explained in the following letter from Sir
Humphry.
TO THE REVEREND DR. GRAY.
23, Grosvenor Street, Dec. 14, 1815.
MY DEAR SIR,
My communication to ---- was, like that I made to you, intended
to be _private_; he has however written to me to apologize for
having made it known at Newcastle, stating, that having seen a
notice of my results in the paper, the motive, as he conceived,
for withholding it was at an end, as he considered my only
reason for wishing to keep back my results from the public eye
was the conviction that they might be rendered more perfect,
and this I have now fully proved.
I trust I shall be able in a very few days to send you a model
of a lantern nearly as simple as a common glass lantern, and
which _cannot_ communicate explosion to the fire-damp. I will
send another to Newcastle, and I will likewise send you the
copy of my paper, which you may reprint in any form you please;
you will find my acknowledgments to you publicly stated.
My principles are these: _First_, a certain mixture of
azote and carbonic acid prevents the explosion of the
fire-damp, and this mixture is necessarily formed in the safe
lantern;--_Secondly_, the fire-damp _will not explode_ in tubes
or feeders of a certain small diameter. The ingress into, and
egress of air from my lantern is through such tubes or feeders;
and therefore, when an explosion is _artificially_ made in the
safe lantern, it does not communicate to the external air.
I have made two or three lanterns of different forms.
Experience must determine which will be the most convenient.
Should there be a little delay in sending them, it will be the
fault of the manufacturer. It is impossible to conceive the
difficulty of getting any thing made in London which is not in
the common routine of business; and I should be very sorry to
send you any thing imperfectly executed.
With best respects to Mrs. Gray, I am, my dear Sir,
Very sincerely your obliged servant,
H. DAVY.
The paper alluded to in the preceding letter, entitled, "On the
Fire-damp of Coal Mines, and on methods of lighting the mine so as
to prevent its explosion," was read before the Royal Society on the
9th of November, 1815.
In this memoir he communicates the results of some chemical
experiments upon the nature of the fire-damp, and announces the
existence of certain properties in that gas, which had previously
escaped observation, and which leads to very simple methods of
lighting the mines without danger.
He confirms the opinion of Dr. Henry, and other chemists, as to
the fire-damp being light carburetted hydrogen gas, and analogous
to the inflammable gas of marshes; but he found that the degree
of its combustibility differed most materially from that of the
other common inflammable gases, which it is well known will
explode by the contact of both red-hot iron and charcoal; whereas
well-burned charcoal, ignited to the strongest red heat, did not
explode any mixture of the air and of the fire-damp; and a fire
made of well-burned charcoal, that is to say, of charcoal that
will burn without flame, was actually blown up to whiteness by
an explosive mixture containing the fire-damp without producing
its inflammation.[31] An iron rod also, at the highest degree of
_red_ heat, and even at the common degree of _white_ heat, did not
inflame explosive mixtures of the fire-damp; but when in brilliant
combustion, it produced the effect.
[31] Whence he observes that, if it be necessary to be present
in a part of the mine where the fire-damp is explosive, for the
purpose of clearing the workings, taking away pillars of coal, or
other objects, the workmen may be safely lighted by a fire made
of charcoal, which burns without flame.
He moreover found that the heat produced by the combustion of
the fire-damp was much less than that occasioned by most other
inflammable gases under similar circumstances; and hence its
explosion was accompanied with comparatively less expansion:
a circumstance of obvious importance in connection with the
propagation of its flame.
Numerous experiments were likewise instituted by him with a view
to determine the proportions of air with which the fire-damp
required to be mixed, in order to produce an explosive atmosphere;
and he found the quantity necessary for that purpose to be very
considerable; even when mixed with three or nearly four times its
bulk of air, it burnt quietly in the atmosphere, and extinguished
a taper. When mixed with between five and six times its volume of
air, it exploded freely. The mixture which seemed to possess the
greatest explosive power was that of seven or eight parts of air to
one of gas.
On adding azote and carbonic acid in different proportions to
explosive mixtures of fire-damp, it was observed that, even in
very small quantities, these gases diminished the velocity of
the inflammation, or altogether destroyed it. In this stage of
the enquiry, the important fact was discovered, that explosive
mixtures could not be fired in metallic tubes of certain lengths
and diameters.[32] In exploding, for instance, a mixture of one
part of gas from the distillation of coal, and eight parts of air,
in a tube of a quarter of an inch in diameter and A foot long, more
than a second was required before the flame reached from one end of
the tube to the other; and not any mixture could be made to explode
in a glass tube of one-seventh of an inch in diameter. In pursuing
these experiments, he found that, by diminishing its diameter, he
might in the same ratio shorten the tube without danger; and that
the same principle of security was obtained by diminishing the
length and increasing the number of the tubes, so that a great
number of small apertures would not pass explosion when their
depth was equal to their diameter. This fact led him to trials
upon sieves made of wire-gauze, or metallic plates perforated with
numerous small holes, and he found that it was impossible to pass
explosions through them.[33]
[32] Mr. Tennant had, some years before, observed that mixtures
of the gas, from the distillation of coal, and air, would not
explode in very small tubes. Davy, however, was not aware of this
at the time of his researches.
[33] The apertures in the gauze should not be more than
one-twentieth of an inch square. As the fire-damp is not inflamed
by ignited wire, the thickness of the wire is not of importance;
but wire from one-fortieth to one-sixtieth of an inch in diameter
is the most convenient.
In reasoning upon these several phenomena, it occurred to him,
that as a high temperature was required for the inflammation of
the fire-damp, and as it produced in burning, comparatively, _a
small degree_ of heat, the effect of carbonic acid and azote, as
well as that of the surfaces of small tubes, in preventing its
explosion, depended upon their cooling powers; that is to say, upon
their lowering the temperature of the exploding mixture to such
a degree, that it was no longer sufficient for its continuous
inflammation. In support of this theory, he ascertained that
metallic tubes resisted the passage of the flame more powerfully
than glass tubes of similar lengths and diameters, metal being the
better conductor of heat; and that carbonic acid was more effective
than azote in depriving the fire-damp of its explosive power, in
consequence, as he considered, of its greater capacity for heat,
and likewise of a higher conducting power connected with its
greater density.
In this short statement, the reader is presented with the whole
theory and operation of the Safety-lamp, which is nothing more
than an apparatus by which the inflammable air, upon exploding
in its interior, cannot pass out without being so far cooled, as
to deprive it of the power of communicating inflammation to the
surrounding atmosphere. The principle having been once discovered,
it was easy to adopt and multiply practical applications of it.
From the result of these researches, it became at once evident,
that to light mines infested with fire-damp, with perfect security,
it was only necessary to use an air-tight lantern, supplied with
air from tubes of small diameter, through which explosions cannot
pass, and with a chimney, on a similar principle, at the upper
part, to carry off the foul air. A common lantern, to be adapted
to the purpose, merely required to be made air-tight in the door
and sides, and to be furnished with the chimney, and the system of
safety apertures below and above the flame of the lamp. Such, in
fact, was Davy's first Safety-lamp; and having afterwards varied
the arrangement of the tubes in different ways, he at length
exchanged them for canals, which consisted of close concentric
hollow metallic cylinders of different diameter, so placed together
as to form circular canals of the diameter of from one-twenty-fifth
to one fortieth of an inch; and of an inch and seven-tenths in
length; by which air is admitted in much larger quantities than
by the small tubes, and they are moreover much superior to the
latter in practical application. He also found, that longitudinal
air-canals of metal might be employed with the same security as
circular canals; and that a few pieces of tin plate, soldered
together with wires to regulate the diameter of the canal, answered
the purpose of the feeder or safe chimney, as well as drawn
cylinders of brass.
The subjoined explanatory sketches will assist in rendering
the scheme intelligible, and obviate the possibility of any
misconception of the subject.
[Illustration]
FIG. 1. represents the first Safe lantern, with its air-feeder
and chimney furnished with safety metallic canals. The sides are
of horn or glass, made air-tight by putty or cement. A. is the
lamp through which the circular air-feeding canals pass. B. is the
chimney containing four such canals; above it is a hollow cylinder,
with a cap to prevent dust from passing into the chimney. C. is
the hole for admitting oil. F. is the rim round the bottom of the
lantern, to enable it to bear motion.
[Illustration]
FIG. 2. exhibits an enlarged view of the safety concentric canals,
which, if one-twenty-fifth of an inch in diameter, must not be less
than two inches in exterior circumference, and one-seventh of an
inch high.
[Illustration]
FIG. 3. exhibits the longitudinal safety canals.
[Illustration]
FIG. 4. represents a Safety-lamp having a glass chimney, covered
with tin-plate, and the safety apertures in a cylinder with a
covering above: the lower part is the same as in the lantern.
[Illustration]
FIG. 5. A glass tube furnished with _flame sieves_, in which a
common candle may be burnt. A A. the flame sieves. B. a little
plate of metal to prevent the upper flame sieve from being acted on
by the current of hot air.
During the short visit of Sir Humphry Davy at Bishop Wearmouth,
he saw the lamp which Dr. Clanny was then engaged in perfecting.
It has been already observed, that it was secured against the
effects of fire-damp by being supplied with atmospheric air
previously conveyed through water.[34] The machinery of this lamp
was far too cumbrous to be of general use; but its inventor was
justly commended by Davy for his ingenuity and perseverance. It
unfortunately happened that, in consequence of some erroneous
representations made to Dr. Clanny, he received the impression
that Sir Humphry had not been disposed to treat his invention with
sufficient respect, nor had given him the credit to which he was so
justly entitled. This suspicion, which had been long industriously
kept alive, was however ultimately removed.
[34] M. de Humboldt conceived and executed the plan of a lamp in
1796, for giving a safe light in mines, upon a similar principle
of entire insulation from the air.--_Journal des Mines_, t. viii.
p. 839.
The following letter refers to this unfortunate circumstance. I
have adverted to it in these memoirs, for the purpose of showing
what an unfair spirit of rivalry, and what a succession of petty
jealousies were excited by those generous and disinterested labours
of Davy, which ought to have called forth nothing but the most
lively expressions of gratitude for his services, and admiration of
his genius.
TO THE REVEREND DR. GRAY.
23, Grosvenor Street, December 13.
MY DEAR SIR,
A Friend of mine has sent me a newspaper--the Tyne Mercury,
containing a very foolish libel upon me. It states, amongst
other things, that I did not mention Dr. Clanny, or his lamp,
in my late paper read before the Royal Society; whereas I
mentioned his lamp as a very ingenious contrivance, and named
him amongst the gentlemen who obligingly furnished me with
information upon the subject.
It will be needless for me to point out to you that my lamp
has no one principle in common with that of Dr. Clanny. He
forces in his air through water by bellows. In mine, the air
passes through safety canals without any mechanical assistance.
Mine is a common lantern made close, and furnished with safety
canals.
I hope I shall not hear that Dr. Clanny has in any way
authorized or promoted so improper a statement as that in the
Tyne Mercury; indeed, I do not think it possible.
I have at last obtained a complete model of my lamp, after many
disappointments from the instrument-maker. I hope in a few days
to send you a _Safe lantern_, as portable as a common-made one,
and the perfect security of which is demonstrable.
I am, my dear Sir, your sincerely obliged,
H. DAVY.
TO THE SAME.
Grosvenor Street, December 15.
MY DEAR SIR,
I shall inclose the first sheet of my paper, and shall be glad
to preface it by some observations when you reprint it.
I shall forward my lanterns and lamps to you in a few days.
They are _absolutely_ safe; and if the miners have any more
explosions from their light, it will be their own fault.
You will find, when you see my construction, that the
principles as well as the execution are entirely new.
You will find in the second sheet of my paper, which I hope to
be able to send to-morrow, the _principles_ of _security_, and
its limits unfolded.
I am, my dear Sir, very sincerely yours,
H. DAVY.
TO THE SAME.
London, January 1, 1816.
MY DEAR SIR,
I fear you will have accused me of procrastination in delaying
to send you my papers and my lamps.
The papers read to the Royal Society have been printed; but
during the period that has elapsed since I last wrote to you,
I have made a discovery much more important than those which I
have already had the honour of communicating to you.
I have made very simple and economical lanterns, and candle
guards, which are not only _absolutely safe_, but which give
light by means of the fire-damp, and which, while they disarm
this destructive agent, make it useful to the miner.
This discovery is a consequence of that which I communicated
to you in my last letter on the wire sieves. I hope to be able
to send you on Wednesday the printed account of my results,
together with models of lamps which will burn and consume all
explosive mixtures of the fire-damp.
I have at last finished my enquiries with perfect satisfaction
to myself, and I feel highly obliged to you for having called
my attention to a subject where my labours will, I hope, be of
some use.
I am, my dear Sir, very sincerely yours,
H. DAVY.
It is impossible to approach the consideration of this last, the
most signal and splendid of his triumphs, without feelings of the
highest satisfaction. He had already, as we have seen, disarmed the
fire-damp of its terrors, it only remained for him to enlist it
into his service. The simple means by which this was effected are
as interesting as their results are important.[35]
[35] "An Account of an Invention for giving Light in explosive
mixtures of Fire-damp in Coal Mines, by consuming the Fire-damp."
Read before the Royal Society, Jan. 11, 1816.
Davy had previously arrived at the fact, that wire-gauze might be
substituted as air-feeders to the lamp, in the place of his tubes
or safety canals; but not until after the lapse of several weeks,
did the happy idea of constructing the lamp entirely of wire-gauze
occur to him:--the history of this elaborate enquiry affords a
striking proof of the inability of the human mind to apprehend
simplicities, without a process of complication which works as the
grappling machinery of truth.
His original lamp with tubes or canals, as already described, was
perfectly safe in the most explosive atmosphere, but its light was
necessarily extinguished by it; whereas in the wire-gauze cage,
the fire-damp itself continues to burn, and thus to afford to the
miner a useful light, while he is equally secured from the fatal
effects of explosion.
[Illustration]
All then required for his guidance and protection in the darkness
of the mine, are candles or lamps surrounded by small wire cages,
which will at once supply air to the flame, and light to the miner;
they may be obtained for a few pence, and be variously modified as
circumstances may render necessary.
The reader is here presented with a sketch of the gauze instrument,
in its first and simplest form. The original lamp is preserved in
the laboratory of the Royal Institution.
Nothing now remained but to ascertain the degree of fineness
which the wire-gauze ought to possess, in order to form a secure
barrier against the passage of flame. For this purpose, Davy
placed his lighted lamps in a glass receiver, through which there
was a current of atmospherical air, and by means of a gasometer
filled with coal gas, he made the current of air which passed into
the lamp more or less explosive, and caused it to change rapidly
or slowly at pleasure, so as to produce all possible varieties
of inflammable and explosive mixtures; and he found that iron
wire-gauze composed of wires from one-fortieth to one-sixtieth of
an inch in diameter, and containing twenty-eight wires, or seven
hundred and eighty-four apertures to the inch, was safe under all
circumstances in atmospheres of this kind; and he consequently
employed that material in guarding lamps for the coal mines, where,
in January 1816, they were immediately adopted, and have long been
in general use.
Observations upon them in their working state, and upon the
circumstances to which they are exposed, have led to a few
improvements or alterations, merely connected with the modes of
increasing light or diminishing heat, which were obvious from the
original construction.
[Illustration]
The annexed woodcut represents the lamp which is in present use.
A is a cylinder of wire-gauze, with a double top, securely and
carefully fastened, by doubling over, to the brass rim B, which
screws on to the lamp C. The whole is protected by strong iron
supports D, to which a ring is affixed for the convenience of
carrying it.
In a paper read before the Royal Society, on the 23rd of January
1817, entitled, "Some new Experiments and Observations on the
Combustion of Gaseous Mixtures, with an Account of a method of
preserving a continued Light in mixtures of inflammable Gases and
Air without Flame," Sir H. Davy announces the application of a
principle which he had discovered in the progress of his researches
for increasing the utility of the Safety-lamp, and which, a century
ago, would have unquestionably exposed its author to the charge of
witchcraft.
Having ascertained that the temperature of flame is infinitely
higher than that necessary for the ignition of solid bodies,
it appeared to him probable that, in certain combinations of
gaseous bodies, although the increase of temperature might not
be sufficient to render the gaseous matters themselves luminous,
they might nevertheless be adequate to ignite solid matters
exposed to them. During his experiments on this subject, he was
led to the discovery of the curious phenomenon of slow combustion
without flame. He observes, that there cannot be a better mode
of illustrating the fact, than by an experiment on the vapour of
ether or of alcohol. Let a few coils of wire of platinum of the
one-sixtieth or one-seventieth of an inch be heated by a hot poker
or candle, and let it be brought into the glass; it will presently
become glowing, almost white hot, and will continue so, as long as
a sufficient quantity of vapour and of air remain in the glass.[36]
[36] This principle has been applied for constructing what has
been termed the _Aphlogistic Lamp_, which is formed by placing
a small coil of platinum wire round the wick of a common spirit
lamp. When the lamp, after being lighted for a few moments,
is blown out, the platinum wire continues to glow for several
hours, as long as there is a supply of spirit of wine, and to
give light enough to read by; and sometimes the heat produced
is sufficient to rekindle the lamp spontaneously. The same
phenomena are produced by the vapour of camphor; and an aromatic
fumigating lamp has lately been advertised for sale, which is no
other than the contrivance above described; and it is evident
that, if the spirit be impregnated with fragrant principles, an
aromatic vinegar will be developed during its slow combustion,
and diffused in fumes through the apartment.
This experiment on the slow combustion of ether is accompanied with
the formation of a peculiar acrid and volatile substance possessed
of acid properties, which has been particularly examined by Mr.
Daniell, who, having at first regarded it as a new acid, proposed
for it the name of _Lampic_ acid, in allusion to the researches
which led to its discovery; he has, however, since ascertained that
its acidity is owing to the acetic acid, which is combined with
some compound of carbon and hydrogen, different both from ether and
alcohol.
The phenomena of slow combustion, as exhibited in certain states of
the mine, by the Safety-lamp, are highly curious and interesting.
By suspending some coils of fine wire of platinum[37] above
the wick of his lamp, the miner will be supplied with light in
mixtures of fire-damp no longer explosive; for should his flame
be extinguished by the quantity of fire-damp, the little coil of
platinum will begin to glow with a light sufficiently bright to
guide him in what would otherwise be impenetrable darkness, and to
lead him into a purer atmosphere, when the heat thus increased will
very frequently be sufficient to rekindle his lamp!
[37] Sir Humphry Davy attempted to produce the phenomena with
various other metals, but he only succeeded with platinum and
palladium; these bodies have low conducting powers, and small
capacities for heat, in comparison with other metals, which seem
to be the causes of their producing, continuing, and rendering
sensible, these slow combustions.
In this case it will be readily perceived, that the combustion of
the fire-damp is continued so slowly, and at so low a temperature,
as not to be adequate to that ignition of gaseous matter which
constitutes flame, although it excites a temperature sufficient to
render platinum wire luminous.
Sir Humphry Davy observes, that there never can be any danger
with respect to respiration, whenever the wire continues ignited;
for even this phenomenon ceases when the foul air forms about
two-fifths of the volume of the atmosphere.
The experiment, as originally performed by the illustrious chemist,
is so interesting and instructive, that I shall here relate it in
his own words.
"I introduced into a wire-gauze Safe lamp a small cage made of
fine wire of platinum of one-seventieth of an inch in thickness,
and fixed it by means of a thick wire of the same metal about
two inches above the wick which was lighted. I placed the whole
apparatus in a large receiver, in which, by means of a gas-holder,
the air could be contaminated to any extent with coal gas. As soon
as there was a slight admixture of coal gas, the platinum became
ignited; the ignition continued to increase till the flame of the
wick was extinguished, and till the whole cylinder became filled
with flame; it then diminished. When the quantity of coal gas was
increased, so as to extinguish the flame, at the moment of the
extinction the cage of platinum became white hot, and presented a
most brilliant light. By increasing the quantity of the coal gas
still farther, the ignition of the platinum became less vivid:
when its light was barely sensible, small quantities of air were
admitted, its heat speedily increased; and by regulating the
admission of coal gas and air, it again became white hot, and soon
after lighted the flame in the cylinder, which as usual, by the
addition of more atmospherical air, rekindled the flame of the
wick."
I have thus related, somewhat in detail, the history of a
discovery, which, whether considered in relation to its scientific
importance, or to its great practical value, must be regarded as
one of the most splendid triumphs of human genius. It was the
fruit of elaborate experiment and close induction; chance, or
accident, which comes in for so large a share of the credit of
human invention, has no claims to prefer upon this occasion; step
by step, may he be followed throughout the whole progress of his
research, and so obviously does the discovery of each new fact
spring from those that preceded it, that we never for a moment lose
sight of our philosopher, but keep pace with him during the whole
of his curious enquiry.
He commenced, as we have seen, with ascertaining the degree of
combustibility of the fire-damp, and the limits in which the
proportions of atmospheric air and carburetted hydrogen can be
combined, so as to afford an explosive mixture. He was then led to
examine the effects of the admixture of azote and carbonic acid
gas; and the result of those experiments furnished him with the
basis of his first plan of security. His next step was to enquire
whether explosions of gas would pass through tubes; and on finding
that this did not happen, if the tubes were of certain lengths and
diameters, he proceeded to examine the limits of such conditions,
and by shortening the tubes, diminishing their diameters, and
multiplying their number, he at length arrived at the conclusion,
that a simple tissue of wire-gauze afforded all the means of
perfect security; and he constructed a lamp, which has been truly
declared to be as marvellous in its operation, as the storied lamp
of Aladdin, realizing its fabled powers of conducting in safety,
through "fiends of combustion," to the hidden treasures of the
earth. We behold a power which, in its effects, seemed to emulate
the violence of the volcano and the earthquake, at once restrained
by an almost invisible and impalpable barrier of network--we
behold, as it were, the dæmon of fire taken captive by Science,
and ministering to the convenience of the miner, while harmlessly
fluttering in an iron cage.
And yet, wonderful as the phenomenon may appear, his experiments
and reasonings have demonstrated, that the interruption of flame by
solid tissues permeable to light and air, depends upon no recondite
or mysterious cause, but simply upon their cooling powers, which
must always be proportional to the smallness of the mesh, and the
mass of the metal.
When it is remembered that the security thus conferred upon the
labouring community, is not merely the privilege of the age in
which the discovery was effected, but must be extended to future
times, and continue to preserve human life as long as coal is dug
from our mines, can there be found in the whole compass of art or
science, an invention more useful and glorious?
The wire-gauze lamp has now been several years extensively used in
the mines, and the most satisfactory and unequivocal testimonies
have been published of the complete security which it affords. They
have amongst the miners obtained the name of _Davys_; and such is
the confidence of the work men in their efficacy, that by their aid
they enter the most explosive atmospheres, and explore the most
remote caverns, without the least dread of their old enemy the
_fire-damp_.
Into the mines of foreign countries the Safety-lamp has been
introduced with similar success; and the illustrious discoverer has
been repeatedly gratified by accounts of the enthusiasm with which
his invention has been adopted in various parts of Europe.[38]
[38] A pamphlet appeared at Mons, in the year 1818, on the
explosions that occur in coal mines, and on the means of
preventing them by Davy's Safety-lamp. It was published under
the direction of the Chamber of Commerce and Manufactures of
Mons, accompanied by notes, and by the results of a series of
experiments that had been conducted by M. Gossart, President
of the Chamber. The province of Hainault is said to be richer
in coal mines than any other part of the Continent of Europe,
and to have no less than one hundred thousand persons employed
in the working them. The same kind of dangerous accidents
occurred in these mines as in those of the North of England,
and various expedients had been adopted for their prevention,
which, however, availed but little in obviating them. "All the
precautions," observe the reporters, "which had been hitherto
known or practised, had not been able to preserve the unfortunate
miners from the terrible effects of explosion. It is therefore an
inappreciable benefit which we confer by making known the equally
simple and infallible method of preventing these accidents, which
has been discovered by the celebrated Humphry Davy."
M. Gossart gives an ample and accurate detail of the properties
of the explosive gas, and confirms the truth of Davy's
experiments, by which the high temperature necessary for its
inflammation, and the consequent means of preventing it, by
reducing that temperature, as effected during its passage through
wire-gauze, are clearly demonstrated.
The lamp appears from this report to have been as useful in the
mines of Flanders as in those of England. The Pamphlet is a
valuable document, inasmuch as it affords an independent proof of
the security of the instrument, and displays the high sense of
obligation which foreign nations entertain to Sir Humphry Davy
for his invention.
Nor is the utility of this invention limited to the operations of
mining. In gas manufactories, spirit warehouses,[39] or druggists'
laboratories, and in various other situations, where the existence
of an explosive atmosphere[40] may expose persons to danger, the
Safety-lamp may be advantageously used; and as science proceeds in
multiplying the resources of art, this instrument will no doubt be
found capable of many new applications.
[39] The danger of carrying a naked light into an atmosphere
impregnated with the fumes of spirit was awfully exemplified
by the loss of the Kent East Indiaman, by fire, in the Bay of
Biscay, on the 1st of March 1825.
[40] In cases where there is any suspicion of accumulations of
carburetted hydrogen from the leakage of gas pipes, or from other
sources, the safety-lamp should always be employed. A terrible
accident occurred some years since at Woolwich, from a room
filled with the vapour of coal-tar, for the purpose of drying and
seasoning timber intended for ship-building. As the combustion
arose from the flame issuing through the flue, which ran along
the apartment, at the moment the damper was applied at the top
of the building, it is evident that, had a wire-gauze guard
been used, the accident could not have occurred. The house was
completely demolished, and nine persons were unfortunately killed.
By the permission of the President and Council of the Royal
Society, several accounts of these researches, and of the invention
and use of the Safety-lamp were printed, and circulated through the
coal districts.
It might have been fairly expected that, in a district which had
been so continually and so awfully visited by explosions, against
which no human foresight had as yet been able to provide a remedy,
the disinterested services of the greatest chemist of the age would
at least have been received without a dissentient voice, and that
his invention of security would have escaped the common fate of all
great discoveries, and been accepted with every homage of respect
and gratitude; but the inventor of the Safety-lamp was doomed to
encounter a bitter hostility from persons whom a spirit of rivalry,
or a feeling of hopeless emulation, had cemented into a faction.
From the period of the first announcement of the Safety-lamp, a
prejudice against its use was industriously circulated amongst the
miners; and some persons even maintained the monstrous proposition,
that any protection against the explosions of fire-damp would
injure more than it could serve the collier, by inducing him to
resume abandoned works, and thus continually to inhale a noxious
atmosphere.
The utility of the lamp having been established, in spite of every
opposition, the claims of Sir H. Davy to its invention were next
publicly challenged.
It will hereafter be scarcely believed that an invention so
eminently philosophic, and which could never have been derived
but from the sterling treasury of science, should have been
claimed in behalf of an engine-wright of Killingworth, of the name
of Stephenson--a person not even professing a knowledge of the
elements of chemistry. As the controversy to which this claim gave
birth has long since subsided, I would willingly have treated it as
a passing cloud, had not its shadow remained. The circumstances,
however, of the transaction stand recorded in the Magazines of the
day, and the biographer of Davy would compromise his rights, by
omitting to notice the attempts that have been made to invalidate
them.
The claims which were made for the priority of Mr. Stephenson's
invention of the Safety-lamp were urged in several communications
in the Newcastle Courant. It has been said in reply, that if dates
were taken as evidence, not merely of priority, but of originality
of invention, it must follow that Mr. Stephenson's lamp was derived
from that of Sir H. Davy. With regard to the first of Stephenson's
lamps, the only one upon which the shadow even of a claim can
be founded, it is unnecessary for the friends of truth to adopt
such a line of defence; indeed, after a deliberate examination of
all that has been published on the subject, I am very willing to
believe that Mr. Stephenson did construct the lamp which dates
its origin from the 21st of October 1815, without any previous
knowledge of the conclusions at which Davy had arrived; for it was
first announced to the Coal-trade by Mr. R. Lambert on the 3rd of
November, to the very meeting at which Sir H. Davy's private letter
was inadvertently read.--But what were the principles, and what the
construction of this lamp?
It would appear that Mr. Stephenson had entertained some vague
notion of the practicability of consuming the fire-damp as fast as
it entered the lamp, and that if admitted only in small quantities,
it would not explode the surrounding atmosphere: for effecting
this object, he constructed a lamp with an orifice, over which
was placed a slide, by the movement of which the opening could be
enlarged, or diminished, and the volume of fire-damp to be admitted
into the lamp regulated according to circumstances. Now such a lamp
could be nothing else than an exploding lamp; for to make it burn
in common air, the orifice must have been so wide that, on going
into an explosive atmosphere, the combustion in the interior could
not have failed to pass it, and to have exploded the mine. Here
then is a _safety_-lamp, which as long as it is safe, will not
burn, and the moment it begins to burn, it becomes unsafe!
The testimonies in favour of the security afforded by this lamp
were evidently procured from persons who were not only ignorant
of the principles of its construction, but of the methods to be
pursued for ascertaining its safety. I am surely justified in such
a statement, when, instead of an _explosive mixture_, I find them
throwing in _pure fire-damp_, which will always extinguish flame,
whether burning in a safe or unsafe lamp.
The importance and utility of Davy's lamp having been completely
established by the severest ordeals, the general gratitude of
the country began more publicly to display itself, and a very
strong feeling prevailed, that some tribute of respect should be
paid to its inventor; in accordance with which, a deputation of
the Coal-owners of the rivers Tyne and Wear, and of the ports of
Hartley and Blyth, requested the honour of an interview with Sir
H. Davy; upon which occasion they presented him with the following
letter, containing an expression of the thanks of the Coal-owners.
TO SIR HUMPHRY DAVY, LL.D. &c.
Newcastle, March 25, 1816.
SIR,
As chairman of the general meeting of proprietors of coal-mines
upon the rivers Tyne and Wear, held in the Assembly-rooms at
Newcastle, on the 18th instant, I was requested to express
to you their united thanks and approbation for the great and
important discovery of your Safety-lamp for exploring mines
charged with inflammable gas, which they consider admirably
calculated to obviate those dreadful calamities, and the
lamentable sacrifice of human life, which of late years have so
frequently occurred in the mines of this country.
They are most powerfully impressed with admiration and
gratitude towards the splendid talents and brilliant
acquirements that have achieved so momentous and important
a discovery, unparalleled in the history of mining, and not
surpassed by any discovery of the present age; and they hope
that, whilst the tribute of applause and glory is showered
down upon those who invent the weapons of destruction, this
great and unrivalled discovery for preserving the lives of our
fellow-creatures, will be rewarded by some mark of national
distinction and honour. I am, Sir,
Your most obedient humble Servant,
GEORGE WALDIE, Chairman.
A plan, however, was under consideration for recording the
admiration and gratitude of the Coal-owners, by a more permanent
and solid memorial. The nature of this proposition will be best
disclosed by inserting the following letter from Mr. Buddle.
TO THE REV. DR. GRAY.
Wall's-End Colliery, August 27, 1816.
SIR,
As I know that you feel much interest in all matters relating
to Sir H. Davy's Safety-lamp, I trust you will excuse the
liberty I take in informing you, that the Committee of the
Tyne, approving highly of the suggestion, that some mark of
acknowledgment and respect should be presented to Sir Humphry
by the Coal-trade of this country, for the happy invention
of his lamp, have convened a general meeting of Coal-owners,
to be holden at my office in Newcastle, on Saturday next the
31st instant, at twelve o'clock, to take the subject into
consideration.
I should have sooner informed you of this proposed meeting,
had I not been detained in Cumberland until yesterday; but I
shall have the pleasure of transmitting to you a copy of its
resolutions.
I am sure that you will be gratified to learn that the lamps
continue to go on as well as possible. We now have twelve dozen
of them in daily use at this place. I have the pleasure to
remain, with the greatest respect, Sir,
Your most obedient humble Servant,
JOHN BUDDLE.
TO THE SAME.
Newcastle, September 7, 1816.
SIR,
I now have the pleasure of sending you a copy of the
Resolutions of the general meeting of Coal-owners on the 31st
instant, and shall take the liberty of informing you of the
future progress of this affair.
Sir Humphry did me the honour yesterday to accompany me
through the workings of a coal-pit at Wall's-End, when I had
an opportunity of witnessing several interesting experiments
on his Safety-lamp; and I have the satisfaction to add, that
I believe he has now advanced it to the highest degree of
perfection.
I am, respectfully, Sir,
Your humble Servant,
JOHN BUDDLE.
The satisfactory result of this visit Sir Humphry communicated to
Mr. Lambton, now Lord Durham; and I shall take this opportunity to
state, that for this as well as for several other letters I shall
hereafter have occasion to introduce, I am indebted to that noble
Lord, through the kind application of my friend Sir Cuthbert Sharp.
TO J. G. LAMBTON, ESQ. M.P.
Newcastle, September 9, 1816.
MY DEAR SIR,
Since I last had the pleasure of seeing you, I have examined
the workings in the Wall's-End collieries by the lamps, and
have tried them in various explosive mixtures.
On Sunday, I went with Mr. Buddle to your _blower_, with the
single lamps furnished with small tin reflectors. This simple
modification rendered them perfectly safe, even in the furious
_blow-pipe_, and at the same time increased their light.
Nothing could be more satisfactory than all the trials.
I have left a paper in the hands of the Rev. J. Hodgson, which
will be printed in a day or two; and I have desired him to send
you ten copies, or as many more as you may like to have.
I trust I have now left nothing undone as to the perfect
security of the lamps, under every possible circumstance.
I feel highly gratified that it was at your mines I effected
the only object that remained to be accomplished--that of
guarding against _blowers_ meeting fresh currents of air.
I thank you very sincerely for the interest you have taken in
the lamps, connected with my efforts to render them applicable
in all cases. I remain, &c.
H. DAVY.
On the 19th of October 1816, a letter appeared in the Durham County
Advertiser, dated "Gosforth, August 22nd, 1816," in the name of
Mr. W. Brandling, in which, alluding to the Resolutions of the
Coal-owners of the 31st of August, he expresses a wish that a
strict examination should take place previous to the adoption of
a measure which might convey a decided opinion to the public, as
to the person to whom the invaluable discovery of the Safety-lamp
is actually due. "The conviction," says he, "upon my mind is, that
Mr. George Stephenson, of Killingworth Colliery, is the person who
first discovered and applied the principle upon which safe lamps
may be constructed; for, whether the hydrogen gas is admitted
through capillary tubes, or through the apertures of wire-gauze,
which may be considered as merely the orifices of capillary tubes,
does not, as I conceive, in the least affect the principle.
"In the communications I have seen from Sir H. Davy, no dates
are mentioned; and it is by a reference to them only that the
question can be fairly decided. For the information of the Meeting,
therefore, I shall take the liberty of enclosing some which I
received from Mr. Stephenson, to the correctness of which, as
far as I am concerned, I can bear testimony; at the same time
I beg leave to add, that the principle of admitting hydrogen
gas in such small detached portions that it would be consumed
by combustion,[41] was, I understand, stated by him to several
gentlemen, as the idea he had embraced two months before his lamp
was originally constructed."
[41] Granted:--but what connexion has that with the principle of
Davy's lamp, or with any _Safety_ lamp?
Mr. Brandling then proceeds to state, that the Killingworth lamp,
with a tube to admit the air, and a slide at the bottom of such
tube to regulate the quantity to be admitted, was first tried in
the Killingworth pits on Saturday October the 21st, 1815; but not
being found to burn well, another was ordered the same day with
three capillary tubes to admit the air; and on being tried in the
mine on the 4th of November following, was found to burn better
and to be perfectly _safe_.[42] On the 17th of November, it was
_tried_[43] at Killingworth office with inflammable air before
Richard Lambert, Esq.; and on the 24th of the same month, before C.
J. Brandling, Esq. and Mr. Murray.
[42] It could not have been safe.
[43] "Tried"--but how was it tried?--by forcing in _pure_
fire-damp, which will extinguish any lamp, instead of exposing
the flame to an explosive mixture, which could alone furnish any
test of its security.
"On the 30th of November," he says, "a lamp was tried in the mine,
in which the air was admitted by means of a double row of small
perforations, and found to be perfectly safe, and to burn extremely
well."[44]
[44] Very likely: but the reader will please to recollect,
that Sir H. Davy had, before this, published an account of his
principle of safety by systems of tubes or canals.
At an adjourned Meeting of the Coal-owners, held on the 11th of
October 1816, J. G. Lambton, Esq. M.P. in the chair; Mr. William
Brandling moved--"That the meeting do adjourn, until, by a
comparison of dates, it shall be ascertained whether the merit
of the Safety-lamp belongs to Sir Humphry Davy or to Mr. George
Stephenson."
On the question being put thereon, THE SAME PASSED IN THE NEGATIVE.
A great number of the Coal-owners, instead of pursuing the idea
which had at first been suggested, of a general contribution on
the vend, immediately commenced a subscription of individual
proprietors of coal-mines; a measure which, it was thought, would
express more distinctly and unequivocally the opinion of the trade
as to the merit of the invention. The plan is developed in the
following letter.
TO THE REVEREND DR. GRAY.
Wall's-End Colliery, October 27, 1816.
SIR,
It is the anxious wish of almost every individual in the trade
to compliment Sir Humphry Davy, in that way which may be most
grateful to his feelings.
It has been suggested that the object will be best attained by
substituting an individual (colliery) subscription, instead of
the proposed contribution on the vend; and it will at the same
time show more distinctly the real opinion of the trade as to
the merit of the invention.
This idea was not suggested till yesterday afternoon, and of
course there has been but little time to communicate it to
the several Coal-owners; but _all_ who have heard of the plan
approve of it.
To facilitate the business, the committee have formed the
annexed scale of contribution.[45]
* * * * *
I trust, Sir, you will excuse the trouble which I have given
you on this subject; but I am aware that you must feel
interested in it; and I hope, Sir, you will allow me to add,
that I am fully sensible of the obligation which the Coal trade
is under to yourself, for having drawn Sir H. Davy's attention
to that particular line of investigation, which has led to the
important discovery of the Safety-lamp. I am, Sir, with the
greatest respect, your most obedient humble servant,
JOHN BUDDLE.
[45] I have not thought it necessary to enumerate the various
sums which the different mines were called upon to contribute.
Some slight alterations were afterwards made in this scheme, in
consequence of a wish having been expressed that the Bishop of
Durham and the Duke of Northumberland should take the lead in a
subscription. The following letter conveys some farther information
upon this subject.
TO THE REVEREND DR. GRAY.
Newcastle, January 11, 1817.
SIR,
I have to acknowledge the receipt of your letter of the 9th
instant, communicating the intention of the Reverend the Dean
and Chapter of Durham, to subscribe fifty guineas towards the
plate to be presented to Sir H. Davy, which, together with two
hundred guineas from the Coal-owners of the Wear, makes the
subscription amount to nearly £1500, and I shall expect some
farther subscriptions.
I am sure it will afford you satisfaction to learn that the
lamps still continue to give the most gratifying proofs of
the advantages resulting from their invention, and that not a
single inch of human skin has been lost by fire, wherever they
have been used.
Sir Humphry has just made another important improvement in the
lamp, by constructing the cylinder of _twisted_ wire-gauze.
Lamps thus constructed, possess the singular property of not
becoming red-hot, under any circumstances of exposure to
explosive mixtures, whether urged by a blast, or in a state of
rest. I am with great respect, Sir, your most obedient humble
servant,
JOHN BUDDLE.
It may be collected from the following letter, that the Committee,
in announcing to Sir H. Davy the intended present of plate,
delicately sounded him as to the form in which it would be most
agreeable to him.
TO N. CLAYTON, ESQ.
Grosvenor Street, March 23, 1817.
SIR,
On my return to town, after an absence of some days, I found
the letter of March the 13th, with which you honoured me, at
the Royal Institution. I shall not lose a moment in replying
to it, and in expressing my grateful feelings for the very
flattering communication it contains.
The gentlemen interested in the coal-mines of the two rivers
Tyne and Wear, cannot offer me any testimony of their kindness,
which I shall not receive with infinite pleasure.
I hardly know how to explain myself on the particular subject
of your letter; but as the Committee express themselves
satisfied as to the utility of the Safety-lamp, I can only
desire that their present, as it is highly honourable to me,
should be likewise useful to my friends, and a small social
circle, which it would be as a dinner-service for ten or twelve
persons.
I wish that even the plate from which I eat should awaken my
remembrance of their liberality, and put me in mind of an event
which marks one of the happiest periods of my life.
I cannot find any language sufficiently strong to express my
thanks to the gentlemen for the manner in which they have
distinguished my exertions in their cause, and in the cause of
humanity. I have the honour to remain, &c.
H. DAVY.
To revert once again to the faction--for such I must denominate
it--which, in opposition to the most unequivocal evidence,
continued to support the unjust claims of Mr. Stephenson; it would
appear from various letters in my possession, that the feelings of
Davy were greatly exasperated by this ungenerous conduct.
I shall introduce one of these letters, playful in the midst of its
wrath, addressed to Mr. Lambton, the friend[46] of his youth, and
the manly and kind supporter of his scientific character, in the
hour of persecution.
[46] It will be remembered that they resided together in the
house of Dr. Beddoes. See page 59, vol. i. of these memoirs.
In the library at Lambton, there is a goodportrait of
Sir Humphry.
TO J. G. LAMBTON, ESQ. M.P.
Queen Square, Bath, Oct. 29, 1816.
MY DEAR SIR,
The severe indisposition of my wife has altered my plans. Your
letter slowly followed me here.
Mr. ---- is one of the persons who, after I had advanced a
principle of security for a lamp, came upon the ground to
endeavour to jockey me. I was not looking to a prize, I merely
came forward to show an animal, the breed of which might be
useful, when Mr.----, Dr.----, &c. brought their sorry jades,
which had never before been seen or heard of, to kick at my
blood mare.
I never heard a word of George Stephenson and his lamps till
six weeks after my principle of security had been published;
and the general impression of the scientific men in London,
which is confirmed by what I heard at Newcastle, is, that
Stephenson had some loose idea floating in his mind, which he
had unsuccessfully attempted to put in practice till after my
labours were made known;--then, he made something like a safe
lamp, except that it is not _safe_, for the apertures below are
four times, and those above, twenty times too large; but, even
if Stephenson's plans had not been posterior to my principles,
still there is no analogy between his glass exploding machine,
and my metallic tissue, permeable to light and air, and
impermeable to flame.
I am very glad that you attended the meeting; your conduct
at no very distant period will be contrasted with that of
some great coal-proprietors, who find reasons for their
indifference, as to a benefit conferred upon them, in
insinuations respecting the claims of Dr. Clanny, Mr.
Stephenson, and others.
Where men resolve to be ungrateful, it is natural that they
should be illiberal; and illiberality often hardens into
malignity.
I shall receive any present of plate under your auspices, and
those of the Committee over which you preside, with peculiar
satisfaction. It will prove to me that my labours have not been
disregarded by men of whose good opinion I am proud.
I hope you will not blame me for not taking any notice of the
attacks of my enemies in the North. I have no desire to go out
of my way to crush gnats that buzz at a distance, and do not
bite me, or to quarrel with persons who shoot arrows at the
moon, and believe, because they have for an instant intercepted
a portion of her light, that they have hit their mark. I am
sensible to the circumstances under which you attended the
meeting.
I offer you my sincere congratulations, and ardent wishes that
you may enjoy all possible happiness.
Believe me, &c.
H. Davy.
On the 13th of September 1817, Sir Humphry Davy being expected to
pass through Newcastle on his return from Scotland, preparations
were made, and notice given of a dinner which it was proposed
should take place on the 25th instant, for the purpose of
presenting to the illustrious philosopher the service of plate
which had been prepared for his acceptance.
Upon this gratifying occasion, a very large party assembled at the
Queen's Head, consisting of a numerous and respectable body of
Coal-owners, and such other gentlemen as had interested themselves
during the progress of the investigation, or taken an active part
in promoting the introduction of the lamp into the mines.
After the dinner had concluded, and certain toasts of form had been
drunk, Mr. Lambton, who filled the chair on the occasion, rose,
and on presenting the service of plate to the illustrious guest,
addressed him, in a tone of great animation and feeling, in nearly
the following terms:
"SIR HUMPHRY,--It now becomes my duty to fulfill the object of
the meeting, in presenting to you this service of plate, from the
Coal-owners of the Tyne and Wear, as a testimony of their gratitude
for the services you have rendered to them and to humanity.
"Your brilliant genius, which has been so long employed in an
unparalleled manner, in extending the boundaries of chemical
knowledge, never accomplished a higher object, nor obtained a
nobler triumph.
"You had to contend with an element of destruction which seemed
uncontrollable by human power; which not only rendered the property
of the coal-owner insecure, but kept him in perpetual alarm for the
safety of the intrepid miner in his service, and often exhibited to
him the most appalling scenes of death, and heart-sickening misery.
"You have increased the value of an important branch of productive
industry; and, what is of infinitely greater importance, you
have contributed to the lives and persons of multitudes of your
fellow-creatures.
"It is now nearly two years that your Safety-lamp has been used by
hundreds of miners in the most dangerous recesses of the earth,
and under the most trying circumstances. Not a single failure
has occurred--its absolute security is demonstrated. I have,
indeed, deeply to lament more than one catastrophe, produced by
fool-hardiness and ignorance, in neglecting to use the safeguard
you have supplied; but these dreadful accidents even, if possible,
exalt its importance.
"If your fame had needed any thing to make it immortal, this
discovery alone would have carried it down to future ages, and
connected it with benefits and blessings.
"Receive, Sir Humphry, this permanent memorial of our profound
respect and high admiration--a testimony, we trust, equally
honourable to you and to us. We hope you will have as much pleasure
in receiving, as we feel in offering it. Long may you live to use
it--long may you live to pursue your splendid career of scientific
discovery, and to give new claims to the gratitude and praise of
the world!" Sir Humphry having received the plate, replied as
follows:
"GENTLEMEN,--I feel it impossible to reply, in an appropriate
manner, to the very eloquent and flattering address of your
distinguished Chairman. Eloquence, or even accuracy of language,
is incompatible with strong feeling; and on an occasion like the
present, you will give me credit for no small degree of emotion.
"I have been informed that my labours have been useful to an
important branch of human industry connected with our arts, our
manufactures, commerce, and national wealth. To learn this from
such practical authority is the highest gratification to a person
whose ardent desire has always been to apply science to purposes of
utility.
"It has been also stated, that the invention which you are this
day so highly honouring, has been subservient to the preservation
of the lives and persons of a most useful and laborious class
of men: this, coming from your own knowledge, founded upon such
ample experience, affords me a pleasure still more exalted--for
the highest ambition of my life has been to deserve the name of a
friend to humanity.
"To crown all, you have, as it were, embodied these sentiments in a
permanent and magnificent memorial of your good opinion. I can make
only imperfect and inadequate efforts to thank you.
"Under all circumstances of my future life, the recollection of
this day will warm my heart; and this noble expression of your
kindness will awaken my gratitude to the latest moment of my
existence."
Sir Humphry having sat down, and the cheering of the company
subsided, the Chairman proposed the health of the illustrious
Chemist, in three times three.
"Gentlemen," said Sir Humphry, "I am overpowered by these
reiterated proofs of your approbation. You have overrated my
merits. My success in your cause must be attributed to my having
followed the path of experiment and induction discovered by
philosophers who have preceded me: willingly would I divide your
plaudits with other men of science, and claim much for the general
glory of scientific discovery in a long course of ages.
"Gentlemen, I might dwell at some length upon the great increase
of wealth and power to the country, within the last half century,
by scientific invention, which never could have existed without
coal-mines:--I shall refer only to the improvement in the
potteries, to the steam-engine, and to the discovery of the gas
lights.
"What an immense impulse has the steam-engine given to the arts
and manufactures! How much has it diminished labour, and increased
the real strength of the country, far beyond a mere increase of
population! By giving facilities to a number of other inventions,
it has produced even a moral effect in rendering capital necessary
for the perfection of labour, credit essential to capital, and
ingenuity and mental energy a secure and dignified species of
property.
"Science, Gentlemen, is of infinitely more importance to a state
than may at first sight appear possible; for no source of wealth
and power can be entirely independent of it; and no class of men
are so well able to appreciate its advantages as that to which I am
now addressing myself. You have not only derived from it the means
of raising your subterraneous wealth, but those also of rendering
it available to the public.
"Science alone has made pit-coal such an instrument in the hands
of the chemist and mechanic; it has made the elements of fire and
water perform operations which formerly demanded human labour, and
it has converted the productions of the earth into a thousand new
forms of use and beauty.
"Gentlemen, allow me to observe, in conclusion, that it was
in pursuing those methods of analogy and experiment, by which
mystery had become science, that I was fortunately led to the
invention of the Safety-lamp. The whole progress of my researches
has been registered in the Transactions of the Royal Society, in
papers which that illustrious body has honoured by their biennial
medal;[47] in which I can conscientiously assert, that I have
gratefully acknowledged even the slightest hints or offers of
assistance which I have received during their composition.
[47] The Rumford Medal, to be hereafter noticed.
"I state this, Gentlemen, not from vain-glory, but on account of
certain calumnious insinuations which have arisen--not in the
scientific world, for to that the whole progress of my researches
is well known, but in a colliery. I must ever treat these
insinuations with contempt; and after the honest indignation which
has been expressed against them by the Coal-owners in general, I
cannot feel any anxiety on the subject, nor should I have referred
to it at all, did I not believe that the very persons amongst whom
these insinuations originated, were extensively benefited by, and
were constantly using the invention they would seek to disparage.
I could never have expected that such persons would have engaged
their respectable connexions in mean attempts to impeach the
originality of a discovery, given to them in the most disinterested
manner, and for which no return was required but an honest
acknowledgment of the benefit, founded upon truth and justice.
"I do not envy them their feelings, particularly at the present
moment: I do not wish to enquire into their motives: I do hope,
however, that their conduct has been prompted by ignorance rather
than by malevolence, by misapprehension rather than by ingratitude.
"It was a new circumstance to me, that attempts to preserve human
life, and to prevent human misery, should create hostile feelings
in persons who professed to have similar objects in view.
"Gentlemen, I have had some opposition, much labour, and more
anxiety, during the course of these researches; but had the
opposition, the labour, and the anxiety been a thousand times
as great, the events of this day would have been more than a
compensation."
Sir Humphry, after drinking the health and happiness of the
company, proposed as a sentiment--"Prosperity to the Coal-trade."
The healths of the Duke of Northumberland, the Bishop of Durham,
and the Reverend Dr. Gray, were drunk in succession.
At ten o'clock, Sir Humphry, accompanied by the chairman, retired
amidst the enthusiastic plaudits of a meeting, the object of
which being one of convivial benevolence, the effect was that of
unclouded hilarity.
The party which had supported the claims of Mr. Stephenson had
also their meeting; and it was held on the 1st of November. At
this meeting it was resolved, "That it was the opinion of the
persons present, that Mr. G. Stephenson having discovered the fact,
that explosions of hydrogen gas will not pass through tubes and
apertures of small dimensions, and having been the first to apply
the principle to the construction of a Safety-lamp, is entitled to
some reward."
A committee was accordingly formed to carry this resolution into
effect, at the head of which was placed the name of the Earl of
Strathmore.
The respectable body of Coal-owners, under whose auspices the
invention of Sir Humphry Davy had been introduced and rewarded,
felt that they owed it to their own characters to repel assertions
which amounted to a charge against themselves of ingratitude and
injustice: a general meeting was accordingly summoned, at the
Assembly-rooms in Newcastle, on the 26th of November 1817, J. G.
Lambton, Esq. M.P. in the chair--when it was resolved,
"That the Resolutions passed at the Meeting of the friends of Mr.
G. Stephenson on the 5th instant, impugn the justice and propriety
of the proceedings of a meeting of the Coal-trade on the 31st of
August 1816:
"That the present meeting, therefore, feel themselves called
upon, as an act of justice to the character of their great and
disinterested benefactor, Sir Humphry Davy, and as a proof that the
Coal-trade of the North in no way sanctions the resolutions of Mr.
Stephenson's friends, to state their decided conviction, that the
merit of having discovered the fact, that explosions of fire-damp
will not pass through tubes and apertures of small dimensions,
and of having applied that principle to the construction of a
Safety-lamp, _belongs to Sir Humphry Davy alone_.
"That this meeting is also decidedly of opinion, from the evidence
produced in various publications by Mr. George Stephenson and his
friends, subsequently to the meeting of the Coal-trade which was
held on the 18th of March 1816, as well as from the documents
which have been read at this meeting, that Mr. Stephenson _did
not_ discover the fact, that explosions of fire-damp will not pass
through tubes and apertures of small dimensions; and that he _did
not_ apply that principle to the construction of a Safety-lamp; and
that the latest lamps made by Mr. Stephenson are evident imitations
of those of Sir Humphry Davy, and that, even with that advantage,
they are so imperfectly constructed as to be actually unsafe.
"That the above resolutions be published thrice in the Newcastle
papers, and in the Courier, Morning Chronicle, and Edinburgh
Courant; and that printed copies thereof be sent to the Lords
Lieutenants of the two counties, to the Lord Bishop of Durham, and
to the principal owners and lessors of collieries upon the Tyne and
Wear."
The following letter from Sir Humphry Davy announces the farther
measures which he also had thought proper to pursue, in order to
counteract the impression which the meeting of Mr. Stephenson's
friends might have produced on the less informed part of the public.
TO J. G. LAMBTON, ESQ. M.P.
November 21, 1817.
MY DEAR SIR,
I shall send off by this post a copy of the resolutions, which
will appear to-morrow in the Chronicle and Courier.
The men of science who have signed these resolutions are the
first chemists and natural philosophers of the country, with
the President of the Royal Society, the most illustrious body
in Europe, at their head.
It is disagreeable to be thus obliged to use artillery for
the destruction of bats and owls; but it was necessary that
something should be done.
The Messrs. ---- have for a long time been endeavouring to
destroy my peace of mind; my offence being that of conferring a
benefit.
The only persons I knew in Newcastle, before I gave the
Safety-lamp to the Coal-owners, were Dr. Headlam and Mr. Bigge,
so that friends I had none; and the few persons with whom I
had a slight acquaintance, and who were civil to me before I
discovered the Safety-lamp, became my enemies. It requires a
deep metaphysician to explain this--Can it be that I did not
make them the medium of communication to the colliers?--But I
quit a subject to which I have no desire to return, and shall
only recollect that day when your eloquence touched my feelings
more than it flattered my self-love.
Believe me, &c. &c.
H. Davy.
The following are the Resolutions of a Meeting adverted to in the
preceding letter, and which was held "for considering the Facts
relating to the Discovery of the Lamp of Safety."
Soho Square, Nov. 20, 1817.
"An advertisement having been inserted in the Newcastle
Courant, of Saturday, November 7, 1817, purporting to contain
the Resolutions of 'A Meeting held for the purpose of
remunerating Mr. George Stephenson, for the valuable service he
has rendered mankind by the invention of his Safety-lamp, which
is calculated for the preservation of human life in situations
of the greatest danger,'
"We have considered the evidence produced in various
publications by Mr. Stephenson and his friends, in support of
his claims; and having examined his lamps, and enquired into
their effects in explosive mixtures, are clearly of opinion--
"First,--That Mr. George Stephenson _is not_ the author of the
discovery of the fact, that an explosion of inflammable gas
will not pass through tubes and apertures of small dimensions.
"Secondly,--That Mr. George Stephenson _was not_ the first to
apply that principle to the construction of a Safety-lamp,
none of the lamps which he made in the year 1815 having been
safe, and there being no evidence even of their having been
made upon that principle.
"Thirdly,--That Sir Humphry Davy not only discovered,
independently of all others, and without any knowledge of the
unpublished experiments of the late Mr. Tennant on Flame, the
principle of the non-communication of explosions through small
apertures, but that he has also the sole merit of having first
applied it to the very important purpose of a Safety-lamp,
which has evidently been imitated in the latest lamps of Mr.
George Stephenson.
(Signed) "JOSEPH BANKS, P.R.S.
"WILLIAM THOMAS BRANDE,
"CHARLES HATCHETT,
"WILLIAM HYDE WOLLASTON."
Thus terminated a controversy, the discussion of which, I am well
aware, many of my readers will consider as having been protracted
to a tedious, and perhaps to an unnecessary extent; but the
biographer had no alternative. In passing it by without a notice,
he would have violated his faith to the public, have given a tacit
acknowledgment of the claims of Stephenson, and, in his judgment,
have committed an act of gross injustice to the illustrious subject
of his history; while by giving only an abridged statement, he
would have furnished a pretext for doubt, and an opportunity for
malevolence.
It is due also to Sir Humphry Davy to observe, that had he
practised more reserve in the communication of his results, the
spirit of rivalry would have expired without a struggle,--for it
derived its only support and power from the generosity of its
victim. Had he secured for himself the advantages of his invention
by patent, he might have realized wealth to almost any extent; but
to barter the products of his intellectual exertions for pecuniary
profit, was a course wholly at variance with every feeling of
Davy's mind; and we therefore find him, in the advancement, as at
the commencement of his fleeting career, spurning the golden apples
from his feet, and hastening to the goal for that prize which could
alone reward all his labours--the meed of immortal fame.
From a letter dated Newcastle, August 1830, which I had the
pleasure to receive from Mr. Buddle, I extract the following
interesting passage:--
"In the autumn of 1815, Sir Humphry Davy accompanied me into some
of our fiery mines, to _prove_ the efficacy of his lamp. Nothing
could be more gratifying than the result of those experiments, as
they inspired every body with perfect confidence in the security
which his invention had afforded.
"Sir Humphry was delighted, and I was overpowered with feelings of
gratitude to that great genius which had produced it.
"I felt, however, that he did not contemplate any pecuniary reward;
and, in a private conversation, I remonstrated with him on the
subject. I said, 'You might as well have secured this invention
by a patent, and received your five or ten thousand a-year from
it.' The reply of this great and noble-minded man was,--'No, my
good friend, I never thought of such a thing; my sole object was
to serve the cause of humanity; and, if I have succeeded, I am
amply rewarded in the gratifying reflection of having done so.' I
expostulated, saying, that his ideas were much too philosophic and
refined for the occasion. He replied, 'I have enough for all my
views and purposes; more wealth might be troublesome, and distract
my attention from those pursuits in which I delight;--more wealth,'
he added, 'could not increase either my fame or my happiness. It
might, undoubtedly, enable me to put four horses to my carriage;
but what would it avail me to have it said that Sir Humphry drives
his carriage-and-four?'"
The present Bishop of Bristol, to whom the world is so greatly
indebted for having first called the attention of Sir Humphry Davy
to the subject of explosions from fire-damp, and who has kindly
interested himself in my arduous and anxious undertaking, was
desirous to obtain for me the latest accounts with respect to the
Safety-lamp, as to the constancy of its use, and the extent of its
security; and his Lordship informs me, that having applied to Mr.
Buddle and Mr. Fenwick for information upon these points, their
answers have been most satisfactory; at the same time, his Lordship
transmitted me much valuable information, which was accompanied by
the following letter from Mr. Buddle.
TO THE RIGHT REVEREND THE LORD BISHOP OF BRISTOL.
Wall's-End, August 11, 1830.
MY LORD,
I have the honour to acknowledge the receipt of your Lordship's
letter of yesterday's date. I am glad your Lordship has
interested yourself in Doctor Paris's work, and I hope that
he will be enabled, through the assistance of Sir Humphry's
friends, to do ample justice to the genius and worth of that
excellent man.
I should be very happy if any letters of mine could assist
Dr. Paris in doing justice to his merits in the invention of
the Safety-lamp; and I shall with pleasure submit to your
Lordship's better judgment and discretion the selection of such
of them as may seem to be conducive to that object.
I do not find that any improvement whatever has been made,
either in the principle or construction of the _original lamp_,
as presented to us by Sir Humphry. His transcendent genius
seems to have anticipated every thing belonging to the subject,
and has left nothing more to be done.
I have the honour to be,
My Lord, with great respect,
Your Lordship's most obedient, humble servant,
JOHN BUDDLE.
In consequence of some late reports of accidents in the mines, I
requested my friend Sir Cuthbert Sharp to make certain enquiries in
the mining districts; and for this purpose, I sent him a string of
queries, to which I begged him to obtain answers. These questions
were submitted to Mr. Buddle, and they produced the following
letter.
TO SIR CUTHBERT SHARP.
Newcastle, August 28, 1830.
MY DEAR SIR CUTHBERT,
I return Dr. Paris's letter, and shall briefly answer his
enquiries.
If the Davy lamp was exclusively used, and due care taken in
its management, it is certain that few accidents would occur
in our coal mines; but the exclusive use of the "_Davy_" is
not compatible with the working of many of our mines, in
consequence of their not being workable without the aid of
gunpowder.
In such mines, where every collier must necessarily fire, on
the average, two _shots_ a-day, we are exposed to the risk of
explosion from the ignition of the gunpowder, even if no naked
lights were used in carrying on the ordinary operations of the
mine.
This was the case in Jarrow Colliery, at the time the late
accident happened. As the use of gunpowder was indispensable,
naked lights were generally used, and the accident was
occasioned by a '_bag_' of inflammable air forcing out a large
block of coal, in the face of a drift, from a fissure in which
it had been pent up, perhaps from the Creation, and firing at
the first naked light with which it came in contact, after
having been diluted down to the combustible point by a due
admixture of atmospheric air.
As to the number of old collieries and old workings which
have been renovated, and as to the quantity of coal which has
been, and will be saved to the public by the invention of the
"_Davy_," it is scarcely possible to give an account, or to
form an estimate.
In this part of the country, 'Walker's Colliery,' after having
been completely worked out, according to the former system,
with candles and steel-mills, and after having been abandoned
in 1811, was reopened in 1818 by the aid of the "_Davy_" and
has been worked on an extensive scale ever since, and may
continue to be worked for an almost indefinite period.
Great part of the formerly relinquished workings of Wall's-end,
Willington, Percy-main, Hebburn, Jarrow, Elswick, Benwell,
&c. &c., as well as several collieries on the Wear, have been
recovered, and are continued in work by the invention of the
"_Davy_."
If I had only what you know perfectly well I have not--TIME, I
could write a volume on this subject.
I shall shortly, through the medium of a friend, get an
important paper on the subject of the "_Davy_," put into Dr.
Paris's hands.
Believe me, my dear Sir Cuthbert,
To remain yours very faithfully,
JOHN BUDDLE.
The Bishop of Bristol has placed at my disposal a communication
from Mr. Fenwick, a gentleman of much practical ability, which
affords additional evidence of the utility of the lamp; from which
the following is an extract.
"Sir H. Davy's safety-lamp has afforded much security in the
general working of mines, particularly by enabling the coal-owner
to work, in several situations, the pillars of coal formerly left
therein, which, under the system of working by candles, or open
flame, was deemed hazardous and impracticable; and, in consequence,
one-sixth part more of coal may be estimated as obtainable from
those mines which are subject to hydrogen gas. Also in the working
of the pillars of coal, (commonly called the second working,) great
advantages and securities, as well as saving of expenses, have
resulted from the use of this lamp, not only to the lessees of
collieries, inasmuch as more coal is obtained from a given space
than before, (particularly in collieries subject to fire-damp,) but
also to the lessor of such mines, by their being more productive,
and of course more durable than heretofore.
"Another advantage results from the use of this Safety-lamp, and in
the working of the pillars in particular. It is found now, through
experience, that the changeable state of the atmosphere, which
our barometers daily indicate, has a most powerful effect on the
noxious air in mines; as, from a sudden change in the atmosphere,
indicated by the rapid fall of the mercury in the barometrical
tube, a rapid discharge of noxious gas into the workings and
excavations of the mine is the consequence, caused by the want of
the atmospheric equilibrium:[48] in which case the mine becomes
suddenly surcharged with hydrogen, and if worked by the light of
_open flame_, an explosion may take place before the possibility
of such a circumstance can even be suspected; but if worked by the
Safety-lamp, it is only shown by the gas in the lamp becoming a
pillar of harmless flame. This circumstance frequently takes place
when any atmospheric change causes the mercury in the barometer to
sink to twenty-eight inches and a half or thereabouts."
[48] This is a very interesting fact, and gives much support to
the theory advanced at page 62 of this volume.
In the year 1825, Sir Humphry Davy had the honour to receive
from the Emperor Alexander of Russia, a superb silver gilt vase,
standing in a circular tray enriched with medallions. On the cover
was a figure, of about sixteen or eighteen inches in height,
representing the God of Fire, weeping over his extinguished torch.
The circumstances under which this vase was presented have been
communicated to me by Mr. Smirnove, Secretary to the Embassy.
TO J. A. PARIS, M.D.
Wigmore Street, May 29, 1830.
DEAR SIR,
It was in the month of April, or May, 1815, that the late Sir
Humphry Davy expressed to Prince, then Count, Lieven, his wish
to offer to the Emperor of Russia a model of his Safety-lamp,
which he had recently improved, accompanied by an explanatory
pamphlet on the subject.
Prince Lieven of course complied with this request; and
the Emperor having been pleased to accept it, ordered the
Ambassador, in November of the same year, to thank Sir Humphry
for it in his Majesty's name, and to assure him how much his
Majesty appreciated the merit of an invention, the double
effect of which was to favour the progress of more than one
branch of industry, and to ensure the safety of persons
employed in the coal-mines, against those fatal accidents
which had hitherto so frequently occurred. The Ambassador,
at the same time, delivered to Sir Humphry a silver-gilt
Vase,[49] in the name of the Emperor, in testimony of the high
satisfaction with which that sovereign had been pleased to
accept the object in question. I beg you to believe me, with
regard and esteem,
Your faithful servant,
JOHN SMIRNOVE.
[49] Of the value of about one hundred and eighty guineas.
It is well known to the friends of Davy, that in his conversation
as well as in his correspondence, he always dwelt with peculiar
satisfaction and delight upon the invention of his Safety-lamp.
Mr. Poole, in a letter lately addressed to me, observes--"How often
have I heard him express the satisfaction which this discovery
had given him. 'I value it,' said he, 'more than any thing I
ever did. It was the result of a great deal of investigation
and labour; but, if my directions be only attended to, it will
save the lives of thousands of poor labourers. I was never more
affected,' he added, 'than by a written address which I received
from the working colliers, when I was in the North, thanking me,
in behalf of themselves and their families, for the preservation
of their lives.' I remember how delighted he was when he showed me
the service of plate presented to him by those very men and their
employers, as a testimony of their gratitude."
The following letter evinces a similar feeling.
TO THOMAS POOLE, ESQ.
Queen's Square, Bath, Oct. 29, 1816.
MY DEAR POOLE,
It is very long since any letters have passed between us. The
affections and recollections of friendly intercourse are of a
very adhesive nature; and I think you will not be displeased at
being put in mind that there is an old friend not very far from
you, who will be very glad to see you.
Bath does not suit me much, nor should I remain here, but
my wife has been indisposed, and the waters seem to benefit
her, and promise to render her permanent service, and if that
happens, I shall be pleased even with this uninteresting city.
I have seen many countries and nations since we met.
* * * * *
I have just come from the North of England, where it has
pleased Providence to make me an instrument for preserving the
lives of some of my fellow-creatures. You, I know, are of that
complexion of mind that the civic crown will please you more
than even the victor's laurel wreath.
I have a bed, though a small one, at your service; if you can
come here for two or three days, I assure you we shall be most
happy to see you. We shall remain in Bath about three weeks.
I shall be absent for a few days in the beginning of next
week, and after that I shall be stationary till the middle of
November. Give me a few lines, and say when we may expect you.
I am, my dear Poole, very sincerely yours,
H. DAVY.
TO THE SAME.
Grosvenor Street, Dec. 3, 1817.
MY DEAR POOLE,
The late melancholy event[50] has thrown a gloom over London,
and indeed over England. The public feeling is highly
creditable to the moral tone of the people.
The loss of a Princess, known only by good qualities, living
in a pure and happy state of domestic peace, is in itself
affecting; but when it is recollected that two generations of
sovereigns of the first people in the world have been lost at
the same moment, the event becomes almost an awful one.
I go on always labouring in my vocation. I am now at work on a
subject almost as interesting as the last which I undertook.
It is too much to hope for the same success; at least I will
deserve it.
When you come to town in the spring, which I trust you will do,
I shall show you my service of plate. I do not think you will
like it the less for the cause of the gift.
I am not sure whether I shall not take a run down to Nether
Stowey and the west for a few days, if you encourage me with
any hopes of the estate[51] and of woodcocks. You will fix my
plans.
I shall be disengaged between the 15th and Christmas, and shall
like to revisit Lymouth, and above all to shake you by the
hand.
Lady D. is in better health than I have ever known her to
possess. She begs her kind remembrances.
I am, my dear Poole, most affectionately yours,
H. DAVY.
[50] The death of the Princess Charlotte.
[51] He here alludes to an estate in the neighbourhood of Nether
Stowey, which he wished to purchase, and about which he had
requested Mr. Poole to make enquiries.
In a strictly scientific point of view, the most interesting
results which have arisen out of the investigation for constructing
a Safety-lamp, are perhaps those which have made us better
acquainted with the true nature of flame, and the circumstances by
which it is modified; and which have led to some practical views
connected with the useful arts.
It is, I think, impossible to enter into the details of those
curious investigations[52] which, under the title of "Some
Researches on Flame," were communicated to the Royal Society, and
read before that body on the 16th of January 1817, without being
forcibly struck with the address by which Davy, in the first
instance, brought abstract science to promote and extend practical
knowledge; and then, as it were by a species of multiplied
reflection, applied the new facts thus elicited for the farther
extension of speculative truth; which in its wider range became
again instrumental in disclosing a fresh store of useful facts.
It may be said to have been the power of dexterously combining
such methods which constituted the felicity of his genius; for, in
general, each of them requires for its successful application a
mind of quite a distinct order and construction. Mr. Babbage has
very justly observed, that those intellectual qualifications which
give birth to new principles or to new methods, are of quite a
different order from those which are necessary for their practical
application. Davy furnished the exception that was necessary to
make good the rule.
[52] A short notice of them first appeared in the third number
of the "Journal of Science and the Arts," edited at the Royal
Institution.
He detects, in the first instance, the general principle of
inflammable gas, in a state of combustion, being arrested in its
progress by capillary tubes; he next applies it to the construction
of a Safety-lamp, and then, by observing the phenomena which this
lamp exhibits, is led to novel views respecting the nature and
properties of flame.--I shall endeavour to offer a popular view
of the curious and interesting truths disclosed by this latter
research.
He had observed that, when the coal gas burnt in the iron cage, its
colour was pale, and its light feeble; whereas the fact is rendered
familiar to us all by the flame of the gas lights, that in the
open air carburetted hydrogen burns with great brilliancy. Upon
reflecting on the circumstances of the two species of combustion,
he was led to believe that the cause of the superiority of the
light in the latter case might be owing to a _decomposition_ of a
part of the gas towards the interior of the flame, where the air
was in the smallest quantity; and that the consequent deposition
of charcoal might first by its _ignition_, and afterwards by its
_combustion_, contribute to this increase of light. A conjecture
which he immediately verified by experiment.[53]
[53] This theory of Davy is well illustrated by the change
produced in the flame of gas-light, when acted upon by the
wind, as may be seen during an illumination. The loss of light
under these circumstances evidently arises from the more rapid
combustion of the gas, by its more complete admixture with air;
in consequence of which the decomposition above described does
not take place.
The intensity therefore of the light of flames depends principally
upon the production and ignition of _solid_ matter in combustion,
so that heat and light are in this process independent phenomena.
These facts, Davy observes, appear to admit of many applications;
in explaining, for instance, the appearance of different flames--in
suggesting the means of increasing or diminishing their light, and
in deducing from their characters a knowledge of the composition of
their constituent parts.
The point of the inner blue flame of a candle or lamp urged by
the blow-pipe, where the heat is the greatest and the light the
least, is the point where the whole of the charcoal is burnt in
its gaseous combinations, without previous ignition. The flames
of phosphorus and of zinc in oxygen, and that of potassium in
chlorine, afford examples of intensity of light depending upon
the production of _fixed_ solid matter in combustion; while on
the contrary, the feebleness of the light of those flames, in
which gaseous and volatile matter is alone produced, is well
illustrated by those of hydrogen and sulphur in oxygen, or by that
of phosphorus in chlorine.
From such facts, he is inclined to think that the luminous
appearance of shooting stars and meteors cannot be owing to any
inflammation of gas, but must depend upon the ignition of solid
matter. Dr. Halley calculated the height of a meteor at ninety
miles, and the great American meteor, which threw down showers of
stones, was estimated at only seventeen miles high. The velocity
of the motion of such bodies must in all cases be immensely great,
and the heat thus produced by the compression of the most rarefied
air, Davy thinks, must be sufficient to ignite the mass; and that
all the phenomena may be explained by assuming that _falling stars_
are small solid bodies moving round the earth in very eccentric
orbits, which become ignited only when they pass with immense
velocity through the upper regions of the atmosphere, and which,
when they contain either combustible or elastic matter, throw out
stones with explosion.
By the application of such a principle did he also infer the
composition of a body from the character of its flame: thus, says
he, Ether, during its combustion, would appear to indicate the
presence of _olefiant gas_. Alcohol burns with a flame similar to
that of a mixture of carbonic oxide and hydrogen; so that the first
is probably a binary compound of olefiant gas and water, and the
second of carbonic oxide and hydrogen.
When the proto-chloride of copper is introduced into the flame of
a candle or lamp, it affords a peculiar dense and brilliant red
light, tinged with green and blue towards the edges, which seems to
depend upon the separation of the chlorine from the copper by the
hydrogen, and the ignition and combustion of the solid copper and
charcoal.
The acknowledged fact of the brightest flames yielding the least
heat is easily reconciled, when we learn that the light depends
upon fixed matter which carries off the heat. It is equally
obvious, that by art we may, for practical purposes, easily modify
these phenomena.
In the next place, having observed that wire-gauze cooled down
flame beyond its combustible point, he was led to enquire into
the nature of pure flame; and he readily demonstrated it to be
_gaseous matter heated so highly as to be luminous_; and that the
temperature necessary for such an effect was much greater than had
been imagined, varying, however, in different cases. The flame of a
common lamp he proved, by a very simple experiment, to exceed even
the white heat of solid bodies, and which is easily shown by the
simple fact of heating a piece of platinum wire over the chimney of
an Argand lamp fed with spirit of wine; when it will be seen that
air, which is not of sufficient temperature to appear luminous,
is still sufficiently hot to impart a white heat to a solid body
immersed in it.
The fact of different gaseous bodies requiring different degrees
of heat to raise them into flame, was an inference immediately
deducible from the phenomena of his _safety gauze_. A tissue of one
hundred apertures to the square inch, made of wire of one-sixtieth,
will, at common temperatures, intercept the flame of a spirit-lamp,
but not that of hydrogen; and, when strongly heated, it will no
longer arrest the flame of the spirit-lamp. A tissue which, when
red-hot, will not interrupt the flame of hydrogen, will still
intercept that of olefiant gas; and a heated tissue, which would
communicate explosion from a mixture of olefiant gas and air, will
stop an explosion of fire-damp. Fortunately for the success of the
Safety-lamp, carburetted hydrogen requires so high a temperature to
carry on its combustion, that even metal, when white-hot, is far
below it; and hence red-hot gauze, in sufficient quantity, and of
the proper degree of fineness, will abstract heat enough from the
flame to extinguish it.
The discovery of the high temperature which is necessary for the
maintenance of flame, suggested to the philosopher the reason of
its extinction under various circumstances. He considers, that
the common operation of blowing out a candle principally depends
upon the cooling power of the current of air projected into the
flame;[54] and he observes, that the hottest flames are those which
are least easily blown out. He farther illustrated this subject by
surrounding a very small flame with a ring of _metal_, which had
the effect of cooling it so far as to extinguish it; but a ring of
_glass_, of similar dimensions and diameter, being a less perfect
conductor of heat, produced no such effect.
[54] _Quere._ Is this theory correct? May not the effect be
mechanical, the appulse of the air separating the flame from
the wick.--Upon the principle suggested by Davy, how are we to
explain the fact of rekindling the flame by a blast?
It had been long known that flame ceased to burn in highly rarefied
air; but the degree of rarefaction necessary for this effect had
been very differently stated. The cause of the phenomenon was
generally supposed to depend upon a deficiency of oxygen.
In the commencement of his enquiry into this subject, Davy observed
that the flame of hydrogen gas, the degree of rarefaction and the
quantity of air being the same, burnt longer when it issued from a
larger than a smaller jet,--a fact the very reverse of that which
must have happened had the flame expired for want of oxygen; he
moreover observed, that when the larger jet was used, the point
of the glass tube became white-hot, and continued red-hot till
the flame was extinguished: he therefore concluded, that the
heat communicated to the gas by this tube was the cause of its
protracted combustion, and that _flame expired in rarefied air,
not for want of nourishment from oxygen, but for want of heat, and
that if its temperature could be preserved by some supplementary
aid, the flame might be kept burning_. The experiment by which he
confirmed this theory was as beautiful as it was satisfactory.
He burnt a piece of camphor in a _glass_ tube, under the receiver
of an air-pump, so as to make the upper part of the tube red-hot;
its inflammation was found to continue when the rarefaction was
nine times; but by repeating the experiment in a _metallic_ tube,
which could not be so considerably heated by it, it ceased after
the rarefaction exceeded six times.
It follows then that by artificially imparting heat,[55] bodies may
be made to burn in a rarefied air, when under other circumstances
they would be extinguished.
[55] "It is upon this principle that, in the Argand lamp, the
Liverpool lamp, and in the best fire-places, the increase of
effect does not merely depend upon the rapid current of air,
but likewise upon the heat preserved by the arrangement of
the materials of the chimney, and communicated to the matters
entering into inflammation." The art of making a good fire
depends also upon the same principle of economising the heat.
The following may be considered as an _experimentum crucis_, in
proof of the fact that combustibility is neither increased nor
diminished by rarefaction.
He introduced the flame of hydrogen, in which was inserted a
platinum wire, into a receiver of rarefied air, and he found
that, as long as the metal remained at a dull red-heat, the flame
continued to burn: now it so happens that the temperature, at which
platinum approaches a red-heat, is precisely that at which hydrogen
inflames under the ordinary pressure of the atmosphere; whence it
follows, that its combustibility is not altered by rarefaction.
The same law was found to apply to the flames of other bodies;
those requiring the least heat for their combustion always
sustaining the greater rarefaction without being extinguished.[56]
[56] From a calculation of the ratio in which the density of the
atmosphere decreases with its altitude, and from that of the
relative combustibility of different bodies, it follows that
the taper would be extinguished at a height of between nine and
ten miles--hydrogen, between twelve and thirteen--and sulphur,
between fifteen and sixteen.
Hitherto he had only considered the effects of rarefaction, when
produced by the diminution of pressure; he had next to investigate
the phenomena of rarefaction when occasioned by expansion from heat.
The experiments of M. de Grotthus had apparently shown that
rarefaction by heat destroys the combustibility of gaseous
mixtures; those of Davy, however, proved that it enables them to
explode at a lower temperature.
In the progress of this research, while passing mixtures of
hydrogen and oxygen through heated tubes, the heat being still
below redness, he observed that steam was formed without any
combustion.
Here was a slow combination without combustion, as long since
observed with respect to hydrogen and chlorine, and oxygen and
metals; and he believes that such a phenomenon will happen at
certain temperatures with most substances that unite by heat. On
trying charcoal, he found that at a temperature which appeared to
be a little above the boiling point of quicksilver, it converted
oxygen pretty rapidly into carbonic acid, without any luminous
appearance, and that, at a dull red-heat, the elements of olefiant
gas combined in a similar manner with oxygen, slowly and without
explosion.
It occurred to Davy, in the progress of these experiments, that,
during this species of slow combination, although the increase of
temperature might not be sufficient to render the gaseous matters
luminous, or to produce flame, it might still be adequate to ignite
solid matters exposed to them. It was while engaged in devising
experiments to ascertain this fact, that he was accidentally led
to the discovery of the continued ignition of platinum wire,
during the slow combination of coal gas with atmospheric air;
the circumstances of which have been already related, as well as
the curious invention to which the application of the fact gave
origin.[57]
[57] See page 100 of this volume.
For this and his preceding papers on the subjects of flame and
combustion, the President and Council of the Royal Society adjudged
to Sir Humphry Davy the gold and silver medals, on the donation of
Count Rumford;[58] and never, I will venture say, did a society in
awarding a prize more faithfully comply with the intentions of its
founder.
[58] At the Anniversary of the Royal Society, November 1796,
Count Rumford transferred one thousand pounds, Three per Cent.
Consols, to the use of the Society, on condition that a premium
should be biennially awarded to the author of the most important
discovery, or useful invention, made known in any part of Europe
during the preceding two years, on the subject of HEAT AND LIGHT.
In regard to the form in which this premium was to be conferred,
he requested that it might always be given in two medals, struck
in the same die, the one of gold, and the other of silver.
Should not any discovery or improvement be made during any terms
of years, he directed that the value of the medals should be
reserved, and being laid out in the purchase of additional stock,
go in augmentation of the capital of this premium.
Medals upon this foundation have been successively voted to
Professor Leslie, for his Experiments on Heat, published in
his work entitled "An Experimental Enquiry into the Nature
and Properties of Heat;"--To Mr. William Murdoch, for his
publication "On the Employment of Gas and Coal for the purpose of
Illumination;"--to M. Malus, for his discoveries of certain new
properties of reflected light;--to Dr. Wells, for his Essay on
Dew;--to Sir Humphry Davy, as above stated;--to Dr. Brewster, for
his Optical Investigations;--and, lastly, to Mr. Fresnel, for his
optical researches.
On the completion of these laborious enquiries, it was thought
expedient to give a wider circulation to their results than
the publication of them in the Philosophical Transactions was
calculated to afford; and Sir Humphry Davy was therefore induced to
reprint his principal memoirs, so as to form an octavo volume,[59]
which might be accessible to the practical parts of the community.
[59] "On the Safety-lamp for Coal Mines, with some Researches on
Flame.--London, 1818."
The enlightened friends of science very reasonably expected that
a service of such importance to society as the invention of the
Safety-lamp, would have commanded the gratitude of the State, and
obtained for its author a high parliamentary reward; nor were there
wanting zealous and disinterested persons to urge the claims of the
Philosopher: but a Government which had bestowed a splendid pension
upon the contriver of an engine[60] for the destruction of human
life, refused to listen to any proposition for the reward of one
who had invented a machine for its preservation. It is true that,
in consideration of various scientific services, they tardily and
inadequately acknowledged the claims of Davy, by bestowing upon
him the dignity of Baronetcy[61]--a reward, it must be confessed,
that neither displayed any regard to his condition, nor implied
the just estimate of his merits. The measure of value, however,
enables us to judge of the standard by which the State rates the
various services to society; and deeply is it to be lamented that
the disproportioned exaltation of military achievement, crowned
with the highest honours, depresses respect for science, and raises
a false and fruitless object of ambition.
[60] Sir William Congreve, in addition to other marks of favour,
received a pension of twelve hundred a-year, for the invention of
his Rocket; or, in the exact terms of the grant, "for inventions
calculated to destroy or annoy the enemy."
[61] He was created a Baronet on the 20th of October, 1818.
The passion for arms is a relict of barbarity derived from the
feudal ages; the progress of civilization, and the cultivation of
the mind, should have led us to prefer intellectual to physical
superiority, and to recognise in the successes of science the
chief titles to honour. This reversal of the objects of importance
can never be redressed until the aristocracy shall be possessed
of a competent share of scientific knowledge, and instructed
to appreciate its value. To effect such a change, the system
of education so blindly and obstinately continued in our great
public schools, must be altered; for minds exclusively applied to
classical pursuits, and trained to recognise no other objects of
liberal study, are indisposed and indeed disqualified for enquiries
ministering to the arts of life, and arrogantly despised for their
very connexion with utility. It is in the early ignorance of the
rudiments of science that the after negligence of science has its
source.
The instances in proof of the extent of the ignorance and
indifference I have noted, and of their pernicious effects upon
the most important interests of society, especially legislation,
and the administration of justice, are abundant. In Parliament,
how is a question of science treated? In our courts of law, and
criminal investigation, it is lamentable to observe the frequent
defeat of justice, arising from erroneous conception, or from the
utter absence of the requisite knowledge. In the ordinary affairs
of life, we see conspicuous, amongst the dupes of quackery and
imposture, those whose stations should imply the best instruction,
and whose conduct, unfortunately, has the effect of example.
A contempt far-spreading, and proceeding from the well-springs
of truth, is rapidly rising against this exalted ignorance; the
industrious classes of society are daily becoming more imbued with
knowledge upon scientific subjects, and the nobility, if they would
preserve their superiority in social consideration, must descend to
the popular improvement.
* * * * *
Before concluding the present chapter, I must carry back my history
to the year 1815, for the purpose of recording a circumstance in
the life of Davy, which, while it exemplifies his general love of
science, evinces the local attachment he retained for the town of
his birth.
In the year 1813, the Geological Society of Cornwall was
established at Penzance. Its objects are to cultivate the sciences
of Mineralogy and Geology, in a district better calculated perhaps
for such pursuits than any other spot in Europe,--to register the
new facts which are continually presenting themselves in the mines,
and to place upon permanent record, the history of phenomena which
had hitherto been entrusted to oral tradition; but, above all,
its object was to bring science in alliance with art; to prevent
the accidents which had so frequently occurred from explosion in
the operation of blasting rocks; and, in short, to render all the
resources of speculative truth subservient to the ends of practical
improvement.
No sooner had the establishment of so useful an institution been
communicated to Davy, than he testified his zeal for its welfare
by a handsome donation to its funds; which was followed by a
present of a very extensive suite of specimens, illustrative of
the volcanic district of Naples, and which had been collected by
himself. He also afterwards communicated to the Society a memoir
on the Geology of Cornwall, which has been published in the first
volume of its Transactions.
In this paper, he discusses several of the more difficult questions
connected with the origin of veins.
He first observed the granitic veins, which have called forth so
much attention from geologists, about the year 1797; probably
before they had excited much scientific notice: he is disposed to
regard them as peculiar to the low metalliferous granite and mica
formations; he had seen several cases of granite veins near Dublin,
in the Isle of Arran, and in other parts of Scotland; he had also
observed several instances near Morlaix in Brittany, but he had in
vain searched for them in the points of junction of the schist and
granite, both in the Maritime, Savoy, Swiss, and Tyrolese Alps, and
likewise in the Oriental Pyrenees.
The _serpentine_ district of Cornwall, he thinks, has not yet met
with the attention it deserves. "I have seen no formation," says
he, "in which the nature of serpentine is so distinctly displayed.
The true constituent parts of this rock appear to be _resplendent
hornblende_ and _felspar_; it appears to differ from _sienite_ only
in the nature of the _hornblende_, and in the chemical composition
of its parts, and in being intersected by numerous veins of
_steatite_ and _calcareous spar_."
The nature and origin of the veins of _steatite_ in serpentine, he
considers as offering a very curious subject for enquiry. "Were
they originally crystallized," he asks, "and the result of chemical
deposition? or have they been, as for the most part they are now
found, mere mechanical deposits?" He is inclined to the latter
opinion. The felspar in serpentine, he observes, is very liable to
decomposition, probably from the action of carbonic acid and water
on its alkaline, calcareous, and magnesian elements; and its parts
washed down by water and deposited in the chasms of the rocks,
he thinks would necessarily gain that kind of loose aggregation
belonging to steatite.
He had some years before made a rude, comparative analysis of the
felspar in serpentine, and of the soap-rock, when he found the same
constituents in both of them, except that there was not any alkali
or calcareous earth in the latter substance. It is very difficult
to conceive, he says, that steatite was originally a crystallized
substance which has been since decomposed; for, in that case,
it ought to be found in its primitive state in veins which are
excluded from the action of air and water; whereas it is easy to
account for the hardness of some species of steatite on the former
hypothesis; for mere mechanical deposits, when very finely divided,
and very slowly made, adhere with a very considerable degree of
force. A remarkable instance of this kind occurred to him amongst
the chemical preparations of the late Mr. Cavendish, which, on the
decease of that illustrious philosopher, had been presented to him
by Lord George Cavendish: there was a bottle which had originally
contained a solution of silica by potash; the cork, during the
lapse of years, had become decayed, and the carbonic acid of the
atmosphere had gradually precipitated the earth, so that it was
found in a state of solid cohesion; the upper part was as soft as
the steatite, but the lower portion was extremely hard, was broken
with some difficulty, and presented an appearance similar to that
of chalcedony.
In speaking generally of the mineralogical interest of Cornwall,
he observes, that "it may be regarded, [Greek: kat' exochên], as
the country of veins; and that it is in veins that the most useful
as well as the most valuable minerals generally exist, that the
pure specimens are found which serve to determine the mineralogical
species, and that the appearances seem most interesting in their
connexion with geological theory. Thus veins, which now may be
considered in the light of the most valuable cabinets of nature,
were once her most active laboratories; and they are equally
important to the practical miner, and to the mineralogical
philosopher."
With regard to the general conformation of Cornwall, he states it
to be in the highest degree curious, and he considers that the
facts which it offers are illustrative of many important points of
geological theory. "It exhibits very extraordinary instances of
rocks broken in almost every direction, but principally from east
to west, and filled with veins again broken in, diversified by
cross lines, and filled with other veins, and exhibiting marks of
various successive phenomena of this kind.
"Respecting the agents that produced the chasms in the primary
strata, and the power by which they were filled with stony and
metallic matter, it would be easy to speculate, but very difficult
to reason by legitimate philosophical induction."
In the concluding passage, however, he very freely admits his
preference for the doctrine of fire.
"It is amongst extinct volcanoes, the surfaces of which have been
removed by the action of air and water, and in which the interior
parts of strata of lavas are exposed, that the most instructive
examples of the operation of slow cooling upon heated masses are to
be found. It is difficult to conceive that water could have been
the solvent of the different granitic and porphyritic formations;
for, in that case, some combinations of water with the pure earths
ought to be found in them. Quartz ought to exist in a state of
_hydrate_, and Wavellite, not Corundum, ought to be the state of
alumina in granite.
"To suppose the primary rocks, in general, to have been produced
by the slow cooling of a mass formed by the combustion of the
metallic bases of the earths, appears to me the most reasonable
hypothesis; yet aqueous agency must not be entirely excluded from
our geological views. In many cases of crystallization, even in
volcanic countries, this cause operates; thus in Ischia, siliceous
_tufas_ are formed from hot springs; and in the lake Albula, or
the lake of Solfaterra, near Tivoli, crystals of calcareous spar
and of sulphur separate from water impregnated with carbonic acid
and hepatic gas; and large strata of calcareous rocks, formed
evidently in late times by water impregnated with carbonic acid,
exist in various parts of Europe. The Travertine marble (_Marmor
Tiburtinum_) is a production of this kind; and it is of this
species of stone that the Colosseum at Rome, and the cathedral of
St. Peter, are built. It is likewise employed in the ancient temple
of Pæstum, and it rivals in durability, if not in beauty, the
primary marble of Paris and Carrara."
CHAPTER XII.
Sir Humphry Davy suggests a chemical method for unrolling
the ancient Papyri.--He is encouraged by the Government
to proceed to Naples for that purpose.--He embarks at
Dover.--His experiments on the Rhine, the Danube, the Raab,
the Save, the Ironzo, the Po, and the Tiber, in order to
explain the formation of mists on rivers and lakes.--His
arrival and reception at Naples.--He visits the excavations
at Herculaneum.--He concludes that it was overwhelmed by
sand and ashes, but had never been exposed to burning
matter.--He commences his attempt of unrolling the Papyri.--His
failure.--He complains of the persons at the head of the
department in the Museum.--He analyses the waters of the
Baths of Lucca.--His return to England.--Death of Sir Joseph
Banks.--He is elected President of the Royal Society.--Some
remarks on that event.--He visits Penzance.--Is honoured by
a public dinner.--Electro-magnetic discoveries of Oersted
extended by Davy.--He examines Electrical Phenomena in
vacuo.--The results of his experiments questioned.--He enquires
into the state of the water, and aëriform matter in the
cavities of crystals.--The interesting results of his enquiry
confirm the views of the Plutonists.
Our history now proceeds to exhibit Sir Humphry Davy in quite a new
field of enquiry;--engaged in investigating, amidst the ruins of
Herculaneum, the nature and effects of the volcanic eruption which
overwhelmed that city in the reign of Titus; and in attempting, by
the resources of modern science, to unfold and to render legible
the mouldering archives which have been recovered from its
excavations, and deposited in the Museum at Naples.
Having witnessed the unsuccessful attempts of Dr. Sickler to unroll
some of the Herculaneum manuscripts, it occurred to him that a
chemical examination of their nature, and of the changes they had
undergone, might suggest some method of separating the leaves from
each other, and of rendering legible the characters impressed
upon them. On communicating this opinion to Sir Thomas Tyrwhitt,
he immediately placed at his disposal fragments which had been
operated upon by Mr. Hayter and by Dr. Sickler: at the same time,
Dr. Young presented him with some small pieces, which he himself
had formerly attempted to unroll.
Davy was very soon convinced by the products of their distillation,
that the nature of these manuscripts had been generally
misunderstood; that they had not, as was usually supposed, been
carbonized by the operation of fire, but were in a state analogous
to peat, or to Bovey coal, the leaves being generally cemented
into one mass by a peculiar substance which had formed, during the
fermentation and chemical change of the vegetable matter composing
them, in a long course of ages. The nature of this substance being
once known, the destruction of it would become a subject of obvious
chemical investigation.
It occurred to him, that as chlorine and iodine do not exert any
action upon pure carbonaceous substances, while they possess a
strong attraction for hydrogen, these bodies might probably be
applied with success for the purpose of destroying the adhesive
matter, without the possibility of injuring the letters of the
Papyri, the ink of the ancients, as it is well known, being
composed of charcoal. He accordingly exposed a fragment of a
brown manuscript, in which the layers were strongly adherent, to
an atmosphere of chlorine; there was an immediate action, the
papyrus smoked, and became yellow, and the letters appeared much
more distinct. After which, by the application of heat, the layers
separated from each other, and fumes of muriatic acid were evolved.
The vapour of iodine had a less distinct, but still a very sensible
action. By the simple application of heat to a fragment in a close
vessel filled with carbonic acid, or with the vapour of ether,
so regulated as to raise the temperature very gradually, and as
gradually to reduce it, there was a marked improvement in the
texture of the papyrus, and its leaves were more easily unrolled.
In all these preliminary trials, however, he found that the success
of the experiment absolutely depended upon the nicety with which
the temperature was regulated.
Different papyri having exhibited different appearances, he
concluded that the same process would not apply in all cases; but
even a partial success he considered as a step gained, and it
served to increase his anxiety to examine in detail the numerous
specimens preserved in the Museum at Naples, as well as to visit
the excavations that still remained open at Herculaneum.
Mr. Hamilton, to whom these views were communicated, with that
ardour which belongs to his character, entered warmly into a plan
which might enable Sir Humphry Davy to accomplish his objects; and
on his representation of them, the Earl of Liverpool and Viscount
Castlereagh placed at his disposal such funds as were requisite for
paying the persons whom it was necessary to engage in the process.
At the same time, Sir Humphry Davy had the honour of an audience
of his late Majesty, then Prince Regent; and on witnessing the
results, his Royal Highness was pleased to express his approbation,
and graciously condescended to patronize the undertaking. Exulting
in the prospect of success, and sanguine as to the importance
of its results to literature, Davy embarked at Dover for the
Continent, in order to proceed to Naples, on the 26th of May 1818.
During his journey, he was engaged in making observations on the
comparative temperature of air incumbent upon land and water,
with a view to account for the formation of mists over the beds
of rivers and lakes. The results of this enquiry were embodied in
a memoir, which was read before the Royal Society on the 25th of
February 1819, and published in the Philosophical Transactions
of that year. This paper, while it records the course of his
observations, informs us of the direction of his route to the
southern shores of Italy.
On the 31st of May, while passing along the Rhine from Cologne to
Coblentz, we find him examining the relative temperature of the
air, and of the water of that river. On the 9th, 10th, and 11th of
June, he was making similar observations on the Danube, during
a voyage from Ratisbonne to Vienna. On the 11th of July, he was
similarly engaged on the Raab, near Kermond in Hungary. In the
end of August he was on the Save in Carniola; in the middle of
September on the Ironzo in the Friul; in the end of that month, on
the Po, near Ferrara; and in the beginning of October, repeatedly
on the Tiber, and on the small lakes in the Campagna of Rome,
extending and multiplying his observations upon the formation of
mists: from the results of which he established the law, that the
formation of mist, on a river or lake, never takes place, if the
temperature of the water be lower than that of the atmosphere; not
even though the latter should be even saturated with vapour.
Possessed of this fact, he was enabled to explain a phenomenon
which all persons who have been accustomed to the observation of
Nature must have frequently witnessed, although it had never yet
been philosophically explained, nor even fully discussed, viz.--the
formation of mists over the beds of rivers and lakes, in calm and
clear weather, after sunset.
Sir Humphry Davy thinks that whoever has considered the phenomena
in relation to the radiation and communication of heat and nature
of vapour, since the publication of the researches of MM. Rumford,
Leslie, Dalton, and Wells, can scarcely have failed to discover
their true causes.
"As soon as the sun has disappeared from any part of the globe,
the surface begins to lose heat by radiation, and in greater
proportions as the sky is clearer; but the land and water are
cooled by this operation in a very different manner: the
impression of cooling on the land is limited to the surface, and
very slowly transmitted to the interior; whereas in water above 45°
Fah., as soon as the upper stratum is cooled, whether by radiation
or evaporation, it sinks in the mass of fluid, and its place is
supplied by warmer water from below, and till the temperature of
the whole mass is reduced nearly to 40°, the surface cannot be
the coolest part.[62] It follows, therefore, that wherever water
exists in considerable masses, and has a temperature nearly equal
to that of the land, or only a few degrees below it, and above 45°
at sunset, its surface during the night, in calm and clear weather,
will be warmer than that of the contiguous land; and the air above
the land will necessarily be colder than that above the water; and
when they both contain their due proportion of aqueous vapour, and
the situation of the ground is such as to permit the cold air from
the land to mix with the warmer air above the water, mist or fog
will be the result; which will be so much the greater in quantity,
as the land surrounding or inclosing the water is higher, the water
deeper, and the temperature of the water, which will coincide with
the quantity or strength of vapour in the air above it, greater."
[62] Water, when cooled down to 40°, expands in volume, and thus
becomes specifically lighter; and therefore at that temperature
remains at the surface.
It will be remembered, that the rivers Inn and Ilz flow into
the Danube below Passau; a circumstance which afforded Davy
an excellent opportunity of confirming, by observation and
experiment, the truth of his theory. On examining the temperature
of these rivers, at six o'clock A. M. June 11, that of the Danube
was found to be 62°, that of the Inn 56.5°, and that of the Ilz
56°: the temperature of the atmosphere on the banks, where their
streams mixed, was 54°. The whole surface of the Danube was covered
with a thick fog; on the Inn there was a slight mist; and on the
Ilz barely a haziness, indicating the deposition of a very small
quantity of water. About one hundred yards below the conflux of
the rivers, the temperature of the central part of the Danube was
59°; and here the quantity of mist was less than on the bed of the
Danube before the junction; but about half a mile below, the warmer
water had again found its place at the surface, and the mist was as
copious as before the union of the three rivers.
After mists have been formed above rivers and lakes, Davy considers
that their increase may not only depend upon the constant operation
of the cause which originally produced them, but likewise upon the
radiation of heat from the superficial particles of water composing
the mist, which produces a descending current of cold air in the
very body of the mist, while the warm water continually sends up
vapour. It is to these circumstances, he says, that the phenomena
must be ascribed of mists from a river or lake sometimes arising
considerably above the surrounding hills. He informs us that he
had frequently witnessed such an appearance during the month of
October, after very still and very clear nights, in the Campagna of
Rome above the Tiber, and on Monte Albano, over the lakes existing
in the ancient craters of this extinguished volcano; and in one
instance, on the 17th of October, before sunrise, there not being a
breath of wind, a dense white cloud, of a pyramidal form, was seen
on the site of Alban Lake, and rising far above the highest peak of
the mountain. Its form gradually changed after sunrise; its apex
first disappeared, and its body, as it were, melted away in the
sunbeams.
Great dryness of the air, or a current of dry air passing across
a river, he found, as we might have expected, to prevent the
formation of mist even when the temperature of the water was much
higher than that of the atmosphere.
Thus did our philosopher, during the course of his journey to
Naples, by a series of observations and experiments, investigate
a phenomenon connected with the deposition of water from the
atmosphere, and which is not without an effect in the economy of
nature; for verdure and fertility, in hot climates, generally
follow the courses of rivers, and by the operation of the law he
established, they are extended to the hills, and even to the plains
surrounding their banks.
On his arrival at Naples, Sir H. Davy found that a letter from his
Royal Highness the Prince Regent to the King, and a communication
made from the Secretary of State for Foreign Affairs to the
Neapolitan Government, had prepared the way for his enquiries, and
procured for him every possible facility in the pursuit of his
objects.
The different rolls of papyri presented very various appearances.
They were of all shades, from a light chestnut brown to a deep
black; some externally were of a glossy black, like jet, which
the superintendents called "varnished;" several contained the
umbilicus, or rolling-stick, in the middle, converted into dense
charcoal. In their texture, also, they were as various as in their
colours.
The persons to whom the care of these MSS. are confided, or who
have worked upon them, have always attributed these different
appearances to the action of fire, more or less intense, according
to the proximity of the lava, which has been imagined to have
covered the part of the city in which they were found; but the
different conclusion at which Davy had arrived, from a chemical
examination in England, was confirmed by a visit to the excavations
that still remained open at Herculaneum.
These excavations are in a loose _tufa_, composed of sand, volcanic
ashes, stones, and dust, cemented by the operation of water, which,
at the time of its action, was probably in a boiling state. The
theatre, and the buildings in the neighbourhood, are incased in
this _tufa_, and, from the manner in which it is deposited in the
galleries of the houses, there can be little doubt that it was
the result of torrents laden with sand and volcanic matter, and
descending, at the same time, with showers of ashes and stone still
more copious than those that covered Pompeii. The excavation in
the house in which the MSS. were found, had been filled up; but
a building, which was said by the guides to be this house, and
which, as is evident from the engraved plan, must at least have
been close to it, at once convinced Davy that the parts nearest
the surface, and, _à fortiori_, those more remote from it, had
never been exposed to any considerable degree of heat. He found a
small fragment of the ceiling of one of the rooms, containing lines
of gold leaf and vermilion, in an unaltered state, which never
could have happened had they been acted upon by any temperature
sufficiently great to convert vegetable matter into charcoal.
The different states of the MSS. exactly coincide with this view,
and furnish evidence of their having undergone a gradual process
of decomposition. The loose chestnut papyri, he observes, were
probably never wetted, but merely changed by the reaction of their
elements, assisted by the operation of a small quantity of air; the
black ones, which easily unroll, may be supposed to have remained
in a moist state, without any percolation of water; while it is
likely that the dense ones, containing earthy matter, have been
acted on by warm water, which not only carried into the folds
earthy matter suspended in it, but likewise dissolved the starch
and gluten used in preparing the papyrus and the glue of the ink,
and distributed them through the substance of the MSS.
As many of the papyri appear to have been strongly compressed when
moist, in different positions, he thinks it probable that they
had been placed on shelves of wood, which were broken down when
the roofs of the houses yielded to the superincumbent mass. That
the operation of fire is not at all necessary for producing such
an imperfect carbonization of vegetable matter as that displayed
by the MSS., is at once proved by an inspection of the houses at
Pompeii, which was covered by a shower of ashes that must have
been cold, as they fell at the distance of seven or eight miles
from the crater of Vesuvius; and yet the wood of its buildings
is uniformly found converted into charcoal, while the colours on
the walls, most of which would have been destroyed or altered by
heat, are perfectly fresh. Where papyri have been found in these
houses, they have appeared in the form of white ashes, as of burnt
paper, an effect produced by the slow action of the air penetrating
through the loose ashes, and which has been impeded or prevented in
Herculaneum by the _tufa_, which, as it were, hermetically sealed
up the town, and prevented any decay, except such as occurs in the
spontaneous decomposition of vegetable substances exposed to the
limited operation of water and air--for instance, peat and Bovey
coal.
Davy ascertained, that what the Neapolitans called varnish,
was decomposed skin that had been used to infold some of the
papyri, and which by chemical changes had produced a brilliant
animal carbonaceous substance, which afforded by distillation a
considerable quantity of ammonia, and left ashes containing much
phosphate of lime.
Only one method, and that a simple and mechanical, though a highly
ingenious one, had been adopted for unrolling the MSS. It was
invented, in the middle of the last century, by Padre Piaggi,
a Roman, and consists in attaching a thin animal membrane, by
a solution of glue, to the back of the MSS. and then carefully
elevating the layers by silk threads, which are gradually moved by
the revolution of wooden pegs. Davy, shortly after his arrival,
desired that the process of unrolling might be continued in his
presence; and in considering the method in its general application,
it occurred to him that some expedient might be used to facilitate
the separation of the layers. For this purpose, he proposed to
mix the solution of glue with a sufficient quantity of alcohol to
gelatinize it, in order that it might not penetrate through three
or four layers, which it was liable to do, when the texture of
the papyrus was loose or broken, and the glue employed was in a
liquid state. He also suggested the application of warm air for
drying the papyrus, in the operation of attaching the membrane. It
is not my intention to follow the chemist through all the various
processes which he instituted for accomplishing his object; they
may, however, be found in his paper entitled "Some Observations and
Experiments on the Papyri found in the Ruins of Herculaneum," which
was read before the Royal Society on the 15th of March 1821, and
published in the Transactions of that year.
It only remains to be stated that Davy was not successful; but
though the process of unrolling hitherto applied may not have
received any considerable improvement from his science, and though
he may not have succeeded in rendering any of the manuscripts
legible, the failure is not to be attributed to his want of zeal,
or to his want of skill, but solely, as it is generally admitted,
to the unfortunate condition of the papyri.
It will be readily supposed that a failure in an investigation,
from which he had anticipated so much advantage, was not sustained
by a person naturally quick and irritable, without some
demonstrations of impatience and dissatisfaction.
It was probably under the influence of such feelings, that he
composed the conclusion of his memoir. "During the two months that
I was actively employed in experiments on the papyri at Naples, I
had succeeded, with the assistance of six of the persons attached
to the Museum, and whom I had engaged for the purpose, in partially
unrolling twenty-three MSS., from which fragments of writing were
obtained, and in examining about one hundred and twenty others,
which afforded no hopes of success; and I should gladly have gone
on with the undertaking, from the mere prospect of a possibility
of discovering some better result, had not the labour, in itself
difficult and unpleasant, been made more so, by the conduct of the
persons at the head of this department in the Museum. At first,
every disposition was shown to promote my researches; for the
papyri remaining unrolled were considered by them as incapable
of affording any thing legible by the former methods, or, to use
their own word, _disperati_; and the efficacy and use of the new
processes were fully allowed by the _Svolgatori_, or unrollers of
the Museum; and I was some time permitted to choose and operate
upon the specimens at my own pleasure. When, however, the Reverend
Peter Elmsley, whose zeal for the promotion of ancient literature
brought him to Naples for the purpose of assisting in the
undertaking, began to examine the fragments unrolled, a jealousy
with regard to his assistance was immediately manifested; and
obstacles, which the kind interference of Sir William A'Court was
not always capable of removing, were soon opposed to the progress
of our enquiries; and these obstacles were so multiplied, and made
so vexatious towards the end of February, that we conceived it
would be both a waste of the public money and a compromise of our
own characters to proceed."
* * * * *
While in Italy, Sir H. Davy visited the baths of Lucca, and
examined the waters which have given to that place so much
celebrity. The results of his analysis formed the subject of a
paper, which was published in the Memoirs of the Royal Academy of
Sciences at Naples, of which Society he was a member.
At the spot where the temperature of the water was the highest,
that is, in what are termed the _Caldi_, or hot baths, a
considerable quantity of a substance is ejected, which produces a
deposit of a brownish-yellow colour. Having collected a quantity
of this deposit, he ascertained it to consist of oxide of iron
and silica, in the proportion of about four parts of the former
to three of the latter; and although the iron, at the time of
its deposition, proved to be a _peroxide_, he thinks it probable
that it existed in the water in the state of _protoxide_. He also
supposes, that the oxide of iron and the silica had been dissolved
together in the water, and been deposited from it in combination.
He conceives that the fact which he had some years before noticed,
of the analogy between the base of silica, and that of boracic
acid, together with those observed by Berzelius, furnish sufficient
reasons for classing silica amongst the acids, and for rendering
it probable, that the oxide of iron and silica undergo a real
chemical combination in the warm water, and that they are separated
from the latter in consequence of the reduction of its temperature,
after it has issued from the mountain.
A small portion of oxide of iron, he observes, is found in the
waters of Bath, in which case it is also accompanied by silica;
and he believes that, in many other instances, the oxide of iron
is dissolved in water through the same agency: he moreover regards
such facts as throwing considerable light upon the manner in which
ochre is generated.
Sir Humphry Davy returned to England in 1820; and, on the 19th of
June, in the same year, his venerable friend Sir Joseph Banks,
who, notwithstanding his increasing infirmities, had continued
to discharge the duties of President of the Royal Society to the
latest period of his life, expired at his villa at Spring Grove, at
the advanced age of seventy-seven.
Discussions necessarily arose as to the appointment of a proper
successor, when persons of high and even exalted rank were proposed
as candidates; but the more influential members of the Society at
once found, in their own Council-chamber, two philosophers, whom
they considered equally entitled to the honour of the situation,
and equally well calculated for the discharge of its duties--Sir
Humphry Davy, and Dr. Wollaston; but the latter having signified
his fixed determination to decline competition, gave the whole
weight of his influence to the former; and, under that arrangement,
he received from the Council the compliment of being placed in
the chair, until the general election of officers at the ensuing
anniversary.
As the period of election approached, a few Fellows of the Society
attempted to raise a clamour in favour of some more aristocratic
candidate. To this circumstance, Davy alludes in the following
letter.
TO THOMAS POOLE, ESQ.
Grosvenor Street, June 1820.
MY DEAR POOLE,
I regret very much that you could not join me at dinner this
day. To-morrow and the following day I shall be occupied
by pressing affairs; but I shall be at home to-morrow till
half-past eleven, and be most happy to see you.
I am not very anxious to remove "mists," for I feel that the
President's chair, after Sir Joseph, will be no light matter;
and unless there is a strong feeling in the majority of the
body that I am the most proper person, I shall not sacrifice my
tranquillity for what cannot add to my reputation, though it
may increase my power of being useful.
I feel it a duty that I owe to the Society to offer myself; but
if they do not feel that they want me, (and the most active
members, I believe, do) I shall not force myself upon them.
I am, my dear Poole, very sincerely yours,
H. DAVY.
On the day of election, (November 30, 1820,) there was a feeble
expression in favour of Lord Colchester, who was abroad at the
time, and had not even been made acquainted with the intention
of his supporters. Davy was therefore elected by an immense
majority of votes. He was conducted into the meeting-room by his
two friends, Mr. Davies Gilbert and Mr. Hatchett, and, to the
gratification of every lover of science, he ascended the chair of
Newton.
The value which he himself attached to this triumph, may be seen in
his answer to a letter of congratulation from his friend Mr. Poole.
TO THOMAS POOLE, ESQ.
Grosvenor Street, Dec. 10.
MY DEAR POOLE,
I am much obliged to you for your congratulations. The contest
to my election defeated itself, for there were only thirteen
votes for Lord Colchester out of nearly one hundred and sixty;
and, had it been known that the attempt would have been made,
I should have had at least double the number. The overwhelming
majority has, however, shown the good opinion of the Society,
which I trust and feel has not been diminished by my conduct in
the chair.
I have never needed any motive to attach me to science, which
I have pursued with equal ardour under all circumstances, for
its own sake, and for the sake of the public, uninfluenced by
the fears of my friends, or the calumnies of my enemies. I
glory in being in the chair of the Royal Society, because I
think it ought to be a reward of scientific labours, and not an
appendage to rank or fortune; and because it will enable me to
be useful in a higher degree in promoting the cause of science.
To this cause, however, I should have been always attached,
even had I not been in such good humour with the public, as I
have reason to be.
Dr. Wollaston, my only formidable opponent in the beginning of
the business, behaved like a true philosopher and friend of
science; and Mr. Gilbert gave me his warmest support.
I am sorry that I have said so much about myself, but
your long letter called for something. I wish I could say
anything satisfactory on the subject of Captain Parry and his
officers.[63] I have every reason to believe Lord Melville
will do all he can on the occasion; no recommendation will
be wanting from the Royal Society that can be given; but the
Admiralty is bound by certain general rules, and will not do
more in this instance than they would do in the case of a
brilliant combat; but these brave and scientific navigators
will be rewarded by a more durable species of glory.
Lady Davy joins me in kind remembrances.
I am, my dear Poole, sincerely yours,
H. DAVY.
[63] Mr. Poole informs me, that he "had been anxious to interest
him, as President of the Royal Society, in favour of those brave
and scientific navigators, particularly Lieutenant, now Captain,
Liddon, who commanded the Griper, in Captain Parry's first
voyage."
It was a question anxiously discussed by the friends of Davy, how
far his elevation to the chair of the Royal Society was calculated
to advance the cause of science, or to increase the lustre of his
own fame. It will be readily perceived that this is a question
perplexed by various conflicting interests, for it not only
involves considerations relating to the character of the person,
but to that also of the constitution and objects of the Society
over which he is called upon to preside.
It is still doubtful whether the Royal Society, in the present
advanced state of science, can derive advantage from possessing in
its President, a philosopher actively engaged in any one branch of
experimental enquiry. Sir Humphry Davy, in his first address from
the chair, took occasion to observe, that "in the early periods of
the establishment, when apparatus was procured with difficulty,
when the greatest philosophers were obliged to labour with their
own hands to frame their instruments, it was found expedient to
keep in the rooms of the Society a collection of all such machines
as were likely to be useful in the progress of experimental
knowledge; and curators and operators were employed, by whom many
capital experiments were made under the eyes of the Society.[64]
But since the improvement of the mechanical and chemical arts
has afforded greater facilities as to the means of carrying on
experimental research, the transactions of the Fellows, recorded
by the Society, have, with some few exceptions, been performed in
their own laboratories, and at their own expense."
[64] The Charter of the Royal Society states that it was
established for the improvement of NATURAL science. This epithet
"_natural_" was originally intended to imply a meaning of
which very few persons, I believe, are aware. At the period of
the establishment of the Society, the arts of witchcraft and
divination were very extensively encouraged; and the word natural
was therefore introduced, in contradistinction to _super_-natural.
Although Sir Walter Scott, in his Demonology, alludes to
the influence of this Society in diminishing the reigning
superstition, he does not appear to have been acquainted with the
circumstance here alluded to.
In deciding upon the qualifications necessary for a President, this
altered state of the Society must not be overlooked; nor can it be
concealed, that the great discoveries of modern science have been
achieved without any direct assistance from the Royal Society. Davy
would have discovered the laws of electro-chemistry, and applied
them for the decomposition of the alkalies--and the genius of
Dalton would, by his atomic doctrine, have "snatched the science
from the chaos of indefinite combination, and have bound it in the
chains of number," had the Society never existed. At the same time,
it must be allowed that, although it may not have directly advanced
the progress of science, it has materially assisted its cause, by
perpetuating the spirit of philosophical enquiry, and the love of
scientific glory--by keeping alive upon the altar the sacred flame
that genius may have kindled.
In the present state of science, the Royal Society imparts an
inspiring principle to its various branches, by affording a
rallying point, a centre of communication, to the philosophers
of all nations, to whom kindred pursuits may render personal
intercourse beneficial; and it becomes the paramount duty of the
chief of this great republic so to preside over its arrangements,
as to foster and encourage such an alliance. To this end, he
must promote feelings of mutual kindness and liberality; and as
the friend and umpire to all parties, it is his office to settle
disagreement, to soothe disappointment, to kindle hope, and to
subdue the vehemence which "engenders strife," in order that
rivalship shall not pass into hostility, nor emulation degenerate
into envy. It is evident that the talents and qualifications
necessary for the discharge of such duties are of the highest
order, extensive in their range, and diversified in their
character. To which, however harshly the word may grate upon the
ear of the philosopher, WEALTH must be considered as an essential
and indispensable condition.
It may be fairly asked, whether a philosopher actively engaged
in the pursuit of any branch of science, is so well adapted
for the performance of such varied duties, as the person who
possesses a general acquaintance with every department, but is not
exclusively devoted to the investigation of any one branch; for,
however correct may be his decisions, or unbiassed his judgment,
the conduct of the former will ever be open to the charge of
partiality, and the bare existence of such a suspicion, though it
may be wholly groundless, will carry with it a train of evils. It
is not in human nature to believe that the looker-on, and he who
plays the game, are alike indifferent to the cards.[65]
[65] I state this opinion with the greater confidence, from a
conviction that it is not singular. On conversing lately upon
the subject with a gentleman to whom the Royal Society is deeply
indebted for the sound judgment and discretion he displayed on
occasions greatly affecting its interests, he replied, "Sir, we
require not an Achilles to fight our battles, but an Agamemnon to
command the Greeks."
On the other hand, it may be urged with some force, that the
Presidency of the Royal Society should be reserved as the fair
reward of scientific labours, and not as an appendage to rank or
to wealth:--that in England, we may in vain search amongst the
aristocracy for one who feels a dignified respect for the sciences,
and who is willing to afford that time which the faithful discharge
of its duties would require.
To assert that Davy retained his popularity, or to deny that he
retired from the office under the frown of a considerable party,
would be dishonest. I would willingly dismiss this part of his life
without too nice an examination; but I am writing a history, not an
eloge.
As a philosopher, his claims to admiration and respect were
allowed in all their latitude; but when he sought for the homage
due to patrician distinction, they were denied with indignation.
How strange it is, that those whom Nature has placed above their
fellow men by the god-like gift of genius, should seek from their
inferiors those distinctions which are generally the rewards
of fortune. When we learn that Congreve, in his interview with
Voltaire, prided himself upon his fashion rather than upon his wit;
that Byron was more vain of his heraldry than of his "Pilgrimage
of Childe Harold;" that Racine pined into an atrophy, because the
monarch passed him without a recognition in the ante-room of the
palace, and that Davy sighed for patrician distinction in the chair
of Newton, we can only lament the weakness from which the choicest
spirits of our nature are not exempt. Will philosophers never feel,
with Walpole, that "a genius transmits more honour by blood than
he can receive?" Had the blood of forty generations of nobility
flowed in the veins of Davy, would his name have commanded higher
homage, or his discoveries have excited greater admiration? But
great minds have ever had their points of weakness: an inordinate
admiration of hereditary rank was the cardinal deformity of Davy's
character; it was the centre from which all his defects radiated,
and continually placed him in false positions; for the man who
rests his claims upon doubtful or ill-defined pretensions, from
a sense of his insecurity, naturally becomes jealous at every
apparent inattention, and he is suspicious of the sincerity of
that respect which he feels may be the fruit of usurpation. If
with these circumstances we take into consideration the existence
of a natural timidity of character, which he sought to conquer by
efforts that betrayed him into awkwardness of manner, and combine
with it an irritability of temperament which occasionally called up
expressions of ill-humour, we at once possess a clue by which we
may unravel the conduct of our philosopher, and the consequences it
brought upon himself during his presidency of the Royal Society.
Nor must we leave out of sight that inattention to certain forms
which, amongst those who are incapable of penetrating beyond
the surface of character, passes for the offensive carelessness
of superiority. Davy, after the example of Sir Joseph Banks,
opened his house on one evening of the week for the reception of
the Fellows of the Royal Society, and of other persons who were
actively engaged in any scientific pursuit; but the invitations to
these _soirées_ were so irregularly managed, that they frequently
gave offence, where they were intended to convey a compliment.
Conflicting opinions, respecting the management of the Royal
Institution, most unfortunately also arose, and the President of
the Royal Society, presuming upon his former alliance with that
establishment, and upon the high obligations conferred upon it
by the splendid discoveries he had achieved within its walls,
was encouraged to exercise an authority which provoked an angry
dissatisfaction;--schisms arose, and the party-spirit thus kindled
in Albemarle Street soon spread to Somerset House.--But let us
turn to the brighter part of the picture. In the discharge of the
more important duties of his office, the Society received the
full benefit of his talents and his virtues. At its meetings,
he was constant in attendance, and dignified in his conduct and
deportment; in its councils, he was firm in his resolves, correct
in his judgments, zealous in his plans,[66] and impartial in his
decisions. It has been said that he unduly favoured the pursuits of
chemistry, to the injury and depression of the other branches of
science: this is not the fact, as a reference to the Philosophical
Transactions will amply testify; and the awards of the Copley
medals will moreover show, that he alike extended the animating
influence of his patronage to every part of natural philosophy.
I am authorised by Sir James South to state, that during his
negotiations with the Government, for the purpose of securing to
the British Nation the unalienable use of his splendid instruments,
by the erection of a permanent observatory, Sir Humphry Davy was
indefatigable in his exertions to accomplish so important an
object; and that on one occasion, in the midst of severe illness,
he travelled at no inconsiderable risk to London, from the distant
seat of his friend Mr. Knight, to advocate a cause so essential, in
his judgment, to the interests of Astronomy.
[66] It was well known to his friends that, had his health not
declined, he would have carried into effect a reform which he
had long contemplated, and by which the Royal Society would have
become, at once, more dignified and more useful.
* * * * *
In the Autumn of 1821, Davy visited his mother and relatives at
Penzance; upon which occasion he received from the inhabitants of
the town, and from the gentlemen resident in its neighbourhood,
a flattering testimony of respect, which made a deep and lasting
impression upon his heart.
At a General Meeting, summoned for the purpose of taking into
consideration some mode by which his fellow-townsmen might express
their sense of his transcendent talents, and of the lustre which
his genius had cast upon the place of his nativity:--It was
unanimously RESOLVED--
"That a public dinner be given to Sir Humphry Davy, and that
the Mayor be desired to wait upon him forthwith, in order to
communicate the Resolution, and respectfully to request that he
would appoint the day, on which it would be agreeable to him to
meet their wishes."
On the day appointed, a deputation of Gentlemen proceeded in
their carriages to the house of his mother, for the purpose of
conducting him to the hotel, where an appropriate entertainment had
been provided for the occasion.
The following letter evinces the sincere satisfaction which this
visit afforded him.
TO THOMAS POOLE, ESQ.
Penzance, July 28, 1821.
MY DEAR POOLE,
An uncontrollable necessity has brought me here. Close to the
Land's-end I am enjoying the majestic in nature, and living
over again the days of my infancy and early youth.
The living beings that act upon me are interesting subjects
for contemplation. Civilization has not yet destroyed in their
minds the semblance of the great Parent of good.
Nature has done much for the inhabitants of Mount's Bay, by
presenting to their senses all things that can awaken in the
mind the emotions of greatness and sublimity. She has placed
them far from cities, and given them forms of visible and
audible beauty.
I am now reviving old associations, and endeavouring to attach
old feelings to a few simple objects.
I am, &c.
H. DAVY.
Although the letter which follows is without date, I am unwilling
to withhold it.
TO THOMAS POOLE, ESQ.
MY DEAR POOLE,
I have been for some weeks absent from London, and have only
just received your letter. When I return in the winter, I shall
be glad to see Mr. A.--I regret that your niece is so much
indisposed. Lady Davy has been obliged to change her climate in
consequence of a long-continued cough, but I am happy in being
able to say she is now quite well.
After the fatigues of a long season in London, I am now
enjoying the Highland scenery and sports with a purer pleasure,
and I find, after the Alps and Pyrenees, even the mountains of
Scotland possessing some peculiar beauties. You ought to come
and see this country, which you would enjoy, both as a lover of
nature and of man. The one is grand and beautiful; the other,
moral, active, and independent.
I am, my dear Poole, your obliged friend,
H. DAVY.
The Philosophical Transactions, during the Presidency of Sir
Humphry Davy, evince the alacrity with which he redeemed the pledge
given to the Society in his address on taking the chair--
"And though your good opinion has, as it were, honoured me with a
rank similar to that of General, I shall be always happy to act as
a private soldier in the ranks of Science."
* * * * *
Many years before even the identity of lightning and electricity
was suspected, it had been observed, on several occasions, that
the magnetism of the compass needle was not only destroyed, which
might have been attributed to heat, but that it was even reversed
by lightning.[67]
[67] Davy observes, that there are many facts recorded in the
Philosophical Transactions, which prove the magnetising powers
of lightning: one in particular, where a stroke of lightning
passing through a box of knives, rendered most of them powerful
magnets.--_Philosophical Transactions_, No. 157, p. 520, and No.
437, p. 57.
In the progress of electrical discoveries, the similarity between
electricity and magnetism had not escaped observation,[68] and
some philosophers had even attempted to establish the existence
of an identity or intimate relation between these two forces.
The experiments of Ritter, however, alone appeared to offer any
confirmation of the supposed analogy; but so obscure was his
language, and so wild and hypothetical his views, that few, if
any, of them were repeated either in France or England, and their
results were for a long time wholly disregarded.
[68] The phenomena of many crystallized minerals which become
electric by heat, and develope opposite electric poles at
their two extremities, offered an analogy so striking to the
polarity of the magnet, that it seemed hardly possible to doubt
a closer connection of the two powers. The developement of a
similar polarity in the Voltaic pile pointed strongly to the
same conclusion; and experiments had even been made with a view
to ascertain whether a pile in a state of excitement might
not manifest a disposition to place itself in the magnetic
meridian.--_Herschel's Discourse_, p. 340.
In a work, entitled "Recherches sur l'identité des Forces Chimiques
et Electriques," published by M. Oersted in the year 1807, the
subject was resumed, and the author advanced the hypothesis,[69]
which twelve years afterwards conducted him to one of the most
important discoveries of the present age, and which has given
origin to a new science, termed ELECTRO-MAGNETISM.[70]
[69] The hypothesis was this:--"In galvanism, the force is more
_latent_ than in electricity, and still more so in magnetism
than in galvanism; it is therefore necessary to try whether
electricity, in its _latent_ state, will not affect the needle."
This passage may be thus explained: When the Voltaic circuit
is interrupted, it possesses opposite electrical poles; and
when continuous, it no longer affects the electrometer, or
the electricity becomes _latent_, which is the condition
theoretically required for the manifestation of its magnetic
action: and the fundamental experiment of Oersted proved that,
under these circumstances, the compass needle was affected.
[70] Mr. Herschel, in speaking of the pertinacity with which
Oersted adhered to the idea of a necessary connection between
electricity and magnetism, observes, that there is something in
it which reminds us of the obstinate adherence of Columbus to his
notion of the necessary existence of the New World.
In the winter of 1819, Professor Oersted, Secretary to the Royal
Society of Copenhagen, published an account of some experiments, in
which the electric current, such as is supposed to pass from the
positive to the negative pole of a Voltaic battery, along a wire
which connects them, caused a magnetic needle near it to deviate
from its natural position, and to assume a new one, the direction
of which was observed to depend upon the relative position of the
needle and the wire.[71]
[71] For this discovery, the President and Council of the Royal
Society adjudged to M. Oersted the medal on Sir Godfrey Copley's
Donation for the year 1820.
It may be necessary to premise, that these experiments were
conducted in a form which had never before suggested itself to the
enquirer; _viz. with the two ends of the pile in communication with
each other_,--a condition which enabled it to discharge itself
freely: this circumstance will, at once, explain the reason of all
preceding failures. It was never before suspected that the electric
current, passing _uninterruptedly_ through a wire, connecting the
two ends of a Voltaic battery, was capable of being manifested
by any effect; the experiments, however, in question furnished
an unequivocal test of its passage by its action on the magnetic
needle; and which may be shortly stated as follows:
The opposite poles of a battery, in full action, were joined by a
metallic wire, which, to avoid circumlocution, has been called the
_uniting conductor_, or the _uniting wire_.
On placing the wire above the magnet and parallel to it, the pole
next the negative end of the battery always moved westward, and
when the wire was placed under the needle, the same pole went
towards the east. If the wire was on the same horizontal plane with
the needle, no declination whatever took place, but the magnet
showed a disposition to move in a vertical direction; the pole next
the negative side of the battery being depressed when the wire was
to the west of it, and elevated when it was placed on the east side.
The extent of the declination occasioned by a battery, depends
upon its power, and the distance of the uniting wire from the
needle. If the apparatus is powerful, and the distance small, the
declination will amount to an angle of forty-five degrees or more;
but this deviation does not give an exact idea of the real effect
which may be produced by galvanism; for the motion of the needle
is counteracted by the magnetism of the Earth. When the influence
of this latter power is destroyed by means of another magnet, the
needle will place itself directly across the connecting wire: so
that the real tendency of a magnet is to stand at right angles to
an electric current. Such phenomena, being wholly at variance with
the laws of simple electrical attraction and repulsion, are only to
be explained upon the supposition that a new energy is generated
by the action of the current of electricity thus brought into
conflict, and which must be identical with, or nearly related to,
magnetism.
It would also appear from the motions of the magnet, when
differently placed with regard to the _uniting wire_, that this
energy circulates, or performs a circular movement around the axis
of the conductor, and thus drives the magnetic pole according to
the direction of the needle with reference to such a current.
This important discovery was no sooner announced to the
philosophical world, than Sir Humphry Davy, with his characteristic
zeal, proceeded to repeat the experiments; and, with his usual
sagacity, so to vary and extend them, as to throw new light upon
this novel department of science. The facts he thus discovered, and
the reasonings founded upon them, were communicated by him to the
Royal Society in three successive memoirs.
THE FIRST, "On the Magnetic Phenomena produced by Electricity," was
read on the 16th of November 1820.
THE SECOND, entitled "Farther Researches on the Magnetic Phenomena
produced by Electricity; with some new Experiments on the
properties of Electrified bodies, in their relations to conducting
powers and Temperature," read July 5th, 1821.
THE THIRD, "On a new Phenomenon of Electro-magnetism," read March
6th, 1823.
The principal experiments communicated in these memoirs were
performed with the battery belonging to the London Institution,[72]
the once powerful apparatus at the Royal Institution having become
old and feeble in his service.
[72] I find from a note addressed to Mr. Pepys, that on the 21st
of June, 1822, Davy worked the two batteries of 1000 plates each
at the London Institution, before the Prince Royal of Denmark.
The experiments were principally electro-magnetic.
The following letter contains an invitation to his friend Mr.
Pepys, to witness his first experiment; a document so far valuable,
as it fixes a date of some importance in the history of discovery.
TO WILLIAM HASLEDINE PEPYS, ESQ.
Grosvenor Street, Oct. 20, 1820.
DEAR PEPYS,
The experiment I wish to show you is no less than the
conversion of electricity into magnetism; but it is a secret as
yet.
I will come to you at twelve on Monday, in the Poultry. If
you will be so good as to order the battery to be charged
to-morrow, it will be ready for us on Monday.
Have you a dipping needle? This, and an air-pump, and the globe
for taking sparks _in vacuo_ by points of charcoal, are all we
shall want.
Perhaps you will invite Dr. Babington, and our worthy friend
Allen.
I will show you the opening of quite a new field of experiment.
Ever yours very sincerely,
H. DAVY.
The discovery of Professor Oersted was limited to the action of
the electric current on needles previously magnetised. Davy
ascertained that the _uniting conductor itself became magnetic_,
during the passage of the electricity through it.[73] It was in
consequence of having observed some anomaly, with respect to the
way in which the uniting wire altered the direction of the magnet,
that he was led to a conjecture which he immediately verified by
a very simple experiment. He threw some iron filings on a paper,
and brought them near the uniting wire, when immediately they
were attracted by the wire, and adhered to it in considerable
quantities, forming a mass round it ten or twelve times the
thickness of the wire: on breaking the communication, they
instantly fell off, proving that the magnetic effect entirely
depended upon the passage of electricity through the wire.
[73] It would appear that M. Arago likewise discovered this fact
at about the same period; but it is evident that the French and
English philosophers arrived at the result independently of each
other; for the experiments which led to it were made by Sir H.
Davy in October 1820; while the September number of the "Annales
de Physique," containing the first account of the Researches of
M. Arago, was not received in London until the 24th of November
in that year; and it may be farther observed, that the numbers of
this journal were very commonly published several months after
the affixed date.
Davy observes, it was easy to imagine that such magnetic effects
could not be exhibited by the electrical wire, without its being
capable of permanently communicating them to steel; and that, in
order to ascertain whether such was the fact, he fastened several
steel needles, in different directions, to the uniting wire, when
those parallel to it were found to act like the wire itself,
while each of those placed across it acquired two poles. Such
as were placed _under_ the wire, the positive end of the battery
being east, had north poles on the south of the wire, and south
poles to the north. The needles _above_ were in the opposite
direction; and this was constantly the case, whatever might be the
inclination of the needle to the wire. On breaking the connexion,
the steel needles, placed _across_ the uniting wire, retained their
magnetism,[74] while those placed _parallel_ to it lost it at the
moment of disunion. The most extraordinary circumstances, however,
connected with these experiments were, first, that _contact_ with
the uniting wire was not found necessary for the production of
the effect,--indeed, it was even produced, though thick glass
intervened; and, secondly, that a needle which had been placed in a
transverse direction to the wire, merely for an instant, was found
as powerful a magnet as one that had been long in communication
with it.
[74] M. Arago also, nearly at the same time, succeeded in
communicating magnetism to the needle; but, at the suggestion
of M. Ampère, it was effected in a different manner. A copper
wire, by being rolled round a solid rod, was twisted into a
spiral, so as to form a _helix_. It was easy, by passing the
wire round the rod, in one direction or the other, to form a
_dextrorsal_ helix, proceeding from the right hand towards the
left, as in the tendrils of many plants; or a _sinistrorsal_,
or left helix, proceeding downwards from the left hand to the
right above the axis. Into the cavity of a spiral thus formed,
connecting the two poles of a battery, a steel needle wrapped
in paper was introduced; and, in order to exclude all influence
of the magnetism of the earth, the conchoidal part of the wire
was kept constantly perpendicular to the magnetic meridian. In a
few minutes the needle had acquired a sufficiently strong dose
of magnetism; and the position of the north and south poles
exactly agreed with M. Ampère's notion, that the electric current
traverses the connecting wire in a direction from the zinc
extremity of the pile to the copper extremity.
The distance to which magnetism is communicated by electricity,
and the fact of its taking place equally through conductors and
non-conductors, are circumstances which, in the opinion of Davy,
are unfavourable to the idea of the identity of electricity and
magnetism.
Davy subsequently ascertained by experiment, that the magnetic
result was proportional to the quantity of electricity passing
through a given space; and this fact led him to believe, that
a wire electrified by the common machine would not occasion a
sensible effect; and this he found to be the case, on placing very
small needles across a fine wire connected with a prime conductor
of a powerful machine and the earth. But as a momentary exposure
in a powerful electrical circuit was sufficient to give permanent
polarity to steel, it appeared equally obvious, that needles placed
transversely to a wire at the time that the electricity of a common
Leyden battery was discharged through it, ought to become magnetic;
and this he found was actually the fact, and according to precisely
the same laws as in the Voltaic circuit; the needle _under_ the
wire, the positive conductor being on the right hand, offering its
north pole to the face of the operator, and the needle _above_,
exhibiting the opposite polarity.
The facility with which experiments are made with the common
Leyden battery, enabled him to ascertain various other important
facts, respecting the communication of magnetism, which it would
be inconsistent with the nature and limits of this work to
particularize. I have merely offered a notice of the more prominent
discoveries communicated by him in his first paper to the Royal
Society, and which he concludes by observing, that "in consequence
of the facts lately developed, a number of curious speculations
cannot fail to present themselves to every philosophical mind;
such as whether the magnetism of the earth may not be owing to its
electricity, and the variation of the needle to the alterations
in the electrical currents of the earth, in consequence of its
motions, internal changes, or its relations to solar heat; and
whether the luminous effects of the auroras at the poles are not
shown, by these new facts, to depend on electricity. This is
evident, that if strong electrical currents be supposed to follow
the apparent course of the sun, the magnetism of the earth ought to
be such as it is found to be."[75]
[75] A very ingenious piece of apparatus was contrived to
illustrate this theory by experiment; but I am uncertain as
to whom the credit of it belongs. It consisted of a globe,
containing metallic wires, arranged in relation to each other
according to the electro-magnetic theory, when, by passing an
electric current in the direction of the ecliptic, the poles
became magnetic.
Davy never overlooked an occasion of applying theory to practice,
and he therefore proposes, upon the principles developed in this
paper, to make powerful magnets, by fixing bars of steel, or
circular pieces of steel, fitted for making horse-shoe magnets,
round the electrical conductors of buildings in elevated and
exposed situations.
His second paper contains an account of experiments instituted
with a view to gain some distinct knowledge on the subject of the
relations of the different conductors to the magnetism produced
by electricity. The results were decisive; but, without entering
minutely into the theory of the subject which they so ably
illustrated, these experiments cannot be clearly described, or
successfully explained. The same observation will apply to the
researches detailed in his third paper, announcing the discovery
of a _new electro-magnetic phenomenon_; for, since they are
inseparably connected with Mr. Faraday's beautiful experiments on
_Magnetic Rotation_, I could scarcely expect to render my analysis
of the memoir sufficiently intelligible, without entering at length
upon that curious subject; I am unwilling, however, to refer the
reader to the original paper in the Transactions, without offering
a remark upon the _phenomenon_, which he says "is the _principal_
object of the paper," but which we might conclude, from the hasty
and imperfect manner in which he dismisses it, to have occupied a
very subordinate place in his estimation. In his anxiety to examine
and describe the rotations produced during this experiment, he
bestows far too little attention upon the more, indeed I might say
the _only_, important phenomenon of the cone of mercury which was
elevated above each of the wires proceeding from the battery; and
which, arising as it evidently did from a repulsive influence,
clearly shows that the presence of electricity establishes between
the particles of matter a repulsive energy, whether that matter
be conducting, or non-conducting in its functions. This law, M.
Ampère subsequently illustrated by a different form of experiment,
and unfairly, as I must think, omitted even to notice Davy's prior
result.
On the 20th of December 1821, Davy communicated to the Royal
Society a memoir "On the Electrical Phenomena exhibited _in vacuo_."
It had been stated by Mr. Walsh, and the opinion had been
subsequently supported by the researches of Mr. Morgan, that the
electrical light was not producible in a perfect Torricellian
vacuum; the latter gentleman also concluded that such a vacuum
prevented the charging of coated glass.
An enquiry of greater importance can scarcely be imagined;
involving in its train several of the most abstruse and difficult
questions of corpuscular philosophy; as, whether electricity be
a subtile fluid, or electrical effect the mere exhibition of the
attractive powers of the particles of bodies; for, if it can be
shown that these effects take place in a perfect vacuum, we shall
advance towards the conclusion, that electrical phenomena depend
upon the agency of an ethereal and transcendental fluid. It was
under such an impression that Davy proceeded to determine, if
possible, "the relations of electricity to space, as nearly void of
matter as it can be made on the surface of the earth."
He was, in the first instance, led to suspect the accuracy of those
conclusions at which Mr. Walsh and Mr. Morgan had arrived, from
considering that, "in the most perfect vacuum which can be obtained
in the Torricellian tube, vapour of mercury, though of extremely
small density, must still always exist." I propose to follow our
philosopher through the paths of this enquiry; and then, with all
the deference due to such high authority, to state the objections
which may be urged against his results.
First, then, as to the results he obtained with quicksilver in
an apparatus simple, but well adapted at once to insure the most
completely attainable vacuum, and to exhibit its capability of
receiving a charge. In all cases where this vacuum was perfect,
he found it to be permeable to electricity, and to be rendered
luminous, either by the common spark, or by the shock from a Leyden
jar; and, moreover, that the coated glass surrounding it became
charged under such circumstances; but the intensity of the light in
these experiments was always in proportion to the temperature, or,
in other words, to the density of the mercurial vapour; and that
at 20° below zero of Fahrenheit, it became so faint as to require
considerable darkness to render it perceptible.
The great brilliancy, on the other hand, of the electrical light
in pure, dense vapour of mercury, was beautifully displayed during
the operation of boiling the metal in an exhausted tube. "In the
formation and condensation of the globules of mercurial vapour, the
electricity produced by the friction of the mercury against the
glass, was discharged through the vapour with sparks so bright as
to be visible in daylight."
The charge likewise communicated to the tinfoil was higher, the
higher the temperature; at 0° Fahrenheit it was extremely feeble.
This, like the phenomenon of the electric light, must, he thinks,
depend upon the different density of the vapour of mercury.
But he was desirous of still farther refining his experiments,
so as to exclude, as far as it was possible, the presence of any
volatile matter; and in this part of the enquiry he displayed,
in a very masterly manner, that happy talent in which he so
far surpassed his contemporaries, of suggesting expedients
and contriving new apparatus in order to vanquish practical
difficulties.
To get rid of a portion of mercurial vapour, he employed a
difficultly fusible amalgam of mercury and tin, which was made to
crystallize by cooling in the tube; but, in this case, the results
were precisely the same as when pure mercury had been used. He then
attempted to make a vacuum above the fusible alloy of bismuth, but
he found it so liable to oxidate and soil the tube, that he soon
renounced farther attempts of this kind. Nothing discouraged, he
determined to try the effects of a comparatively fixed metal in
fusion. By melting freshly cut pieces of grain tin, in a tube made
void after having been filled with hydrogen, and by long-continued
heat and agitation, he obtained a column of fixed metal which
appeared to be entirely free from gas; and yet the vacuum made
above this exhibited the same phenomena as the mercurial vacuum,
except that they were not perceptibly increased by heat: a fact
which Davy must have anticipated, as he attributed the greater
display of electrical light, at high temperatures, to the effect
of increased density of vapour; it is therefore a matter of
surprise that he did not give more importance to the phenomenon.
He made two experiments on electrical and magnetic repulsions and
attractions in the mercurial vacuum, and he found that two balls,
the one of platinum, the other of steel, properly arranged for the
purpose, repelled each other, when the conducting wire to which
they were attached was electrified in the most perfect mercurial
vacuum, as they would have done in the usual cases: and that the
steel globules were as obedient to the magnet as in the air; which
last result, he observes, it was easy to have anticipated.
He also made some comparative experiments, with the view of
ascertaining, whether below the freezing point of water the
diminution of the temperature of the Torricellian vacuum diminished
its power of transmitting electricity, or of being rendered
luminous by it. To about twenty degrees, this appeared to be the
case; but between twenty degrees above, and twenty degrees below
zero, the lowest temperature he could produce by pounded ice and
muriate of lime, it seemed stationary; and, as well as he could
determine, the electrical phenomena were very nearly of the same
intensity as those produced in the vacuum above tin.
"It is evident," he says, "from these general results, that
the light (and probably the heat) generated in electrical
discharges depends _principally_ on some properties or substances
belonging to the ponderable matter through which it passes: but
they prove likewise that space, where there is no appreciable
quantity of this matter, is still capable of exhibiting electric
phenomena--viz. those of attraction and repulsion, &c.: a fact
unquestionably favourable to the idea of the phenomena of
electricity being produced by a highly subtile fluid or fluids, of
which the particles are repulsive with respect to each other, and
attractive of the particles of other matter."
However much we may admire the experimental address displayed in
this paper, we must confess that its results are very far from
being satisfactory. His having assumed, without proof, and even
without examination, the theory that a perfect vacuum cannot be
produced in the Torricellian tube, and made it the foundation of
his reasonings, appears to me to have vitiated all his conclusions.
Mr. Faraday has rendered it extremely probable, that a _limit_
does actually exist to the production of vapour by bodies placed
_in vacuo_,[76] beneath which they are perfectly fixed; and if
this be true, it is evident that, at low temperatures, a perfect
vacuum may be produced in the Torricellian tube; and it is highly
probable that Davy did thus actually produce one in several of his
experiments; especially in those where he found that, by a farther
reduction of temperature, no farther diminution of electrical
effect was perceptible: he had in fact arrived at this limit to
vaporization, and therefore a farther reduction of temperature
could not possibly influence the phenomena. In this point of view,
the electrical light would seem to be _primary_, or independent of
foreign matter.--But though the premises be granted, let the reader
pause before he hastens to any conclusion; for the cloud of mystery
has not been dissipated, it has only changed its place. At the
termination of his paper, Davy indulges in a conjecture subversive
of every conclusion deduced from experiments _in vacuo_. "When the
intense heat," says he, "produced by electricity, and the strong
attractive powers of differently electrified surfaces, and the
rapidity of the changes of state, are considered, it does not seem
at all improbable, that the superficial particles of bodies, which,
when detached by the repulsive power of heat, form vapour, may be
likewise detached by electrical powers, and that they may produce
luminous appearances in a vacuum free from all other matter, by the
annihilation of their opposite electrical states."
[76] "On the Existence of a Limit to Vaporization. By M. Faraday,
F.R.S. Corresponding Member of the Royal Academy of Sciences at
Paris." Phil. Trans. 1826. See also a more recent paper by the
same Philosopher in the first number of the new Journal of the
Royal Institution.
During the course of the enquiry, Davy is led to suppose that air
may exist in mercury, in the same invisible state as it does in
water, that is, distributed through its pores; and that absorption
of air may, therefore, explain the difference of the heights of
the mercury in different barometers. This, it must be confessed,
if true, is a most disheartening fact, as it at once precludes the
possibility of any thing like accuracy in our barometers; but Mr.
Daniell, to whom on all subjects of meteorology we are bound to pay
the greatest deference, differs altogether from our philosopher
upon this point, and he adduces a single observation which he
thinks nearly disproves the supposition. "All fluids," says he,
"which are known to absorb air into their pores, invariably emit
it when the pressure of the atmosphere is removed; but, upon an
extensive examination of large bodies of mercury, variously heated
in the vacuum of an air-pump, I never saw a bubble of air given off
from the surface of the metal." Davy, it must be stated, obtained
a far different result; but an observation of Mr. Daniell explains
the cause of it. "Air," he continues, "will rise from the contact
of the mercury with the glass in which it is contained, in exact
inverse proportion to the care with which it has been filled,
but it _never rises from the surface of the mercury alone_. The
difficulty of properly filling a barometer tube, I attribute to the
attraction between the glass and the air--not to that between the
mercury and the air."[77]
[77] "Meteorological Essays and Observations," p. 363.--See
also Bellani's experiments upon this subject, which are so
satisfactory as to remove every doubt from the subject.
On the 13th of June 1822, a memoir was read before the Royal
Society, "On the state of Water and Aëriform matter in cavities
found in certain Crystals. By Sir Humphry Davy, Bart. P.R.S."
It is generally admitted by Geologists, that the greater number of
the crystalline substances of the mineral kingdom must have been
previously in a liquid state; but different schools have assumed
different causes for their solution; some attributing the effect
principally to the agency of water, others to that of heat.
In the paper under consideration, the author very freely avows
himself as the champion of the latter doctrine.
"When it is considered," says he, "that the solvent power of water
depends upon its temperature, and its deposition of solid matters
upon its change of state or of temperature, and that, being a
gravitating substance, the same quantity must always belong to the
globe, it becomes difficult to allow much weight to the arguments
of the Wernerians, or Neptunists, who have generally neglected, in
their speculations, the laws of chemical attraction.
"There are many circumstances, on the contrary, favourable to that
part of the views of the Huttonians, or Plutonists, relating to the
cause of crystallization; such as the form of the earth, that of
an oblate spheroid flattened at the poles; the facility with which
heat, being a radiating substance, may be lost and dissipated in
free space; and the observations which seem to show the present
existence of a high temperature in the interior of the globe."
He had often, he tells us, in the course of his chemical
researches, looked for facts, or experiments, which might throw
some light on this interesting subject, but without success, till
it occurred to him, as he was considering the state of the fluid
and aëriform matters which are found included in certain crystals,
that these curious phenomena might be examined in a manner to
afford some important arguments as to the formation of the crystal
itself.
Having obtained, through the liberality of his friends, a variety
of appropriate specimens of rock-crystal, he proceeded to submit
them to experiment. Their cavities were opened by means of diamond
drills, under either distilled water, oil, or mercury; the gas was
then expelled from them by the introduction of slender wires, and
the included fluids were drawn out by the aid of fine capillary
tubes.
As soon as an opening was effected, the fluid under which the
operation had been performed rushed into the cavity, and the
globule of elastic fluid contracted so as to appear from six to ten
times less than before the experiment. The fluid was found to be
nearly pure water,--the gas appeared to be azote.
It was an interesting point to ascertain whether the same
circumstances occurred in productions found in rocks which have
been generally considered as of igneous origin, such as the
basaltic rocks in the neighbourhood of Vicenza, the chalcedonies
of which so often afford water. On examining such specimens, when,
to obviate the possibility of any fallacy, they were previously
ascertained to be impermeable to the atmosphere, analogous results
were obtained: water, containing very minute quantities of saline
impregnations, was found to be the fluid, and the gas, as in the
former instances, was ascertained to be azote; but it was in a much
more rarefied state than in the rock-crystals, being between sixty
and seventy times as rare as atmospheric air.
The fact of azote being found in these cavities, he explains, by
supposing that atmospheric air might have been originally included
in the crystals, and that the oxygen had been separated from it by
the attraction of the water; a conjecture which a direct experiment
appeared to confirm.
In reasoning upon the vacuum, or rarefied state of the aëriform
matter in the cavities of rock-crystals and chalcedonies, he very
justly states, that the phenomenon cannot be easily accounted for,
except on the supposition of their having been formed at a higher
temperature than that now belonging to the surface of the globe:
and he thinks it most probable that the water and the silica were
in chemical union, and separated from each other by cooling, since
there are strong grounds for believing that a liquid _hydrate of
silica_ would exist at high temperatures under pressure, and that,
like all liquid bodies in the atmosphere, it would contain small
quantities of atmospheric air. If this be granted, we may readily
explain the phenomena presented by the gaseous and liquid matters
in rock-crystal and chalcedony.
Thus then did Davy assail the Neptunists in their own camp, and
vanquish them with their own weapons; for the fact, which had been
confidently considered by the disciples of Werner, as, above all
others, hostile to the idea of the igneous origin of crystalline
rocks, namely, the existence of water in them, has been made to
afford a decisive argument in favour of the very opinion it had
been brought forward to oppose.[78]
[78] I well remember with what triumph the late Dr. Clarke, in
his popular lectures on Mineralogy at Cambridge, paraded a fine
crystal containing water in its cavity. "Gentlemen," said he,
"there is water enough in the very crystals in my cabinet to
extinguish all the fires of the Plutonists."
In an appendix to the foregoing paper, the examination of two other
crystals is detailed; the results afforded were very different from
those of the preceding ones, but not less favourable to the theory
of igneous origin. One of these crystals was found to contain a
bituminous fluid; on piercing it under distilled water, the water
rushed in, and entirely filled the cavity, so that no aëriform
matter but the vapour of the substance could have been present. The
fact of almost a perfect vacuum existing in a cavity containing an
expansible but difficultly volatile substance, must be considered
as highly favourable to the theory of the igneous origin of
crystals.
In the other crystal, the quantity of aëriform matter was unusually
small in proportion to the quantity of fluid, and from the
peculiarity of its motion, it appeared to be more likely to be
compressed than rarefied elastic fluid; and in piercing the sides
of the cavities, Davy found that this was the case; it enlarged in
volume from ten to twelve times; the fluid was water, but the gas
was too minute in quantity to be examined. There is but one mode of
accounting for this phenomenon. The crystal must have been formed
under an immense weight of atmosphere or fluid, sufficient to
produce a compression much more than adequate to compensate for the
expansive effects of heat.[79]
[79] An explanation which the experiments of Mr. Faraday, on the
condensation of the gases, to be immediately described, will most
fully justify.
CHAPTER XIII.
The Liquefaction of Chlorine Gas first effected by Mr. Faraday,
and witnessed by the Author.--Sir H. Davy continues the
investigation.--His paper on the application of Liquefiable
Gases as mechanical agents.--Other probable uses of these
bodies.--He proposes several methods to prevent the fumes which
arise from Smelting-furnaces.--Importance of the subject. His
Letters to Mr. Vivian.--The Government solicit the advice of
the Royal Society on the subject of protecting the Copper
Sheathing of Ships from the action of sea-water.--Sir H.
Davy charges himself with this enquiry.--He proposes a plan
of protection founded on Voltaic principles.--His numerous
experiments.--He embarks on board the Comet steam-vessel
bound to Heligoland, in order to try his plan on a vessel
in motion.--He arrives at Mandal, lands, and fishes in the
lakes.--The Protectors washed away.--He teaches the inhabitants
of Christiansand to crimp fish--He remains a few days at
Arendal.--A Norwegian dinner.--The Protectors are examined and
weighed.--Results of the experiment.--The steam-vessel proceeds
up the Glommen.--He visits the great waterfall--Passes into
Sweden.--Has an interview with the Crown Prince of Denmark,
and afterwards with Prince Christian at Copenhagen.--He
visits Professor Oersted.--He proceeds to Bremen to see Dr.
Olbers.--Returns to England.--His third paper read before the
Royal Society.--Voltaic influence of patches of rust.--A small
quantity of fluid sufficient to complete the circuit.--He
receives from the Royal Society the Royal Medal.--The Progress
of Voltaic discovery reviewed.--The principle is of extensive
application.--The Author's researches into the cause of the
solution of Lead in spring water.--An account of the numerous
trials of Protectors.--Failure of the plan.--Report of the
French on the state of the protected frigate La Constance.--Dr.
Revere's new plan of Protection.
Every incident, however trifling, if it relates to a great
scientific discovery, merits the attention of the historian. As
it accidentally occurred to me, and to me alone, to witness the
original experiment by which Mr. Faraday first condensed chlorine
gas into a liquid, I shall here state the circumstances under which
its liquefaction was effected.
I had been invited to dine with Sir Humphry Davy, on Wednesday
the 5th of March 1823, for the purpose of meeting the Reverend
Uriah Tonkin, the heir of his early friend and benefactor of that
name.[80] On quitting my house for that purpose, I perceived that
I had time to spare, and I accordingly called in my way at the
Royal Institution. Upon descending into the laboratory, I found
Mr. Faraday engaged in experiments on chlorine and its hydrate
in closed tubes. It appeared to me that the tube in which he was
operating upon this substance contained some oily matter, and I
rallied him upon the carelessness of employing soiled vessels.
Mr. Faraday, upon inspecting the tube, acknowledged the justness
of my remark, and expressed his surprise at the circumstance. In
consequence of which, he immediately proceeded to file off the
sealed end; when, to our great astonishment, the contents suddenly
exploded, and the oily matter vanished!
[80] Sir Humphry had expressed to me, on the preceding Thursday,
at the Royal Society, his wish to purchase the old house in
Penzance, which, as the reader will remember, was the early scene
of his chemical operations; and, at his request, I conversed with
Mr. Tonkin upon the subject; but it immediately appeared that
the interest which the Corporation of Penzance possessed in the
estate presented an insurmountable obstacle to the accomplishment
of his object.
Mr. Faraday was completely at a loss to explain the occurrence, and
proceeded to repeat the experiment with a view to its elucidation.
I was unable, however, to remain and witness the result.
Upon mentioning the circumstance to Sir Humphry Davy after dinner,
he appeared much surprised; and after a few moments of apparent
abstraction, he said, "I shall enquire about this experiment
to-morrow."
Early on the next morning, I received from Mr. Faraday the
following laconic note:
DEAR SIR,
The _oil_ you noticed yesterday turns out to be liquid chlorine.
Yours faithfully,
M. FARADAY.
It is well known that, before the year 1810, the solid substance
obtained by exposing chlorine, as usually procured, to a low
temperature, was considered as the gas itself reduced into that
form: Sir Humphry Davy, however, corrected this error, and first
showed it to be a hydrate, the pure gas not being condensable even
at a temperature of-40° Fahrenheit.
Mr. Faraday had taken advantage of the cold season to procure
crystals of this hydrate, and was proceeding in its analysis,[81]
when Sir Humphry Davy suggested to him the expediency of observing
what would happen if it were heated in a close vessel; but this
suggestion was made in consequence of the inspection of results
already obtained by Mr. Faraday, and which must have led him to the
experiment in question, had he never communicated with Sir Humphry
Davy upon the subject. This avowal is honestly due to Mr. Faraday.
[81] The results are contained in a short paper in the Quarterly
Journal of Science, vol. xv.
On exposing the hydrate, in a tube hermetically sealed, to a
temperature of 100°, the substance fused, the tube became filled
with a bright yellow atmosphere, and, on examination, was found
to contain two fluid substances: the one, about three-fourths of
the whole, was of a faint yellow colour, having very much the
appearance of water; the remaining fourth was a heavy, bright
yellow fluid, lying at the bottom of the former, without any
apparent tendency to mix with it.
By operating on the hydrate in a bent tube hermetically sealed,
Mr. Faraday found it easy, after decomposing it by a heat of 100°,
to distil the yellow fluid to one end of the tube, and thus to
separate it from the remaining portion. If the tube were now cut in
the middle, the parts flew asunder, as if with an explosion, the
whole of the yellow portion disappeared, and there was a powerful
atmosphere of chlorine produced; the pale portion, on the contrary,
remained, and when examined, proved to be a weak solution of
chlorine in water, with a little muriatic acid, probably from the
impurity of the hydrate used. When that end of the tube in which
the yellow fluid lay was broken under a jar of water, there was an
immediate production of chlorine gas.
After several conjectures as to the nature of the changes thus
produced, Mr. Faraday arrived at its true explanation; viz. that
the chlorine had been entirely separated from the water by the
heat, and condensed into a dry fluid by the mere pressure of its
own abundant vapour. He subsequently confirmed these views by
condensing chlorine in a long tube, by mechanical pressure, applied
by means of a condensing syringe, and which farther enabled him to
ascertain that the degree of pressure necessary for this effect was
about that of four atmospheres.
To Mr. Faraday's paper upon this subject, published in the
Philosophical Transactions for the year 1823, Sir Humphry Davy
thought proper to add a "Note on the condensation of muriatic acid
gas into the liquid form."
The circumstances under which this was effected are briefly these.
On the morning (Thursday, March 6th,) after Mr. Faraday had
condensed chlorine, Sir Humphry Davy had no sooner witnessed the
result, than he called for a strong glass tube, and, having placed
in it a quantity of muriate of ammonia and sulphuric acid, and then
sealed the end, he caused them to act upon each other, and thus
condensed the muriatic acid, which was evolved, into a liquid. The
condensation of carbonic acid gas, nitrous oxide gas, and several
others, were in succession treated with similar success; but, as I
regard the discovery as strictly belonging to Mr. Faraday, I shall
confine myself to the relation of those experiments and deductions
which, with equal justice, I must assign to Sir Humphry Davy.
He observes, "that the generation of elastic substances in close
vessels, either with or without heat, offers much more powerful
means of approximating their molecules than those dependent upon
the application of cold, whether natural or artificial: for, as
gases diminish only about 1/450 in volume for every--degree of
Fahrenheit's scale, beginning at ordinary temperatures, a very
slight condensation only can be produced by the most powerful
freezing mixtures, not half as much as would result from the
application of a strong flame to one part of a glass tube, the
other part being of ordinary temperature: and when attempts
are made to condense gases into liquids by sudden mechanical
compression, the heat, instantly generated, presents a formidable
obstacle to the success of the experiment; whereas, in the
compression resulting from their slow generation in close vessels,
if the process be conducted with common precautions, there is no
source of difficulty or danger; and it may be easily assisted by
artificial cold in cases when gases approach near to that point of
compression and temperature at which they become vapours."
On the 17th of April 1823, he communicated to the Royal Society a
paper "On the application of Liquids formed by the condensation of
Gases as mechanical agents."
He states that doubts may, for various philosophical reasons, exist
as to the economical results to be obtained by employing the steam
of water under great pressures, and at very elevated temperatures;
but that no doubts can arise with respect to the use of such
liquids as require for their existence even a compression equal to
that of the weight of thirty or forty atmospheres; and where common
temperatures, or slight elevations of them, are sufficient to
produce an immense elastic force; and when the principal question
to be discussed is, whether the effect of mechanical motion is to
be most easily produced by an increase or diminution of heat by
artificial means.
With the assistance of Mr. Faraday, he made several experiments
on the differences between the increase of elastic force in gases
under high and low pressures, by similar increments of temperature.
In an experiment made with carbonic acid, its force was found to be
nearly equal to that of air compressed to one-twentieth at 12° Fah.
and of air compressed to one-thirty-sixth at 32 degrees, making an
increase equal to the weight of thirteen atmospheres by an increase
of twenty of temperature!
In applying, however, the condensed gases as mechanical agents,
Davy admits that there will be some difficulty; "the materials
of the apparatus must be as strong and as perfectly joined as
those used by Mr. Perkins in his high-pressure steam-engine:
but the small differences of temperature to produce an elastic
force equal to the pressure of many atmospheres, will render the
risk of explosion extremely small;" and he adds, "that if future
experiments should realize the views here developed, the mere
difference of temperature between sunshine and shade, and air and
water, or the effects of evaporation from a moist surface, will be
sufficient to produce results, which have hitherto been obtained
only by a great expenditure of fuel."
If this be true, who can say that future generations shall not
perform their voyages in _gas_-vessels, across the Atlantic Ocean,
with no other fuel than that which a common taper may supply? I
fear, however, that in this scientific reverie, Davy merely looked
at the difference of the sensible temperatures, and entirely
neglected, in his calculation, the quantity of heat rendered latent
during the change of the liquid into the gaseous state; and which,
perhaps, is far more considerable in the application of these
fluids than in that of water; but even in this latter case, the
great expenditure of heat in working the steam-engine, is in the
portion rendered latent, and which cannot, by any contrivance, be
brought again into operation, after it has performed its duty. That
a philosopher who had, during the whole progress of his researches,
directed such unremitting attention to the subject of Heat, should
have wholly overlooked an objection arising out of one of its most
familiar phenomena, is scarcely less extraordinary than his having,
on another occasion,[82] advanced to a conclusion in direct
opposition to the very principle of Electricity, which his own
discoveries had established.
[82] I here allude to an anecdote related by Mr. Babbage, in
his "Reflections on the Decline of Science in England;" a work,
by the by, which strongly reminds me of a practical bull. A
gentleman, anxious to escape the tax on armorial bearings,
wrote a long letter to the Commissioners, stating I do not know
how many reasons to show that he could never have used them;
and, after all, sealed the letter with his own coat of arms!
Had Mr. Babbage hoped to convince the reader that Science was
actually on the decline in this country, he should never have
written a work which gives the lie to the title-page. Now for
the anecdote.--"Meeting Dr. Wollaston one morning in the shop
of a bookseller, I proposed this question: If two volumes of
hydrogen and one of oxygen are mixed together in a vessel, and
if by mechanical pressure they can be so condensed as to become
of the same specific gravity of water, will the gases, under
these circumstances, unite and form water? 'What do you think
they will do?' said Dr. W. I replied, that I should rather expect
they would unite. 'I see no reason to suppose it,' said he. I
then enquired whether he thought the experiment worth making.
He answered, that he did not, for that he should think it would
certainly _not_ succeed.
"A few days after, I proposed the same question to Sir Humphry
Davy. He at once said, 'They will become water of course:' and
on my enquiring whether he thought the experiment worth making,
he observed that it was a good experiment, but one which it was
hardly necessary to make, as it must succeed.
"These were off-hand answers, which it might perhaps be hardly
fair to have recorded, had they been of persons of less eminent
talent; and it adds to the curiosity of the circumstance to
mention, that I believe Dr. Wollaston's reason for supposing no
union would take place, arose from the nature of the electrical
relations of the two gases remaining unchanged: an objection
which did not weigh with the philosopher whose discoveries had
given birth to it."
Davy succeeded in liquefying gases by a method which, at first
view, appears very paradoxical--_by the application of heat!_ The
method consists in placing them in one leg of a bent sealed tube,
confined by mercury, and applying heat to ether, or alcohol, or
water, in the other end. In this manner, by the pressure of the
vapour of ether, he liquefied prussic gas and sulphurous acid gas;
which gases, on being reproduced, occasioned cold.
There can be little doubt, he thinks, that these general facts
of the condensation of the gases will have many practical
applications. They offer, for instance, easy methods of
impregnating liquids with carbonic acid and other gases, without
mechanical pressure. They afford means of producing great
diminutions of temperature, by the rapidity with which large
quantities of liquids may be rendered aëriform; and as compression
occasions similar effects to cold, in preventing the formation of
elastic substances, there is great reason to believe that it may be
successfully employed for the preservation of animal and vegetable
substances for the purposes of food.
Davy might also have added, that the same general views will
explain natural and other phenomena not previously understood. They
certainly afford a plausible explanation of the nature of _blowers_
in coal-mines; and they may lead to more satisfactory views on
other subjects of geology. They assign a limit to the expansive
force of gas under increasing pressure, and account for effects
connected with the _blasting_ of rocks, which would otherwise
appear anomalous.[83]
[83] In the year 1812, Mr. Babbage attempted to ascertain whether
pressure would prevent decomposition: for this purpose, a hole
about thirty inches deep, and two inches in diameter, was bored
downward into a limestone rock, into which was then poured a
quantity of strong muriatic acid, and a conical wooden plug, that
had been previously soaked in tallow, was immediately driven
hard into the mouth of the hole. It was expected either that the
decomposition would be prevented, or that the gas developed would
split the rock by its expansive force: but nothing happened.
Now, it is most probable that a part of the carbonic acid had
condensed into a liquid, and thus prevented that developement of
power which Mr. Babbage had expected would have torn the rock
asunder.
It may be stated, greatly to the honour of Davy, that there never
occurred any question of scientific interest or difficulty in
which he did not cheerfully offer his advice and assistance. Few
Presidents of the Royal Society have ever exerted their influence
and talents with so much unaffected zeal for the promotion of
scientific objects, and for the welfare of scientific men. In the
year 1821, the Great Hafod copper-works, in the neighbourhood
of Swansea, were indicted for a nuisance, in consequence of the
alleged destructive effects of the fumes which arose during the
smelting of the ores. When we learn that the amount of wages
paid by the proprietors of the works in this district exceeds
50,000_l._, per annum; that twelve thousand persons, at least,
derive their support from the smelting establishments; that a sum
of not less than 200,000_l._ sterling is annually circulated in
Glamorganshire and the adjoining county, in consequence of their
existence; that they pay to the collieries no less than from
100,000_l._ to 110,000_l._ per annum for coal; that one hundred and
fifty vessels are employed in the conveyance of ore, and, supposing
each upon an average to be manned by five seamen, that they give
occupation to seven hundred and fifty mariners, a more serious
calamity can scarcely be imagined than the stoppage of such works:
we may therefore readily believe, that Davy entered most ardently
into the consideration of some plan by which the fumes might be
prevented, and the alleged nuisance abated.
Through the kind attention of my friend Mr. Vivian, I am enabled to
insert the following letters.
TO JOHN HENRY VIVIAN, ESQ.
London, Jan. 9, 1822.
MY DEAR SIR,
As you expressed a wish that I should commit to writing those
opinions which I mentioned in conversation, when I had the
pleasure of visiting you at Marino, after inspecting your
furnaces and witnessing your experiments on the smoke arising
from them, I lose no time in complying with your desire.
It is evident that the copper ore cannot be properly calcined
without a copious admission of air into the furnaces, which
must cause the sulphurous acid gas formed in the calcination
to be mixed with very large quantities of other elastic
fluids, which presents great mechanical, as well as chemical
difficulties to its condensation or decomposition.
To persons acquainted with chemistry, a number of modes of
effecting these objects are known. Of condensation, for
instance, by water, by the formation of sulphuric acid, by
alkaline lixivia, by alkaline earths, &c. Of decomposition,
by hydrogen, by charcoal, by hydro-carbonous substances, and
by metals; but to most of these methods there are serious and
insurmountable objections, depending upon the diluted state of
the acid gas, and the expenses required.
To form sulphuric acid, or to decompose by charcoal or
hydrogen, or to condense by alkaline lixivia, or by alkaline
earths, from the nature of the works, and of the operations for
which they were intended, I conceive impracticable except at an
expense that could not be borne; and the only processes which
remain to be discussed are those by hydro-carbonous substances,
and by the action of water.
There can be no doubt that the gas may be decomposed by the
action of heated hydro-carbonous gases from the distillation
of coal; but for this purpose there must be a new construction
of the furnaces, and more than double, probably triple,
the quantity of fuel would be required, supposing even the
Swansea coal to contain the common average of bitumen; and
this method must be infinitely more expensive, and liable to
many more objections, than the one you have so ingeniously
employed--absorption by water.
As water costs nothing, and as a supply is entirely in
your power, the application of it offers comparatively few
difficulties; and it has the great advantage of freeing the
smoke from fluoric and arsenious compounds, which would not be
perfectly effected by any other method.
The experiments of MM. Phillips and Faraday prove, that your
shower baths have already entirely destroyed all the fluoric
and arsenious fumes of the smoke, and by a _certain_ quantity
of water, the smoke may undoubtedly be entirely freed from
sulphurous acid gas.
This, _your own_ plan, is the one that I strongly recommend to
you to proceed with, and, if necessary, to extend.
Perhaps you may find an additional shower bath near the colder
part of the flue useful. I have no idea that steam passed into
the hot part of the flue can be of the least service; but if
passed out with the smoke through the stack, it may tend to
convert such residual portion of sulphurous acid gas, exposed
to fresh air, into sulphuric acid. Could you not likewise
try a stream of _cold_ water passing along the bottom of the
horizontal flue?[84]
I do not think the advantages of your improvements can be
fairly appreciated, till the effects of your smoke are
determined by actual experiments and fair trials.
Yours, &c.
H. DAVY.
[84] For the purpose of acting by its cooling power in condensing
vapour, which would carry down sulphurous acid with it. It would
likewise assist by direct absorption. H. D.
TO THE SAME.
London, May 12, 1823.
MY DEAR SIR,
I return you my thanks for the copies you were so good as
to send me of your work on the modes you have adopted for
rendering copper smoke innoxious, &c. I have read it with very
great pleasure, and I am sure there can be but one feeling, and
that of strong admiration, at the exertions you have made, and
the resources you have displayed, in subduing the principal
evils of one of our most important national manufactures. I
trust you will have no more trouble on this subject, and that
it will only occur to you in an agreeable form, with the high
approbation as well as grateful feelings of your neighbours;
and that your example will be followed.
A Committee of the Royal Society has been formed for
investigating the causes of the decay of copper sheeting in
the Navy, as I mentioned to you. The Navy Board has sent us a
number of specimens of copper in different stages of decay. We
have our first meeting to examine them on Thursday, and I shall
have much pleasure in communicating to you our results. I wish
I could do it in person.
I am going into Hampshire on Sunday next to fish near
Fordingbridge for a week, and to try the Avon and its tributary
streams.
I was going to give you an account of some experiments which
Mr. Faraday has made by my directions in generating gases in
close vessels as liquids, but I find I have not time. I have
already found an application of this discovery, which I hope
will supersede _steam_, as a difference of a few degrees of
temperature gives the elastic force of many atmospheres.
Hoping to see you soon, I am, with best respects to Mrs.
Vivian, and love to the charming little Bessy,
My dear Sir, yours sincerely obliged,
H. DAVY.
* * * * *
I proceed now to relate the history of an elaborate experimental
enquiry, instituted for the purpose of ascertaining the chemical
nature and causes of the well-known corrosive action of sea-water
upon metallic copper; in order, if possible, to obviate that
serious evil in naval economy--the rapid decay of the copper
sheathing on the bottoms of our ships. An investigation which Sir
Humphry Davy commenced in the year 1823, and prosecuted with his
characteristic zeal and happy talent during a considerable period;
when, at length, paradoxical as it may appear, the truth of his
theory was completely established by the failure of his remedy!
From the several original documents which have been placed at my
disposal, and from the valuable communications and kind assistance
of my friend Mr. Knowles, I trust I shall be enabled to offer to
the scientific reader a more complete and circumstantial history
of this admirable enquiry than has been hitherto presented to the
public.
The results he produced are equally interesting and important,
whether we contemplate them biographically, as indicative of the
peculiar genius by which they were obtained; or, scientifically, in
their connexion with the electro-chemical theory, to the farther
developement and illustration of which they have so powerfully
contributed; or, economically, as the probable means by which the
hand of Time may be averted, an increased durability imparted to
rapidly perishable works of art, and monuments of human genius
transmitted to posterity, in all their freshness, through a long
succession of ages.
It is probable that, in the earliest period of naval architecture,
some expedient[85] was practised, in order to protect ships'
bottoms from the ravages of marine worms.[86] The use of metallic
sheathing, however, is of ancient date. The galley supposed to
have belonged to the Emperor Trajan was sheathed with sheets of
lead, which were fastened with copper nails.[87] The same metal
was also used in the earlier periods of our naval history;[88] and
it is worthy of remark, that the circumstances which led to its
disuse, were the rapid corrosion of the _rother irons_, (from the
formation of a Voltaic circle,) and the accumulation of sea-weed.
[85] Mr. Knowles, in his "Inquiry into the Means which have been
taken to preserve the British Navy," observes, that the first
sheathing was probably the hides of animals covered with pitch,
or with asphaltum, which led to the use of thin boards, having,
in some cases, lime, and in others lime and hair, between them
and the bottom of the ships.
[86] The worms infesting the timber of ships are--the _Teredo_,
the _Lepisma_, and the _Pholas_. The first of these, however,
which was imported from India, is by far the most destructive;
and I am informed by Mr. Knowles, that it is more abundant at
Plymouth than on any other part of the coast where there is a
dock-yard; and although on the shores of England it is not of a
very large size, yet it is a formidable enemy to the safety of
those ships which have not a metallic sheathing to cover their
bottoms. In the East Indies, and off the coast of Africa, the
_Teredo_ is of very large size; and holes have been bored by them
in the timber of at least seven-eighths of an inch in diameter.
[87] Alberti Archeti.
[88] In the year 1670, an Act of Parliament was passed, granting
unto Sir Philip Howard and Francis Watson, Esq. the sole use of
the manufacture of milled lead for sheathing ships; and, in the
year 1691, twenty ships had been sheathed with lead, manufactured
by them, and which was fastened with copper nails.--See
_Knowles's Inquiry_.
In the year 1761, copper plates were first used as sheathing on
the Alarm frigate, of thirty-two guns;[89] a second underwent this
operation in 1765, a third in 1770, four in 1776, nine in 1777;
and, in the course of the three following years, the whole British
navy was coppered: an event which may be considered as forming an
important era in the naval annals of the country.
[89] The copper sheathing was removed from this ship in 1763,
when all the iron was found to be much corroded, the pintles and
braces nearly eaten through, and the false keel lost, from the
decay of the keel staples and the bolt fastenings. Thus, in the
very first coppered ship, the Voltaic effect, produced by the
contact of copper and iron, was displayed in a very striking
manner.
The expense attending the use of copper for this purpose, in
consequence of its corrosion and decay by salt-water, has
always been felt as a serious objection to its use, and various
suggestions have from time to time occurred, and numerous
experiments been made, in the hope of obviating the evil,[90] but
without any great degree of success.
[90] An experiment was tried by painting or varnishing their
inner surfaces, but the use of brown paper which has been dipped
in tar, and placed between the wood and copper, is now considered
to be the best mode. A solution of caoutchouc spread on paper
was tried on the bottom of Sir W. Curtis's yacht; but, on
examination, it was pronounced to be less efficacious than tarred
paper.
The solution of the metal, however, has been found to vary in
degree at different anchorages: at Sheerness, for instance,
its rapidity is very great, in consequence of the copper being
subjected to the alternate action of the sea, which flows in there
from the British Channel, and to the flux of water down the two
great rivers, the Thames and Medway, loaded, as they necessarily
must be, with the products of animal and vegetable decomposition.
In order, if possible, to obtain a remedy for this evil, the naval
departments of the Government requested, in the latter part of the
year 1823, the advice of the President and Council of the Royal
Society, as to the best mode of manufacturing copper sheets, or of
preserving them, while in use, against the corrosive effects of
oxidation.
Sir H. Davy charged himself with this enquiry; the results of
which he communicated to the Royal Society, in three elaborate
memoirs. The first was read on the 22nd of January 1824; the
second, on the 17th of June, in the same year; and the third, and
concluding paper, on the 9th of June 1825.
A very general belief prevailed, that sea-water had little or no
action on _pure_ copper, and that the rapid decay of that metal on
certain ships was owing to its impurity. On submitting, however,
various specimens of copper to the action of the sea-water, Sir
H. Davy came to a conclusion, in direct opposition to such an
opinion;[91] and Mr. Knowles informed me, in a late conversation
upon the subject, that the attempts to purify the metal, since the
Government has manufactured its own copper sheathing, has been the
cause of its more rapid decay. It will however presently appear,
that the relative durability of the metallic sheets must also be
influenced by circumstances wholly independent of their quality,
some of which are very probably, even in our present advanced state
of chemical knowledge, not thoroughly understood.
[91] In two instances, the copper (from the Batavier and from
the Plymouth yacht) which had remained perfect for twenty-seven
years, was found to be alloyed. In the former one there was an
alloy of one three-hundredth part of zinc; and, in the latter,
the same proportion of tin. On the other hand, in the case of
the copper on the Tartar's bottom, which was nearly destroyed in
four years, upon being submitted to chemical examination by Mr.
Phillips, it was found to be very pure copper.
Alloys of copper have generally been found more durable than the
unmixed metal; and various patents have been taken out for the
fabrication of such compounds; but metallic sheets so composed
have been found to be too hard and brittle, and not to admit of
that flexibility which is necessary for their application to a
curved surface; the consequence of which has been, that they have
cracked upon the ship's bottom.
Sir H. Davy, on entering upon the examination of this subject,
very justly considered, that to ascertain the exact nature of the
chemical changes which take place in sea-water, by the agency of
copper, ought to be the first step in the enquiry; for, unless the
cause were thoroughly understood, how could the evil be remedied?
On keeping a polished piece of copper in contact with sea-water,
the following were the effects which successively presented
themselves. In the course of two or three hours, the surface of
the metal exhibited a yellow tarnish, and the water in which it
was immersed contracted a cloudiness, the hue of which was at
first white, but gradually became green. In less than a day, a
bluish-green precipitate appeared, and constantly continued to
accumulate in the bottom of the vessel; at the same time, the
surface of the copper corroded, appearing red in the water, and
grass-green where it was in contact with air. Upon this grass-green
matter carbonate of soda formed; and these changes continued
until the water became much less saline. The green precipitate he
ascertained to consist of an insoluble compound of copper, (which
he thinks may be considered as a _hydrated sub-muriate_,) and
hydrate of magnesia.[92]
[92] The Muriate of Magnesia is the most active salt in sea-water.
According to his own views of the nature of chlorine, he
immediately perceived that neither soda nor magnesia could appear
in sea-water by the action of a metal, unless in consequence of an
absorption or transfer of oxygen, which in this case must either be
derived from the atmosphere, or from the decomposition of water:
his experiments determined that the former was the source which
supplied it. By reasoning upon these phenomena, and applying for
their explanation his electro-chemical theory, which had shown
that chemical attractions may be exalted, modified, or destroyed,
by changes in the electrical states of bodies, he was led to the
discovery of a remedy for the corrosion of copper, by the very
principle which enabled him, sixteen years before, to decompose the
fixed alkalies.
When he considered that copper is but weakly positive in the
electro-chemical scale, and that it can only act upon sea-water
when in a positive state, it immediately occurred to him that, if
it could be rendered slightly negative, the corroding action of
sea-water upon it would be null. But how was this to be effected?
At first, he thought of using a Voltaic battery; but this could
hardly be applicable in practice. He next thought of the contact of
zinc, tin, or iron; but he was prevented for some time from trying
this, by the recollection that the copper in the Voltaic battery,
as well as the zinc, was dissolved by the action of dilute nitric
acid; and by the fear, that too large a mass of oxidable metal
would be required to produce decisive results. After reflecting,
however, on the slow and weak action of sea-water on copper, and
the small difference which must exist between their electrical
powers; and knowing that a very feeble chemical action would be
destroyed by a very feeble electrical force, he was encouraged to
proceed; and the results were highly satisfactory and conclusive. A
piece of zinc, not larger than a pea, or the point of a small iron
nail, was found fully adequate to preserve forty or fifty square
inches of copper,--and this, wherever it was placed, whether at the
top, bottom, or in the middle of the sheet of copper, and whether
the copper was straight or bent, or made into coils. And where the
connexion between the different pieces of copper was completed by
wires, or thin filaments of the fortieth or fiftieth of an inch in
diameter, the effect was the same; every side, every surface, every
particle of the copper, remained bright; whilst the iron, or the
zinc, was slowly corroded.
A piece of thick sheet copper, containing on both sides about sixty
square inches, was cut in such a manner as to form seven divisions,
connected only by the smallest filaments that could be left, and
a mass of zinc, of the fifth of an inch in diameter, was soldered
to the upper division. The whole was plunged under sea-water;
the copper remained perfectly polished. The same experiment was
repeated with iron, and after the lapse of a month, the copper was
in both instances found as bright as when it was first introduced;
whilst similar pieces of copper, undefended, underwent in the same
water very considerable corrosion, and produced a large quantity of
green deposit in the bottom of the vessel.
Numerous other experiments were performed, and with results equally
conclusive of the truth of the theory which had suggested them.
There was however one point which still remained for enquiry. As
the ocean may be considered in its relation to the quantity of
copper in a ship, as an infinitely extended conductor, it became
necessary to ascertain whether that circumstance would influence
the results. For this purpose, he placed two very fine copper
wires, one undefended, the other defended by a particle of zinc, in
a very large vessel of sea-water, which water might be considered
to bear the same relation to so minute a portion of metal, as the
sea to the metallic sheathing of a ship. The result was perfectly
satisfactory. The defended copper underwent no change; the
undefended tarnished, and deposited a green powder.[93]
[93] During the course of some experiments in which I have been
lately engaged, a simple mode of exhibiting the principle of
protection occurred to me, which, I believe, has not before
been suggested; at least, I cannot find any notice of such
an experiment. As I consider it admirably calculated for
illustration, I will here describe it. Let two slips of copper
of equal size, the one protected with a piece of zinc, the other
unprotected, be plunged into two wine-glasses filled with a
solution of ammonia. In a short time, the liquor containing the
unprotected copper will assume an intensely blue colour; the
other will remain colourless for any length of time. The theory
is obvious. When metallic copper is placed in contact with an
ammoniacal solution, a protoxide of the metal is formed which
is colourless,--and will remain so, if the contact of air be
prevented; but on exposure to the atmosphere, it passes into
a state of peroxide, which is dissolved by the ammonia, and
produces an intensely blue solution. In the case of the protected
copper, the metal is incapable of attracting a single atom of
oxygen, in consequence of having been rendered negative by the
zinc, and consequently no solution can take place.
Davy having thus satisfied his own mind as to the truth of his
views, communicated to Government, in January 1824, the important
fact of his having discovered a remedy for the evil of which they
had complained; and that the corrosion of the copper sheathing of
his Majesty's ships might be prevented by rendering the copper
electro-positive, by means of the contact of tin, zinc, lead, iron,
or any other easily oxidable metal; and that he was prepared to
carry his plan into effect.
A proposition from a philosopher of such known science, and upon a
subject of such great importance to the navigation and commerce of
the country, immediately obtained all the attention it deserved;
and an order was made that the plan of protection should, under the
superintendence of Sir H. Davy, be forthwith tried upon the bottom
of a sailing cutter.
To give to his discovery farther publicity, Sir Humphry requested
that three models of ships might be exhibited in the spacious hall
of the Navy Office in Somerset House; the copper of one of which he
proposed should be protected by bands of zinc, that of another by
plates of wrought iron soldered on the sheathing, while the third
should have its copper exposed without any protection whatever.
These models were floated in sea-water for several months; and the
experiment fully confirmed the results he had previously obtained
in his laboratory. The models were from time to time examined by
persons of the highest scientific character, as well as by others
of great naval celebrity; and so alluring was the theory, and so
conclusive the experiments, that, instead of waiting the result
of the slow but more certain ordeal to which the plan had been
submitted, it was immediately put into extensive practice, both in
the Government service and on the bottoms of ships belonging to
private individuals.
To those the least acquainted with the principles of Voltaic
action, it was only necessary to state the proposition, in order
to command their assent to its truth. The utility of the plan
therefore was never questioned, but the claims of Davy to the
originality of the invention were doomed to meet with immediate
opposition.[94]
[94] Amongst other counter-claims, there appeared, in a weekly
publication entitled "The Mechanic's Magazine," a statement in
favour of a person of the name of Wyatt, founded on the following
advertisement in "The World" newspaper of April 16, 1791. "By
the King's Patent, tinned copper sheets and pipes manufactured
and sold by Charles Wyatt of Birmingham. These sheets, amongst
other advantages, are particularly recommended for sheathing of
ships, as they possess all the good properties of copper, with
others obviously superior." It is unnecessary to observe that,
except their object, there is nothing in common in the inventions
of Davy and Wyatt. The superiority claimed by Wyatt consisted
merely in coating the copper with some substance less corrosive
by sea-water than that metal: an idea borrowed from the common
practice of tinning copper vessels.
The correctness of the principle having been established, it
became, in the next place, necessary to determine the most eligible
metal to be used for protection; the proportion which it must bear
to the surface of the copper-sheathing below the waterline; the
form least likely to offer resistance to the sea, and to impede the
sailing of the vessel; and lastly, its most convenient position on
the ship's bottom. To ascertain these several points, Lord Melville
and the Lords of the Admiralty desired the Commissioners of the
Navy Board, and of the Dock-yards, to afford Sir Humphry every
assistance and facility for prosecuting the necessary experiments;
and he accordingly made many very extensive trials, not only on
copper sheets which were immersed in the sea, but also on the
bottoms of a considerable number of boats which had been coppered
for that purpose, and exposed to the flow of the tide in Portsmouth
harbour; upon which occasions he varied the nature as well as the
proportions of the protecting metal. The results were communicated
to the Royal Society, and they constituted the materials for his
second memoir on the subject.
"When the metallic protector was from 1/20 to 1/110 parts of
its surface, there was no corrosion nor decay of the copper;
with smaller quantities, such as from 1/200 to 1/400, the copper
underwent a loss of weight, which was greater in proportion as the
protector was smaller; and, as a proof of the universality of the
principle, it was found that even 1/1000 part of cast iron saved a
certain proportion of the copper.
"The sheeting of boats and ships, protected by the contact of zinc,
or cast and malleable iron in different proportions, compared with
those of similar boats and sides of ships unprotected, exhibited
bright surfaces; whilst the unprotected copper underwent rapid
corrosion, becoming first red, then green, and losing a part of
its substance in scales. Fortunately, in the course of these
experiments, it was proved that cast iron, the substance which is
cheapest and most easily procured, is likewise most fitted for the
protection of the copper. It lasts longer than malleable iron, or
zinc; and the plumbaginous substance which is left by the action of
sea-water upon it, retains the original form of the iron, and does
not impede the electrical action of the remaining metal."
In the earlier stage of the investigation, it had been suggested
by Mr. Knowles, and several other persons, that by rendering the
copper innoxious, it was probable sea-weeds might adhere to the
sheets; but this objection he answered by stating, that negative
electricity could not be supposed favourable to animal and
vegetable life; and as it occasioned the deposition of magnesia,
a substance exceedingly noxious to land vegetables, upon the
copper surface, he entertained no difficulty upon that subject: in
this, however, he was fatally mistaken. He found, after a trial
of several weeks, that the metallic surface became coated with
carbonate of lime and magnesia, and that, under such circumstances,
weeds adhered to the coatings, and marine insects collected upon
them; but at the same time he observed, that when the proportion of
cast iron, or zinc, was below 1/150, the electrical power of the
copper being less negative, no such deposition occurred; and that
although the surface had undergone a slight degree of solution,
it remained perfectly clean: a fact which he considered of great
importance, as it pointed out the _limits of protection_; and makes
the application of a _very small_ quantity of the oxidable metal
more advantageous, in fact, than that of a larger one.
During the course of these experiments, many singular facts occurred
to him, which tended to confirm his views of electro-chemical
action. Amongst the various details which remained for his
investigation, the relations between the surface of the
protector, and that of the copper sheathing, under the different
circumstances of temperature, saltness of the sea, and rapidity
of the ship's motion, presented themselves as objects of great
importance; and an opportunity occurred which enabled him to
pursue them by actual observation and experiment.
In the month of June 1824, a steam-vessel, H.M. ship the Comet,
was, at the express request of the King of Denmark, ordered to
proceed to Heligoland, for the purpose of fixing with precision, by
means of numerous chronometers, the longitude of that island, in
order to connect the Danish with the British survey; and the Board
of Longitude having recommended that the voyage should be extended
as far as the Naze of Norway, for the purpose of ascertaining also
the longitude of that important point, Sir H. Davy thought that
this vessel would afford him the means of performing his desired
experiments upon protected and unprotected copper sheets, when
under the influence of rapid motion; and upon application to the
Board of Admiralty, he obtained the entire disposal of the vessel
after the required observations had been completed, as long as the
season would allow her going to sea; and, that every facility might
be afforded him, a skilful carpenter was put on board, to prepare
whatever might be necessary for the prosecution of the enquiry.
For the following account of his adventures upon this occasion I
am indebted to Dr. Tiarks, who, in his character of astronomical
observer, superintended the expedition.
In the first instance, Davy directed to be constructed a number of
oblong, rectangular, thin plates of copper, the surface of which
should exceed that of a square foot: in the centre of these plates
was fastened a slip of copper, by means of which other pieces
of copper, which had small plates of iron of various dimensions
attached to them, were fixed to the plate, by merely sliding them
into the groove thus prepared for their reception. The plates
were all carefully weighed previously to the experiment, and
the pieces of iron were considered as representing the various
proportions of iron and copper surfaces within whose limits Sir H.
Davy had been led, by former experiments, to expect that the best
proportion would be found. These plates were afterwards slipped
into wooden frames, and nailed to the ship's side, over a piece
of thick canvass, for the purpose of intercepting every possible
communication between them and the copper sheathing.
It was proposed that, after each trip, these plates should be
accurately weighed, in order to ascertain the loss which they
severally might sustain from the corrosive action of the sea, while
thus protected by different proportions of iron surface; and, to
ensure every possible accuracy, he carried with him the excellent
balance, constructed by Ramsden, which is in possession of the
Royal Society.
Sir H. Davy, accompanied by Lord Clifton, embarked at Greenwich on
the 30th of June, and the vessel arrived at Heligoland on the 2nd
of July. Here, as they remained not more than one day, the plates
were not examined, although the Master expressed strong doubts
as to their safety. The vessel then proceeded, by order of Sir
Humphry, to Norway, a country which he was, for several reasons,
very desirous of visiting, especially for the sake of determining
a doubtful point in ornithology, upon which he subsequently
corresponded with Professor Rheinhard, of Copenhagen.
The difference of longitude, also, between that country and
Greenwich, not having been accurately ascertained, offered perhaps
an additional reason for thus deviating from a course which, it
must be confessed, was at variance with the original plan of the
expedition.
After a severe gale of wind on the 4th of July, the vessel arrived,
on the day following, at Rleve, near Mandal, and afterwards
proceeded to this latter place, at which Davy remained for several
days, during which interval the vessel made a tour to the Naze, and
took in coal.
On the arrival of the vessel in the port, the plates were
immediately examined; but, to the great disappointment of Sir
Humphry, it was discovered that every one of the protectors had
been washed away, and that most of the plates had sustained
considerable injury.
With the country around Mandal he was much pleased; for, although
it is far from being fertile, the scenery is rendered exceedingly
striking and beautiful by the numerous lakes which wash the feet of
high and sometimes perpendicular mountains, at that time clothed
with the rich verdure of their summer herbage.
Sir Humphry made several excursions into the interior of the
country, and derived much amusement from angling in the lakes;
and had it not been from his own inspection of the roads, and the
information which he collected respecting them, together with an
indisposition of his fellow-traveller, Lord Clifton, he would have
made an extensive land journey through the country; but, under the
existing circumstances, he determined to return to England through
Denmark and Germany. He therefore at once resolved to take the
steam-boat with him as far as Sweden, where the excellent roads
would enable him, without inconvenience, to reach Gottenburg, and
thence to continue his route through Denmark to Germany. The vessel
proceeded accordingly to Christiansand, the chief town of a country
of the same name.
Having been provided with some spare plates and protectors, he
fixed them to the ship's side at Mandal, as he was informed that
the voyage could be entirely performed within the rocks, with which
the whole coast of Norway is so plentifully studded; but a short
traverse through an open part of the sea, not far from Mandal,
again defeated his object. The protectors were washed away, and no
result was obtained.
At Christiansand he remained a few days, in order to try some new
plates, which were constructed there under his own inspection. Upon
this occasion he made an excursion to the falls of the Torjedahl,
distant about six miles from the town. The river abounds with
salmon, which were easily caught in their descent from the falls,
by an apparatus contrived for that purpose. Sir Humphry amused
himself by teaching the inhabitants the operation of _crimping_,
and he declared the flavour of the fish to be superior to any
salmon he had ever tasted.
It was at Christiansand that he became acquainted with the
Norwegian race of ponies, so well adapted for mountainous
countries; and which, at his recommendation, were afterwards
introduced into England by Mr. Knight, of Downton Castle.
From Christiansand the vessel proceeded on her route eastward to
Arendal, where she arrived on the 12th, after a passage of only a
few hours. The route lay entirely within the rocks,--and so narrow
were the passages, that the vessel could frequently not pass the
rocks on either side without touching them.
At Arendal, which is the chief place of a remarkable mining
district, Sir Humphry was well received by the Messrs. Dedehamys,
two brothers, and the leading merchants of the place, with whom
he made several excursions to the neighbouring mines. He was also
invited by them to meet at their beautiful country seats the most
respectable inhabitants of the town.
In the house of Mr. Dedehamy, Davy was introduced into Norwegian
society, and, for the first time, had an opportunity of witnessing
the customs and manners of the country.
A short time before dinner, the guests were summoned to partake
of pickled fish, anchovies, and smoked salmon, with rum, brandy,
and wine, which were placed on small tables in the drawing-room in
which the company assembled. This custom of taking salt provisions,
together with spirits, just before dinner, is very general in
the North, and is considered as the best means of preparing the
stomach, and of provoking an appetite for the approaching meal.
The very numerous party, which, with the exception of the hostess
and her daughter, consisted entirely of men, were then ushered
into two large rooms, one not being sufficiently spacious to
accommodate them, and each person took his seat promiscuously. At
the beginning of the dinner, large basins filled with sugar were
carried round by the host's daughter, followed by a servant, from
which each gentleman took a large handful. Sir Humphry, surprised
at so singular a ceremony, enquired its meaning; when the host very
good-humouredly answered, that in Norway they thought, if the wine
was good it could not be spoiled by sugar,--and if bad, that it
would be improved by it. Davy immediately followed the example of
the company, and helped himself to the sugar.
Amongst the party present were several members of the Diet
(Storthing), which had recently refused the applications of the
King for various grants of money. This subject excited much
animated conversation, and the majority of the persons present
expressed their approbation at so bold and independent a measure.
This called forth a political toast relating to the situation
of their country; when the whole company, elated with wine and
conversation, simultaneously burst forth into the national chorus
of Norway, which had been composed as a prize poem during the short
struggle against the union of that country with Sweden, and which
was much admired by the Norwegians, and on all occasions sung by
them with the utmost enthusiasm of feeling; but, notwithstanding
the liberal politics of the party, they drank Sir Humphry's
toast--"THE KING OF NORWAY AND SWEDEN"--with much apparent loyalty.
A succession of toasts followed, the last of which recommended
"THE BRITISH CONSTITUTION AS A MODEL FOR ALL THE WORLD." With
this sentiment the festivities concluded--a momentary silence
ensued; the custom of the country assigned to a stranger the
honourable office of returning to the host and hostess the thanks
of the company for their hospitable reception; all eyes were
anxiously fixed upon the English philosopher; and as soon as he
was made acquainted with the duty he was expected to perform, he
rose from his seat, and in allusion to the sentiment so recently
drunk in compliment to himself, he proposed as a concluding toast,
"NORWEGIAN HOSPITALITY A MODEL FOR ALL THE WORLD."
From Arendal the vessel proceeded to Laurvig, where she stopped
only a few hours; but Sir Humphry seized this opportunity to go on
shore to view the country, and he afterwards weighed the copper
plates which had been attached to the ship in Christiansand, as
the vessel was now to cross that deep bay, at the bottom of which
is situated Christiana, the capital of the kingdom. The few plates
were found to be in good order; and the results, which however
must be allowed to have been very incomplete, confirmed, as far
as they went, the conclusions to which he had been led by former
experiments, viz. that 1/200 of iron surface was the proportion
best calculated to defend the copper, without so overprotecting
it as to favour the adhesion of marine productions; while they
moreover proved that there is a mechanical as well as a chemical
wear of the copper, which, in the most exposed part of the ship,
and in the most rapid course, bears a relation to it of nearly 2 to
4.55.
The country increased in fertility towards the eastern parts of it;
but it possessed much less beauty than the neighbourhood of Mandal.
As soon as Davy perceived that the vessel had to pass near the
mouth of the Glommen, the largest river of Norway, he directed that
she should enter it. Steam-boats appeared to have been entirely
unknown in that part of the country. The inhabitants of the town of
Frederickstadt were alarmed by the belief that the vessel was on
fire, and they ran down to the beach in multitudes. As the vessel
proceeded up the river, the people every where left their work,
looked on awhile in silent amazement, and then shouted with delight.
The vessel anchored a mile below the great fall of the Glommen,
called _Sarpen_, and which Davy visited on the following day
(July 15). Three Kings of Denmark have visited this fall, and a
name commemorates the spot whence they viewed this grand scene of
nature. The fall is not one perpendicular descent, but consists
of three sheets of water closely succeeding each other; and, by
means of a barometer, he ascertained the entire altitude to be
little more than a hundred feet. In comparing the character of this
waterfall with those of the others he had visited, he observes,
that size is merely comparative; and that he prefers the Velino at
Terni, on account of the harmony that exists in all its parts. It
displays all the force and power of the element, in its rapid and
precipitous descent; and you feel that even man would be nothing in
its waves, and would be dashed to pieces by its force. The whole
scene is embraced at once by the eye, and the effect is almost as
sublime as that of the Glommen, where the river is at least one
hundred times as large; for the Glommen falls, as it were, from a
whole valley upon a mountain of granite; and unless where you see
the giant pines of Norway, fifty or sixty feet in height, carried
down by it and swimming in its whirlpools like straws, you have no
idea of its magnitude and power. Considering these waterfalls in
all their relations, he is disposed to think, that while that of
Velino is the most perfect and beautiful, the fall of the Glommen
is the most awful.
On both sides of this fall are extensive saw-mills, with machinery
of very imperfect construction. Davy spent some time with the
proprietors of these mills, who were acquainted with the English
language, and showed him every attention in their power. As an
angler, he spoke with regret of the immense quantity of sawdust
which floated in the water, and formed almost hills along the
banks, and which, he observed, must be poisonous to the fish,
by sometimes choking their gills, and interfering with their
respiration.
From the Glommen the steam-vessel passed through the Svinesund
to Strömstadt, the first town in Sweden beyond the frontier of
Norway, from which Charles XII. essayed to besiege the neighbouring
fortress of Frederickstadt in Norway. From Strömstadt, Davy set out
on the 17th of July, and reached Gottenburg by land in two days,
where he remained for a short time, in consequence of a slight
indisposition. On his journey, he had a conversation with Oscar,
the Crown Prince of Denmark, who, under the direction of Berzelius,
had diligently devoted himself to the study of chemistry. He
conversed with our philosopher upon various subjects connected with
that science; and Davy, on his return to England, declared that he
had never met with a more enlightened person.
The Crown Prince expressed great surprise, as indeed did every body
in Sweden, on hearing that it was not Davy's intention to visit
Professor Berzelius at Stockholm; and his astonishment was still
farther increased, when he was informed by himself, that he came to
Norway and Sweden with no other view than to enjoy the diversion
of hunting and fishing! He however did by accident afterwards meet
Berzelius, but his interview was but of short duration.
From Gottenburg he hastened to Copenhagen, where he renewed his
acquaintance with Prince Christian of Denmark, cousin of the
King, and heir presumptive of the crown; in whose company he
had some years before observed an eruption of Mount Vesuvius.
He also visited Professor Oersted, and earnestly requested that
he might see the apparatus by which that philosopher had made
those electro-magnetic experiments which had rendered his name so
celebrated throughout Europe.
He next proceeded to Neuburg and Altona, where he intended to
re-embark for England in the steam-vessel which had, during the
interval of his continental tour, made a voyage to England, and
was again on her way to the Elbe. At the suggestion, however, of
Professor Schumacher, the astronomical professor at Copenhagen,
but residing at Altona, in whose society he passed a great portion
of his time, he accompanied that gentleman to Bremen, in order to
make the acquaintance of the venerable Dr. Olbers, who, since his
retirement from an extensive medical practice, had entirely devoted
his time to the pursuit of his favourite science astronomy; as well
as to be introduced to Professor Gauss, of Gottingen, who happened
to be at that time carrying on his geodetical operations for the
admeasurement of the kingdom of Hanover.
Davy expressed a great desire to see the telescope with which Dr.
Olbers had discovered the two planets, Pallas and Vesta, and which
to his great surprise turned out to be a very ordinary instrument.
His personal intercourse with these two celebrated philosophers
appeared to afford him the highest satisfaction; and he spent two
days most agreeably in their society.
In his "Salmonia," he gives us some account of his adventures as
an angler during this short excursion to Norway and Sweden. "All
the Norwegian rivers," says he, "that I tried (and they were in
the southern parts) contained salmon. I fished in the Glommen, one
of the largest rivers in Europe; in the Mandals, which appeared
to me the best fitted for taking salmon; and in the Arendal; but,
though I saw salmon rise in these rivers, I never took a fish
larger than a sea-trout; of these I always caught many--and even
in the _fiords_, or small inland salt-water bays; but, I think,
never any one more than a pound in weight. It is true that I was
in Norway in the beginning of July, in exceedingly bright weather,
and when there was no night; for even at twelve o'clock the sky
was so bright, that I read the smallest print in the columns of
a newspaper. I was in Sweden later--in August: I fished in the
magnificent Gotha, below that grand fall, Trollhetta, which to see
is worth a voyage from England; but I never raised there any fish
worth taking. I caught, in this noble stream, a little trout about
as long as my hand; and the only fish I got to eat at Trollhetta
was bream."
He again embarked, on the 14th of August, on board the Comet
steam-vessel, which had ascended the Weser as high as her draught
of water would allow, and reached England, after a very boisterous
passage, on the 17th of the same month; indeed, the vessel left
the mouth of the Weser with a contrary wind, and the pilot was
unwilling to put to sea, but Davy insisted on proceeding without
delay. During the whole passage he suffered extremely from
sea-sickness, and in a letter written to Professor Schumacher,
shortly after landing, he remarks that "the sea is a glorious
dominion, but a wretched habitation."
* * * * *
On the 9th of June 1825, Sir Humphry read before the Royal
Society his third and most elaborate paper upon Copper sheathing,
entitled "Farther Researches on the Preservation of Metals by
Electro-chemical Means."
In this memoir, he states it to be his belief, that there is
nothing in the poisonous nature of the copper to prevent the
adhesion of weeds and testaceous animals; for he observes, that
they will readily adhere to the poisonous salts of lead which
commonly form upon the metal protecting the fore-part of the keel;
and even upon copper, provided it be in such a state of chemical
combination as to be insoluble. It is then, in his opinion, the
_solution_ of the metal--the _wear_ of its surface, by keeping it
smooth, which prevents the adhesion of foreign matter. Whenever the
copper is unequally worn, deposits will, without doubt, rest in the
rough parts, or depressions in the metal, and afford a soil or bed
in which sea-weeds can fix their roots, and to which zoophytes and
shell-fish can adhere; but there is another cause of foulness on
the protected sheathing, arising from the deposit of earthy matter
upon the copper, in consequence of its electro-negative condition.
In relation to this subject, Davy has offered some observations
upon the effects produced by partial formations of rust, which
appear to me to be exceedingly interesting and important.
When copper has been applied to the bottom of a ship for a
certain time, he says, a green coating, or rust, consisting of
oxide, sub-muriate, and carbonate of copper, forms upon it; not
equally throughout, but partially, and which, it is evident, must
produce a _secondary_, partial, and unequal action, since those
substances are negative with respect to metallic copper, and will
consequently, by producing with it a Voltaic circuit, occasion a
more rapid corrosion of those parts still exposed to sea-water:
from this cause, sheets are often found perforated with holes in
one part, after having been used for five or six years; while in
other parts they are comparatively sound.[95] In like manner, the
heads of the mixed metal nails, consisting of copper alloyed by a
small quantity of tin, which are in common use in the Navy, give
rise to oxides that are negative with respect to the copper, so
that the latter is often worn into deep and irregular cavities in
their vicinity.
[95] The rusting of a common piece of iron, if carefully
inspected, furnishes a beautiful illustration of this secondary
action. The oxide, at first a mere speck, and formed perhaps by a
globule of water, becomes negative with respect to the contiguous
surface, and by thus forming a Voltaic circuit, exalts its
oxidability, and the rust consequently extends in a circle.
A series of very interesting experiments, fully detailed in this
memoir, which were instituted for the purpose of ascertaining the
extent of the diminution of electrical action in instances of
imperfect or irregular conducting surfaces, led him to the general
conclusion, that a very small quantity of the imperfect or fluid
conductor was sufficient to transmit the electrical power, or to
complete the chain. This induced him to try whether copper, if
nailed upon wood, and protected merely by zinc or iron on its
_under_ surface, or on that next the wood, might not be defended
from corrosion: a question of great practical moment with regard
to the arrangement of protectors. For this purpose, he covered
a piece of wood with small sheets of copper, a nail of zinc of
about 1/100 part of the surface having been previously driven
into the wood: the copper surface remained perfectly bright in
sea-water for many weeks; and when the result was examined, it
was found that the zinc had only suffered partial corrosion; that
the wood was moist, and that, on the interior of the copper there
was a considerable portion of revived zinc, so that the negative
electricity, by its operation, provided materials for its future
and constant excitement. In several trials of the same kind, iron
was used with similar results; and in all these experiments there
appeared to be this peculiarity in the appearance of the copper,
that unless the protecting metal below was in a large mass, there
were no depositions of calcareous or magnesian earths upon the
metal; it was clean and bright, but never coated. The copper in
these experiments was nailed sometimes upon paper, sometimes upon
the mere wood, and sometimes upon linen; and the communication was
partially interrupted between the external and internal surfaces by
cement; but even one side or junction of a sheet seemed to allow
sufficient communication between the moisture on the under surface
and the sea-water without, to produce the electrical effect of
preservation. This last experiment of Davy is of greater importance
than may at first appear, in showing what a small proportion of
conducting fluid will complete a circuit, and in thus explaining
phenomena, as I shall presently show, which might not otherwise be
suspected to have an electrical origin.
These results upon perfect and imperfect conductors led him
to another enquiry, important as it relates to the practical
application of the principle, namely, as to the extent and nature
of the contact or relation between the copper and the preserving
metal. He was unable to produce any protecting action of zinc
or iron upon copper through the thinnest stratum of air, or the
finest leaf of mica, or of dry paper; but the action of the metals
did not seem to be much impaired by the ordinary coating of
oxide or rust; nor was it destroyed when the finest bibulous, or
_silver-paper_, as it is commonly called, was between them, being
moistened with sea-water. He made an experiment with different
folds of this paper. Pieces of copper were covered with one, two,
three, four, five, and six folds; and over them were placed pieces
of zinc, which were fastened closely to them by thread; each piece
of copper, thus protected, was exposed in a vessel of sea-water, so
that the folds of paper were all moist.
It was found in the case in which a single leaf of paper was
between the zinc and the copper, there was no corrosion of the
copper; in the case in which there were two leaves, there was a
very slight effect; with three, the corrosion was distinct; and it
increased, till with six folds the protecting power appeared to
be lost; and in the case of the single leaf, the result differed
only from that produced by immediate contact, in there not being
any deposition of earthy matter. Other experiments likewise proved
that there was no absolute contact of the metals through the moist
paper; for, although a thin plate of mica, as before stated,
entirely destroyed the protecting effect of zinc, yet when a hole
was made in it, so as to admit a very thin layer of moisture
between the zinc and copper, the corrosion of the latter, though
not prevented, was considerably diminished.
The experimental part of this paper concludes with an account of
various trials to determine the electro-chemical powers of metals
in menstrua out of the contact, or to a certain extent removed
from the contact of air; in order, if possible, to diminish the
rapid waste of the protecting metals. In the progress of these
experiments he exhibits, in a most beautiful manner, the singular
effect of different proportions of a fixed alkali, when mixed with
sea-water, in rendering the iron, in its Voltaic connection with
copper, more or less negative.
He terminates the paper with some observations of a practical
nature, relative to the best modes of rendering iron applicable
to the purposes of protection; but, as these have been already
embodied in the investigation, it is not necessary to notice them
farther in this place.
That I may give to the history of this subject all the perspicuity
which it can derive from the connexion of its several parts, I
shall now, in defiance of chronological order, proceed to consider
his last Bakerian Lecture, "On the Relations of Electrical
Changes," which was read before the Royal Society, on the 8th
of June 1826. In which, after referring to his former papers
on the chemical agencies of electricity, and the general laws
of decomposition which were developed in them, he enters into
some historical details respecting the origin and progress of
electro-chemical science; being induced so to do, from a knowledge
of the very erroneous statements which had been published upon the
subject abroad, and repeated in this country. At the conclusion of
this lecture, in reverting to the subject of Voltaic protection, he
says: "A great variety of experiments, made in different parts of
the world, have proved the full efficacy of the electro-chemical
means of preserving metals, particularly the copper sheathing
of ships; but a hope I had once indulged, that the peculiar
electrical state would prevent the adhesion of weeds or insects,
has not been realized; protected ships have often indeed returned,
after long voyages, perfectly bright,[96] and cleaner than
unprotected ships; yet this is not always the case; and though
the _whole_ of the copper may be preserved from chemical solution
in steam-vessels (from the rapidity of their motion) by these
means,--yet they must be adopted in common ships only so as to
preserve a portion,--so applied, as to suffer a certain solution
of the copper;[97] and an absolute remedy for adhesions is to be
sought for by other more refined means of protection, and which
appear to be indicated by these researches.
[96] The Carnbrea Castle, a large vessel, of upwards of six
hundred and fifty tons, was furnished with four protectors,
two on the stern, and two on the bow, equal together to about
1-104th of the surface of copper. She had been protected more
than twelve months, and had made the voyage to Calcutta and back.
She came into the river perfectly bright; and, when examined in
the dry-dock, was found entirely free from any adhesion, and
offered a beautiful and almost polished surface; and there seemed
to be no greater wear of copper than could be accounted for from
mechanical causes.
[97] A common cause of adhesions of weeds or shell-fish, is the
oxide of iron formed and deposited round the protectors. In the
only experiment in which zinc has been employed for this purpose
in actual service, the ship returned after two voyages to the
West Indies, and one to Quebec, perfectly clean. The experiment
was made by Mr. Lawrence, of Lombard Street, who states that the
rudder, which was not protected, had corroded in the usual manner.
"The nails used in ships are an alloy of copper and tin, which I
find to be slightly negative with respect to copper, and it is
on these nails that the first adhesions uniformly take place: a
slightly positive and slightly decomposable alloy would probably
prevent this effect, and I have made some experiments favourable to
the idea."
He next proceeds to state some circumstances, in addition to
those he had formerly noticed, by which the electrical relations
of copper are altered. "I found," says he, "copper hardened by
hammering, _negative_ to rolled copper;--copper (to use the
technical language of manufacturers) both _over-poled_ and
_under-poled_,[98] containing, in one case, probably a little
charcoal, and in the other a little oxide, _negative_ to pure
copper. A specimen of brittle copper, put into my hands by Mr.
Vivian, but in which no impurity could be detected, was negative
with respect to soft copper. In general, very minute quantities of
the oxidable metals render the alloy positive, unless it becomes
harder, in which case it is generally negative."
[98] The _poling_ of copper is an operation, the theory of which
is involved in a great deal of mystery. Copper, when taken from
the smelting furnace, is what is termed _dry_, that is, it is
brittle, has an open grain and crystalline structure, and is of a
purplish red colour. The following is the process by which it is
refined, or _toughened_, by the process of _poling_. The surface
of the melted metal in the furnace is, in the first place,
covered with charcoal. A pole, commonly of birch, is then plunged
into the liquid metal, which produces a considerable ebullition
from the evolution of gaseous matter, and this operation is
continued, fresh charcoal being occasionally added, so that the
surface may be always kept covered, until the refiner judges
from the assays that the metal is malleable. The delicacy of the
operation consists in the difficulty of hitting the exact mark:
if the surface should by accident be uncovered, it will return to
its _dry_ state; and should the process be carried too far, it
will be _over-poled_, by which the metal would be rendered even
more brittle than when in a _dry_ state. When this is found to be
the case, or, as they say, _gone too far_, the refiner directs
the charcoal to be drawn off from the surface of the metal, and
the copper to be exposed to the action of the air, by which means
it is again brought back to its _proper pitch_, that is, become
again malleable. Now the question is, what are the changes thus
produced in the copper? Is the metal in its _dry_ state combined
with a minute portion of oxygen, of which _poling_ deprives it,
and thus renders it malleable? and does the _over-poling_ impart
to it a minute portion of carbon, and is copper, like iron, thus
rendered brittle both by oxygen and carbon? Or, is the effect of
the pole merely mechanical, that of closing the grain, and of
altering the texture of the metal? Something might be said in
support of all these opinions. Mr. Faraday, who has attentively
examined the subject, is unable to detect any chemical difference
between _poled_ and _unpoled_ copper. On the other hand, when the
metal is _over-poled_, it is found to oxidate more slowly, and
its surface when in the furnace is so free from oxidation, that
it is like a mirror, and reflects every brick in the roof. This
certainly looks very much like carbonization.--See "An Account of
Smelting Copper, as conducted at the Hafod Copper-works; by J. H.
Vivian, Esq."--_Annals of Philosophy_, vol. v. p. 113.
These are important facts, and should dispose those who may preside
over judicial enquiries, to pause before they infer the inferiority
of copper sheeting from the rapidity of its decay.[99]--I have
now concluded a review of those admirable researches which led
Sir Humphry Davy to suggest and mature a plan for arresting the
corrosion of the copper sheathing of vessels by Voltaic action.
Mr. Babbage has said that he was authorised in stating, that "this
was regarded by Laplace as the greatest of Davy's discoveries." I
do not think, however, that it should be considered in the light
of a separate performance: we do injustice to the philosopher by
regarding it as an independent and isolated discovery; for it
was the result of a long series of enquiries, which commenced by
establishing the laws of electro-chemistry,--which led him to
the decomposition of the alkalies and earths,--suggested to his
unwearied genius a succession of novel researches, in a new field
of enquiry,--and concluded, as we have seen, in producing the most
striking results by means of the greatest simplicity. Not once
during the progress of this enquiry had he any occasion to retrace
his steps for the purpose of correction: justly has he observed
in his last Bakerian Lecture, that, notwithstanding the various
novel views which have been brought forward in this and other
countries, and the great activity and extension of science, it is
peculiarly satisfactory to find that he has nothing to alter in the
fundamental theory laid down in his original communication; and
which, after the lapse of twenty years, has continued, as it was in
the beginning, the guide and foundation of all his researches.
[99] This observation was suggested by an examination of a late
judgment of the Court of Common Pleas, in the case of Jones
_v._ Bright and others, on showing cause against rule for a new
trial. This was an action brought by the Plaintiff against the
Defendants for selling him copper, for the purpose of sheathing
the ship Isabella, which, from the rapidity of its corrosion,
was inferred to have an inherent defect in its composition. In
this case it was held, that with respect to _warranty_, there is
a very wide difference as it applies to articles which are not
the subject of manufacture, and those which are the produce of
manufacture and of human industry. In the one case, it may be
that no prudence, no care, could have guarded against a secret
defect; in the other, by using due care, and providing proper
materials, any defect in the manufacture may be guarded against.
"In the case of the bowsprit, the man did not make the timber
which composed the bowsprit; he merely cut it out, and fitted
it to meet the purpose, and could therefore by no means have
guarded against the rottenness in the centre of that bowsprit:
but if a man makes copper, he may guard against inherent defects
in that copper, by taking care that the copper contains a proper
proportion of pure copper; and also by taking care that it is so
well manufactured, that it does not drink in a greater quantity
of oxygen than ought to be admitted into it, and that that
oxygen, which of necessity gets in, (for some will,) shall be
so distributed, that it shall not operate, as in the opinion of
an intelligent witness the oxygen in this case did operate, by
forming itself in patches, and thereby rendering it soft, and
rendering the copper incapable of resisting the influence of
salt-water--that he can guard against." With all due deference
to the learned Judge, suppose it be shown that no human wisdom
can guard against those circumstances by which a portion of the
copper surface may be rendered more highly electro-positive,
what becomes of the judgment? That the decay of copper sheathing
is effected by extrinsic causes, and does not necessarily
depend upon an inherent defect in the metal, may be proved in
numerous ways. If it were owing to the quality of the copper,
why should five, ten, or twenty sheets out of a hundred, made
from the same charge of metal in a furnace and manufactured under
precisely similar circumstances, be affected, and the remainder
be perfectly sound? Why, again, should sheets, made from several
distinct charges, placed on a particular vessel, be acted upon,
while the same copper on other bottoms is not more than usually
dissolved? Did any inherent defect exist in the metal, it surely
must have equally affected the whole batch.
It is possible that, in some cases, in consequence of the sheets
not having been properly cleansed before they are rolled, a
portion of the oxide may be pressed into them by the rollers. In
such a case, a Voltaic effect might be produced, and portions of
the metallic surface rendered more electro-positive.
The President and Council of the Royal Society appear to have
been swayed by this consideration, when they adjudged to him "A
Royal Medal,[100] for his Bakerian Lecture on the relations of
electrical changes, considered as the last link, in order of time,
of the splendid chain of discoveries in chemical electricity, which
have been continued for so many years of his valuable life."
[100] In the year 1825, His Majesty George IV. communicated to
the Royal Society, through Mr. Peel, his intention to found two
gold medals, of the value of fifty guineas each, to be awarded
annually by the Council of the Royal Society, in such a manner
as shall, by the excitement of competition among men of science,
seem best calculated to promote the object for which the Royal
Society was instituted.
Thus had Davy now received from the Royal Society all the honours
they were capable of conferring upon him. In the year 1805, they
adjudged to him the medal on Sir Godfrey Copley's donation for his
various communications published in the Philosophical Transactions;
in 1817, they awarded him the Rumford medals for his papers on
combustion and flame; and in 1827, upon the grounds just stated,
the President and Council expressed their unabated admiration
by conferring upon him the only medal which remained for his
acceptance--that which had been recently founded by their patron,
his late Majesty.
Having thus disposed of the speculative part of his admirable
enquiry, it will be interesting to pause in our narrative, in
order to take a philosophical review of the progress of Voltaic
discovery, in its relations to this particular object. It is
a subject well calculated to afford a valuable lesson to the
experimentalist, and at the same time to furnish illustrations,
more striking even than that of the safety-lamp, of the necessity
of that complicated species of machinery, without which the human
mind is frequently unable to grapple with the simplicities of
truth. It is true, that the fact of a galvanic effect being
excited by the contact of two dissimilar metals was noticed in the
earliest stages of the enquiry, but it is equally evident that the
phenomena which attended it, and the laws by which it was directed,
required for their discovery and elucidation the assistance of the
Voltaic battery. In reference to Davy, it may be here repeated,
that the power of obtaining simple results, through complicated
means, was one of the most distinguishing features of his genius.
It has been stated, that the Alarm frigate, the first coppered ship
in our Navy, displayed very striking evidence of the effect of
Voltaic action, in the rapid corrosion of its iron.[101] As early
as 1783, after copper sheathing had become general, the Government
issued orders that all the bolts under the line of fluitation
should, in future, be of copper; but at that period, it was not
possible that any idea could be entertained as to the true nature
of the operation by which the iron was thus rapidly corroded, for
it was only in the year 1797 that Dr. Ash noticed, for the first
time, a phenomenon which was subsequently referred to the action of
a simple Voltaic circuit.
[101] Numerous are the instances of later date which might be
adduced in illustration of the same fact; and it is now generally
supposed that it may have been a frequent cause of ships
foundering at sea. By oxidation, the volume of the iron at first
increases, and then diminishes; in consequence of which the ship
leaks, or, to use a technical expression, becomes "_bolt sick_."
When the Salvador del Mundo was docked at Plymouth, in February
1815, the iron fastenings were in such a state of corrosion, that
five planks near the bilge dropped into the dock when the water
left her.
It is a very curious circumstance in the history of this subject,
that, for many years after the Voltaic influence had been
recognised as the agent in metallic corrosion, so far from the
existence of the accompanying phenomenon of preservation being
suspected, it was even supposed that the metals mutually corroded
each other. At so late a date as 1813, we find Davy himself, in the
letter addressed to M. Alavair, published in these memoirs,[102]
dwelling upon the necessity of avoiding metallic contact, in order
to prevent _corrosion_, without throwing out the most distant hint
as to the simultaneous production of a converse effect.
[102] Page 13 of this Volume.
The first distinct notice of a metal being preserved from oxidation
by the contact of a dissimilar metal, is at once referred to a
chemical law, without a reference even to its possible connection
with Voltaic action; and, striking as the fact may now appear, it
never attracted much attention. M. Proust observed, that although
copper vessels be so imperfectly tinned, as to leave portions of
the surface uncovered, still, in cooking utensils, we shall be
equally protected from the poisonous effects of the former metal;
because, says he, the superior readiness with which tin is oxidized
and acted upon by acids, when compared with copper, will not
allow this latter metal to appropriate to itself a single atom of
oxygen.[103] The same chemist observes, that if lead be associated
with tin, it will be incapable of furnishing to acids any saturnine
impregnation, since the latter, being more oxidable than the
former, will exclusively dissolve, and thus prevent the former from
being attacked.
[103] As far as the principle of Voltaic protection goes,
this may be very true; but it must be remembered that the
acid generally present upon these occasions is acetic acid,
which rises in distillation with water, so that at the boiling
temperature it will be carried beyond the sphere of Voltaic
influence, and may thus act upon the denuded copper as much as
though tin were not present.
Whether the principle of Voltaic protection be applicable or not to
the purpose of preserving copper sheathing, it is evident that it
will suggest numerous other expedients of high importance in the
arts, while it will explain phenomena previously unintelligible.
By introducing a piece of zinc, or tin, into the iron boiler of
the steam-engine, we may prevent the danger of explosion, which
generally arises, especially where salt-water is used, as in those
of steam-boats, from the wear of one part of the boiler. Another
important application is in the prevention of the wear of the
paddles, or wheels, which are rapidly dissolved by salt-water.
Mr. Pepys has also extended the principle for the preservation of
steel instruments by guards of zinc: razors and lancets may be thus
defended with perfect success. In the construction of monuments
which are to transmit to posterity the record of important events,
the artist will be careful in avoiding the contact of different
metals: it is thus that the Etruscan inscriptions, engraved upon
pure lead, are preserved to the present day; while medals of mixed
metals of a much more recent date are corroded.
Numerous are the facts daily presented before us, which receive
from this principle a satisfactory explanation. To the philosopher,
the examination of its agencies will furnish a perpetual source of
instruction and amusement; and I will here enumerate a few simple
instances of its effects: in the first place, for the purpose of
showing that, whenever a principle or discovery involves or unfolds
a law of Nature, its applications are almost inexhaustible, and
that, however abstracted it may appear, it is sooner or later
employed for the common purposes of life; and in the next place, in
the hope of convincing the reader, that there does not exist any
source of pleasure so extensive and so permanent as that derived
from the stores of philosophy. The saunterer stumbles over the
stone that may cross his path, and vents only his vexation at the
interruption; but to the philosopher there is not a body, animate
or inanimate, with which he can come in contact, that does not
yield its treasures at his approach, and contribute to extend the
pleasures of his existence.
I well remember some years ago, that, in passing through Deptford,
my curiosity was excited by the extraordinary brilliancy of a
portion of the gilded sign of an inn in that town, while its other
parts had entirely lost their metallic lustre. Having obtained a
ladder, I ascended to the sign, in order, if possible, to solve the
problem that had so greatly interested me: the mystery immediately
vanished; for an iron nail appeared in the centre of the spot,
which had protected the copper leaf for several inches around it.
Any person may easily satisfy himself of the efficacy of such
protection, in his rambles through the metropolis, by noticing
the gilded, or rather coppered, sugar-loaves[104] so commonly
suspended over the shops of grocers, when he will frequently
perceive that the parts into which the iron supports have
entered, unless the latter have been painted, shine preeminently
brilliant. If a still more familiar example of the effect of a
simple Voltaic circuit be required, it is afforded by the iron
palisadoes, where the iron is constantly corroded at its point
of contact with the lead by which it is cemented into the stone.
These examples are not only interesting from their simplicity,
but from their demonstrating the small quantity of a conducting
fluid which is sufficient to transmit the electrical power, or to
complete a simple circuit: a fact which, it will be remembered, the
experiments of Davy had before established.[105]
[104] There is an excellent example at this time in the London
Road leading to the Elephant-and-Castle.
[105] Page 248 of this Volume.
As our knowledge advances, these principles will no doubt derive
other illustrations, and be found capable of more extensive
application; for as yet we are but in the infancy of the enquiry.
I have lately been engaged in a series of experiments, the results
of which, I confidently anticipate, will lead to some new facts
connected with the changes produced on the negative metal of a
Voltaic circuit; an account of which I hope shortly to submit to
the Royal Society. I shall on this occasion merely notice one
result, which appears to me to admit of an immediate application
to one of the most important circumstances of life--the purity of
water contained in leaden cisterns.
My attention has for several years been directed to the state of
the water with which the metropolis is supplied; and upon having
been lately requested to propose a remedy for preventing the
action of a spring in the neighbourhood of London upon lead, which
it had been found to corrode in a very rapid manner, I suggested
the expediency of protecting the pipes and cisterns with surfaces
of iron; but before such a plan was put in execution, I proposed
to try its efficacy in the laboratory:--the first result was very
startling; for, instead of preventing, as I had anticipated, I
found that it greatly increased, the solution of the lead. After
various experiments, I arrived at the conclusion, that lead, when
rendered negative by iron, and placed in contact with weak saline
solutions,--such, for instance, as common spring water,--was
dissolved; in consequence of the decomposition of the salts and
the transference of their elements according to the general law,
the acid passing to the iron, and the alkali to the lead; and so
powerfully is this latter body acted upon by an alkali, that, if
a slip of it be immersed in a solution of potash or soda, its
crystalline texture is so rapidly developed, that its surface
exhibits an appearance similar to that presented by tin-plate, and
which is designated by the term _moirée_.
I apprehend that most of the anomalous cases of the solution of
lead in common water, which have for so many years embarrassed the
chemist, may thus receive an explanation. An eminent physician
lately informed me, that some time since he was called upon to
attend a family who had evidently suffered from the effects of
saturnine poison, and that he well remembers there was an iron
pump in the cistern that supplied the water. Upon showing the
results of my experiment to a no less eminent chemist, he was
immediately reminded of a circumstance which occurred at Islington,
where the water was found to corrode the lead in which it was
received: in this vessel there was an iron bar; and the fact would
not have attracted his notice, nor have been impressed upon his
recollection, but from the unusual state of corrosion in which it
appeared.
I shall conclude these observations by an account of "the change
which some musket balls, taken out of Shrapnell's shells, had
undergone," by Mr. Faraday, and which is published in the 16th
volume of the Quarterly Journal of Science, for the year 1823. This
history is not only interesting on account of the high chemical
character of its author, but satisfactory as being in direct
opposition to previously established facts; and cannot therefore
have received any bias from preconceived theory.
"Mr. Marsh of Woolwich gave me some musket balls, which had been
taken out of Shrapnell's shells. The shells had lain in the
bottoms of ships, and probably had sea-water amongst them. When
the bullets are put in, the aperture is merely closed by a common
cork. These bullets were variously acted upon: some were affected
only superficially, others more deeply, and some were entirely
changed. The substance produced is hard and brittle; it splits
on the ball, and presents an appearance like some hard varieties
of hæmatite; its colour is brown, becoming, when heated, red; it
fuses on platinum foil into a yellow flaky substance like litharge.
Powdered and boiled in water, no muriatic acid or lead was found in
solution. It dissolved in nitric acid without leaving any residuum,
and the solution gave very faint indications only of muriatic
acid. It is a _protoxide of lead_, perhaps formed, in some way, by
the galvanic action of the iron shell and the leaden ball, assisted
probably by the sea-water. It would be very interesting to know the
state of the shells in which a change like this has taken place
to any extent. _It might have been expected, that as long as any
iron remained, the lead would have been preserved in the metallic
state._"
In one experiment, I found that a piece of lead protected by iron
underwent solution in water containing nitrate of potash, while it
resisted the action of very dilute nitric acid: upon this point,
however, farther enquiry is necessary; for I subsequently failed in
producing the same effect, owing, no doubt, to having employed too
strong an acid.
Let us return from this digression to the subject of Sir Humphry
Davy's Protectors. It only remains for me to relate the results
which followed the practical application of the Voltaic principles
which his various experiments had developed.
In the month of May 1824, directions were issued by the Lords of
the Admiralty to protect, in future, the copper sheathing of all
his Majesty's ships which might be taken into dock, upon the plan
proposed by Sir Humphry Davy.
The protectors were bars of iron six inches wide at their base,
three inches in thickness in their centre, and, in outward form,
the segment of an extended circle. They were usually placed on each
side of the ship in a horizontal position, viz. in midships about
three feet under water--on the keel in a line with these--and the
remainder in the fore and afterparts of the ship (about three feet
under the line of fluitation), as far forward and abaft as the
curvatures of their respective bodies would allow of their lying
flat upon the surface of the copper.
As it is difficult by verbal description alone to convey a
sufficiently distinct idea of this subject to persons unacquainted
with naval architecture, I have introduced a sketch, exhibiting
the _general_ position of the _Protectors_, although they are
necessarily exaggerated in size, or they would have appeared as
mere specks upon the drawing.
[Illustration: A. A. Line of Fluitation.]
On several ships, some of the protectors, in the stem and the
stern, were placed _vertically_; in which case they were fastened
to the stems and stern-posts; and in this manner they were found
to act more powerfully in preserving the copper, than when they
were all placed horizontally. The ends of the protectors were
rounded, in order to prevent any great resistance to the water,
and they were fastened to the bottoms of the ships with copper
bolts, the iron being counter-sunk to receive their heads, and
the holes were then filled with carbonate of lime, or Parker's
cement. To bring about the best possible contact of all the copper
sheets, their edges, which lap over each other, where the nails are
driven to fasten them to the ships, were rubbed bright, first with
sand-paper, and finally with glass-paper.
Shortly after the ships thus protected were sent to sea, it was
evident to all on board, from their dull sailing, that the bottoms
had become very foul; and on being examined in dry docks, it
was found that the copper was completely covered with sea-weed,
shell-fish of various kinds, and myriads of small marine insects.
Upon their removal, however, it was found, on weighing the sheets,
that the copper had suffered little or no loss; thus proving that,
although its practical application had failed from unforeseen
circumstances, the principle of protection was true, and had fully
justified the expectation of its success.
The copper near the protectors was much more foul than that at a
greater distance from them; and there was, moreover, a considerable
deposit of carbonate of lime, and of carbonate and hydrate of
magnesia, in their vicinity.
Sir Humphry Davy immediately suggested, as a remedy for this evil,
that the bottoms should be scraped, and the copper washed with a
small quantity of acidulous water; and he also proposed that the
protectors should in future be placed under, instead of over, the
copper sheathing. This plan was immediately adopted. Discs of
cast-iron three and a half inches in diameter, and one-fourth of
an inch in thickness, were let into the plank of the bottom of the
Glasgow, of fifty guns, on the starboard side only--the larboard
side having been left without any protection. These discs were in
the proportion of one to every four sheets of copper, and over
them were placed pieces of brown paper, and over the paper thin
sheet-lead, so that the latter metal was in contact with the
copper sheathing. A similar experiment was also tried on the Zebra,
of eighteen guns, substituting, however, discs of zinc[106] for
those of iron.
[106] It would appear that Davy latterly preferred zinc to
iron, as the protecting metal. In a letter, dated October
1826, addressed to a ship-owner, who had made some enquiries
of him upon the subject, he says--"The rust of iron, if a ship
is becalmed, seems to promote the adhesion of weeds; I should
therefore always prefer pieces of zinc, which may be very much
smaller, and which, in the cases I have heard of their being
used, have had the best effect."
The bottom of the Glasgow was examined twelve months afterwards,
when the discs of iron were found oxidated throughout, presenting
in their appearance the characters of plumbago. The copper on
the starboard side was preserved, but covered with weeds and
shell-fish. The sheets on the larboard had undergone the usual
waste, but were clean.
The Zebra was docked four years after the experiment had commenced,
when the zinc protectors were perfect, and it did not appear that
they had exerted any influence in preserving the copper, as it
had wasted equally on both sides. It may be presumed in this case
that the Voltaic circuit had by some fault in the arrangement been
interrupted.
The apparent conversion of iron into a substance resembling
plumbago, by the action of sea-water, has been frequently noticed.
The protectors thus changed[107] were, to a considerable depth from
the surface, so soft as to be easily cut by a knife; but after
being exposed for some time to the action of the atmosphere, they
became harder, and even brittle. A portion of this soft substance
having been wrapped in paper for the purpose of examination, and
placed in the pocket of a shipwright, gave rise to a very curious
and unexpected result: at first, the artist, like Futitorious with
his chestnuts, thought he perceived a genial warmth; but the effect
was shortly less equivocal; the substance became hot, and presently
passed into a state of absolute ignition. Various theories have
been suggested for its explanation: Mr. Daniell has advanced an
opinion which supposes the formation of silicon, and thus accounts
for the spontaneous ignition by the action of air.
[107] In the Annals of Philosophy (vol. v.) may be found a paper
by Dr. Henry, on the conversion of cast iron pipes into plumbago.
This change appears to have been effected by the action of water
containing muriate of soda, and the muriates of lime and of
magnesia. Cast iron contains a considerable portion of carbon;
the change is therefore readily explained on the supposition of
the removal of the principal metallic part by these salts. The
muriates of lime and magnesia have been observed by Dr. Henry to
discharge writing ink from the labels of bottles, to which they
had been accidentally applied; and the same ingenious chemist has
been baffled in his attempts to restore the legibility of ink
upon paper which had been exposed to sea-water. The texture of
the paper was not injured, but the iron basis of the ink, as well
as the gallic acid, was entirely removed.
The disadvantages which arise from the foulness of ships' bottoms,
particularly when on foreign stations, where there are no dry docks
to receive them, are so serious, that the Government was obliged,
in July 1825, to order the discontinuance of the protectors on
all sea-going ships; but directed that they should still be used
upon all those that were laid up in our ports. When, however, an
examination of the latter took place, they were found to be much
more foul than those which had been in motion at sea: shell-fish
of various kinds had adhered to them so closely, that it was even
necessary to use percussion to remove them, which not only indented
the copper, but in many instances actually fractured it.
Under all these discouraging circumstances, the unwelcome
conviction was forced upon the agents of Government, that the plan
was incapable of successful application, and it was accordingly
altogether abandoned in September 1828.
Such were the results of the experiments carried on in the ports of
England, for the protection of copper sheathing, from the success
of which Sir H. Davy justly expected honours, fame, and reward.
That his disappointment was great, may be readily imagined, and
it is supposed to have had a marked influence upon his future
character. It is much to be regretted that his vexation should
have been heightened by the unjust and bitter attacks made upon
him by the periodical press, and by those subalterns in science,
who, unable to appreciate the beauty of the principle he had so
ably developed, saw only in its details an object for sarcasm,
and in its failure an opportunity for censure; while those whose
stations should have implied superior knowledge, in the pride and
arrogance of assumed contempt, sought a refuge from the humiliation
of ignorance.
That Davy was severely hurt by these attacks, is a fact well known
to his friends. In a letter to Mr. Children he says: "A mind of
much sensibility might be disgusted, and one might be induced
to say, Why should I labour for public objects, merely to meet
abuse?--I am irritated by them more than I ought to be; but I am
getting wiser every day--recollecting Galileo, and the times when
philosophers and public benefactors were burnt for their services."
In another letter he alludes to the sycophancy of a chemical
journal, which, after the grossest abuse, suddenly turned round,
and disgusted him with its adulation. "I never shake hands," says
he, "with chimney sweepers, even when in their May-day clothes, and
when they call me '_Your honour_.'"
While the trials above related were proceeding in the ports of
England, the naval department of France was prosecuting a similar
enquiry; and as experiments of this nature are conducted with
greater care, and examined with superior science, in that country,
it may not be uninteresting to the English reader to receive a
detail of the examination of the bottom of La Constance frigate, in
which the protectors bore a much larger proportion to the copper
surface than was ever practised in the British navy. This document,
I may observe, is now published for the first time.
"The inspection of the bottom of the frigate La Constance, has
given rise to some interesting observations on the effect of
protectors, and it has confirmed the fact before advanced of the
great inconvenience which attends the application of too large a
proportion of the protecting metal.
"The surface of this metal, which was of cast iron, placed on each
side of the keel, and in long scarphs of iron plates situated
towards the stem and stern-post and the water line, appeared to
have been about the 1-30th part of the surface of the copper,
instead of the 1-250th part as now practised.
"The galvanic action has been extreme, both in rapidity and
intensity. The scarphs are entirely destroyed, and have absolutely
disappeared; and we should have been ignorant of their having ever
existed, had we not been informed of the fact, and observed dark
stains which marked their position, and discovered the nails still
entire by which they had been fastened.
"The plates, which were in the first instance about three inches
thick, were covered throughout their whole length by a thick,
unequal coating, spotted with yellow oxide. This was principally
owing to the absorption of about twenty-five per cent. of its
weight of water. Under this, the iron was as soft as plumbago, and
there remained scarcely an inch of metal of its original metallic
hardness.
"The bulky and irregular appendage (the protectors) at the lower
part of the ship's bottom caused a great noise in the sea, in
consequence of the dead water which it occasioned, and doubtless
lessened the speed of the vessel. But that which contributed most
to this unfortunate result, was the exceedingly unclean state of
the copper, arising from the excess of the iron employed: this,
carried to so great an extent, having the effect of extracting
matter from the water, which, forming a concretion on the sheets,
enabled the marine animals the more easily to attach themselves.
The sheathing was covered with a multitude of _lepas anatifera_,
shells with five valves, suspended by a pedicle of three or four
centimetres long, collected into groups; of _lepas tintinnabulum_,
a shell with six valves; of oysters with _opercula_; of _polypi_,
&c. No part of the bottom was free from them.
"Below, the copper was certainly preserved from oxidation; and up
to within a few sheets of the water line, it did not appear to be
worn. But to save expense, it was obliged to be cleansed without
removal, by rubbing it hard with bricks and wet sand, which has
succeeded very well in restoring its copper colour."
The following is the description of shells above enumerated:--
Genus _Anatifa_, Encyclopedia.--(_Lepas_, Linnæus.)
[Illustration: Fig. 1.]
FIG. 1. Smooth _Anatifa_ (_Lepas anatifera_, Linn.)--Shell
consisting of five valves, of which two larger and two smaller
ones are opposite to each other; and a fifth, which is narrow, is
arched and rests upon the ends of the first four: these valves
are not connected by any hinge; they are held together by the
skin of the animal, which lines their interior and opens in front
by a longitudinal separation. Their colour is orange during
the life of the animal. The base of the shell is united to a
fleshy tube, tendinous, cylindrical, susceptible of contraction,
saffron-coloured, becoming brown and black in drying.
[Illustration: Fig. 2.]
FIG. 2. Smooth _Anatifa_, as seen from the other side, the pedicle
dry and contracted.
[Illustration: Fig. 3.]
FIG. 3. Smooth _Anatifa_, as seen in front, showing the
longitudinal separation.
Genus _Anomia_.
[Illustration]
Shell with valves, unequal, irregular, having an operculum;
adhering by its operculum; valve usually pierced, flattened, having
a cavity in the upper part; the other valve a little larger,
concave, entire; operculum small, elliptical, bony, fixed on some
foreign body, and to which the interior muscle of the animal is
attached.
[Illustration]
Species, Onion-peel _Anomia_.--(_Ephippium_, Linn.)
Shell common, whitish and yellowish, found in the Mediterranean and
the ocean.
Besides the abovementioned species, which were found in large
quantities, there were also some muscles and oysters.--(_Mytilus
afer. Baccina._--Linn. Gmel. 3358.)
Genus "_Balane de Blainville_."
(_Balanite_, Encyclopedia.--_Lepas_, Linn.)
[Illustration: Fig. 1.]
FIG. 1. Tulip Balanus.--(_Lepas tintinnabulum_, Linn.)
Shell with six unequal valves articulated by a scaly suture, of
which the edges appear to be finely crenellated in the cavity;
the form of the valves is conical, aperture ample, and nearly
quadrangular.
Operculum composed of four triangular pieces crenellated and marked
with very projecting transverse striæ, which appear to extend from
the top to the bottom; the two posterior pieces are perpendicular,
and are applied to the hinder partition of the cavity of the
shell; they are terminated by two conical prolongations, of which
the points are sharp and diverging. The two foremost pieces are
placed in the aperture, in an oblique direction. The colour of this
balanus from clear red to violet and brown.
[Illustration: Fig. 2.]
FIG. 2. View of the upper part of the Tulip Balanus.
[Illustration: Fig. 3.]
FIG. 3. View of the base.
Genus Oyster, (_Ostrea._)
[Illustration]
Species of oyster, nearly similar to the common oyster, (_Ostrea
edulis_,) and of the Huître cuilier, (_Ostrea cochlear_,) their
shell rather fragile, almost without lamellæ; upper valve concave,
colour rather deep violet, form variable.
"Besides these three kinds of Molluscæ, of which the number was
considerable, several species of calcareous polypi were found; but
those which could be obtained were too imperfect to allow of their
being correctly described.
"The iron which was used to protect the copper on the bottom of the
Constance frigate having been subjected to chemical analysis, the
following are the results.
"This iron, which was in small fragments, very friable, little
attracted by the loadstone, soft to the touch, and soiling the
fingers like plumbago, gave out in rubbing it a very strong smell,
very much like that of burnt linseed oil. Its colour on the
exterior was a brownish yellow, and its interior a blackish grey,
studded with little points extremely brilliant.
"A short time after they had been taken from the keel of the
frigate, where they were covered with a layer of hydrated peroxide
of iron, of six or eight lines in thickness, and been enclosed in
a paper box, these fragments became strongly heated, and underwent
a real combustion by means of the oxygen of the atmosphere; the
combustion was accompanied by the production of a certain quantity
of aqueous vapour.
"In order to ascertain whether this elevation of temperature
was really alone owing to the absorption of the oxygen, a case
containing twelve _grammes_ of this iron was placed under a
receiver, which contained two hundred millimetres, inverted over
a tube of mercury; and it was observed, in the course of an hour,
that this air had diminished by forty millimetres, or one-fifth
of its volume. Examining afterwards that which remained in the
receiver, it was discovered that it had no effect whatever either
on lime-water or the tincture of _tournesol_,--that it was not
inflammable,--that it extinguished a candle; in a word, that it
presented all the negative qualities of azotic gas, strongly
infected with the smell before stated.
"It must be evident that the oxygen which was absorbed in this
experiment was employed solely in burning the iron, which was
already in a state of _protoxide_, as was indicated by its little
degree of cohesion, by the avidity with which it seized this
principle, and by its dissolving in sulphuric acid, which operated
without effervescence, and without disengaging hydrogen gas.
"Five _grammes_ of this oxidized iron being reduced to an
impalpable powder, and then made red-hot in a platina crucible,
and mixed with three parts of _potasse à l'alcool_, were reduced
to a clammy mass, coloured on its edges with a clear beautiful
green, and with a greenish yellow on the other parts; which at once
indicated the presence of a small portion of manganese, and that
of a little _chrôme_; metals which are found united in almost all
sorts of iron. Treated in the usual way, this mass exhibited--
"First, Traces, scarcely sensible, of these two metals.
"Secondly, One _gramme_ of brilliant black powder, soft to the
touch, staining paper, insoluble in muriatic acid when applied
boiling: it was therefore a true percarburet of iron.
"Thirdly, Three _grammes_ and ten _decigrammes_ of peroxide of iron.
"On being subjected to the action of boiling water, five grammes
of this pulverized iron gave out three _decigrammes_ of soluble
matter, composed, for the greater part, of _hydrochlorate_ of
iron, and a trace of hydrochlorate of magnesia, together with a
little organic matter, the combination of which with the iron will
account for the insufferable smell which it gave out when the iron
was heated. This saline solution sensibly reddened the litmus
paper: an effect which was owing to the muriatic acid, which, in
uniting with oxidized iron, and with most other metallic oxides,
never forms combinations which are perfectly neutral, but which are
always more or less acid.
"It has in vain been attempted to discover in this oxidized iron
the presence of silex, of alumina, and of the sulphuric and
carbonic acids, either free, or in combination.
"It results from this analysis, that the fragments of the
protectors, which have been the object of it, are composed, in a
hundred parts, of about
64 oxidized iron,
20 of plumbago, or percarburet of iron,
6 of matter soluble in water, hydrochlorate of magnesia,
hydrochlorate of iron, hydrochlorate of soda, hydrochlorate of
magnesia, and organic matter, and
10 of water; as in fragments pulverised and heated for half an
hour at a temperature of 100°, they lost 1-10th of their weight.
"As to the reddish yellow matter, with small protuberances
like nipples, which formed a thick layer on the surface of the
protectors, it was formed of 75 parts of oxide of iron at the most,
and 25 parts of water, besides some atoms of hydrochlorate of iron,
hydrochlorate of soda, and hydrochlorate of magnesia."
* * * * *
Had not the health of Davy unfortunately declined at the very
period when his energies were most required, such is the unbounded
confidence which all must feel in his unrivalled powers of
vanquishing practical difficulties, and of removing the obstacles
which so constantly thwart the applications of theory, that little
doubt can be entertained but he would soon have discovered some
plan by which the adhesion of marine bodies to the copper sheathing
might have been prevented, and his principle of Voltaic protection
thus rendered available. An experiment indeed, altogether founded
upon this same principle, has been already proposed, and will be
shortly tried in the British navy, by building a schooner, and
fastening its materials together with copper bolts, and afterwards
sheathing the bottom with thin plates of iron, which are to be
protected by bands of zinc. At the same time, another schooner is
to be built, in which the fastenings are to consist entirely of
iron bolts and nails, the former to be protected by a zinc ring
under each head or clench, and the latter to have a small piece of
zinc soldered under its head.
This plan of protection was first adopted in America, at the
recommendation of Dr. Revere; and upon its successful issue, that
gentleman was lately induced to take out letters patent not only
in England, but in all the maritime countries of Europe, for the
sole right of manufacturing iron sheathing, bolts, and nails, thus
protected.
As no doubt now exists as to the principle of the protection of
iron by zinc, the bolts and nails may be expected to remain free
from rust as long as the more oxidable metal lasts; but with
regard to the success of the iron sheathing, it is impossible
to entertain the same confidence; for what, in this case, is to
prevent the adhesion of shell-fish and sea-weed upon its surface?
Let it be remembered, that it is only when the copper is in the act
of solution in sea-water that the sheathing remains clean. In the
year 1829, the Tender to the Flagship at Plymouth had her copper on
one side of the bottom painted with white lead: in six months, this
side was covered with long weeds; while the other side, which had
been left bright, and consequently exposed to the solvent action of
the salt-water, was found entirely free from all such adhesions.
CHAPTER XIV.
The failure of the Ship protectors a source of great vexation
to Davy.--His Letters to Mr. Poole.--He becomes unwell.--He
publishes his Discourses before the Royal Society.--Critical
Remarks--and Quotations.--He goes abroad in search of
health.--His Letter to Mr. Poole from Ravenna.--He resigns the
Presidency of the Royal Society.--Mr. Gilbert elected _pro
tempore_.--Davy returns to England, and visits his friend Mr.
Poole.--Salmonia, or Days of Fly-fishing.--An Analysis of the
Work, with various extracts to illustrate its character.
The friends of Sir Humphry Davy saw with extreme regret that the
failure of his plan for protecting copper sheathing had produced in
his mind a degree of disappointment and chagrin wholly inconsistent
with the merits of the question; that while he became insensible
to the voice of praise, every nerve was jarred by the slightest
note of disapprobation. I apprehend, however, that the change of
character which many ascribed to the mortification of wounded
pride, ought in some measure to be referred to a declining state
of bodily power, which had brought with it its usual infirmities
of petulance and despondency. The letters I shall here introduce
may perhaps be considered as indicating that instinctive desire
for quiet and retirement which frequently marks a declining state
of health, and they will be followed by others of a less equivocal
character.
TO THOMAS POOLE, ESQ.
Grosvenor Street, Nov. 24, 1824.
MY DEAR POOLE,
It is very long since I have heard from you, Mr. A----, whom
you introduced to me, has sometimes given me news of you, and I
have always heard of your health and well-being with pleasure.
My immediate motive for writing to you now is somewhat, though
not entirely selfish. You know 1 have always admired your
neighbourhood, and I have lately seen a place advertised there,
called, I think,----, not far from Quantock, and combining,
as far as advertisement can be trusted, scenery, fishing,
shooting, interest for money, &c.
If it is not sold, pray give me a little idea of it; I have
long been looking out for a purchase,--perhaps this may suit
me. After all, it may be sold; if so, no harm is done.
I go on labouring for utility, perhaps more than for glory;
caring something for the judgment of my contemporaries, but
more for that of posterity; and confiding with boldness in the
solid judgment of Time.
I have lately seen some magnificent country in the Scandinavian
peninsula, where Nature, if not a kind, is at least a beautiful
mother.--I wonder there have not been more poets in the North.
I am, my dear Poole,
Very affectionately your old friend,
H. DAVY.
TO THE SAME.
January 5, 1825.
MY DEAR POOLE,
My proposition to come into Somersetshire about the 10th was
founded upon two visits which I had to pay in this county,
Hants; I am now only about sixty miles from you; and had you
been at home, I should have come on to Nether Stowey. The 13th
is the first meeting of the Royal Society after the holidays;
and though I might do my duty by deputy, yet I feel that this
would not be right, and I will not have the honour of the chair
without conscientiously taking the labours which its possession
entails. I regret therefore that I cannot be with you next
week. God bless you.
Believe me always, my dear Poole,
Your affectionate friend,
H. DAVY.
TO THE SAME.
Park Street, Feb. 11, 1825.
MY DEAR POOLE,
* * * * *
I had a letter a few days ago from C----, who writes in good
spirits, and who, being within a few miles of London, might, as
far as his friends are concerned, be at John a Grot's house.
He writes with all his ancient power. I had hoped that, as his
mind became subdued, and his imagination less vivid, he might
have been able to apply himself to persevere, and to give to
the world some of those trains of thought, so original, so
impressive, and at which we have so often wondered.
I am writing this letter at a meeting of the Trustees of the
British Museum, which will account for its want of correction.
Lest I should be more desultory, I will conclude by subscribing
myself, my dear Poole, your old and affectionate friend,
H. DAVY.
TO THE SAME.
Feb. 28, 1825.
MY DEAR POOLE,
I am very much obliged to you for your two letters, which I
received in proper time. I have deferred writing, in the hopes
that I might be able to pay you a visit and see the property,
but I now find this will be impossible. I have a cold, which
has taken a stronger and more inflammable character than usual,
which obliges me to lay myself up; and in this weather it would
be worse than imprudent to travel.
I have seen Mr. Z----, and can perfectly re-echo your
favourable sentiments respecting him. I saw the plan of the
estate, and heard every thing he had to say respecting the
value, real and imaginary, of the lands. He certainly hopes at
this moment for a fancy price, and he is right if he can get it.
* * * * *
I have less fancy for the place, from finding the trout-stream
a brook in summer, where salmon-trout, or salmon, could not
be propagated; for one of my favourite ideas in a country
residence is varied and multiplied experiments on the increase
and propagation of fish.
What I should really like would be a place with a couple of
hundred acres of productive land, and plenty of moor, a river
running through it, and the sea before it; and not farther from
London than Hampshire--a day's journey. There are such places
along the coast, though perhaps in my lifetime they will not
be disposed of. I should also like to be within a few miles of
you; for it is one of the regrets in the life which I lead,
that devotion to the cause of science separates me very much
from friends that I shall ever venerate and esteem. God bless
you, my dear Poole,
Very affectionately yours,
H. DAVY.
TO THE SAME.
Pixton near Dulverton, Nov. 1, 1826.
MY DEAR POOLE,
I cannot be in your neighbourhood, without doing my best to see
you; and it is my intention to come to Stowey on Sunday. I hope
I shall find you at home, and quite well.
Mr. T----, who is here, gives me a very good account of you,
which I trust I shall be personally able to verify.
If you are at leisure, I will try to shoot a few woodcocks on
Monday on the Quantock hills; on Tuesday I must go east.
I have not been well lately. I cannot take the exercise which
twenty years ago I went lightly and agreeably through. Will you
have the kindness to hire a pony for me, that I may ride to
your hills?
I am sorry I did not know of your journey to Ireland and
Scotland. I was in both those countries at the time you visited
them, and should have been delighted to have met you.
Do not write to me; for, even if you should not be at home,
Stowey is not more than ten or twelve miles out of my way; but
I hope I shall find you.
I am, my dear Poole,
Your old and sincere friend,
H. DAVY.
The complaints, as to the loss of his strength, which are expressed
in the preceding letter, were but too well founded. Mr. Poole
informs me that, during this visit in 1826, it was affecting to
observe the efforts he made to continue his field sports. From
being unable to walk without fatigue, he was compelled to have a
pony to take him to the field, from which he dismounted only on the
certainty of immediate sport.
On his return to London, his indisposition increased: he complained
to me of palpitation of the heart, and of an affection in the
trachea, which led him to fear that he might be suffering under the
disease of which his father died.
The fatigue attendant upon the duties of the anniversary of the
Royal Society (November 30th) completely exhausted him; and after
his re-election as President, he was reluctantly obliged to retire,
and to decline attending the usual dinner upon that occasion.
In January 1827, Sir Humphry Davy published the Discourses which
he had delivered before the Royal Society, at six successive
anniversary meetings, on the award of the Royal and Copley medals.
They were published in compliance with a resolution of a meeting of
the Council, held on the 21st of December 1826.
The practice of delivering an annual oration before the Royal
Society, on the occasion of presenting the medal upon Sir Godfrey
Copley's donation, prevailed during the presidency of Sir John
Pringle; it was, however, during a long interval discontinued, and
only revived during the latter years of Sir Joseph Banks.
The discourse usually commenced with a short tribute of respect to
the memory of those distinguished Fellows who had died since the
preceding anniversary. It then proceeded to announce the choice of
the Council in its award of the medals, enumerating the objects
and merits of the several communications which had been honoured
with so distinguished a mark of approbation, and stating the
circumstances which had directed the judges in their decision.
Much has been said and written upon the inutility, and even upon
the mischievous tendency of this practice; and great stress has
been laid upon the vices inseparably connected, as it is asserted,
with the style of composition to which it gives origin. It appears
to me, however, that it is only against the meretricious execution,
not against the temperate use of such discourses, that this charge
can be fairly and consistently sustained; and in the chaste and
yet powerful addresses of Davy, such an opinion will find its best
sanction, and obtain its strongest support.
Does it follow, because praise, when unduly lavished upon the
labours of the scientific dead, may create comparisons and
preferences injurious to the living, that we are to stifle the
noblest aspirations of our nature, and become as cold and silent
as the grave that encloses their remains? Does it follow, because
an undisciplined ardour may have occasionally exaggerated the
merits of our contemporaries, that we are henceforth to withhold
from them a just tribute of applause at their discoveries--to
forego the advantages which science must derive from a plan so
well calculated to awaken the flagging attention, to infuse into
stagnant research a renewed spirit of animation, and to encourage
the industry of the labourer in the abstract regions of science,
with prospects gleaming with sunshine, and luxuriant in the
fruitfulness which is to reward him?
Such was the character, such the effect of Davy's discourses. They
exhibit a great assemblage of diversified talents, and display the
refined views he entertained with respect to the mutual relations
which the different sciences maintain with each other; they evince,
moreover, a great command of language, and a power to give exact
expression to what his mind had conceived.
To these six Discourses is prefixed his Address upon taking the
chair of the Royal Society for the first time; the subject of
which is "The present state of that Body, and the Progress and
Prospects of Science." Upon this occasion, he particularly adverts
to the light which the different branches of science may reflect
upon each other. "In pure Mathematics--though their nature, as a
work of intellectual combination, framed by the highest efforts
of human intelligence, renders them incapable of receiving aids
from observations of external phenomena, or the invention of new
instruments, yet they are, at this moment, abundant in the promise
of new applications; and many of the departments of philosophical
enquiry which appeared formerly to bear no relation to quantity,
weight, figure, or number, as I shall more particularly mention
hereafter, are now brought under the dominion of that sublime
science, which is, as it were, the animating principle of all the
other sciences."
"In the theory of light and vision, the researches of Huygens,
Newton, and Wollaston, have been followed by those of Malus;
and the phenomena of polarization are constantly tending to new
discoveries; and it is extremely probable that those beautiful
results will lead to a more profound knowledge than has hitherto
been obtained, concerning the intimate constitution of bodies,
and establish a near connexion between mechanical and chemical
philosophy."
"The subject of heat, so nearly allied to that of light, has
lately afforded a rich harvest of discovery; yet it is fertile
in unexplored phenomena. The question of the materiality of
heat will probably be solved at the same time as that of the
undulating hypothesis of light, if, indeed, the human mind should
ever be capable of understanding the causes of these mysterious
phenomena. The applications of the doctrine of heat to the atomic
or corpuscular philosophy of chemistry abound in new views, and
probably at no very distant period these views will assume a
precise mathematical form."
"In Electricity, the wonderful instrument of Volta has done
more for the obscure parts of physics and chemistry, than the
microscope ever effected for natural history, or even the telescope
for astronomy. After presenting to us the most extraordinary and
unexpected results in chemical analysis, it is now throwing a new
light upon magnetism.
'Suppeditatque novo confestim lumine lumen.'
"I must congratulate the Society on the rapid progress made in the
theory of definite proportions, since it was advanced in a distinct
form by the ingenuity of Mr. Dalton. I congratulate the Society on
the promise it affords of solving the recondite changes, owing to
motions of the particles of matter, by laws depending upon their
weight, number, and figure, and which will be probably found as
simple in their origin, and as harmonious in their relations, as
those which direct the motions of the heavenly bodies, and produce
the beauty and order of the celestial systems.
"The crystallizations, or regular forms of inorganic matter,
are intimately connected with definite proportions, and depend
upon the nature of the combinations of the elementary particles;
and both the laws of electrical polarity, and the polarization
of light, seem related to these phenomena. As to the origin of
the primary arrangement of the crystalline matter of the globe,
various hypotheses have been applied, and the question is still
agitated, and is perhaps above the present state of our knowledge;
but there are two principal facts which present analogies on the
subject,--one, that the form of the earth is that which would
result, supposing it to have been originally fluid; and the other,
that in lavas, masses decidedly of igneous origin, crystalline
substances, similar to those belonging to the primary rocks, are
found in abundance."
It is the privilege of genius to be in advance of the age, and to
see, "as by refraction, the light, as yet below the horizon." It is
with such a feeling that I have introduced the foregoing extracts,
which I cannot but regard as prophetic of future discoveries.
The first discourse was delivered on the 30th of November 1821, on
the occasion of announcing the award of two medals, on Sir Godfrey
Copley's donation; one to J. F. W. Herschel, Esq. for his various
papers on mathematical and physico-mathematical subjects; and the
other, to Captain Edward Sabine, R.A., for his papers containing an
account of his various experiments and observations made during a
voyage and expedition in the Arctic regions.
As I am desirous that the reader should be made acquainted with
the nature and style of the address with which he accompanied the
presentation of the medal, I cannot select a happier example, or
one in the sentiments of which every person will more readily
participate, than the following:--
"MR. HERSCHEL--Receive this medal, Sir, as a mark of our
respect, and of our admiration of those talents which you
have applied with so much zeal and success, and preserve it
as a pledge of future exertions in the cause of Science and
of the Royal Society; and, believe me, you can communicate
your labours to no public body by whom they will be better
received, or through whose records they will be better known to
the philosophical world. You are in the prime of life, in the
beginning of your career, and you have powers and acquirements
capable of illustrating and extending every branch of physical
enquiry; and, in the field of science, how many are the spots
not yet cultivated! Where the laws of sensible become connected
with those of insensible motions, the mechanical with the
chemical phenomena, how little is known! In electricity,
magnetism, in the relations of crystallized forms to the
weight of the elements of bodies, what a number of curious and
important objects of research! and they are objects which you
are peculiarly qualified to pursue and illustrate.
"May you continue to devote yourself to philosophical pursuits,
and to exalt your reputation, already so high--
'Virtutem extendere factis.'
And these pursuits you will find not only glorious, but
dignified, useful, and gratifying in every period of life:
this, indeed, you must know best in the example of your
illustrious father, who, full of years and of honours, must
view your exertions with infinite pleasure; and who, in the
hopes that his own imperishable name will be permanently
connected with yours in the annals of philosophy, must look
forward to a double immortality."
In the discourse of the succeeding year, it was his painful duty
to announce the death of the elder Herschel, whom, in his former
address, he had eulogized in such eloquent and touching language.
In alluding to the labours and discoveries of Sir William Herschel,
he observed, that "they have so much contributed to the progress of
modern astronomy, that his name will probably live as long as the
inhabitants of this earth are permitted to view the solar system,
or to understand the laws of its motions. The world of science--the
civilized world, are alike indebted to him who enlarges the
boundaries of human knowledge, who increases the scope of
intellectual enjoyment, and exhibits the human mind in possession
of new and unknown powers, by which it gains, as it were, new
dominions in space; acquisitions which are imperishable--not like
the boundaries of terrestrial states and kingdoms, or even the
great monuments of art, which, however extensive and splendid, must
decay--but secured by the grandest forms and objects of nature, and
registered amongst her laws."
One more quotation, and I shall conclude with the conviction that
the splendid specimens I have adduced must fully justify the
opinion already offered as to the taste, power, and eloquence with
which, as President of the Royal Society, he discharged the most
delicate and arduous of all its duties.
In his address to Mr. (now Dr.) Buckland, on delivering to him the
medal for his important memoir on the fossile remains discovered in
the cave near Kirkdale, he thus concludes:--"If we look with wonder
upon the great remains of human works, such as the columns of
Palmyra, broken in the midst of the desert; the temples of Pæstum,
beautiful in the decay of twenty centuries; or the mutilated
fragments of Greek sculpture in the Acropolis of Athens, or in
our own Museum, as proofs of the genius of artists, and power and
riches of nations now past away; with how much deeper a feeling of
admiration must we consider those grand monuments of nature which
mark the revolutions of the globe--continents broken into islands;
one land produced, another destroyed; the bottom of the ocean
become a fertile soil; whole races of animals extinct, and the
bones and exuviæ of one class covered with the remains of another;
and upon these graves of past generations--the marble or rocky
tombs, as it were, of a former animated world, new generations
rising, and order and harmony established, and a system of life
and beauty produced, as it were, out of chaos and death, proving
the infinite power, wisdom, and goodness of the Great Cause of all
being!"
* * * * *
I have noticed the apparent commencement of that general
indisposition which had for some time been stealing upon him,
undermining his powers, oppressing his spirits, and subduing his
best energies; but in the end of 1826, his complaint assumed a
more decided and alarming form. Feeling more than usually unwell,
while on a visit to his friend Lord Gage, he determined to return
to London, and was seized while on his journey, at Mayersfield,
with an apoplectic attack. Prompt and copious bleeding, however, on
the spot, arrested the symptoms more immediately threatening the
extinction of life, and enabled him to reach home; but paralysis,
the usual consequence of such seizures, had obviously, though at
first but slightly, diminished his muscular powers, and given an
awkwardness to his gait.
As soon as the more immediate danger of the attack had passed
away, it was thought expedient to recommend, as the best means of
his farther recovery, a residence in the southern part of Europe,
where he would be removed from all the cares and anxieties that
were inseparably connected with his continuance in London; and he
accordingly quitted England, with the intention of spending what
remained of the winter in Italy.
The following interesting letter to his friend will sufficiently
explain the serious character of his malady, and the degree of
bodily infirmity which accompanied it.
TO THOMAS POOLE, ESQ.
Ravenna, March 14, 1827.
MY DEAR POOLE,
I should have answered your letter immediately, had it been
possible; but I was, at the time I received it, very ill, in
the crisis of the complaint under which I have long suffered,
and which turned out to be a determination of the blood to the
brain; at last producing the most alarming nervous symptoms,
and threatening the loss of power and of life.
Had I been in England, I should gladly have promoted the
election of your friend at the Athenæum: your certificate of
character would always be enough for me; for, like our angling
evangelical Isaac Walton, I know you choose for your friends
only good men.
I am, thank God, better, but still very weak, and wholly
unfit for any kind of business and study. I have, however,
considerably recovered the use of all the limbs that were
affected; and as my amendment has been slow and gradual, I
hope in time it may be complete: but I am leading the life of
an anchorite, obliged to abstain from flesh, wine, business,
study, experiments, and all things that I love; but this
discipline is salutary, and for the sake of being able to do
something more for science, and, I hope, for humanity, I submit
to it; believing that the Great Source of intellectual being so
wills it for good.
I am here lodged in the Apostolical Palace, by the kindness of
the Vice-Legate of Ravenna, a most admirable and enlightened
prelate, and who has done every thing for me that he could have
done for a brother.
I have chosen this spot of the declining empire of Rome, as one
of solitude and repose, as out of the way of travellers, and
in a good climate; and its monuments and recollections are not
without interest. Here Dante composed his divine works. Here
Byron wrote some of his best and most moral (if such a name can
be applied) poems; and here the Roman power that began among
the mountains with Romulus, and migrated to the sea, bounding
Asia and Europe under Constantine, made its last stand, in the
marshes formed by the Eridanus, under Theodorick, whose tomb is
amongst the wonders of the place.
After a month's travel in the most severe weather I ever
experienced, I arrived here on the 20th of February. The
weather has since been fine. My brother and friend, who is
likewise my physician, accompanied me; but he is so satisfied
with my improvement, as to be able to leave me for Corfu; but
he is within a week's call.
I have no society here, except that of the amiable Vice-Legate,
who is the Governor of the Province; but this is enough for me,
for as yet I can bear but little conversation. I ride in the
pine forest, which is the most magnificent in Europe, and which
I wish you could see. You know the trees by Claude Lorraine's
landscapes: imagine a circle of twenty miles of these great
fan-shaped pines, green sunny lawns, and little knolls of
underwood, with large junipers of the Adriatic in front, and
the Apennines still covered with snow behind. The pine wood
partly covers the spot where the Roman fleet once rode,--such
is the change of time!
It is my intention to stay here till the beginning of April,
and then to go to the Alps, for I must avoid the extremes of
heat and cold.
God bless you, my dear Poole. I am always your old and sincere
friend,
H. DAVY.
Feeling that his recovery was tardy, and that perfect mental repose
was more than ever necessary for its advancement, he determined to
resign the chair of the Royal Society; and he accordingly announced
that intention, by a letter to his friend Mr. Davies Gilbert,
Vice-President of the Society.
TO DAVIES GILBERT, ESQ. M.P. V.P.R.S. &c. &c.
Salzburgh, July 1, 1827.
MY DEAR SIR,
Yesterday, on my arrival here, I found your two letters. I am
sorry I did not receive the one you were so good as to address
to me at Ravenna; nor can I account for its miscarriage. I
commissioned a friend there to transmit to me my letters from
that place after my departure, and I received several, even so
late as the middle of May, at Laybach, which had been sent to
Italy, and afterwards to Illyria. I did not write to you again,
because I always entertained hopes of being able to give a
better account of the state of my health. I am sorry to say the
expectations of my physicians of a complete and rapid recovery
have not been realized. I have gained ground, under the most
favourable circumstances, very slowly; and though I have had no
new attack, and have regained, to a certain extent, the use of
my limbs, yet the tendency of the system to accumulate blood
in the head still continues, and I am obliged to counteract
it by a most rigid vegetable diet, and by frequent bleedings
with leeches and blisterings, which of course keep me very low.
From my youth up to last year, I had suffered, more or less,
from a slight hemorrhoidal affection; and the fulness of the
vessels, then only a slight inconvenience, becomes a serious
and dangerous evil in the head, to which it seems to have been
transferred. I am far from despairing of an ultimate recovery,
but it must be a work of time, and the vessels which have been
over distended only very slowly regain their former dimensions
and tone: and for my recovery, not only diet and regimen and
physical discipline, but a freedom from anxiety, and from all
business and all intellectual exertion, is absolutely required.
Under these circumstances, I feel it would be highly imprudent
and perhaps fatal for me, to return, and to attempt to perform
the official duties of President of the Royal Society. And as
I had no other feeling for that high and honourable situation,
except the hope of being useful to society, so I would not keep
it a moment without the security of being able to devote myself
to the labour and attention it demands. I beg therefore you
will be so good as to communicate my resignation to the Council
and to the Society at their first meeting in November, after
the long vacation; stating the circumstances of my severe and
long continued illness, as the cause. At the same time, I beg
you will express to them how truly grateful I feel for the high
honour they have done me in placing me in the chair for so many
successive years. Assure them that I shall always take the same
interest in the progress of the grand objects of the Society,
and throughout the whole of my life endeavour to contribute to
their advancement, and to the prosperity of the body.
Should circumstances prevent me from sending, or you from
receiving any other communication from me before the autumn
(for nothing is more uncertain than the post in Austria, as
they take time to read the letters), I hope this, which I
shall go to Bavaria to send, will reach you safe, and will be
sufficient to settle the affair of resignation.
It was my intention to have said nothing on the subject of my
successor. I will support by all the means in my power the
person that the leading members of the Society shall place in
the chair; but I cannot resist an expression of satisfaction
in the hope you held out, that an illustrious friend of the
Society, illustrious from his talents, his former situation,
and, I may say, his late conduct, is likely to be my successor.
I wish my name to be in the next Council, as I shall certainly
return, _Deo volente_, before the end of the session, and I
may, I think, be of use; and likewise, because I hope it may
be clearly understood that my feelings for the Society are, as
they always were, those of warm attachment and respect. Writing
still makes my head ache, and raises my pulse. I will therefore
conclude, my dear Sir, in returning you my sincere thanks for
the trouble you have had on my account, and assuring you that I
am
Your obliged and grateful friend and servant,
H. DAVY.
Pray acknowledge the receipt of this letter, by addressing me,
"_poste restante_, Laybach, Illyria, Austria;" and let me know
if Mr. Hudson is still Assistant-Secretary, and where Mr. South
is. I send this letter from Frauenstein, Bavaria, July 2, that
it may not be opened, as all my letters were at Salzburgh.
There was one of them must have _amused_ Prince Metternich, on
the state of parties in England, from a Member of the Upper
House.
In consequence of this letter, the Council of the Royal Society,
by a resolution passed at a very full meeting held on the 6th of
November, 1827, appointed Mr. Davies Gilbert to fill the chair,
until the general body should elect a President, at the ensuing
anniversary.
The following letter will show his subsequent course of proceeding.
TO THOMAS POOLE,
Park Street, Grosvenor Square,
Oct. 29, 1827.
MY DEAR POOLE,
I hope you received a letter which I addressed to you from
Ravenna in the spring. It was my intention to have returned to
Italy from the Alpine countries, where I spent the summer; but
my recovery has been so slow, and so much uneasiness in the
head and weakness in the limbs remained in September, that I
thought it wiser to return to my medical advisers in London.
I have consulted all the celebrated men who have written upon
or studied the nervous system. They all have a good opinion
of my case, and they all order absolute repose for at least
twelve months longer, and will not allow me to resume my
scientific duties or labours at present; and they insist upon
my leaving London for the next three or four months, and advise
a residence in the west of England. Now, my dear friend, you
recollect our conversation upon the subject of a residence--I
think Mr. C.'s is not very far from you. Pray let me know
something on this head. I want very little of any thing, for I
am almost on a vegetable diet; and a little horse exercise, a
very little shooting, and a little quiet society, are what I am
in search of, with some facilities of procuring books. I have
thought of Minehead, Ilfracombe, Lymouth, and Penzance; but I
have not yet determined the point.
Horse exercise and shooting are necessary to bring back my
limbs to their former state, and therefore Bath and Brighton
will not do for me. God bless you, my dear Poole, and pray let
me hear from you.
Your affectionate,
H. DAVY.
P.S. I hope you got the copy of my discourses.
TO THE SAME.
Firle, near Lewes, Nov. 4, 1827.
MY DEAR POOLE,
I have this moment received your very kind and most friendly
letter. I have made my first visit to my friend Lord G----,
where I was taken ill last year; and have borne the journey
well, and have enjoyed the small society here; but I am very
weak indeed, and I cannot yet walk more than a mile. One of
three plans, I shall hope to adopt; two of them you have most
amiably suggested, the other is to go to Penzance. My only
objection to the last is the fear of too much society. Whatever
I do, I will first come to you and take your advice.
When I returned, I had little hopes of recovery; but the
assurances of my physicians that I may again, with care, be
re-established, have revived me, and I have certainly gained
ground, and gained strength, by the plan I am now pursuing.
As soon as I return to London, I will write to you. If I can
find a companion, I think Mr. C----'s house will do admirably;
but I must see it, as a temperate situation is a _sine quâ non_.
I need not say how grateful I am for your kindness, and if
I recover, how delighted I shall be to owe the means to so
excellent and invaluable a friend. God bless you.
I am, my dear Poole, your affectionate,
H. DAVY.
TO THE SAME.
Firle, Nov. 7.
MY DEAR POOLE,
I am going to London to-morrow, and after staying two or
three days, to try a new plan of medical treatment, which my
physicians recommend, I shall come westward, and profit by your
kindness, and adopt whichever of the plans will promise to be
most salutary.
If I take Mr. C----'s house, Lady Davy will come to me. With
respect to society, I want only a friend, or one person or two
at most, to prevent entire solitude, and I am too weak to bear
much conversation, and wholly unfit to receive any but persons
with whom I am in the habits of intimacy.
I can hardly express to you how deeply I feel your kindness.
* * * * *
As I must travel slowly, I shall not probably be at Stowey
before Wednesday or Thursday next. Pray do not ask any body
to meet me. I am upon the _strictest_ diet,--a wing of a
chicken and a plain rice or bread pudding is the extreme of my
_gourmanderie_. God bless you.
My dear Poole, your affectionate friend,
H. DAVY.
Mr. Poole has been so obliging as to communicate to me some
interesting particulars connected with the visit to which the
foregoing letters allude.
"During this last visit, (November and December 1827,) his bodily
infirmity was very great, and his sensibility was painfully alive
on every occasion. Unhappily, he had to sustain the affliction of
the sudden death of Mr. R----, the son of a friend whom he highly
valued; and though this afflicting event was, by the considerate
and anxious attention of Lady Davy, first communicated to me by
letter, to be imparted to him with every precaution, to avoid
his being suddenly shocked, yet it was many days before he could
recover his usual spirits, feeble as they were, and resume his
wonted occupation.
"On his arrival, he said, 'Here I am, the ruin of what I was;'
but nevertheless, the same activity and ardour of mind continued,
though directed to different objects. He employed himself two
or three hours in the morning on his _Salmonia_, which he was
then writing; he would afterwards take a short walk, which he
accomplished with difficulty, or ride. After dinner, I used to
read to him some amusing book. We were particularly interested by
Southey's Life of Nelson. 'It would give Southey,' he said, 'great
pleasure, if he knew how much his narrative affected us.'[108]
[108] His admiration of this work bursts forth in his _Salmonia_,
which he was writing at that time. He styles it "an immortal
monument raised by Genius to Valour."
"In the evening, Mr. and Mrs. W----, the former of whom he had
long known, frequently came to make a rubber at whist. He was
averse to seeing strangers; but on being shown the drawings of
Natural History of a friend of mine of great talent, Mr. Baker
of Bridgwater, he was anxious to know him, and was much pleased
with his company. He suggested to him various subjects for
investigation, concerning insects, and fish, particularly the eel.
What pleasure would it give him were he now alive, to learn the
interesting result of those suggestions! I hope the public will
soon be made acquainted with them.
"Natural History in general had been a favourite subject with him
throughout his protracted illness; and during this last visit
to me, he paid attention to that only; 'for,' said he, 'I am
prohibited applying, and indeed I am incapable of applying, to any
thing which requires severe attention.'
"During the same visit, I remember his inherent love of the
laboratory, if I may so express myself, being manifested in a
manner which much interested me at the moment. On his visiting
with me a gentleman in this neighbourhood, who had offered him
his house, and who has an extensive philosophical apparatus,
particularly complete in electricity and chemistry, he was fatigued
with the journey, and as we were walking round the house very
languidly, a door opened, and we were in the laboratory. He threw a
glance around the room, his eyes brightened in the action, a glow
came over his countenance, and he looked like himself, as he was
accustomed to appear twenty years ago.
"You are aware that he was latterly a good shot, always an expert
angler, and a great admirer of old Isaac Walton; and that he highly
prided himself upon these accomplishments. I used to laugh at him,
which he did not like; but it amused me to see such a man give
so much importance to those qualifications. He would say, 'It is
not the sport only, though there is great pleasure in successful
dexterity,[109] but it is the ardour of pursuit, pure air, the
contemplation of a fine country, and the exercise--all tend to
invigorate the body, and to excite the mind to its best efforts.'
[109] Mr. Children has just communicated to me the following
amusing anecdote, which may be adduced in illustration of the
delight he took in that sporting dexterity to which he alludes
in the above passage. Davy, with a party of friends, had
been engaged for several hours in fishing for pike, but very
unsuccessfully; our philosopher gave up the sport in despair,
but his companions having determined to try some more propitious
spots, left him to his contemplations. About an hour afterwards,
Mr. Children, on returning to his friend, saw him at a distance
seated upon a gate, and apparently lashing the air with his
fishing-line. What could be his object? As soon as Mr. Children
came sufficiently near to make a signal, Davy, by his gestures,
earnestly entreated him to keep away, while he continued his
mysterious motions. At length, however, Mr. Children's patience
was exhausted, and he walked up to him. "Was ever any thing more
provoking!" exclaimed Davy; "if you had only remained quiet
another minute I should have caught him--it is most vexatious!"
"Caught what?" asked Mr. Children. "A dragon-fly," (_Libellula_,)
answered Davy. "During your absence I have been greatly amused by
watching the feeding habits of that insect, and having observed
the eagerness with which they snapped up the little '_midges_,'
I determined to arm my hook with one, and I can assure you I
have had no small degree of sport; and had it not been for your
unwelcome intrusion, I should most undoubtedly have captured one
of them."
"These amusements seemed to become more and more important in his
estimation, as his health declined. It was affecting to observe the
efforts he made to continue them with diminished strength. From
being unable to walk without fatigue for many hours, he was, when
he came to me in November 1826, obliged to have a pony to carry him
to the field, from which he dismounted only on the certainty of
immediate sport. In the following year, he could only take short
and occasional rides to the covers, with his dogs around him, and
his servant walking by his side and carrying his gun, but which I
believe he never fired.
"During this visit, he more than once observed, 'I do not wish to
live, as far as I am personally concerned; but I have views which I
could develope, if it pleased God to save my life, which would be
useful to science and to mankind.'"
Davy returned to town in December, and after an interval wrote the
following letter:
TO THOMAS POOLE, ESQ.
Park Street, Grosvenor Square, Dec. 27, 1827.
MY VERY DEAR FRIEND,
I know no reason why I have not written to you. It has been my
intention every day, and I have been every day prevented by the
sense of want of power, which is so painful a symptom of my
malady.
I continue much as I was. My physicians augur well, and I have
some repose in the hopes connected with the indefinite future.
In the last twelve-month, which I hope is a large portion, on
the whole, of my purgatory expiation for crimes of commission
or omission, the most cheerful, or rather the least miserable,
days that I spent, were a good deal owing to your kindness,
which I shall never forget. I would, if it were possible, make
my letter something more than a mere bulletin of health, or the
expression of the feelings of a sick man; but I can communicate
no news. The papers will tell you more than is true; and our
politicians seem ignorant of what they are to do at home, much
more abroad.
* * * * *
I have got for you a copy of my lectures on the Chemistry
of Agriculture, which I shall send to you by the first
opportunity. God bless you, my dear Poole.
I am always your sincere,
Grateful, and affectionate friend,
H. DAVY.
In the letter which follows, Davy dwells upon a subject in Natural
History, which appears to have greatly occupied his thoughts, and
to have continued a predominant subject of his contemplation, even
to the latest day of his life.
TO THOMAS POOLE, ESQ.
Park Street, January 1, 1828.
MY DEAR FRIEND,
I write to you immediately, because that part of your letter
which relates to Mr. Baker's pursuits interests me very much:
but before I begin on this subject, I will give you a short
bulletin of the state of my health. I go on much as I did at
Stowey, and my physicians have made no alterations in the plan
of treatment: I am not worse, and they tell me I shall be
better. Now for Mr. Baker--I am very glad that he is occupied
with those enquiries. I am particularly anxious for information
on the generation of eels; it is an unsolved problem since
the time of Aristotle. I am sure that all eels come from the
sea, where they are bred; but there may be one or two species
or varieties of them. What Mr. Baker says about the difference
between the common eel and the conger is well worthy of
attention; but I have known changes more extraordinary than
the obliteration, or destruction, of a small tubular member
occasioned by difference of habits.
Were the salt-water eels and the fresh-water eels which he
examined of the same size? Many individuals of various sizes
should be examined to establish the fact of their specific
difference. This would be the season for examining the genital
organs of eels, for they breed in winter; and were I a little
better, I should go to the sea for the purpose of making
enquiries on the subject.
Sir Everard Home is firmly convinced that the animal is
hermaphrodite and impregnates itself: this, though possible,
appears to me very strange in so large an animal. If Mr. Baker
will determine this point, I can promise him an immortality
amongst our philosophical anglers and natural historians; and
if he will give us the history of water-flies, imitated by
fly-fishers, he will command our immediate gratitude.
Pray communicate this letter to him with my best wishes, and
with my hopes that his talents, which are very great, will be
applied to enlighten us.
I can give you no news; the weather is dreadful, and the blacks
and yellows are descending in fog. I long for the fresh air of
your mountains.
God bless you, my dear Poole. Many--many happy new years to
you. Pray remember me, with the compliments of this day, to
your excellent neighbours at Stowey. Your affectionate friend,
H. DAVY.
TO THE SAME.
MY DEAR POOLE, Park Street, March 26.
Your letter has given me great pleasure; first, because you,
who are an enlightened judge in such matters, approve of my
humble contribution to agriculture; and, secondly, because it
makes me acquainted with your kind feelings, health, and Mr.
Baker's interesting pursuits.
Mr. Baker appears to me to have distinctly established the
point that the eel and conger are of different species; and
from his zeal and activity, I hope the curious problem of the
generation of these animals will be solved. I shall expect with
impatience the results of his enquiries.
Now for my health, my very dear friend. I wish I could speak
more favourably; I certainly do not lose ground, but I am
doubtful if I gain any; but I do not despair.
I am going, by the advice of my physicians, to try another
Continental journey. If I get considerably better, I shall
winter in Italy, where, in this case, I shall hope to see you,
and where I shall have an apartment ready for you in Rome.
I have not been idle since I left your comfortable and
hospitable house. I have finished my _Salmonia_, and sent it
to the press.--"_Flumina amo sylvasque inglorius._"--I do not
think you will be displeased with this little _jeu_ of my sick
hours.
Mr. A---- was very amiable in calling on me. There is nothing
that annoys me so much in my illness as my helplessness in not
being able to indulge in society.
Your grateful and affectionate friend,
H. DAVY.
We will now, for a while, leave our philosopher to pursue his
journey to Italy, while we take a review of his SALMONIA; the
first edition of which was published in the Spring of 1828. The
second, and much improved edition,[110] from which I shall take my
extracts, is dated from Laybach, Illyria, September 28, 1828, but
which did not appear until 1829.
[110] "Salmonia, or Days of Fly-fishing; in a series
of Conversations; with some account of the habits of
Fishes belonging to the genus Salmo. By an Angler. Second
edition.--London, John Murray, 1829."
We are told in the preface, that these pages formed the occupation
of the author during some months of severe and dangerous illness,
when he was wholly incapable of attending to more useful studies,
or of following more serious pursuits;--that they constituted his
amusement in many hours, which otherwise would have been unoccupied
and tedious;--and that they are published in the hope that they
may possess an interest for those persons who derive pleasure from
the simplest and most attainable kind of rural sports, and who
practise the art, or patronise the objects of contemplation, of the
philosophical angler.
He informs us that the conversational manner and discursive style
were chosen as best suited to the state of health of the author,
who was incapable of considerable efforts and long continued
attention; and he adds, that he could not but have in mind a model,
which has fully proved the utility and popularity of this method of
treating this subject--"The Complete Angler," by Walton and Cotton.
The characters chosen to support these conversations, were HALIEUS,
who is supposed to be an accomplished fly-fisher--ORNITHER, who is
to be regarded as a gentleman generally fond of the sports of the
field, though not a finished master of the art of angling--POIETES,
who is to be considered as an enthusiastic lover of nature, and
partially acquainted with the mysteries of fly-fishing; and
PHYSICUS, who is described uninitiated as an angler, but as a
person fond of enquiries in natural history and philosophy.
Such are the personages by whose aid the machinery is to be
worked; but he tells us that they are of course imaginary, though
the sentiments attributed to them, the author may sometimes have
gained from recollections of real conversations with friends, from
whose society much of the happiness of his early life had been
derived; and he admits that, in the portrait of the character of
HALIEUS, given in the last dialogue, a likeness will not fail to be
recognised to that of the character of a most estimable physician,
ardently beloved by his friends, and esteemed and venerated by the
public.
The work is dedicated to Dr. Babington, "in remembrance of some
delightful days passed in his society, and in gratitude for an
uninterrupted friendship of a quarter of a century."
I am informed by Lady Davy, that the engravings of the fish,
by which the work is illustrated, are from drawings of his own
execution; so that he could not, like old Isaac Walton, "take the
liberty to commend the excellent pictures to him that likes not the
book, because they concern not himself."
It has frequently happened that, while works of deep importance
have justly conferred celebrity upon the author, his minor
productions have been entirely indebted to his name for their
popularity, and to his authority for their value. This, however,
cannot be said of Salmonia, for it possesses the stamp of original
genius, and bears internal evidence of a talent flowing down from
a very high source of intelligence. In a scientific point of view,
it exhibits that penetrating observation by which a gifted mind is
enabled to extract out of the most ordinary facts and every-day
incidents, novel views and hidden truths; while it shows that a
humble art (I beg pardon of the brothers of the Angle) may, through
the skill of the master, be made the means of calling forth the
affections of the heart, and of reflecting all the colours of
the fancy. By regarding the work in relation to the history and
condition of its author, it certainly acquires much additional
interest. The familiar and inviting style of the dialogue, whenever
he discusses questions of natural history, must convince us that he
was as well calculated to instruct in the Lyceum, as we long since
knew him to be to teach in the Academy.
Composed in the hour of sickness and prostration, the work displays
throughout its composition a tone of dignified morality and an
expansion of feeling, which may be regarded as in unison with a
mind chastened but not subdued, and looking forward to a better
state of existence. "I envy," says he, "no quality of the mind
or intellect in others; be it genius, power, wit, or fancy: but
if I could choose what would be most delightful, and I believe
most useful to me, I should prefer a firm religious belief to
every other blessing; for it makes life a discipline of goodness;
creates new hopes, when all earthly hopes vanish; and throws over
the decay, the destruction of existence, the most gorgeous of all
lights; awakens life even in death, and from corruption and decay
calls up beauty and divinity; makes an instrument of torture and
of shame the ladder of ascent to paradise; and, far above all
combinations of earthly hopes, calls up the most delightful visions
of palms and amaranths, the gardens of the blest, the security of
everlasting joys, where the sensualist and the sceptic view only
gloom, decay, annihilation, and despair!"
While describing an animated scene of insect enjoyment, he bursts
into an apostrophe, highly characteristic of that quick and happy
talent for seizing analogies, which so eminently distinguished all
his writings. I shall quote the passage.
"_Physicus._--Since the sun has disappeared, the cool of the
evening has, I suppose, driven the little winged plunderers to
their homes; but see, there are two or three humble bees which seem
languid with the cold, and yet they have their tongues still in
the fountain of honey. I believe one of them is actually dead, yet
his mouth is still attached to the flower. He has fallen asleep,
and probably died whilst making his last meal of ambrosia.
"_Ornither._--What an enviable destiny, quitting life in the moment
of enjoyment, following an instinct, the gratification of which
has been always pleasurable! so beneficent are the laws of Divine
Wisdom.
"_Physicus._--Like Ornither, I consider the destiny of this
insect as desirable, and I cannot help regarding the end of human
life as most happy, when terminated under the impulse of some
strong energetic feeling, similar in its nature to an instinct. I
should not wish to die like Attila, in a moment of gross sensual
enjoyment; but the death of Epaminondas or Nelson, in the arms of
victory, their whole attention absorbed in the love of glory, and
of their country, I think really enviable.
"_Poietes._--I consider the death of the martyr or the saint as
far more enviable; for, in this case, what may be considered as a
Divine instinct of our nature is called into exertion, and pain is
subdued, or destroyed, by a secure faith in the power and mercy of
the Divinity. In such cases, man rises above mortality, and shows
his true intellectual superiority. By intellectual superiority,
I mean that of his spiritual nature, for I do not consider the
results of reason as capable of being compared with those of faith.
Reason is often a dead weight in life, destroying feeling, and
substituting, for principle, calculation and caution; and, in the
hour of death, it often produces fear or despondency, and is rather
a bitter draught than nectar or ambrosia in the last meal of life.
"_Halieus._--I agree with Poietes. The higher and more intense
the feeling under which death takes place, the happier it may be
esteemed; and I think even Physicus will be of our opinion, when
I recollect the conclusion of a conversation in Scotland. The
immortal being never can quit life with so much pleasure as with
the feeling of immortality secure, and the vision of celestial
glory filling the mind, affected by no other passion than the pure
and intense love of God."
We are not to suppose that, however soothing and consolatory such
feelings and hopes may have been, they weaned him from the world,
or diminished his natural love of life; on the contrary, no one
would have more gratefully received the services of a Medea, as
the following passage will sufficiently testify. "Ah! could I
recover any thing like that freshness of mind which I possessed
at twenty-five, and which, like the dew of the dawning morning,
covered all objects and nourished all things that grew, and in
which they were more beautiful even than in midday sunshine,--what
would I not give! All that I have gained in an active and not
unprofitable life. How well I remember that delightful season,
when, full of power, I sought for power in others; and power was
sympathy, and sympathy power;--when the dead and the unknown, the
great of other ages and of distant places were made, by the force
of the imagination, my companions and friends;--when every voice
seemed one of praise and love;--when every flower had the bloom
and odour of the rose; and every spray or plant seemed either the
poet's laurel, or the civic oak--which appeared to offer themselves
as wreaths to adorn my throbbing brow. But, alas! this cannot
be.----"
After the example of the great Patriarch of Anglers, the author
of Salmonia commences, through the assistance of the principal
interlocutor of the dialogue, HALIEUS, to enumerate the delights of
his art, and to vindicate it from the charge of cruelty.
"_Halieus._--The search after food is an instinct belonging to our
nature; and from the savage in his rudest and most primitive state,
who destroys a piece of game, or a fish, with a club or spear, to
man in the most cultivated state of society, who employs artifice,
machinery, and the resources of various other animals, to secure
his object, the origin of the pleasure is similar, and its object
the same: but that kind of it requiring most art may be said to
characterize man in his highest or intellectual state; and the
fisher for salmon and trout with the fly employs not only machinery
to assist his physical powers, but applies sagacity to conquer
difficulties; and the pleasure derived from ingenious resources
and devices, as well as from active pursuit, belongs to this
amusement. Then, as to its philosophical tendency, it is a pursuit
of moral discipline, requiring patience, forbearance, and command
of temper. As connected with natural science, it may be vaunted
as demanding a knowledge of the habits of a considerable tribe of
created beings,--fishes, and the animals that they prey upon, and
an acquaintance with the signs and tokens of the weather, and its
changes, the nature of waters, and of the atmosphere. As to its
poetical relations, it carries us into the most wild and beautiful
scenery of nature; amongst the mountain lakes, and the clear and
lovely streams that gush from the higher ranges of elevated hills,
or that make their way through the cavities of calcareous strata.
How delightful in the early spring, after the dull and tedious
time of winter, when the frosts disappear and the sunshine warms
the earth and waters, to wander forth by some clear stream, to see
the leaf bursting from the purple bud, to scent the odours of the
bank perfumed by the violet, and enamelled, as it were, with the
primrose and the daisy; to wander upon the fresh turf below the
shade of trees, whose bright blossoms are filled with the music of
the bee; and on the surface of the waters to view the gaudy flies
sparkling like animated gems in the sunbeams, whilst the bright and
beautiful trout is watching them from below; to hear the twittering
of the water birds, who, alarmed at your approach, rapidly hide
themselves beneath the flowers and leaves of the water-lily; and,
as the season advances, to find all these objects changed for
others of the same kind, but better and brighter, till the swallow
and the trout contend, as it were, for the gaudy Mayfly, and till,
in pursuing your amusement in the calm and balmy evening, you
are serenaded by the songs of the cheerful thrush and melodious
nightingale, performing the offices of paternal love, in thickets
ornamented with the rose and woodbine."
On vindicating the pursuit from the charge of cruelty, he has
advanced an argument that has not been commonly adduced upon this
occasion. We have indeed all heard, that the operation of skinning
is a matter of indifference to eels when they are used to it; but
we are now told fish are so little annoyed by the hook, that though
a trout has been hooked and played with for some minutes, he will
often, after his escape with the artificial fly in his mouth,
take the natural fly, and feed as if nothing had happened; having
apparently learnt only from the experiment, that the artificial fly
is not proper food. "I have caught pikes with four or five hooks in
their mouths, and tackle which they had broken only a few minutes
before; and the hooks seemed to have had no other effect than that
of serving as a sort of _sauce piquante_, urging them to seize
another morsel of the same kind."
Our author, however, takes a more special defence, by observing
that, unlike old Isaac, he employs an artificial fly, instead of
a living bait. Our notions about the cruelty of field sports is
extremely capricious. Until the time of the Reformation, the canon
law prohibited the use of the sanguinary recreations of hunting,
hawking, and fowling, while the clergy, on account of their
leisure, were allowed to exercise the harmless and humane art of
angling. In later days, the indignation against this art has been
excited by the supposed sufferings of the worm or bait, rather than
by those of the fish; and thus far the author of Salmonia assumed
a strong posture of defence; but he did not avail himself of all
the advantages it commanded. He might have pleaded, that every
fish he caught by his artificial fly was destined to prey upon an
insect, and that by substituting a piece of silk for the latter,
he would for every fish he might destroy, save from destruction
many of those fairy beings that animate the air and sparkle in the
sunbeam;--but it is, after all, folly to argue upon the subject of
cruelty in our field sports. That animals should live by preying
upon each other is the very basis of the scheme of creation; and
in these days it is not necessary to expose the absurdities of the
system of Samos and Indostan. Dr. Franklin, at one period of his
life, entertained a sentimental abhorrence at eating any thing that
had possessed life; and the reader may, perhaps, not object to be
reminded of the manner in which he was cured of his prejudice.
"I considered," says he, "the capture of every fish as a sort of
murder, committed without provocation, since these animals had
neither done, nor were capable of doing, the smallest injury to
any one that should justify the measure. This mode of reasoning
I conceived to be unanswerable. Meanwhile, I had formerly been
extremely fond of fish; and when one of the cod was taken out of
the frying-pan, I thought its flavour delicious. I hesitated some
time between principle and inclination, till at last recollecting
that, when the cod had been opened, some small fish were found
in its belly, I said to myself, 'If you eat each other, I see no
reason why we may not eat you,'--(His "wish was father to that
thought")--I accordingly dined on the cod with no small degree of
pleasure, and have since continued to eat like the rest of mankind."
HALIEUS is made to admit the danger of analysing too closely
the moral character of any of our field sports; and yet, in the
concluding chapter, he very unfairly and inconsistently attempts
to ridicule the pursuit of a fox-hunter, "risking his neck to see
the hounds destroy an animal which he preserves to be destroyed,
and which is good for nothing." He who pursues a pleasure because
it is rational, reasons because he cannot feel. "When the heart,"
says Sterne, "flies out before the understanding, it saves the
judgment a world of pains."
Having, as the author thinks satisfactorily, settled the
preliminary questions, HALIEUS, succeeds in persuading PHYSICUS to
join him in fishing excursions; just as _Piscator_ is represented
by old Isaac, as having enlisted _Venator_ into the brotherhood of
the angle.
The dialogue now proceeds with great animation, during which the
art and mystery of Piscatory tactics are unfolded with great skill;
for the details of which the reader must be referred to the work
itself. If, however, he be not already an angler, it may save him
a world of pains to be informed, that to learn to fish by the book
is little less absurd than "to make hay by the fair days in the
almanack."
The manner in which he treats the various subjects of natural
history necessarily connected with the pursuit is both amusing and
instructive; and the whole work is studded and gemmed, as it were,
with the most poetical descriptions.
In speaking of the swallow, _Poietes_ exclaims--"I delight in this
living landscape! The swallow is one of my favourite birds, and a
rival of the nightingale; for he cheers my sense of seeing as much
as the other does my sense of hearing. He is the glad prophet of
the year, the harbinger of the best season: he lives a life of
enjoyment amongst the loveliest forms of nature: winter is unknown
to him; and he leaves the green meadows of England in autumn, for
the myrtle and orange groves of Italy, and for the palms of Africa:
he has always objects of pursuit, and his success is secure.
Even the beings selected for his prey are poetical, beautiful,
and transient. The ephemeræ are saved by his means from a slow
and lingering death in the evening, and killed in a moment, when
they have known nothing of life but pleasure. He is the constant
destroyer of insects--the friend of man; and, with the stork and
the ibis, may be regarded as a sacred bird. His instinct, which
gives him his appointed seasons, and teaches him always when and
where to move, may be regarded as flowing from a divine source;
and he belongs to the oracles of Nature, which speak the awful and
intelligible language of a present Deity."
_Poietes_ considers a full and clear river as the most poetical
object in Nature.--"I will not fail to obey your summons. Pliny
has, as well as I recollect, compared a river to human life.
I have never read the passage in his works; but I have been a
hundred times struck with the analogy, particularly amidst mountain
scenery. The river, small and clear in its origin, gushes forth
from rocks, falls into deep glens, and wantons and meanders through
a wild and picturesque country, nourishing only the uncultivated
tree or flower by its dew or spray. In this, its state of infancy
and youth, it may be compared to the human mind, in which fancy and
strength of imagination are predominant--it is more beautiful than
useful. When the different rills or torrents join, and descend
into the plain, it becomes slow and stately in its motions; it is
applied to move machinery, to irrigate meadows, and to bear upon
its bosom the stately barge;--in this mature state it is deep,
strong, and useful. As it flows on towards the sea, it loses its
force and its motion, and at last, as it were, becomes lost, and
mingled with the mighty abyss of waters."
_Halieus_ adds--"One might pursue the metaphor still farther, and
say, that in its origin--its thundering and foam, when it carries
down clay from the bank, and becomes impure, it resembles the
youthful mind, affected by dangerous passions. And the influence
of a lake, in calming and clearing the turbid water, may be
compared to the effect of reason in more mature life, when the
tranquil, deep, cool, and unimpassioned mind is freed from its
fever, its troubles, bubbles, noise, and foam. And, above all,
the sources of a river--which may be considered as belonging to
the atmosphere--and its termination in the ocean, may be regarded
as imaging the divine origin of the human mind, and its being
ultimately returned to, and lost in, the infinite and eternal
Intelligence from which it originally sprang."
_Halieus_ offers some curious observations with respect to the
recollection of fish being associated with surrounding objects.
"I have known a fish that I have pricked retain his station in the
river, and refuse the artificial fly, day after day, for weeks
together; but his memory may have been kept awake by this practice,
and the recollection seems local, and associated with surrounding
objects; and if a pricked trout is chased into another pool, he
will, I believe, soon again take the artificial fly. Or, if the
objects around him are changed, as in autumn, by the decay of
weeds, or by their being cut, the same thing happens; and a flood
or a rough wind, I believe, assists the fly-fisher, not merely by
obscuring the vision of the fish, but, in a river much fished, by
changing the appearance of their haunts: large trouts almost always
occupy particular stations, under, or close to, a large stone
or tree; and probably, most of their recollected sensations are
connected with this dwelling.
"_Physicus._--I think I understand you, that the memory of the
danger and pain does not last long, unless there is a permanent
sensation with which it can remain associated,--such as the station
of the trout; and that the recollection of the mere form of the
artificial fly, without this association, is evanescent.
"_Ornither._--You are diving into metaphysics; yet, I think, in
fowling, I have observed that the memory of birds is local. A
woodcock that has been much shot at and scared in a particular
wood, runs to the side where he has usually escaped, the moment he
hears the dogs; but if driven into a new wood, he seems to lose his
acquired habits of caution, and becomes stupid."
In alluding to the migrations of fishes, _Physicus_ observes, "That
he has always considered that the two great sources of change
of place of animals, was the providing of food for themselves,
and resting-places and food for their young. The great supposed
migrations of herrings from the poles to the temperate zone appear
to be only the approach of successive shoals from deep to shallow
water, for the purpose of spawning. The migrations of salmon and
trout are evidently for the purpose of depositing their ova, or of
finding food after they have spawned."
In explaining the circumstances which render a migration into
shallow water necessary for the developement of the ova,
Davy evidently bears in mind the result of his very first
experiment.[111]
[111] Vol. i. page 40.
"Carp, perch, and pike, deposit their ova in still water, in
spring and summer, _when it is supplied with air by the growth
of vegetables; and it is to the leaves of plants, which afford a
continual supply of oxygen to the water, that the impregnated eggs
usually adhere_." Again: "Fish in spawning-time always approach
great shallows, or shores covered with weeds, _which, in the
process of their growth, under the influence of the sunshine,
constantly supply pure air to the water in contact with them_."
The following passage will afford a good specimen of the familiar
dialogue, while it will convey to the reader some curious facts
connected with the influence of sunshine.
"_Halieus._--Well, gentlemen, what sport?
"_Poietes._--The fish are rising every where; but though we have
been throwing over them with all our skill for a quarter of an
hour, yet not a single one will take; and I am afraid we shall
return to breakfast without our prey.
"_Halieus._--I will try; but I shall go to the other side, where
I see a very large fish rising--There!--I have him at the very
first throw--Land this fish, and put him into the well. Now, I have
another; and I have no doubt I could take half-a-dozen in this very
place, where you have been so long in fishing without success.
"_Physicus._--You must have a different fly; or, have you some
unguent or charm to tempt the fish?
"_Halieus._--No such thing. If any of you will give me your rod and
fly, I will answer for it. I shall have the same success. I take
your rod, Physicus--and lo! I have a fish!
"_Physicus._--What can be the reason of this? It is perfectly
inexplicable to me. Yet Poietes seems to throw as light as you do,
and as well as he did yesterday.
"_Halieus._--I am surprised that you, who are a philosopher, cannot
discover the reason of this--Think a little.
"_All._--We cannot.
"_Halieus._--As you are my scholars, I believe I must teach you.
The sun is bright, and you have been, naturally enough, fishing
with your backs to the sun, which, not being very high, has thrown
the shadows of your rods and yourselves upon the water, and you
have alarmed the fish, wherever you have thrown a fly. You see, I
have fished with my face towards the sun, and though inconvenienced
by the light, have given no alarm. Follow my example, and you will
soon have sport, as there is a breeze playing on the water.
"_Physicus._--Your sagacity puts me in mind of an anecdote which
I remember to have heard respecting the late eloquent statesman,
Charles James Fox; who, walking up Bond Street from one of the
club-houses with an illustrious personage, laid him a wager, that
he would see more cats than the Prince in his walk, and that he
might take which side of the way he liked. When they got to the
top, it was found, that Mr. Fox had seen thirteen cats, and the
Prince not one. The Royal personage asked for an explanation of
this apparent miracle, and Mr. Fox said, 'Your Royal Highness took,
of course, the shady side of the way, as most agreeable; I knew
that the sunny side would be left to me,--and cats always prefer
the sunshine.'
"_Halieus._--There! Poietes, by following my advice, you have
immediately hooked a fish; and while you are catching a brace, I
will tell you an anecdote, which as much relates to fly-fishing as
that of Physicus, and affords an elucidation of a particular effect
of light.
"A manufacturer of carmine, who was aware of the superiority of
the French colour, went to Lyons for the purpose of improving his
process, and bargained with the most celebrated manufacturer in
that capital for the acquisition of his secret, for which he was
to pay a thousand pounds. He was shown all the processes, and saw
a beautiful colour produced, yet he found not the least difference
in the French mode of fabrication and that which he had constantly
adopted. He appealed to the manufacturer, and insisted that he
must have concealed something. The manufacturer assured him that
he had not, and invited him to see the process a second time.
He minutely examined the water and the materials, which were the
same as his own, and, very much surprised, said, 'I have lost my
labour and my money, for the air of England does not permit us to
make good carmine.'--'Stay,' says the Frenchman, 'do not deceive
yourself; what kind of weather is it now?'--'A bright, sunny day,'
said the Englishman.--'And such are the days,' said the Frenchman,
'on which I make my colour. Were I to attempt to manufacture it on
a dark or cloudy day, my result would be the same as yours. Let me
advise you, my friend, always to make carmine on bright and sunny
days.'--'I will,' says the Englishman, 'but I fear I shall make
very little in London.'
"_Poietes._--Your anecdote is as much to the purpose as Physicus's;
yet I am much obliged to you for the hint respecting the effect of
shadow, for I have several times, in May and June, had to complain
of too clear a sky, and wished, with Cotton, for
'A day with not too bright a beam;
A warm, but not a scorching sun.'"
A very amusing and philosophical conversation on those natural
phenomena, which have been vulgarly viewed as prophetic of dry or
wet weather, may be well adduced as illustrative of that genius
which, by the aid of a light of its own, imparts to the most trite
objects all the charms of novelty.
"_Poietes._--I hope we shall have another good day to-morrow, for
the clouds are red in the west.
"_Physicus._--I have no doubt of it, for the red has a tint of
purple.
"_Halieus._--Do you know why this tint portends fine weather?
"_Physicus._--The air when dry, I believe, refracts more red, or
heat-making rays; and as dry air is not perfectly transparent, they
are again reflected in the horizon. I have generally observed a
coppery or yellow sunset to foretell rain; but, as an indication of
wet weather approaching, nothing is more certain than a halo round
the moon, which is produced by the precipitated water; and the
larger the circle, the nearer the clouds, and consequently the more
ready to fall.
"_Halieus._--I have often observed, that the old proverb is
correct--
'A rainbow in the morning is the shepherd's warning;
A rainbow at night is the shepherd's delight.'
--Can you explain this omen?
"_Physicus._--A rainbow can only occur when the clouds containing
or depositing the rain are opposite to the sun; and in the evening
the rainbow is in the east, and in the morning in the west; and as
our heavy rains in this climate are usually brought by the westerly
wind, a rainbow in the west indicates that the bad weather is on
the road, by the wind, to us; whereas the rainbow in the east
proves, that the rain in these clouds is passing from us.
"_Poietes._--I have often observed, that when the swallows fly
high, fine weather is to be expected or continued; but when they
fly low and close to the ground, rain is almost surely approaching.
Can you account for this?
"_Halieus._--Swallows follow the flies and gnats, and flies and
gnats usually delight in warm strata of air; and as warm air is
lighter, and usually moister than cold air, when the warm strata of
air are high, there is less chance of moisture being thrown down
from them by the mixture with cold air; but when the warm and moist
air is close to the surface, it is almost certain, that as the cold
air flows down into it, a deposition of water will take place.
"_Poietes._--I have often seen sea-gulls assemble on the land, and
have almost always observed, that very stormy and rainy weather was
approaching. I conclude that these animals, sensible of a current
of air approaching from the ocean, retire to the land to shelter
themselves from the storm.
"_Ornither._--No such thing. The storm is their element; and the
little petrel enjoys the heaviest gale; because, living on the
smaller sea insects, he is sure to find his food in the spray
of a heavy wave. And you may see him flitting above the edge of
the highest surge. I believe that the reason of the migration of
sea-gulls and other sea birds to the land, is their security of
finding food. They may be observed, at this time, feeding greedily
on the earth worms and larvæ driven out of the ground by severe
floods; and the fish on which they prey in fine weather in the sea,
leave the surface when storms prevail, and go deeper. The search
after food, as we agreed on a former occasion, is the principal
cause why animals change their places. The different tribes of
the wading birds always migrate when rain is about to take place;
and I remember once in Italy having been long waiting, in the end
of March, for the arrival of the double snipe in the Campagna of
Rome: a great flight appeared on the 3rd of April, and the day
after heavy rain set in, which greatly interfered with my sport.
The vulture, upon the same principle, follows armies; and I have
no doubt, that the augury of the ancients was a good deal founded
upon the observation of the instincts of birds. There are many
superstitions of the vulgar owing to the same source. For anglers,
in spring, it is always unlucky to see _single_ magpies; but _two_
may be always regarded as a favourable omen; and the reason is,
that in cold and stormy weather, one magpie alone leaves the nest
in search of food, the other remaining sitting upon the eggs or the
young ones; but when two go out together, the weather is warm and
mild, and thus favourable for fishing.
"_Poietes._--The singular connexions of cause and effect, to which
you have just referred, make superstition less to be wondered at,
particularly amongst the vulgar; and when two facts, naturally
unconnected, have been accidentally coincident, it is not singular
that this coincidence should have been observed and registered, and
that omens of the most absurd kind should be trusted in. In the
West of England, half a century ago, a particular hollow noise on
the sea-coast was referred to a spirit or goblin, called Bucca, and
was supposed to foretell a shipwreck; the philosopher knows, that
sound travels much faster than currents in the air--and the sound
always foretold the approach of a very heavy storm, which seldom
takes place on that wild and rocky coast, surrounded as it is by
the Atlantic, without a shipwreck on some part of its extensive
shores.[112]
[112] Davy might also have adduced an equally striking
superstition, in illustration of his subject, from the Cornish
mines. The miners not unfrequently hear the echo of their own
pickaxes, which they attribute to little fairies at work, and
consider it as a happy omen. They say upon such occasions, that
there will be good luck, as the Piskeys are at work. It is well
known that the echo depends upon some cavity in the vicinity of
the workmen,--and a cavity, or vogue, is always an indication of
subterranean wealth.
"_Physicus._--All the instances of omens you have mentioned are
founded on reason; but how can you explain such absurdities as
Friday being an unlucky day, the terror of spilling salt, or
meeting an old woman? I knew a man of very high dignity, who
was exceedingly moved by these omens, and who never went out
shooting without a bittern's claw fastened to his button-hole by a
riband--which he thought ensured him good luck.
"_Poietes._--These, as well as the omens of deathwatches,
dreams, &c. are for the most part founded upon some accidental
coincidences; but spilling of salt, on an uncommon occasion, may,
as I have known it, arise from a disposition to apoplexy, shown by
an incipient numbness in the hand, and may be a fatal symptom; and
persons dispirited by bad omens sometimes prepare the way for evil
fortune; for confidence in success is a great means of insuring
it. The dream of Brutus, before the field of Philippi, probably
produced a species of irresolution and despondency, which was the
principal cause of his losing the battle; and I have heard, that
the illustrious sportsman, to whom you referred just now, was
always observed to shoot ill, because he shot carelessly, after one
of his dispiriting omens.
"_Halieus._--I have in life met with a few things which I found
it impossible to explain, either by chance, coincidences, or by
natural connexions; and I have known minds of a very superior class
affected by them,--persons in the habit of reasoning deeply and
profoundly.
"_Physicus._--In my opinion, profound minds are the most likely to
think lightly of the resources of human reason; it is the pert,
superficial thinker who is generally strongest in every kind of
unbelief. The deep philosopher sees chains of causes and effects
so wonderfully and strangely linked together, that he is usually
the last person to decide upon the impossibility of any two series
of events being independent of each other; and in science, so many
natural miracles, as it were, have been brought to light,--such as
the fall of stones from meteors in the atmosphere, the disarming a
thunder-cloud by a metallic point, the production of fire from ice
by a metal white as silver, and referring certain laws of motion of
the sea to the moon,--that the physical enquirer is seldom disposed
to assert, confidently, on any abstruse subjects belonging to the
order of natural things, and still less so on those relating to the
more mysterious relations of moral events and intellectual natures."
Old Isaac Walton has amused us with a variety of absurd fables
and superstitions: the author of Salmonia, on the other hand,
touches, as with the spear of Ithuriel, the monsters and prodigies
of the older writers, and they at once assume the forms of
well-ascertained animals, or vegetables. The _sea snake_ seen by
American and Norwegian captains, appears as a company of porpoises,
which in their gambols, by rising and sinking in lines, would give
somewhat the appearance of the coils of a snake. The _Kraken_, or
island fish, is reduced into an assemblage of _urticæ marinæ_, or
sea blubbers. The _Mermaid_, into the long-haired seal;[113] and
lastly, the celebrated Caithness Mermaid assumes the unpoetical
form of a stout young traveller;--but this story is far too amusing
to be dismissed with a passing notice.
[113] A pretended Mermaid was exhibited some time since in
London, said to have been caught in the Chinese seas. It was soon
discovered to have been manufactured by joining together the head
and bust of two different apes to the lower part of a kipper
salmon, which had the fleshy fin, and all the distinct characters
of the _Salmo Salar_.
"A worthy Baronet, remarkable for his benevolent views and active
spirit, has propagated a story of this kind, and he seems to claim
for his native country the honour of possessing this extraordinary
animal; but the mermaid of Caithness was certainly a _gentleman_,
who happened to be travelling on that wild shore, and who was
seen bathing by some young ladies at so great a distance, that
not only _genus_ but gender was mistaken. I am acquainted with
him, and have had the story from his own mouth. He is a young man,
fond of geological pursuits, and one day in the middle of August,
having fatigued and heated himself by climbing a rock to examine
a particular appearance of granite, he gave his clothes to his
Highland guide, who was taking care of his pony, and descended
to the sea. The sun was just setting, and he amused himself for
some time by swimming from rock to rock, and having unclipped hair
and no cap, he sometimes threw aside his locks, and wrung the
water from them on the rocks. He happened the year after to be at
Harrowgate, and was sitting at table with two young ladies from
Caithness, who were relating to a wondering audience the story of
the mermaid they had seen, which had already been published in the
newspapers: they described her, as she usually is described by
poets, as a beautiful animal with remarkably fair skin and long
green hair. The young gentleman took the liberty, as most of the
rest of the company did, to put a few questions to the elder of
the two ladies,--such as, on what day and precisely where this
singular phenomenon had appeared. She had noted down not merely
the day, but the hour and minute, and produced a map of the place.
Our bather referred to his journal, and showed that a human animal
was swimming in the very spot at that very time, who had some of
the characters ascribed to the mermaid, but who laid no claim to
others, particularly the green hair and fish's tail, but, being
rather sallow in the face, was glad to have such testimony to the
colour of his body beneath his garments."
With this story, I must conclude my review of "Salmonia,"--a work
of considerable scientific and popular interest, and which cannot
fail to become the favourite companion of the philosophical angler.
The only production with which it can be at all compared is that
of the "Complete Angler, by Izaac Walton." I agree with the critic
who regards the two authors as pilgrims bound for the same shrine,
resembling each other in their general habit--the scalloped hat,
the dalmatique, and the knobbed and spiked staff--which equalize
all who assume the character; yet, though alike in purpose, dress,
and demeanour, the observant eye can doubtless discern an essential
difference betwixt those devotees. The burgess does not make his
approach to the shrine with the stately pace of a knight or a
noble; the simple and uninformed rustic has not the contemplative
step of the philosopher, or the quick glance of the poet. The palm
of originality and of exquisite simplicity, which cannot perhaps be
imitated with entire success, must remain with the common father
of anglers--the patriarch Izaac; but it would be absurd to compare
his work with the one written by the most distinguished philosopher
of the nineteenth century, whose genius, like a sunbeam, illumined
every recess which it penetrated, imparting to scarcely visible
objects, definite forms and various colours.
If the advanced age of Walton was pleaded by himself as a
sufficient reason for procuring "_a writ of ease_," the friends
of Davy may surely claim at the hands of the critic an indulgent
reception for a congenial work written in the hour of bodily
lassitude and sickness. This benevolent feeling, however, did
not penetrate every heart. A passage, which I shall presently
quote, appears to have given great offence to the President of the
Mechanics' Institute, and to have been considered by him as the
indication of a covert hostility to the spread of knowledge. The
earth had scarcely closed upon the remains of the philosopher,
when, in his anniversary speech,[114] the Autocrat of all the
Mechanics, availing himself of this pretext, assailed his character
with the charge of "conceit, pride, and arrogance."
[114] See a Report of the President's speech, at the sixth
anniversary of the Mechanics' Institute, as reported in all the
journals of the day, December 5, 1829.
The following is the passage in Salmonia, which provoked this angry
and unjust philippic.
"I am sorry to say, I think the system carried too far in England.
God forbid, that any useful light should be extinguished! let the
persons who wish for education receive it; but it appears to me
that, in the great cities in England, it is, as it were, forced
upon the population; and that sciences, which the lower classes
can only very superficially acquire, are presented to them; in
consequence of which they often become idle and conceited, and
above their usual laborious occupations. The unripe fruit of
the tree of knowledge is, I believe, always bitter or sour; and
scepticism and discontentment--sicknesses of the mind--are often
the result of devouring it."
Methinks I hear the reader exclaim--"How little could Davy imagine
that his prophetic words would have been so soon fulfilled!"--But
I would seriously recommend to the President of the Mechanics'
Institute, an anecdote which, if properly applied, cannot fail to
be instructive.--When Diogenes, trampling with his dirty feet on
the embroidered couch of Plato, cried out--"_Thus do I trample
on the pride of Plato!_" the philosopher shook his head, and
replied--"_Truly, but with more pride thou dost it, good Diogenes._"
CHAPTER XV.
Sir H. Davy's paper on the Phenomena of Volcanoes.--His
experiments on Vesuvius.--Theory of Volcanic action.--His
reception abroad.--Anecdotes.--His last letter to Mr.
Poole from Rome.--His paper on the Electricity of the
Torpedo.--Consolations in Travel, or the Last Days of a
Philosopher.--Analysis of the work.--Reflections suggested by
its style and composition.--Davy and Wollaston compared.--His
last illness.--Arrival at Geneva.--HIS DEATH.
A short time before Sir Humphry Davy quitted England, to which he
was destined never to return, he communicated to the Royal Society
a paper "On the Phenomena of Volcanoes;" which was read on the 20th
of March 1828, and published in the Transactions of that year.
The object of this memoir was to collect and record the various
observations and experiments which he had made on Vesuvius,
during his several visits to that volcano. The appearances which
it presented in 1814 and 1815 have been already noticed; it was
in December 1819, and during the two succeeding months, that
the mountain offered a favourable opportunity for making those
experiments which form the principal subject of the present
communication.
It was a point of great importance to determine whether any
combustion was going on at the moment the lava issued from the
mountain; for this fact being once discovered, and the nature of
the combustible matter ascertained, we should gain an immense step
towards a just theory of the sources of volcanic action. For this
purpose, he carefully examined both the lava and the elastic fluids
with which it was accompanied. He was unable, however, to detect
any thing like deflagration with nitre, which must have taken place
had the smallest quantity of carbonaceous matter been present; nor
could he, by exposing the ignited mass to portions of atmospheric
air, discover that any appreciable quantity of oxygen had been
absorbed. On immersing fused lava in water, no decomposition of
that fluid followed, so that there could not have existed any
quantity of the metallic bases of the alkalies or earths. Common
salt, chloride of iron, the sulphates and muriates of potash, and
soda, generally constituted the mass of solid products; while
steam, muriatic acid fumes, and occasionally sulphurous acid
vapours, formed the principal elastic matters disengaged.
He informs us it was on the 26th of January 1820, that he had the
honour to accompany his Royal Highness the Prince of Denmark in an
excursion to the mountain, on which occasion his friend, Cavalier
Monticelli, was also present. At this time, the lava was seen
nearly white hot through a chasm near the place where it flowed
from the mountain; and yet, although he threw nitre upon it in
large quantities through this chasm, there was no more increase
of ignition than when the experiment was made on lava exposed to
the free air. He observed that the appearance of the sublimations
was very different from that which they had presented on former
occasions; those near the aperture were coloured green and blue
by salt of copper; but there was, as usual, a great quantity of
muriate of iron. On the 5th, the sublimate of the lava was pure
chloride of sodium; in the sublimate of January 6th, there were
both sulphate of soda and indications of sulphate of potash; but in
those which he collected during this last visit, the sulphate of
soda was in much larger quantities, and there was much more of a
salt of potash.
For nearly three months the craters, of which there were two, were
in activity. The larger one threw up showers of ignited ashes and
stones to a height apparently of from two hundred to two hundred
and fifty feet; and from the smaller crater steam arose with great
violence. Whenever the crater could be approached, it was found
incrusted with saline matter: and the walk to the edge of the small
crater, on the 6th of January, was through a mass of loose saline
matter, principally common salt coloured by muriate of iron, in
which the foot sunk to some depth. It was easy, even at a great
distance, to distinguish between the steam disengaged by one of the
craters, and the earthy matter thrown up by the other. The steam
appeared white in the day, and formed perfectly white clouds, which
reflected the morning and evening light of the purest tints of red
and orange. The earthy matter always appeared as a black smoke,
forming dark clouds, and in the night it was highly luminous at the
moment of the explosion.
He concludes this paper on Volcanoes with some observations on
the theory of their phenomena. "It appears," says he, "almost
demonstrable, that none of the chemical causes anciently assigned
for volcanic fires can be true. Amongst these, the combustion
of mineral coal is one of the most current; but it seems wholly
inadequate to account for the phenomena. However large the stratum
of pit-coal, its combustion under the surface could never produce
violent and excessive heat; for the production of carbonic
acid gas, when there was no free circulation of air, must tend
constantly to impede the process: and it is scarcely possible
that carbonaceous matter, if such a cause existed, should not be
found in the lava, and be disengaged with the saline or aqueous
products from the bocca or craters. There are many instances in
England of strata of mineral coal which have been long burning; but
the results have been merely baked clay and schists, and it has
produced no result similar to lava.
"If the idea of Lemery were correct, that the action of sulphur on
iron may be a cause of volcanic fires, sulphate of iron ought to
be the great product of the volcano; which is known not to be the
case; and the heat produced by the action of sulphur on the common
metals is quite inadequate to account for the appearances. When
it is considered that volcanic fires occur and intermit with all
the phenomena that indicate intense chemical action, it seems not
unreasonable to refer them to chemical causes. But for phenomena
upon such a scale, an immense mass of matter must be in activity,
and the products of the volcano ought to give an idea of the
nature of the substances primarily active. Now, what are these
products? Mixtures of the earths in an oxidated and fused state,
and intensely ignited; water and saline substances, such as might
be furnished by the sea and air, altered in such a manner as might
be expected from the formation of fixed oxidated matter. But it may
be said, if the oxidation of the metals of the earths be the causes
of the phenomena, some of these substances ought occasionally to
be found in the lava, or the combustion ought to be increased
at the moment the materials passed into the atmosphere. But the
reply to this objection is, that it is evident that the changes
which occasion volcanic fires take place in immense subterranean
cavities; and that the access of air to the acting substances
occurs long before they reach the exterior surface.
"There is no question but that the ground under the solfaterra
is hollow; and there is scarcely any reason to doubt of a
subterraneous communication between this crater and that of
Vesuvius: whenever Vesuvius is in an active state, the solfaterra
is comparatively tranquil. I examined the bocca of the solfaterra
on the 21st of February 1820, two days before the activity of
Vesuvius was at its height: the columns of steam which usually
arise in large quantities when Vesuvius is tranquil, were now
scarcely visible, and a piece of paper thrown into the aperture
did not rise again; so that there was every reason to suppose
the existence of a descending current of air. The subterraneous
thunder heard at such great distances under Vesuvius is almost a
demonstration of the existence of great cavities below filled with
aëriform matter: and the same excavations which, in the active
state of the volcano, throw out, during so great a length of time,
immense volumes of steam, must, there is every reason to believe,
in its quiet state, become filled with atmospheric air.[115]
[115] "Vesuvius is a mountain admirably fitted, from its form and
situation, for experiments on the effect of its attraction on
the pendulum: and it would be easy in this way to determine the
problem of its cavities. On Etna the problem might be solved on a
larger scale."
"To what extent subterraneous cavities may exist, even in common
rocks, is shown in the limestone caverns of Carniola, some of
which contain many hundred thousand cubical feet of air; and in
proportion as the depth of an excavation is greater, so is the air
more fit for combustion.
"The same circumstances which would give alloys of the metals of
the earths the power of producing volcanic phenomena, namely, their
extreme facility of oxidation, must likewise prevent them from
ever being found in a pure combustible state in the products of
volcanic eruptions; for before they reach the external surface,
they must not only be exposed to the air in the subterranean
cavities, but be propelled by steam; which must possess, under the
circumstances, at least the same facility of oxidating them as
air. Assuming the hypothesis of the existence of such alloys of
the metals of the earths as may burn into lava in the interior,
the whole phenomena may be easily explained from the action of the
water of the sea and air on those metals; nor is there any fact, or
any of the circumstances which I have mentioned in the preceding
part of this paper, which cannot be easily explained according to
that hypothesis. For almost all the volcanoes in the old world of
considerable magnitude are near, or at no considerable distance
from the sea: and if it be assumed that the first eruptions are
produced by the action of sea-water upon the metals of the earths,
and that considerable cavities are left by the oxidated metals
thrown out as lava, the results of their action are such as might
be anticipated; for, after the first eruptions, the oxidations
which produce the subsequent ones may take place in the caverns
below the surface; and when the sea is distant, as in the volcanoes
of South America, they may be supplied with water from great
subterranean lakes, as Humboldt states that some of them throw up
quantities of fish.
"On the hypothesis of a chemical cause for volcanic fires, and
reasoning from known facts, there appears to me no other adequate
source than the oxidation of the metals which form the bases of the
earths and alkalies; but it must not be denied, that considerations
derived from thermometrical experiments on the temperature of mines
and of sources of hot water, render it probable that the interior
of the globe possesses a very high temperature: and the hypothesis
of the nucleus of the globe being composed of fluid matter offers a
still more simple solution of the phenomena of volcanic fires than
that which has been just developed."
It must be admitted that the concluding sentence of this memoir
is rather equivocal. He states that the metalloidal theory of
volcanoes is most chemical, but that the hypothesis which assumes
the high temperature of the interior of the globe is the most
simple; but he leaves us in doubt as to his own belief upon the
subject. In his "Last Days," however, we shall find that he offers
a less reserved opinion upon this question.
* * * * *
With respect to Sir Humphry Davy's last journey to Rome, I have
nothing of particular interest to relate. Universally known
and respected, a member of almost every scientific society in
Europe, there was not a part of the Continent in which he felt
as a stranger in a foreign land. I might, in addition to the
circumstances which have been already mentioned, relate several
anecdotes in proof of the widely-extended popularity which
his genius and discoveries had secured for him. The following
striking incidents deserve particular notice.--Whilst sporting
in Austria, he was assaulted by some peasants; and the outrage
was no sooner made known to the Emperor, than he expressed his
sorrow and indignation in the strongest language, and immediately
directed that a party of troops should surround the district, and
a most rigorous search be made for the culprits. The search was
of course successful, and the "Carinthian boors" received merited
chastisement.
For the following anecdote I am indebted to Lady Davy. Her Ladyship
was travelling alone, on account of ill health, and upon arriving
at Basle, she naturally felt a strong desire to visit its far-famed
library; it so happened, however, that Sunday was the only day
which afforded her this opportunity, and so strictly is the sabbath
observed at that place, that she was at once informed that an
admission to the library, under any circumstances, was altogether
impossible. She nevertheless addressed a note to the librarian,
stating to him her name, and the reasons for her unusual request.
He immediately returned an answer, and appointed the hour of ten
for her visit. Having shown her all that deserved inspection, he
concluded his attentions by saying, "Madam, I have held the keys
of this library for thirty years, during which period only three
persons have been admitted to see its treasures on the Sunday;
two of these were crowned heads, the third the wife of the most
celebrated philosopher in Europe."
The following is the last letter which Davy ever wrote to his
much-valued friend Mr. Poole.--
TO THOMAS POOLE, ESQ.
MY DEAR POOLE, Rome, Feb. 6, 1829.
I have not written to you during my absence from England,
because I had no satisfactory account of any marked progress
towards health to give you, and the feelings of an invalid are
painful enough for himself, and should, I think, never form a
part of his correspondence; for they are not diminished by the
conviction that they are felt by others. Would I were better! I
would then write to you an agreeable letter from this glorious
city; but I am here _wearing away_ the winter; a ruin amongst
ruins! I am anxious to hear from you,--very anxious, so pray
write to me with this address, "Sir H. Davy, Inglese, posta
restanti, Rovigo, Italia." You know you must pay the postage
to the frontier, otherwise the letters, like one a friend sent
to me, will go back to you. Pray be so good as to be particular
in the direction,--the "Inglese" is necessary. I hope you got a
copy of my little trifle "_Salmonia_." I ordered copies to be
sent to you, to Mr. W----, and to Mr. Baker: but as the course
of letters in foreign countries is uncertain, I am not sure you
received them; if not, you will have lost little; a _second
edition_ will soon be out, which will be in every respect more
worthy of your perusal, being, I think, twice (not saying much
for it) as entertaining and philosophical. I will take care by
early orders that you have this book. I write and philosophize
a good deal, and have nearly finished a work with a higher
aim than the little book I speak of above, and which I shall
dedicate to you. It contains the essence of my philosophical
opinions, and some of my poetical reveries. It is, like the
"Salmonia," an amusement of my sickness; but "_paulo majora
canamus_." I sometimes think of the lines of Waller, and seem
to feel their truth:
"The soul's dark cottage, batter`d and decay'd,
Lets in new lights through chinks that Time has made."
I have, notwithstanding my infirmities, attended to scientific
objects whenever it was in my power, and I have sent the Royal
Society a paper which they will publish, on the peculiar
Electricity of the Torpedo, which I think bears remotely
upon the functions of life. I attend a good deal to Natural
History, and I think I have recognised in the Mediterranean
a _new species of eel_, a sort of link between the conger
and the muræna of the ancients. I have no doubt Mr. Baker is
right about the distinction between the conger and the common
eel. I am very anxious to hear what he thinks about _their
generation_. Pray get from him a distinct opinion on this
subject. I am at this moment getting the _eels in the markets_
here dissected, and have found _ova_ in plenty. Pray tell me
particularly what Mr. Baker has done; this is a favourite
subject with me, and you can give me no news so interesting.
My dear friend, I shall never forget your kindness to me. You,
with one other person, have given me the little happiness I
have enjoyed since my severe visitation.
I fight against sickness and fate, believing I have still
duties to perform, and that even my illness is connected in
some way with my being made useful to my fellow-creatures. I
have this conviction full on my mind, that intellectual beings
spring from the same breath of Infinite Intelligence, and
return to it again, but by different courses. Like rivers, born
amidst the clouds of heaven, and lost in the deep and eternal
ocean--some in youth, rapid and short-lived torrents; some in
manhood, powerful and copious rivers; and some in age, by a
winding and slow course, half lost in their career, and making
their exit through many sandy and shallow mouths. I hope to
be at Rovigo about the first week in April. I travel slowly
and with my own horses. If you will come and join me there, I
can give you a place in a comfortable carriage, and can show
you the most glorious country in Europe--Illyria and Styria,
and take you to the French frontier before the beginning
of autumn,--perhaps to England. If you can come, do so at
once. I have two servants, and can accommodate you with every
thing. I think of taking some baths before I return, in Upper
Austria; but I write as if I were a strong man, when I am like
a pendulum, as it were, swinging between death and life.
God bless you, my dear Poole.
Your grateful and affectionate friend,
H. DAVY.
Pray remember me to our friends at Stowey.
His paper on the Electricity of the Torpedo, to which he alludes in
the foregoing letter, appears to have been written shortly after he
had finished his "Salmonia," as it is dated from Lubiana, Illyria,
on the 24th of October, and it was read before the Royal Society
on the 20th of November 1828, and published in the first part of
the Transactions for 1829. It will be remembered, that this subject
had long engaged his attention; and he expresses his surprise that
the electricity of living animals should not have been an object of
greater attention, both on account of its physiological importance,
and its general relation to the science of electro-chemistry.
When Volta discovered his wonderful pile, he imagined he had made
a perfect resemblance of the organ of the Gymnotus and Torpedo;
and Davy observes, that whoever has felt the shocks of the natural
and artificial instruments must have been convinced, as far as
sensation is concerned, of their strict analogy.
After the discovery of the _chemical_ power of the Voltaic
instrument, he was naturally desirous of ascertaining whether this
property was possessed by the electrical organs of living animals;
for which purpose, he instituted various experiments, but he could
not discover that such was the fact. Upon mentioning his researches
to Signor Volta, with whom he passed some time in the summer of
1815, the Italian philosopher showed him a peculiar form of his
instrument, which appeared to fulfil the conditions of the organs
of the torpedo; _viz._ a pile, of which the fluid substance was
a very imperfect conductor, such as honey or a strong saccharine
extract, which required a certain time to become charged, and which
did not decompose water, though it communicated weak shocks.
The discovery by Oersted of the effects of Voltaic electricity on
the magnetic needle induced Davy to examine whether the electricity
of living animals possessed a similar power. Having, after some
trouble, procured two lively and recently caught Torpedoes, he
passed the shocks from the largest of these animals a number
of times through the circuit of an extremely delicate magnetic
electrometer, but, although every precaution was used, not the
slightest deviation of, or effect on, the needle could be perceived.
"These negative results," says he, "may be explained by supposing
that the motion of the electricity in the torpedinal organ is in
no measurable time, and that a current of some continuance is
necessary to produce the deviation of the magnetic needle; and I
found that the magnetic electrometer was equally insensible to the
weak discharge of a Leyden jar as to that of the torpedinal organ;
though whenever there was a continuous current from the smallest
surfaces in Voltaic combinations of the weakest power, but in which
some chemical action was going on, it was instantly and powerfully
affected. Two series of zinc and silver, and paper moistened in
salt and water, caused the permanent deviation of the needle
several degrees, though the plates of zinc were only one-sixth of
an inch in diameter.
"It would be desirable to pursue these enquiries with the
electricity of the Gymnotus, which is so much more powerful than
that of the Torpedo; but if they are now to be reasoned upon,
they seem to show a stronger analogy between common and animal
electricity, than between Voltaic and animal electricity; it is
however, I think, more probable that animal electricity will be
found of a distinctive and peculiar kind.
"Common electricity is excited upon non-conductors, and is readily
carried off by conductors and imperfect conductors. Voltaic
electricity is excited upon combinations of perfect and imperfect
conductors, and is only transmitted by perfect conductors, or
imperfect conductors of the best kind.
"Magnetism, if it be a form of electricity, belongs only to perfect
conductors; and, in its modifications, to a peculiar class of them.
"The animal electricity resides only in the imperfect conductors
forming the organs of living animals, and its object in the economy
of nature is to act on living animals.
"Distinctions might be established in pursuing the various
modifications or properties of electricity in these different
forms; but it is scarcely possible to avoid being struck by another
relation of this subject. The torpedinal organ depends for its
powers upon the will of the animal. John Hunter has shown how
copiously it is furnished with nerves. In examining the columnar
structure of the organ of the Torpedo, I have never been able to
discover arrangements of different conductors similar to those in
galvanic combinations, and it seems not improbable that the shock
depends upon some property developed by the action of the nerves.
"To attempt to reason upon any phenomena of this kind as dependent
upon a specific fluid would be wholly vain. Little as we know of
the nature of electrical action, we are still more ignorant of
the nature of the functions of the nerves. There seems, however,
a gleam of light worth pursuing in the peculiarities of animal
electricity,--its connexion with so large a nervous system, its
dependence upon the will of the animal, and the instantaneous
nature of its transfer, which may lead, when pursued by adequate
enquirers, to results important for physiology."
He concludes this paper by expressing his fear that the weak state
of his health will prevent him from following the subject with the
attention it seems to deserve; and he therefore communicates these
imperfect trials to the Royal Society, in the hope that they may
lead to more extensive and profound researches.
We come now to the consideration of the last production of
his genius--"Consolations in Travel, or the Last Days of a
Philosopher:" A work which, he informs us in the preface, was
composed immediately after Salmonia, under the same unfavourable
and painful circumstances, and at a period when his constitution
suffered from new attacks. From this exercise of the mind, he
tells us, that he derived some pleasure and some consolation,
when most other sources of consolation and pleasure were closed
to him; and he ventures to hope that those hours of sickness may
be not altogether unprofitable to persons in perfect health. His
brother, Dr. Davy, who edited the work after the decease of Sir
Humphry, informs us that it was concluded at the very moment of the
invasion of the author's last illness, and that, had his life been
prolonged, it is probable some additions and some changes would
have been made.
"The characters of the persons of the dialogue," continues the
Editor, "were intended to be ideal, at least in great part;--such
they should be considered by the reader; and it is to be hoped,
that the incidents introduced, as well as the persons, will be
viewed only as subordinate and subservient to the sentiments and
the doctrines. The dedication, it may be specially noticed, is
the Author's own, and in the very words dictated by himself at a
time when he had lost the power of writing, except with extreme
difficulty, owing to the paralytic attack, although he retained in
a very remarkable manner all his mental faculties unimpaired and
unclouded." The words of the Dedication are "TO THOMAS POOLE, ESQ.
of Nether Stowey; in remembrance of thirty years of continued and
faithful friendship."
This is a most extraordinary and interesting work: extraordinary,
not only from the wild strength of its fancy, and the extravagance
of its conceptions, but from the bright light of scientific truth
which is constantly shining through its metaphorical tissue, and
irradiating its most shadowy imaginings. It may be compared to the
tree of the lower regions in the Æneid, to every leaf of which was
attached a dream; and yet, however wildly his fancy may dream, his
philosophy never sleeps; and in his exit from the land of phantoms,
the author can in no instance be accused of having mistaken the
gate of ivory for that of horn. To the biographer, the work is of
the highest interest and value, by confirming, in a remarkable
manner, the opinion so frequently expressed in the course of these
memoirs, with respect to the diversified talents of Sir Humphry
Davy; and above all, by elucidating that rare combination of
imagination with judgment, which imparted to his genius its more
striking peculiarities.
The work consists of six Dialogues:--1. THE VISION; 2. DISCUSSIONS
CONNECTED WITH THE VISION IN THE COLOSÆUM; 3. THE UNKNOWN; 4. THE
PROTEUS, OR IMMORTALITY; 5. THE CHEMICAL PHILOSOPHER; and 6. POLA,
OR TIME.
The interlocutors of the first dialogue are two intellectual
Englishmen, one of whom the author calls _Ambrosio_; a man of
highly cultivated taste, great classical erudition, and minute
historical knowledge: a Catholic in religion, but so liberal in
his sentiments, that in another age he might have been secretary
to Ganganelli. The other friend, whom he calls _Onuphrio_, was
a man of a very different character: belonging to the English
aristocracy, he had some of the prejudices usually attached to
birth and rank; but his manners were gentle, his temper good, and
his disposition amiable. Having been partly educated at a northern
university in Britain, he had adopted views in religion which went
even beyond toleration, and which might be regarded as entering the
verge of scepticism. For a patrician, he was very liberal in his
political views. His imagination was poetical and discursive, his
taste good, and his tact extremely fine,--so exquisite, indeed,
that it sometimes approached to morbid sensibility, and disgusted
him with slight defects, and made him keenly sensible of small
perfections to which common minds have been indifferent.
The author, with these his two friends, makes an excursion to the
Colosæum, and the conversation, which a view of those magnificent
ruins produced, together with the account of a dream, or vision,
which occurred to him while left alone amidst these mouldering
monuments, forms the subject-matter of the first dialogue. It is
impossible for any person of the least imagination to contemplate
this decay of former magnificence without strong emotion; but the
direction and tone of such feeling will be necessarily modified by
the qualities of the mind in which it is excited; and the author
has therefore very properly assigned to each of the _dramatis
personæ_, such opinions as might best correspond with his character
and temperament.
They are all represented as being struck with the transiency
of human monuments; but _Ambrosio_ views with triumph the
sanctifying influence of a few crosses planted around the ruins, in
arresting the farther decay of the pile. "Without the influence
of Christianity," he exclaims, "these majestic ruins would have
been dispersed or levelled to the dust. Plundered of their lead
and iron by the barbarians, Goths and Vandals, and robbed even of
their stones by Roman princes--the Barberini, they owe what remains
of their relics to the sanctifying influence of that faith which
has preserved for the world all that was worth preserving, not
merely arts and literature, but likewise that which constitutes
the progressive nature of intellect, and the institutions which
afford to us happiness in this world, and hopes of a blessed
immortality in the next." And he continues,--"What a contrast the
present application of this building, connected with holy feelings
and exalted hopes, is to that of the ancient one, when it was used
for exhibiting to the Roman people the destruction of men by wild
beasts, or of men more savage than wild beasts by each other, to
gratify a horrible appetite for cruelty, founded upon a still more
detestable lust, that of universal domination! And who would have
supposed, in the time of Titus, that a faith, despised in its
insignificant origin, and persecuted from the supposed obscurity
of its founder and its principles, should have reared a dome to
the memory of one of its humblest teachers, more glorious than
was ever framed for Jupiter or Apollo in the ancient world, and
have preserved even the ruins of the temples of the Pagan deities,
and have burst forth in splendour and majesty, consecrating truth
amidst the shrines of error, employing the idols of the Roman
superstition for the most holy purposes, and rising a bright and
constant light amidst the dark and starless night which followed
the destruction of the Roman empire!"
It was not to be expected that _Onuphrio_, whose views are
represented as verging upon scepticism, should have tacitly
coincided in these opinions of _Ambrosio_. He admits, indeed, that
some little of the perfect state in which these ruins exist may
have been owing to the causes just described; but these causes,
he maintains, have only lately begun to operate, and the mischief
was done before Christianity was established at Rome. "Feeling
differently on these subjects," says he, "I admire this venerable
ruin rather as the record of the destruction of the power of
the greatest people that ever existed, than as a proof of the
triumph of Christianity; and I am carried forward, in melancholy
anticipation, to the period when even the magnificent dome of St.
Peter's will be in a similar state to that in which the Colosæum
now is, and when its ruins may be preserved by the sanctifying
influence of some new and unknown faith; when perhaps the statue
of Jupiter, which at present receives the kiss of the devotee, as
the image of St. Peter, may be employed for another holy use, as
the personification of a future saint or divinity; and when the
monuments of the Papal magnificence shall be mixed with the same
dust as that which now covers the tombs of the Cæsars.
"Such, I am sorry to say, is the general history of all the works
and institutions belonging to humanity. They rise, flourish, and
then decay and fall; and the period of their decline is generally
proportional to that of their elevation. In ancient Thebes or
Memphis, the peculiar genius of the people has left us monuments
from which we can judge of their arts, though we cannot understand
the nature of their superstitions. Of Babylon and of Troy, the
remains are almost extinct; and what we know of those famous cities
is almost entirely derived from literary records. Ancient Greece
and Rome we view in the few remains of their monuments; and the
time will arrive when modern Rome shall be what ancient Rome now
is; and ancient Rome and Athens will be what Tyre or Carthage now
are, known only by coloured dust in the desert, or coloured sand,
containing the fragments of bricks, or glass, washed up by the wave
of a stormy sea."
For this desponding view of passing events, _Onuphrio_ finds
consolation in the evidences of revealed religion. In the origin,
progress, elevation, decline, and fall of the empires of antiquity,
he sees proofs that they were intended for a definite end in the
scheme of human redemption; and he finds prophecies which have been
amply verified. He regards the foundation or the ruin of a kingdom,
which appears in civil history so great an event, as comparatively
of small moment in the history of man and in his religious
institutions. He considers the establishment of the worship of one
God amongst a despised and contemned people, as the most important
circumstance in the history of the early world. He regards the
Christian dispensation as naturally arising out of the Jewish, and
the doctrines of the Pagan nations all preparatory to the triumph
and final establishment of a creed fitted for the most enlightened
state of the human mind, and equally adapted to every climate and
every people.
We cannot but regard these passages with great interest, as
indicating the train of thought which must have occupied the mind
of their author, and as proving that, in his latter days, he
not only studied the doctrines of Christianity, but derived the
greatest consolation from its tenets.
After some farther conversation, _Onuphrio_ and _Ambrosio_ leave
their friend the author to pursue his meditations amidst the
solitude of the ruins.
Seated in the moonshine on one of the steps leading to the seats
supposed to have been occupied by the patricians in the Colosæum
at the time of the public games, the train of ideas in which he
had before indulged continued to flow with a vividness and force
increased by the stillness and solitude of the scene, and by the
full moon, which, he observes, has always a peculiar effect on
these moods of feeling in his mind, giving to them a wildness and
a kind of indefinite sensation, such as he supposes belong at all
times to the true poetical temperament.
"It must be so," thought he, "no new city will rise again out of
the double ruins of this; no new empire will be founded upon these
colossal remains of that of the old Romans. The world, like the
individual, flourishes in youth, rises to strength in manhood,
falls into decay in age; and the ruins of an empire are like the
decrepid frame of an individual, except that they have some tints
of beauty, which nature bestows upon them. The sun of civilization
arose in the East, advanced towards the West, and is now at its
meridian; in a few centuries more, it will probably be seen sinking
below the horizon, even in the new world; and there will be left
darkness only where there is a bright light, deserts of sand
where there were populous cities, and stagnant morasses where the
green meadow, or the bright corn-field once appeared. Time," he
exclaimed, "which purifies, and, as it were, sanctifies the mind,
destroys and brings into utter decay the body; and even in nature
its influence seems always degrading. She is represented by the
poet as eternal in her youth; but amongst these ruins she appears
to me eternal in her age, and here, no traces of renovation appear
in the ancient of days."
He had scarcely concluded this ideal sentence, when his reverie
became deeper, and his imagination called up a spirit, who, having
rebuked him for his ignorance and presumption, undeceives him in
his views of the history of the world, by unfolding to him in
a vision the progress of man from a state of barbarity to that
of high civilization. He is first shown a country covered with
forests and marshes; wild animals were grazing in large savannahs,
and carnivorous beasts, such as lions and tigers, occasionally
disturbing and destroying them. Man appeared as a naked savage,
feeding upon wild fruits, or devouring shell-fish, or fighting
with clubs for the remains of a whale which had been thrown upon
the shore. His habitation was a cave in the earth--"See the birth
of Time!" exclaimed the Genius; "look at man in his newly-created
state, full of youth and vigour. Do you see aught in this state to
admire or envy?"
In the next scene, a country opened upon his view, which appeared
partly wild and partly cultivated; and men were seen covered with
the skins of animals, and driving cattle to enclosed pastures;
others were reaping and collecting corn, and others again were
making it into bread. Cottages appeared furnished with many of the
conveniences of life. The Genius now said, "Look at these groups
of men who are escaped from the state of infancy; they owe their
improvement to a few superior minds still amongst them. That aged
man whom you see with a crowd around him taught them to build
cottages; from that other they learnt to domesticate cattle; from
others, to collect and sow corn and seeds of fruit. And these arts
will never be lost; another generation will see them more perfect.
You shall be shown other visions of the passages of time; but as
you are carried along the stream which flows from the period of
creation to the present moment, I shall only arrest your transit
to make you observe some circumstances which will demonstrate
the truths I wish you to know." He then proceeds to describe in
succession the different scenes as they appeared before him, and to
relate the observations by which his genius, or intellectual guide,
accompanied him.
A great extent of cultivated plains, large cities on the sea-shore,
palaces, forums, and temples, were displayed before him. He saw men
associated in groups, mounted on horses, and performing military
exercises; galleys moved by oars on the ocean; roads intersecting
the country covered with travellers, and containing carriages
moved by men or horses. The Genius now said, "You see the early
state of civilization of man: the cottages of the last race you
beheld have become improved into stately dwellings, palaces, and
temples, in which use is combined with ornament. The few men to
whom, as I said before, the foundations of these improvements were
owing, have had divine honours paid to their memory. But look at
the instruments belonging to this generation, and you will find
they were only of brass. You see men who are talking to crowds
around them, and others who are apparently amusing listening groups
by a kind of song or recitation; these are the earliest bards and
orators; but all their signs of thought are oral, for written
language does not yet exist."
The Genius next presented to him a scene of varied business and
imagery. He saw a man who bore in his hands the same instruments
as our modern smiths, presenting a vase, which appeared to be made
of iron, amidst the acclamations of an assembled multitude; and he
saw in the same place men who carried rolls of papyrus in their
hands, and wrote upon them with reeds containing ink, made from
the soot of wood mixed with a solution of glue.--"See," the Genius
said, "an immense change produced in the condition of society by
the two arts of which you now see the origin; the one, that of
rendering iron malleable, which is owing to a single individual,
an obscure Greek; the other, that of making thought permanent in
written characters,--an art which has gradually arisen from the
hieroglyphics which you may observe on yonder pyramids. You will
now see human life more replete with power and activity."
In the scenes that succeeded, he saw bronze instruments thrown
away; malleable iron converted into hard steel, and applied to
a thousand purposes of civilized life; bands of men traversing
the sea, founding colonies, building cities, and, wherever they
established themselves, carrying with them their peculiar arts. He
saw the Roman world succeeded by cities filled with an idle and
luxurious population, and the farms which had been cultivated by
warriors, who left the plough to take the command of armies, now
in the hands of slaves; and the militia of free men supplanted by
bands of mercenaries, who sold the Empire to the highest bidder.
He saw immense masses of warriors collecting in the North and
East, carrying with them no other proofs of cultivation but their
horses and steel arms. He saw these savages every where plundering
cities and destroying the monuments of arts and literature. Ruin,
desolation, and darkness were before him, and he closed his eyes
to avoid the melancholy scene. "See," said the Genius, "the
termination of a power believed by its founders invincible, and
intended to be eternal. But you will find, though the glory and
greatness belonging to its military genius have passed away, yet
those belonging to the arts and institutions by which it adorned
and dignified life, will again arise in another state of society."
Upon again opening his eyes, he saw Italy recovering from her
desolation, towns arising with governments almost upon the model
of ancient Athens and Rome, and these different small states rivals
in arts and arms;--he saw the remains of libraries, which had been
preserved in monasteries and churches by a holy influence, which
even the Goth and Vandal respected, again opened to the people;--he
saw Rome rising from her ashes, the fragments of statues found
amidst the ruins of her palaces and imperial villas, becoming the
models for the regeneration of art;--he saw magnificent temples
raised in this city, become the metropolis of a new and Christian
world, and ornamented with the most brilliant master-pieces of the
arts of design.--"Now," the Genius said, "society has taken its
modern and permanent aspect. Consider for a moment its relations
to letters and to arms, as contrasted with those of the ancient
world." He looked, and he saw that, in the place of the rolls
of papyrus, libraries were now filled with books. "Behold," the
Genius said, "THE PRINTING PRESS! By the invention of Faust, the
productions of genius are, as it were, made imperishable, capable
of indefinite multiplication, and rendered an unalienable heritage
of the human mind. By this art, apparently so humble, the progress
of society is secured, and man is spared the humiliation of
witnessing again scenes like those which followed the destruction
of the Roman Empire. Now look to the warriors of modern times; you
see the spear, the javelin, and the cuirass are changed for the
musket and the light artillery. The German monk who discovered
gunpowder did not meanly affect the destinies of mankind; wars are
become less bloody by becoming less personal; mere brutal strength
is rendered of comparatively little avail; all the resources of
civilization are required to move a large army; wealth, ingenuity,
and perseverance become the principal elements of success;
civilized man is rendered in consequence infinitely superior to the
savage, and gunpowder gives permanence to his triumph, and secures
the cultivated nations from being ever again overrun by the inroads
of millions of barbarians."[116]
[116] This is a question which Gibbon has very eloquently
discussed ("_General Observations on the Fall of the Roman Empire
in the West_," vol. vi.) "Cannon and fortifications now form
an impregnable barrier against the Tartar horse; and Europe is
secure from any future irruption of barbarians; since, before
they can conquer, they must cease to be barbarous." What an
extraordinary illustration does this principle find in the
history of our possessions in India, where, to speak in round
numbers, thirty thousand Europeans keep no less than one hundred
million of natives in subjection!
The Genius then directs his attention to scenes in which are
displayed the triumphs of modern science; such as the steam-engine,
and the thousand resources furnished by the chemical and mechanical
arts; and she concludes by endeavouring to impress upon him the
conviction, "That the results of intellectual labour, or of
scientific genius, are permanent, and incapable of being lost.
Monarchs change their plans, governments their objects, a fleet or
an army effect their purpose and then pass away; but a piece of
steel touched by the magnet preserves its character for ever, and
secures to man the dominion of the trackless ocean. A new period
of society may send armies from the shores of the Baltic to those
of the Euxine, and the empire of the followers of Mahomet may be
broken in pieces by a Northern people, and the dominion of the
Britons in Asia may share the fate of Tamerlane or Zengis-khan; but
the steam-boat which ascends the Delaware, or the St. Lawrence,
will be continued to be used, and will carry the civilization of
an improved people into the deserts of North America, and into the
wilds of Canada. In the common history of the world, as compiled
by authors in general, almost all the great changes of nations are
confounded with changes in their dynasties, and events are usually
referred either to sovereigns, chiefs, heroes, or their armies,
which do, in fact, originate from entirely different causes, either
of an intellectual or moral nature."
Having instructed him in the history of man as an inhabitant of
the earth, the Genius proceeds to reveal to him the mysteries
of spiritual natures, in which the author evidently shows his
attachment to the belief that our intellectual essence is destined
hereafter to enjoy a higher and better state of planetary
existence,[117] drinking intellectual light from a purer source,
and approaching nearer to the Infinite and Divine mind. I shall
not attempt to follow him and his Genius to the verge of the solar
system, witnessing in his career the inhabitants of planets and
comets. We may upon this occasion truly apply to the author the
words of Lucretius--
"Processit longe flammantia moenia mundi."
"His vigorous and active mind was hurl'd
Beyond the flaming limits of the world."--CREECH.
In the former part of the dialogue, his poetical coruscations
appeared only as brilliant sparks thrown off by the rapidity of
the machinery which he worked for a useful end and for a definite
purpose; his vivid imagination may now be compared to a display
of fire-works, which dazzle and confound without enlightening the
senses, and leave the spectator in still more profound darkness.
[117] Under the article 'Sensation,' in the Philosophical
Dictionary, we find Voltaire indulging in a similar speculation.
"It may be, that in other globes the inhabitants possess
sensations of which we can form no idea. It is possible that the
number of our senses augments from globe to globe, and that an
existence with innumerable and perfect senses will be the final
attainment of all being."
His SECOND DIALOGUE, entitled "Discussions connected with the
Vision in the Colosæum," may be considered as a commentary upon
the views he had unfolded; and a more appropriate spot, perhaps,
could not have been selected for a conversation upon the progress
of civilization, than the summit of Vesuvius, from which, to adopt
the language of _Ambrosio_, "We see not only the power and activity
of man as existing at present, and of which the highest example
may be represented by the steam-boat departing from Palermo, but
we may likewise view scenes which carry us into the very bosom of
antiquity, and as it were make us live with the generations of past
ages."
The author, who assumes throughout this dialogue the name of
_Philalethes_, after having been duly rallied by his friends on the
subject of his vision, thus expresses himself:--"I will acknowledge
that the vision in the Colosæum is a fiction; but the most
important parts of it really occurred to me in sleep, particularly
that in which I seemed to leave the earth and launch into the
infinity of space, under the guidance of a tutelary genius. And
the origin and progress of civil society form likewise parts of
another dream which I had many years ago; and it was in the reverie
which happened when you quitted me in the Colosæum, that I wove all
these thoughts together, and gave them the form in which I narrated
them to you.--I do not say that they are strictly to be considered
as an accurate representation of my waking thoughts; for I am not
quite convinced that dreams are always the representations of the
state of the mind, modified by organic diseases or by associations.
There are certainly no absolutely new ideas produced in sleep; yet
I have had more than one instance, in the course of my life, of
most extraordinary combinations occurring in this state, which have
had considerable influence on my feelings, my imagination, and my
health."
_Philalethes_ now relates a fact to which his preceding observation
more immediately referred; he anticipates unbelief,--but he
declares that he mentions nothing but a simple fact.
"Almost a quarter of a century ago, I contracted that terrible form
of typhus fever known by the name of jail fever,--I may say, not
from any imprudence of my own, but whilst engaged in putting in
execution a plan for ventilating one of the great prisons of the
metropolis.[118] My illness was severe and dangerous; as long as
the fever continued, my dreams and deliriums were most painful and
oppressive; but when weakness consequent to exhaustion came on,
and when the probability of death seemed to my physicians greater
than that of life, there was an entire change in all my ideal
combinations. I remained in an apparently senseless or lethargic
state, but, in fact, my mind was peculiarly active; there was
always before me the form of a beautiful woman, with whom I was
engaged in the most interesting and intellectual conversation."
[118] See page 287, vol. i. for an account of this event.
_Ambrosio_ and _Onuphrio_ very naturally suggest that this could
have been no other than the image of some favourite maiden which
had haunted his imagination; but _Philalethes_ rejects with
indignation such an explanation of the vision. "I will not," he
exclaims, "allow you to treat me with ridicule on this point,
till you have heard the second part of my tale. Ten years after
I had recovered from the fever, and when I had almost lost the
recollection of the vision, it was recalled to my memory by a very
blooming and graceful maiden fourteen or fifteen years old, that
I accidentally met during my travels in Illyria; but I cannot say
that the impression made upon my mind by this female was very
strong. Now comes the extraordinary part of the narrative: ten
years after,--twenty years after my first illness, at a time when
I was exceedingly weak from a severe and dangerous malady, which
for many years threatened my life, and when my mind was almost in
a desponding state, being in a course of travels ordered by my
medical advisers, I again met the person who was the representative
of my visionary female; and to her kindness and care, I believe,
I owe what remains to me of existence. My despondency gradually
disappeared, and though my health still continued weak, life began
to possess charms for me which I had thought were for ever gone;
and I could not help identifying the living angel with the vision
which appeared as my guardian genius during the illness of my
youth."
The reader will probably agree with _Onuphrio_, in seeing in this
history nothing beyond the influence of an imagination excited by
disease.
The discourse now turns upon that part of the vision in the
Colosæum in which was exhibited the early state of man, after
his first creation, and which _Ambrosio_ considers as not only
incompatible with revelation, but likewise with reason and every
thing that we know respecting the history or traditions of the
early nations of antiquity.
I shall merely state the objection which _Ambrosio_ offers. I must
then refer the reader to the work itself for an account of the
discussion it provoked.
"_Ambrosio._--You consider man, in his early state, a savage like
those who now inhabit New Holland, or New Zealand, acquiring, by
the little use that they make of a feeble reason, the power of
supporting and extending life. Now, I contend that, if man had been
so created, he must inevitably have been destroyed by the elements,
or devoured by savage beasts, so infinitely his superiors in
physical force."
During the discussion, an opinion is advanced by _Ambrosio_, so
singular, that I must be allowed to quote it. "I consider," says
he, "all the miraculous parts of our religion as effected by
changes in the sensations or ideas of the human mind, and not by
physical changes in the order of nature! To Infinite Wisdom and
Power, a change in the intellectual state of the human being may
be the result of a momentary will, and the mere act of faith may
produce the change. How great the powers of imagination are, even
in ordinary life, is shown by many striking facts, and nothing
seems impossible to this imagination when acted upon by Divine
influence."
This is surely a most extraordinary line of argument for the
apologist of the Christian faith, and of the miracles by which it
is supported.
In the THIRD DIALOGUE, called the Unknown, the author and his
friends, _Ambrosio_ and _Onuphrio_, make an excursion to the
remains of the temples of Pæstum. "Were my existence to be
prolonged through ten centuries," exclaims the author, "I think I
could never forget the pleasure I received on that delicious spot."
In contemplating beautiful scenery, much of its interest depends
upon the feelings and associations of the moment; and the author
was upon this occasion evidently in that poetical frame of mind
which sheds a magic light over every landscape, and converts the
most ordinary objects into emblems of morality: in the admixture
of the olive and the cypress tree, he saw a connection, to
memorialize, as it were, how near each other are life and death,
joy and sorrow; while the music of the birds, and, above all, the
cooing of the turtle-doves, by overpowering the murmuring of the
waves and the whistling of the winds, served but to show him that,
in the strife of nature, the voice of love is predominant.
With their hearts touched by the scene they had witnessed, the
travellers descended to the ruins, and began to examine those
wonderful remains which have outlived even the name of the people
by whom they were raised. While engaged in measuring the Doric
columns in the interior of the Temple of Neptune, a stranger,
remarkable both in dress and appearance, was observed to be writing
in a memorandum book; the author immediately addresses him, and
becoming mutually pleased with each other, they enter into a
conversation of high scientific interest.
The sentiments delivered by the "UNKNOWN," for by this title is the
philosopher designated, notwithstanding their dramatic dress, are
evidently to be received as the bequest of the latest scientific
opinions of Sir H. Davy upon several important subjects, and must
consequently command our respect and consideration.
To a question relative to the nature of the masses of travertine,
of which the ruins consisted, the Unknown replied, that they
were certainly produced by deposition from water; and he rather
believed, that a lake in the immediate neighbourhood of the city
furnished the quarry. The party are then described as visiting this
spot.
"There was something peculiarly melancholy in the character of this
water; all the herbs around it were grey, as if incrusted with
marble; a few buffaloes were slaking their thirst in it, which ran
wildly away at our approach, and appeared to retire into a rocky
excavation or quarry at the end of the lake. 'There,' said the
stranger, 'is what I believe to be the source of those large and
durable stones which you see in the plain before you. This water
rapidly deposits calcareous matter, and even, if you throw a stick
into it, a few hours is sufficient to give it a coating of this
substance. Whichever way you turn your eyes, you see masses of this
recently produced marble, the consequence of the overflowing of the
lake during the winter floods.'
* * * * *
"This water is like many, I may say most, of the sources which rise
at the foot of the Apennines; it holds carbonic acid in solution,
which has dissolved a portion of the calcareous matter of the rock
through which it has passed:--this carbonic acid is dissipated
in the atmosphere, and the marble, slowly thrown down, assumes a
crystalline form, and produces coherent stones. The lake before us
is not particularly rich in the quantity of calcareous matter, for,
as I have found by experience, a pint of it does not afford more
than five or six grains; but the quantity of fluid and the length
of time are sufficient to account for the immense quantities of
tufa and rock which, in the course of ages, have accumulated in
this situation.
* * * * *
"It can, I think, be scarcely doubted that there is a source of
volcanic fire at no great distance from the surface, in the whole
of southern Italy; and, this fire acting upon the calcareous rocks
of which the Apennines are composed, must constantly detach from
them carbonic acid, which rising to the sources of the springs,
deposited from the waters of the atmosphere, must give them their
impregnation, and enable them to dissolve calcareous matter. I need
not dwell upon Ætna, Vesuvius, or the Lipari Islands, to prove that
volcanic fires are still in existence; and there can be no doubt
that, in earlier periods, almost the whole of Italy was ravaged by
them; even Rome itself, the eternal city, rests upon the craters of
extinct volcanoes; and I imagine that the traditional and fabulous
record of the destruction made by the conflagration of Phaeton, in
the chariot of the Sun, and his falling into the Po, had reference
to a great and tremendous igneous volcanic eruption which extended
over Italy, and ceased only near the Po, at the foot of the Alps.
Be this as it may, the sources of carbonic acid are numerous, not
merely in the Neapolitan but likewise in the Roman and Tuscan
states. The most magnificent waterfall in Europe, that of the
Velino near Terni, is partly fed by a stream containing calcareous
matter dissolved by carbonic acid, and it deposits marble, which
crystallizes even in the midst of its thundering descent and foam,
in the bed in which it falls.
"There is a lake in Latium, a few yards above the Lacus Albula,
where the ancient Romans erected their baths, which sends down a
considerable stream of tepid water to the larger lake; but this
water is less strongly impregnated with carbonic acid; the largest
lake is actually a saturated solution of this gas, which escapes
from it in such quantities in some parts of its surface, that it
has the appearance of being actually in ebullition. Its temperature
I ascertained to be, in the winter, in the warmest parts, above
80 degrees of Fahrenheit, and as it appears to be pretty constant,
it must be supplied with heat from a subterraneous source, being
nearly twenty degrees above the mean temperature of the atmosphere.
Kircher has detailed, in his _Mundus Subterraneus_, various wonders
respecting this lake, most of which are unfounded; such as, that
it is unfathomable,--that it has at the bottom the heat of boiling
water, and that floating islands rise from the gulf which emits it.
It must certainly be very difficult, or even impossible, to fathom
a source which rises with so much violence from a subterraneous
excavation; and at a time when chemistry had made small progress,
it was easy to mistake the disengagement of carbonic acid for an
actual ebullition. The floating islands are real; but neither the
Jesuit, nor any of the writers who have since described this lake,
had a correct idea of their origin, which is exceedingly curious.
The high temperature of this water, and the quantity of carbonic
acid that it contains, render it peculiarly fitted to afford a
pabulum or nourishment to vegetable life; the banks of travertine
are every where covered with reeds, lichens, confervæ, and various
kinds of aquatic vegetables; and at the same time that the process
of vegetable life is going on, the crystallizations of the
calcareous matter, which is every where deposited in consequence of
the escape of carbonic acid, likewise proceed, giving a constant
milkiness to what from its tint would otherwise be a blue fluid. So
rapid is the vegetation, owing to the decomposition of the carbonic
acid, that even in winter, masses of confervæ and lichens, mixed
with deposited travertine, are constantly detached by the current
of water from the bank, and float down the stream, which being a
considerable river, is never without many of these small islands
on its surface; they are sometimes only a few inches in size,
and composed merely of dark green confervæ, or purple or yellow
lichens; but they are sometimes even of some feet in diameter, and
contain seeds and various species of common water-plants, which are
usually more or less incrusted with marble. There is, I believe, no
place in the world where there is a more striking example of the
opposition or contrast of the laws of animate and inanimate nature,
of the forces of inorganic chemical affinity and those of the
powers of life. Vegetables, in such a temperature, and every where
surrounded by food, are produced with a wonderful rapidity; but
the crystallizations are formed with equal quickness, and they are
no sooner produced than they are destroyed together. The quantity
of vegetable matter and its heat make it the resort of an infinite
variety of insect tribes; and, even in the coldest days in winter,
numbers of flies may be observed on the vegetables surrounding its
banks or on its floating islands, and a quantity of their larvæ
may be seen there, sometimes incrusted and entirely destroyed by
calcareous matter, which is likewise often the fate of the insects
themselves, as well as of various species of shell-fish that are
found amongst the vegetables which grow and are destroyed in the
travertine on its banks.
* * * * *
"I have passed many hours, I may say, many days, in studying the
phenomena of this wonderful lake; it has brought many trains of
thought into my mind connected with the early changes of our globe,
and I have sometimes reasoned from the forms of plants and animals
preserved in marble in this warm source, to the grander depositions
in the secondary rocks, where the zoophytes or coral insects have
worked upon a grand scale, and where palms and vegetables now
unknown are preserved with the remains of crocodiles, turtles, and
gigantic extinct animals of the _Sauri_ genus, and which appear to
have belonged to a period when the whole globe possessed a much
higher temperature.
* * * * *
"Then, from all we know, this lake, except in some change in its
dimensions, continues nearly in the same state in which it was
described seventeen hundred years ago by Pliny, and I have no doubt
contains the same kinds of floating islands, the same plants,
and the same insects. During the fifteen years that I have known
it, it has appeared precisely identical in these respects; and
yet it has the character of an accidental phenomenon depending
upon subterraneous fire. How marvellous then are those laws by
which even the humblest types of organic existence are preserved,
though born amidst the sources of their destruction, and by which
a species of immortality is given to generations, floating, as it
were, like evanescent bubbles on a stream raised from the deepest
caverns of the earth, and instantly losing what may be called its
spirit in the atmosphere!"
From this interesting discourse on the formation of Travertine,
the conversation naturally turned to Geology; and I shall here
again be compelled to give another copious extract, in order
to show what were the latest opinions of Sir H. Davy upon this
subject. If any doubt could exist as to the views here given being
those entertained by the author, it is at once removed by his
letter to Mr. Poole, in which, alluding to the work under review,
he says, "_It contains the essence of my philosophical opinions._"
"On the geological scheme of the early history of the globe,
there are only analogies to guide us, which different minds may
apply and interpret in different ways; but I will not trifle
with a long preliminary discourse. Astronomical deductions and
actual measures by triangulation prove that the globe is an oblate
spheroid flattened at the poles; and this form, we know, by strict
mathematical demonstrations, is precisely the one which a fluid
body revolving round its axis and become solid at its surface by
the slow dissipation of its heat or other causes, would assume. I
suppose, therefore, that the globe, in the first state in which
the imagination can venture to consider it, was a fluid mass with
an immense atmosphere, revolving in space round the sun, and that
by its cooling, a portion of its atmosphere was condensed in water
which occupied a part of the surface. In this state, no forms of
life, such as now belong to our system, could have inhabited it;
and I suppose the crystalline rocks, or, as they are called by
geologists, the _primary_ rocks, which contain no vestiges of a
former order of things, were the results of the first consolidation
on its surface. Upon the farther cooling, the water which more
or less had covered it, contracted; depositions took place,
shell-fish, and coral insects of the first creation began their
labours, and islands appeared in the midst of the ocean, raised
from the deep by the productive energies of millions of zoophytes.
These islands became covered with vegetables fitted to bear a high
temperature, such as palms, and various species of plants similar
to those which now exist in the hottest part of the world. And
the submarine rocks or shores of these new formations of land
became covered with aquatic vegetables, on which various species
of shell-fish and common fishes found their nourishment. The
fluids of the globe in cooling deposited a large quantity of the
materials they held in solution, and these deposits agglutinating
together the sand, the immense masses of coral rocks, and some of
the remains of the shells and fishes found round the shores of the
primitive lands, produced the first order of _secondary_ rocks.
"As the temperature of the globe became lower, species of the
oviparous reptiles were created to inhabit it; and the turtle,
crocodile, and various gigantic animals of the _Sauri_ kind, seem
to have haunted the bays and waters of the primitive lands. But in
this state of things there was no order of events similar to the
present,--the crust of the globe was exceedingly slender, and the
source of fire a small distance from the surface. In consequence of
contraction in one part of the mass, cavities were opened, which
caused the entrance of water, and immense volcanic explosions
took place, raising one part of the surface, depressing another,
producing mountains and causing new and extensive depositions from
the primitive ocean. Changes of this kind must have been extremely
frequent in the early epochas of nature; and the only living forms
of which the remains are found in the strata that are the monuments
of these changes, are those of plants, fishes, birds, and oviparous
reptiles, which seem most fitted to exist in such a war of the
elements.
"When these revolutions became less frequent, and the globe
became still more cooled, and the inequalities of its temperature
preserved by the mountain chains, more perfect animals became
its inhabitants, many of which, such as the mammoth, megalonix,
megatherium, and gigantic hyena, are now extinct. At this period,
the temperature of the ocean seems to have been not much higher
than it is at present, and the changes produced by occasional
eruptions of it have left no consolidated rocks. Yet one of
these eruptions appears to have been of great extent and of some
duration, and seems to have been the cause of those immense
quantities of water-worn stones, gravel, and sand, which are
usually called _diluvian_ remains;--and it is probable that this
effect was connected with the elevation of a new continent in the
southern hemisphere by volcanic fire. When the system of things
became so permanent, that the tremendous revolutions depending
upon the destruction of the equilibrium between the heating and
cooling agencies were no longer to be dreaded, the creation of man
took place; and since that period there has been little alteration
in the physical circumstances of our globe. Volcanoes sometimes
occasion the rise of new islands, portions of the old continents
are constantly washed by rivers into the sea, but these changes are
too insignificant to affect the destinies of man, or the nature of
the physical circumstances of things. On the hypothesis that I have
adopted, however, it must be remembered, that the present surface
of the globe is merely a thin crust surrounding a nucleus of fluid
ignited matter; and consequently, we can hardly be considered as
actually safe from the danger of a catastrophe by fire.
* * * * *
"I beg you to consider the views I have been developing as
merely hypothetical, one of the many resting-places that may be
taken by the imagination in considering this subject. There are,
however, distinct facts in favour of the idea, that the interior
of the globe has a higher temperature than the surface; the heat
increasing in mines the deeper we penetrate, and the number of warm
sources which rise from great depths, in almost all countries,
are certainly favourable to the idea. The opinion, that volcanoes
are owing to this general and simple cause, is, I think, likewise
more agreeable to the analogies of things, than to suppose them
dependent upon partial chemical changes, such as the action of air
and water upon the combustible bases of the earths and alkalies,
though it is extremely probable that these substances may exist
beneath the surface, and may occasion some results of volcanic
fire;--and on this subject my notion may perhaps be the more
trusted, as for a long while I thought volcanic eruptions were
owing to chemical agencies of the newly discovered metals of the
earths and alkalies, and I made many and some dangerous experiments
in the hope of confirming this notion, but in vain.
* * * * *
"I have no objection to the '_refined Plutonic view_,' (of
Professor Playfair and Sir James Hall,) as capable of explaining
many existing phenomena; indeed, you must be aware that I have
myself had recourse to it. What I contend against is, its
application to explain the formations of the secondary rocks, which
I think clearly belong to an order of facts not at all embraced by
it. In the Plutonic system, there is one simple and constant order
assumed, which may be supposed eternal. The surface is constantly
imagined to be disintegrated, destroyed, degraded, and washed into
the bosom of the ocean by water, and as constantly consolidated,
elevated, and regenerated by fire; and the ruins of the old form
the foundations of the new world. It is supposed that there are
always the same types both of dead and living matter,--that the
remains of rocks, of vegetables, and animals of one age are found
imbedded in rocks raised from the bottom of the ocean in another.
Now, to support this view, not only the remains of living beings
which at present people the globe, might be expected to be found in
the oldest secondary strata, but even those of the art of man, the
most powerful and populous of its inhabitants, which is well known
not to be the case. On the contrary, each stratum of the secondary
rocks contains remains of peculiar and mostly now unknown species
of vegetables and animals. In those strata which are deepest, and
which must consequently be supposed to be the earliest deposited,
forms even of vegetable life are rare; shells and vegetable remains
are found in the next order; the bones of fishes and oviparous
reptiles exist in the following class; the remains of birds, with
those of the same genera mentioned before, in the next order; those
of quadrupeds of extinct species in a still more recent class;
and it is only in the loose and slightly consolidated strata of
gravel and sand, and which are usually called diluvian formations,
that the remains of animals, such as now people the globe, are
found, with others belonging to extinct species. But in none of
these formations, whether called secondary, tertial, or diluvial,
have the remains of man, or any of his works, been discovered. It
is, I think, impossible to consider the organic remains found in
any of the earlier secondary strata, the lias-limestone and its
congenerous formations, for instance, without being convinced,
that the beings whose organs they formed belonged to an order of
things entirely different from the present. Gigantic vegetables,
more nearly allied to the palms of the equatorial countries than
to any other plants, can only be imagined to have lived in a very
high temperature; and the immense reptiles, the _Megalosauri_, with
paddles instead of legs, and clothed in mail, in size equal, or
even superior to the whale; and the great amphibia _Plethiosauri_,
with bodies like turtles, but furnished with necks longer than
their bodies, probably to enable them to feed on vegetables growing
in the shallows of the primitive ocean, seem to show a state in
which low lands, or extensive shores, rose above an immense calm
sea, and when there were no great mountain chains to produce
inequalities of temperature, tempests, or storms. Were the surface
of the earth now to be carried down into the depths of the ocean,
or were some great revolution of the waters to cover the existing
land, and it was again to be elevated by fire, covered with
consolidated depositions of sand or mud, how entirely different
would it be in its characters from any of the secondary strata!
Its great features would undoubtedly be the works of man: hewn
stones, and statues of bronze and marble, and tools of iron, and
human remains, would be more common than those of animals, on
the greatest part of the surface; the columns of Pæstum, or of
Agrigentum, or the immense iron bridges of the Thames, would offer
a striking contrast to the bones of the crocodiles, or _Sauri_,
in the older rocks, or even to those of the mammoth, or _Elephas
primogenius_, in the diluvial strata. And whoever dwells upon this
subject must be convinced, that the present order of things, and
the comparatively recent existence of man, as the master of the
globe, is as certain as the destruction of a former and a different
order, and the extinction of a number of living forms, which have
now no types in being, and which have left their remains wonderful
monuments of the revolutions of nature."
The FOURTH DIALOGUE, to which is given the title of "The Proteus,
or Immortality," is of a more desultory nature than those which
precede it. It contains many beautiful descriptions of scenery in
the Alpine country of Austria; furnishes an interesting account
of that most singular reptile the _Proteus Anguinus_, which is
found only in the limestone caverns of Carniola, and concludes with
reflections upon the indestructibility of the sentient principle.
The author's companion, during the tour he describes, is a
scientific friend, whom he calls _Eubathes_. The dialogue opens
with a passage of considerable pathos and eloquence: the author
having been recalled to England by a melancholy event, the death of
a very near and dear relation, describes his feelings on entering
London.
"In my youth, and through the prime of manhood, I never entered
London without feelings of pleasure and hope. It was to me as
the grand theatre of intellectual activity, the field of every
species of enterprise and exertion, the metropolis of the world
of business, thought, and action. There, I was sure to find
the friends and companions of my youth, to hear the voice of
encouragement and praise. There, society of the most refined kind
offered daily its banquets to the mind, with such variety that
satiety had no place in them, and new objects of interest and
ambition were constantly exciting attention either in politics,
literature, or science.
"I now entered this great city in a very different tone of
mind--one of settled melancholy, not merely produced by the
mournful event which recalled me to my country, but owing likewise
to an entire change in the condition of my physical, moral, and
intellectual being. My health was gone, my ambition was satisfied;
I was no longer excited by the desire of distinction; what I
regarded most tenderly was in the grave; and to take a metaphor,
derived from the change produced by time in the juice of the grape,
my cup of life was no longer sparkling, sweet, and effervescent; it
had lost its sweetness without losing its power, and it had become
bitter."
There is perhaps not a more splendid passage to be found in the
work; and it is scarcely inferior to Dr. Johnson's memorable
conclusion to the preface of his Dictionary.
"After passing a few months in England," says he, "and enjoying (as
much as I could enjoy any thing) the society of the few friends
who still remained alive, the desire of travel again seized me.
I had preserved amidst the wreck of time, one feeling strong and
unbroken--the love of natural scenery; and this, in advanced life,
formed a principal motive for my plans of conduct and action."
The fall of the Traun, about ten miles below Gmünden, was one of
his favourite haunts; and he describes an accident of the most
awful description which befell him at this place. While amusing
himself on the water by a rapid species of locomotion, in a
boat so secured by a rope as to allow only of a limited range,
the tackle gave way, and he was rapidly precipitated down the
cataract. He remained for some time after his rescue in a state
of insensibility, and on recovering found himself attended by his
mysterious friend the "Unknown," who had so charmed him in his
excursion to Pæstum.
With this stranger, he proceeded on his tour; and he again becomes
the medium through which much philosophical information is conveyed
to the reader.
They visit together the grotto of the Maddalena at Adelsberg, and
he gives us the conversation that took place in that extraordinary
cavern.
"_Philalethes._--If the awful chasms of dark masses of rock
surrounding us appear like the work of demons, who might be
imagined to have risen from the centre of the earth, the beautiful
works of nature above our heads may be compared to a scenic
representation of a temple or banquet-hall for fairies or genii,
such as those fabled in the Arabian romances.
"_The Unknown._--A poet might certainly place here the palace of
the king of the Gnomes, and might find marks of his creative power
in the small lake close by, on which the flame of the torch is now
falling; for, there it is that I expect to find the extraordinary
animals which have been so long the objects of my attention.
"_Eubathes._--I see three or four creatures, like slender fish,
moving on the mud below the water.
"_The Unknown._--I see them; they are the Protei,--now I have them
in my fishing-net, and now they are safe in the pitcher of water.
At first view, you might suppose this animal to be a lizard, but it
has the motions of a fish. Its head, and the lower part of its body
and its tail, bear a strong resemblance to those of the eel; but
it has no fins; and its curious bronchial organs are not like the
gills of fishes; they form a singular vascular structure, as you
see, almost like a crest, round the throat, which may be removed
without occasioning the death of the animal, who is likewise
furnished with lungs. With this double apparatus for supplying air
to the blood, it can live either below or above the surface of
the water. Its fore-feet resemble hands, but they have only three
claws or fingers, are too feeble to be of use in grasping, or
supporting the weight of the animal; the hinder feet have only two
claws or toes, and in larger specimens are found so imperfect as to
be almost obliterated. It has small points in place of eyes, as if
to preserve the analogy of nature. Its nasal organs appear large;
and it is abundantly furnished with teeth, from which it may be
concluded that it is an animal of prey; yet in its confined state
it has never been known to eat, and it has been kept alive for many
years by occasionally changing the water in which it is placed.
"_Eubathes._--Is this the only place in Carniola where these
animals are found?
"_The Unknown._--They were first discovered here by the late Baron
Zois; but they have since been found, though rarely, at Sittich,
about thirty miles distant, thrown up by water from a subterraneous
cavity; and I have lately heard it reported that some individuals
of the same species have been recognised in the calcareous strata
in Sicily. I think it cannot be doubted, that their natural
residence is an extensive deep subterranean lake, from which in
great floods they sometimes are forced through the crevices of the
rocks into this place where they are found; and it does not appear
to me impossible, when the peculiar nature of the country in which
we are is considered, that the same great cavity may furnish the
individuals which have been found at Adelsberg and at Sittich.
* * * * *
"This adds one more instance to the number already known of the
wonderful manner in which life is produced and perpetuated in every
part of our globe, even in places which seem the least suited to
organized existence. And the same infinite power and wisdom which
has fitted the camel and the ostrich for the deserts of Africa, the
swallow that secretes its own nest for the caves of Java, the whale
for the Polar seas, and the morse and white bear for the Arctic
ice, has given the Proteus to the deep and dark subterraneous
lakes of Illyria,--an animal to whom the presence of light is not
essential, and who can live indifferently in air and in water, on
the surface of the rock, or in the depths of the mud."
Much interesting physiological discussion follows. I shall,
however, merely notice the opinion delivered by the "Unknown,"
on the subject of respiration, and which I think shows that, at
the conclusion of his career, Davy entertained the same notions,
with regard to the communication of some ethereal principle to the
blood, as he maintained in the earlier part of his life.[119]--"The
obvious chemical alteration of the air is sufficiently simple in
this process; a certain quantity of carbon only is added to it,
and it receives an addition of heat or vapour; the volumes of
elastic fluid inspired and expired (making allowance for change
of temperature,) are the same, and if ponderable agents only were
to be regarded, it would appear as if the only use of respiration
were to free the blood from a certain quantity of carbonaceous
matter. But it is probable that this is only a secondary object,
and that the change produced by respiration upon the blood is of
a much more important kind. Oxygen, in its elastic state, has
properties which are very characteristic; it gives out light by
compression, which is not certainly known to be the case with any
other elastic fluid except those which oxygen has entered without
undergoing combustion; and from the fire it produces in certain
processes, and from the manner in which it is separated by positive
electricity in the gaseous state from its combinations, it is
not easy to avoid the supposition, that it contains, besides its
ponderable elements, some very subtile matter which is capable of
assuming the form of heat and light. _My idea_ is, that the common
air inspired enters into the venous blood entire, in a state of
dissolution, carrying with it its subtile or ethereal part, which
in ordinary cases of chemical change is given off; that it expels
from the blood carbonic acid gas and azote; and that, in the course
of the circulation, its ethereal part and its ponderable part
undergo changes which belong to laws that cannot be considered
as chemical,--the ethereal part probably producing animal heat
and other effects, and the ponderable part contributing to form
carbonic acid and other products. The arterial blood is necessary
to all the functions of life, and it is no less connected with the
irritability of the muscles and the sensibility of the nerves than
with the performance of all the secretions."
[119] See vol. i. page 70.
The FIFTH DIALOGUE is entitled "The Chemist." Its object is to
demonstrate the importance of this noble science. An interlocutor
is made to disparage its utility, and to mark its weaker points.
These of course are answered, the sceptic becomes a true believer,
and the intellectual gladiators separate mutually satisfied with
each other.
"_Eubathes._--I feel disposed to join you in attacking this
favourite study of our friend, _but merely_ to provoke him to
defend it, in order to call forth his skill and awaken his
eloquence.
"_The Unknown._--I have no objection. Let there be a fair
discussion: remember, we fight only with foils, and the point of
mine shall be covered with velvet."
After having enumerated the scientific attainments necessary to
constitute the chemist, and described the apparatus essential
for understanding what has been already done in the science, he
proceeds to define the intellectual qualities which he considers
necessary for discovery, or for the advancement of the science.
Amongst them, patience, industry, and neatness in manipulation,
and accuracy and minuteness in observing and registering the
phenomena which occur, are essential. A steady hand and a quick eye
are most useful auxiliaries; but there have been very few great
chemists who have preserved these advantages through life; for
the business of the laboratory is often a service of danger, and
the elements, like the refractory spirits of romance, though the
obedient slaves of the magician, yet sometimes escape the influence
of his talisman, and endanger his person. Both the hands and eyes
of others, however, may be sometimes advantageously made use of. By
often repeating a process or an observation, the errors connected
with hasty operations or imperfect views are annihilated; and,
provided the assistant has no preconceived notions of his own,
and is ignorant of the object of his employer in making the
experiment, his simple and bare detail of facts will often be
the best foundation for an opinion. With respect to the higher
qualities of intellect necessary for understanding and developing
the general laws of the science, the same talents, I believe, are
required as for making advancement in every other department of
human knowledge; I need not be very minute. The imagination must
be active and brilliant in seeking analogies; yet entirely under
the influence of the judgment in applying them. The memory must be
extensive and profound; rather, however, calling up general views
of things than minute trains of thought;--the mind must not be like
an Encyclopedia,--a burthen of knowledge, but rather a critical
Dictionary, which abounds in generalities, and points out where
more minute information may be obtained.
* * * * *
"In announcing even the greatest and most important discoveries,
the true philosopher will communicate his details with modesty and
reserve; he will rather be a useful servant of the public, bringing
forth a light from under his cloak when it is needed in darkness,
than a charlatan exhibiting fire-works, and having a trumpeter to
announce their magnificence.
"I see you are smiling, and think what I am saying in bad taste;
yet, notwithstanding, I will provoke your smiles still farther,
by saying a word or two on his other moral qualities. That he
should be humble-minded, you will readily allow, and a diligent
searcher after truth, and neither diverted from this great object
by the love of transient glory or temporary popularity, looking
rather to the opinion of ages than to that of a day, and seeking
to be remembered and named rather in the epochas of historians
than in the columns of newspaper writers or journalists. He should
resemble the modern geometricians in the greatness of his views
and the profoundness of his researches, and the ancient alchemists
in industry and piety. I do not mean that he should affix written
prayers and inscriptions[120] of recommendations of his processes
to Providence, as was the custom of Peter Wolfe, who was alive in
my early days; but his mind should always be awake to devotional
feelings; and in contemplating the variety and the beauty of the
external world, and developing its scientific wonders, he will
always refer to that Infinite Wisdom, through whose beneficence he
is permitted to enjoy knowledge; and, in becoming wiser, he will
become better,--he will rise at once in the scale of intellectual
and moral existence, his increased sagacity will be subservient to
a more exalted faith, and in proportion as the veil becomes thinner
through which he sees the causes of things, he will admire more the
brightness of the divine light by which they are rendered visible."
[120] In illustration of the pious custom here alluded to by Sir
H. Davy, it may be observed, that the vessels of the alchemists
very commonly bore some emblem; such, for instance, as that of
the cross; and from which, indeed, the word _crucible_ derived
its appellation.
The SIXTH AND LAST DIALOGUE, entitled "POLA, or TIME," presents a
series of reflections, to which a view of the decaying amphitheatre
at Pola, an ancient town in the peninsula of Istria, is represented
as having given origin. On former occasions, the inspection of the
mouldering works of past ages called up trains of thought rather of
a moral than of a physical character; in the present dialogue, the
effects of time are considered in their relations to the mechanical
and chemical laws by which material forms are destroyed, or rather
changed,--for the author has shown by a number of beautiful
examples, that without decay there can be no reproduction, and that
the principle of change is a principle of life.
Having considered the influence of gravitation, the chemical
and mechanical agencies of water, air, and electricity, and the
energies of organized beings, in producing those diversified
phenomena which, in our metaphysical abstractions, we universally
refer to Time, he proceeds to enquire how far art can counteract
their operation. A great philosopher, he observes, has said, "Man
can in no other way command Nature but in obeying her laws:" it is
evident that, by the application of some of those principles which
she herself employs, we may for a while arrest the progress of
changes which are ultimately inevitable.
"Yet, when all is done that can be done in the work of
conservation, it is only producing a difference in the degree of
duration. It is evident that none of the works of a mortal can be
eternal, as none of the combinations of a limited intellect can
be infinite. The operations of Nature, when slow, are no less
sure; however man may, for a time, usurp dominion over her, she
is certain of recovering her empire. He converts her rocks, her
stones, her trees, into forms of palaces, houses, and ships; he
employs the metals found in the bosom of the earth, as instruments
of power, and the sands and clays which constitute its surface,
as ornaments and resources of luxury; he imprisons air by water,
and tortures water by fire to change, or modify, or destroy the
natural forms of things. But in some lustrums his works begin to
change, and in a few centuries they decay and are in ruins; and his
mighty temples, framed as it were for immortal and divine purposes,
and his bridges formed of granite and ribbed with iron, and his
walls for defence, and the splendid monuments by which he has
endeavoured to give eternity even to his perishable remains, are
gradually destroyed; and these structures, which have resisted the
waves of the ocean, the tempests of the sky, and the stroke of the
lightning, shall yield to the operation of the dews of heaven,--of
frost, rain, vapour, and imperceptible atmospheric influences;
and as the worm devours the lineaments of his mortal beauty, so
the lichens and the moss and the most insignificant plants shall
feed upon his columns and his pyramids, and the most humble and
insignificant insect shall undermine and sap the foundations of his
colossal works, and make their habitations amongst the ruins of his
palaces and the falling seats of his earthly glory."
On no occasion can such a subject be presented to a contemplative
mind, without filling it with awe and wonder; but the circumstances
under which these reflections are presented to us, in the
last days of our philosopher, impress upon them an almost
oracular solemnity. When we remember that while the mind of the
philosopher was thus engaged in identifying the processes of
decay with those of renovation in the system of nature, his body
was palsied, and the current of his life fast ebbing, we cannot
but admire that active intelligence which sparkled with such
undiminished lustre amidst the wreck of its earthly tenement.
In the extracts which have been introduced from this last work,
I trust the pledge that was given in the earlier part of these
memoirs, has been redeemed by showing that a powerful imagination
is not necessarily incompatible with a sound judgment, that the
flowers of fancy are not always blighted by the cold realities of
science, but that the poet and philosopher may, under the auspices
of a happy genius, mutually assist each other in expounding the
mysteries of nature. It cannot be denied, as a general aphorism,
that the tree which expands its force in flowers is generally
deficient in fruit; but the mind of Davy, to borrow one of his own
metaphors, may be likened to those fabled of the Hesperides, which
produced at once buds, leaves, blossoms, and fruits.
The happy effects resulting from this rare and nicely adjusted
combination of talents, offer themselves as interesting subjects
of biographical contemplation, and they can be studied only with
success by a comparative analysis of different minds.
That the superiority of Davy greatly depended upon the vivacity
and compass of his imagination cannot be doubted, and such an
opinion was well expressed by Mr. Davies Gilbert, in his late
address to the Society:--"The poetic bent of Davy's mind seems
never to have left him. To that circumstance I would ascribe the
distinguishing features in his character and in his discoveries:--a
vivid imagination sketching out new tracks in regions unexplored,
for the judgment to select those leading to the recesses of
abstract truth."
I have always thought that the mind of the late Dr. Clarke, the
Mineralogical Professor of Cambridge, was little less imaginative
than that of Davy; but it was deficient in judgment, and therefore
often conducted him to error instead of to truth. Dr. Black was not
deficient in imagination, and certainly not in judgment; but there
was a constitutional apathy, arising probably from ill health,
which damped his noblest efforts.[121]
[121] In addition to the anecdote already related of him, the
following may serve to give a still greater force to this
opinion. Soon after the appearance of Mr. Cavendish's paper on
hydrogen gas, in which he made an approximation to the specific
gravity of that body, showing that it was at least ten times
lighter than common air, Dr. Black invited a party of his
friends to supper, informing them that he had a curiosity to
show them. Dr. Hutton and several others assembled, when, having
the allentois of a calf filled with hydrogen gas, upon setting
it at liberty, it immediately ascended, and adhered to the
ceiling. The phenomenon was easily accounted for: it was taken
for granted that a small black thread had been attached to the
allentois,--that this thread passed through the ceiling, and that
some one in the apartment above, by pulling the thread, elevated
it to the ceiling, and kept it in that position. This explanation
was so probable, that it was acceded to by the whole company;
though, like many other plausible theories, it was not true;
for when the allentois was brought down, no thread whatever was
found attached to it. Dr. Black explained the cause of the ascent
to his admiring friends; but such was his unaccountable apathy,
that he never gave the least account of this curious experiment
even to his class; and more than twelve years elapsed before this
obvious property of hydrogen gas was applied to the elevation of
air balloons, by M. Charles, in Paris.
I am indebted for this anecdote to the "History of Chemistry," a
very able work by Dr. Thomson, constituting the third number of
the National Library.
It is by the rarity with which the talent of seizing upon remote
analogies is associated with a spirit of patient and subtile
investigation of details, and a quick perception of their value,
that the fact so truly stated by Mr. Babbage is to be explained;
_viz._ that long intervals frequently elapse between the discovery
of new principles in science and their practical application: thus
he observes, that "the principle of the hydrostatic paradox was
known as a speculative truth in the time of Stevinus, as far back
as the year 1600,--and its application to raising heavy weights has
long been stated in elementary treatises on natural philosophy,
as well as constantly exhibited in lectures; yet it may fairly be
regarded as a mere abstract principle, until the late Mr. Bramah,
by substituting a pump, instead of the smaller column, converted
it into a most valuable and powerful engine. The principle of the
convertibility of the centres of oscillation and suspension in the
pendulum, discovered by Huygens more than a century and a half
ago, remained, until within these few years, a sterile though most
elegant proposition; when, after being hinted at by Prony, and
distinctly pointed out by Bonenberger, it was employed by Captain
Kater as the foundation of a most convenient method of determining
the length of the pendulum. The interval which separated the
discovery of Dr. Black, of latent heat, from the beautiful and
successful application of it to the steam-engine, was comparatively
short; but it required the efforts of two minds; and both were of
the highest order."[122]
[122] "Reflections on the Decline of Science in England," page 15.
The discoveries of Davy present themselves in striking contrast
with such instances. The same powerful genius that developed the
laws of electro-chemical decomposition, was the first to apply them
for the purpose of obviating metallic corrosion; and the nature of
_fire-damp_, and the fact of its combustion being arrested in its
passage through capillary tubes, were alike the discoveries of him
who first applied them for the construction of a safety-lamp.[123]
[123] While upon this subject, it is impossible not to notice the
discoveries of Dr. Franklin, who combined in a remarkable degree
a fertile imagination with a solid judgment; and the fruit of
this union is to be seen in the invention of conductors for the
security of ships and buildings against the effects of lightning.
The philosopher who, predicating the identity of lightning and
electricity, conceived the bold and grand idea of drawing it
down from the thunder-cloud, an experiment which in another age
would have consigned him to the dungeon for impiety, or to the
stake for witchcraft, himself applied this wonderful discovery to
the preservation of buildings, by the invention of pointed rods
of iron. Of this invention it may be truly said, that he beat
Nature with her own weapons, and triumphed over her power by an
obedience to her own laws.
In contrasting the genius of Wollaston with that of Davy, let me
not be supposed to invite a comparison to the disparagement of
either, but rather to the glory of both, for by mutual reflection
each will glow the brighter. If the animating principle of
Davy's mind was a powerful imagination, generalizing phenomena,
and casting them into new combinations, so may the striking
characteristic of Wollaston's genius be said to have been an almost
superhuman perception of minute detail. Davy was ever imagining
something greater than he knew; Wollaston always knew something
more than he acknowledged:--in Wollaston, the predominant principle
was to avoid error; in Davy, it was the desire to discover truth.
The tendency of Davy, on all occasions, was to raise probabilities
into facts; while Wollaston as continually made them subservient to
the expression of doubt.
Wollaston was deficient in imagination, and under no circumstances
could he have become a Poet; nor was it to be expected that his
investigations should have led him to any of those comprehensive
generalizations which create new systems of philosophy. He well
knew the compass of his powers, and he pursued the only method by
which they could be rendered available in advancing knowledge.
He was a giant in strength, but it was the strength of Antæus,
mighty only on the earth. The extreme caution and reserve of his
manner were inseparably connected with the habits of his mind; they
pervaded every part of his character; in his amusements and in his
scientific experiments, he displayed the same nice and punctilious
observation,--whether he was angling for trout,[124] or testing for
elements,
[124] Sir Humphry Davy has told us an anecdote which well
illustrates this observation, while it affords a gratifying
testimony of the kind feeling he entertained towards a kindred
philosopher.--"There was--alas! that I must say _there was!_--an
illustrious philosopher, who was nearly of the age of fifty
before he made angling a pursuit, yet he became a distinguished
fly-fisher, and the amusement occupied many of his leisure hours,
during the last twelve years of his life. He indeed applied his
preeminent acuteness, his science, and his philosophy, to aid the
resources and exalt the pleasures of this amusement. I remember
to have seen Dr. Wollaston, a few days after he had become
a fly-fisher, carrying at his button-hole a piece of Indian
rubber, when by passing his silkworm link through a fissure in
the middle, he rendered it straight, and fit for immediate use.
Many other anglers will remember other ingenious devices of my
admirable and ever-to-be-lamented friend."--_Salmonia. Additional
Note_, Edit. 2. he alike relied for success upon his subtile
discrimination of minute circumstances.
By comparing the writings as well as the discoveries of these two
great philosophers, we shall readily perceive the intellectual
distinctions I have endeavoured to establish. "From their fruits
shall ye know them." The discoveries of Davy were the results of
extensive views and new analogies; those of Wollaston were derived
from a more exact examination of minute and, to ordinary observers,
scarcely appreciable differences. This is happily illustrated by a
comparison of the means by which each discovered new metals. The
alkaline bases were the products of a comprehensive investigation,
which had developed a new order of principles; the detection of
palladium and rhodium among the ores of platinum, was the reward
of delicate manipulation, and microscopic scrutiny. As chemical
operators, I have already pointed out their striking peculiarities,
and they will be found to be in strict keeping with the other
features of their respective characters. I might extend the
parallel farther; but Dr. Henry, in the eleventh edition of his
"System of Chemistry," has delineated the intellectual portraits of
these two philosophers with so masterly a hand, that by quoting the
passage, all farther observation will be rendered unnecessary.
"To those high gifts of nature, which are the characteristics of
genius, and which constitute its very essence, both those eminent
men united an unwearied industry and zeal in research, and habits
of accurate reasoning, without which even the energies of genius
are inadequate to the achievement of great scientific designs.
With these excellencies, common to both, they were nevertheless
distinguishable by marked intellectual peculiarities. Bold,
ardent, and enthusiastic, Davy soared to greater heights; he
commanded a wider horizon; and his keen vision penetrated to its
utmost boundaries. His imagination, in the highest degree fertile
and inventive, took a rapid and extensive range in pursuit of
conjectural analogies, which he submitted to close and patient
comparison with known facts, and tried by an appeal to ingenious
and conclusive experiments. He was imbued with the spirit, and
was a master in the practice, of the inductive logic; and he has
left us some of the noblest examples of the efficacy of that
great instrument of human reason in the discovery of truth. He
applied it, not only to connect classes of facts of more limited
extent and importance, but to develope great and comprehensive
laws, which embrace phenomena that are almost universal to the
natural world. In explaining those laws, he cast upon them the
illumination of his own clear and vivid conceptions;--he felt an
intense admiration of the beauty, order, and harmony, which are
conspicuous in the perfect Chemistry of Nature;--and he expressed
those feelings with a force of eloquence which could issue only
from a mind of the highest powers and of the finest sensibilities.
With much less enthusiasm from temperament, Dr. Wollaston was
endowed with bodily senses[125] of extraordinary acuteness and
accuracy, and with great general vigour of understanding. Trained
in the discipline of the exact sciences, he had acquired a powerful
command over his attention, and had habituated himself to the
most rigid correctness, both of thought and of language. He was
sufficiently provided with the resources of the mathematics, to be
enabled to pursue with success profound enquiries in mechanical and
optical philosophy, the results of which enabled him to unfold the
causes of phenomena not before understood, and to enrich the arts
connected with those sciences, by the invention of ingenious and
valuable instruments. In Chemistry, he was distinguished by the
extreme nicety and delicacy of his observations; by the quickness
and precision with which he marked resemblances and discriminated
differences; the sagacity with which he devised experiments and
anticipated their results; and the skill with which he executed
the analysis of fragments of new substances, often so minute as
to be scarcely perceptible by ordinary eyes. He was remarkable,
too, for the caution with which he advanced from facts to general
conclusions: a caution which, if it sometimes prevented him from
reaching at once to the most sublime truths, yet rendered every
step of his ascent a secure station, from which it was easy to rise
to higher and more enlarged inductions. Thus these illustrious men,
though differing essentially in their natural powers and acquired
habits, and moving, independently of each other, in different
paths, contributed to accomplish the same great ends--the evolving
new elements; the combining matter into new forms; the increase of
human happiness by the improvement of the arts of civilized life;
and the establishment of general laws, that will serve to guide
other philosophers onwards, through vast and unexplored regions of
scientific discovery."
[125] Mr. Babbage considers it as a great mistake to suppose
that Dr. Wollaston's microscopic accuracy depended upon the
extraordinary acuteness of the bodily senses; a circumstance,
he says, which, if it were true, would add but little to his
philosophical character. He is inclined to view it in a far
different light, and to see in it one of the natural results of
the precision of his knowledge and of the admirable training of
his intellectual faculties.
* * * * *
My history draws towards a conclusion.--Sir Humphry Davy, during
the latter days of his life, was cheered by the society and
affectionate attentions of his godson, the son of his old friend
Mr. James Tobin.[126] He had been the companion of his travels, and
he was the solace of his declining hours.
[126] This inestimable man died on his plantation at Nevis, on
the 19th of October 1814, in the forty-eighth year of his age.
He had been resident for some months at Rome, where he occupied
the second floor of a house in Via di Pietra, a street that leads
out of the Corso. During this period, he declined receiving any
visitors, and had constantly some one by his side reading light
works of interest to him, an amusement which was even continued
during his meals.
As soon as the account of Sir Humphry having sustained another
paralytic seizure was communicated to Lady Davy, who was in
London at the time, she immediately set off, and so rapidly was
her journey performed, that she reached Rome in little more than
twelve days. Dr. John Davy, also, hastened from Malta, on receiving
intelligence of his brother's imminent danger.
During his slow and partial recovery from this seizure, he
learnt the circumstance of his name having been introduced into
parliamentary proceedings, in the following manner. On the 26th
of March 1829, on presenting a petition in favour of the Catholic
claims from a very great and most respectable meeting at Edinburgh,
Sir James Mackintosh, after having mentioned the name of Sir
Walter Scott as being at the head of the petitioners, continued
thus:--"Although not pertinent to this petition, yet connected
with the cause, I indulge in the melancholy pleasure of adding to
the first name in British literature the first name in British
science--that of Sir Humphry Davy. Though on a sick-bed at Rome, he
was not so absorbed by his sufferings as not to feel and express
the glow of joy that shot across his heart at the glad tidings of
the introduction of a bill which he hailed as alike honourable to
his religion and his country."
I am assured that the last mark of satisfaction which he evinced
from any intelligence communicated to him was on reading the
above passage. He showed a pleasure unusual in his state of
languor at the justice thus done, in the face of his country, to
his consistency, to his zeal for religion and liberty, and to the
generous sentiments which cheered his debility. The marks of his
pleasure were observed by those who were brought most near to him
by the performance of every kind office.
Although there appeared some faint indications of reviving power,
his most sanguine friends scarcely ventured to indulge a hope
that his life would be much longer protracted. Nor did he himself
expect it. The expressions in his Will (printed in an Appendix)
sufficiently testify the opinion he had for some time entertained
of the hopelessness of his case.
In addition to this Will, he left a paper of directions, which have
been religiously observed by his widow. He desires, for instance,
that the interest arising from a hundred pounds stock may be
annually paid to the Master of the Penzance Grammar School, on
condition that the boys may have a holiday on his birthday.[127]
There is something singularly interesting in this favourable
recollection of his native town, and of the associations of his
early youth. It adds one more example to show that, whatever may
have been our destinies, and however fortune may have changed our
conditions, where the heart remains uncorrupted, we shall, as the
world closes upon us, fix our imaginations upon the simplicities of
our youth, and be cheered and warmed by the remembrance of early
pleasures, hallowed by feelings of regard for the memory of those
who have long since slept in the grave.
[127] I understand that the present Master, the Reverend Mr.
Morris, has expressed his intention to apply the above sum to
purchasing a medal, which he intends to bestow as a Prize to the
most meritorious scholar.
With that restlessness which characterises the disease under
which Sir Humphry Davy suffered, he became extremely desirous of
quitting Rome, and of establishing himself at Geneva. His friends
were naturally anxious to gratify every wish; and Lady Davy kindly
preceded him on the journey, in order that she might at each stage
make arrangements for his comfortable reception. Apartments were
prepared for him at _L'Hotel de la Couronne_, in the Rue du Rhone;
and at three o'clock on the 28th of May, having slept the preceding
evening at Chambery, he arrived at Geneva, accompanied by his
brother, Mr. Tobin, and his servant.
At four o'clock he dined, ate heartily, was unusually cheerful,
and joked with the waiter about the cookery of the fish, which he
appeared particularly to admire; and he desired that, as long as
he remained at the hotel, he might be daily supplied with every
possible variety that the lake afforded. He drank tea at eleven,
and having directed that the feather-bed should be removed, retired
to rest at twelve.
His servant, who slept in a bed parallel to his own, in the same
alcove, was however very shortly called to attend him, and he
desired that his brother might be summoned. I am informed that,
on Dr. Davy's entering the room, he said, "I am dying," or words
to that effect; "and when it is all over, I desire that no
disturbance of any kind may be made in the house; lock the door,
and let every one retire quietly to his apartment." He expired at a
quarter before three o'clock, without a struggle.
On the following morning, his friends Sismondi[128] and De Candolle
were sent for; and the Syndics, as soon as the circumstance of
his death was communicated to them, gave directions for a public
funeral on the Monday; at which the magistrates, the professors,
the English residents at Geneva, and such inhabitants as desired
it, were invited to attend. The ceremony was ordered to be
conducted after the custom of Geneva, which is always on foot--no
hearse; nor did a single carriage attend. The cemetery is at
Plain-Palais, some little distance out of the walls of the town.
The Couronne being at the opposite extremity, the procession was
long.
[128] Simond de Sismondi, the celebrated author of the History of
the Italian Republic.
The following was the order of the procession:--[129]
[129] For these particulars I am indebted to Sir Egerton Brydges.
The Two Syndics, (_in their robes_) { M. MASTOW,
{ M. GALLATIN.
Magistrates of the Republic, { M. FAZIO,
{ M. SALLADIN.
Professors of the College, in their robes,
MM. Simond de Sismondi--A. de Candolle.
THE ENGLISH.
Lord EGLINGTON,
Lord TWEDELL,
Right Hon. WM. WYCKHAM,
Capt. ARCHIBALD HAMILTON,
Mr. CAMPBELL,
Mr. FRANKS,
WM. HAMILTON, Esq., Ex-Ambassador at Naples.
Sir EGERTON BRYDGES, Bart.
Colonel ALCOCK,
Captain SWINTERS,
Mr. ALCOCK,
Mr. DREW,
Mr. HEYWOOD,
Mr. SITWELL,
&c.
The Students of the College.
The Citizens of Geneva.
The English service was performed by the Rev. John Magers, of
Queen's College, and the Rev. Mr. Burgess.
The grave was stated in the public prints to be next to that of his
friend the late Professor M. A. Pictet: this is not the fact. It is
far away from it, on the second line of No. 29, the fourth grave
from the end of the west side of the Cemetery.
* * * * *
Sir Humphry Davy having died without issue, his baronetcy has
become extinct.
At present, the only memorial raised to commemorate the name of
this distinguished philosopher is a Tablet placed in Westminster
Abbey by his widow. It is thus inscribed:--
TO THE MEMORY OF
SIR HUMPHRY DAVY, BARONET;
DISTINGUISHED THROUGHOUT THE WORLD
BY HIS
DISCOVERIES IN CHEMICAL SCIENCE.
PRESIDENT OF THE ROYAL SOCIETY;
MEMBER OF THE NATIONAL INSTITUTE OF FRANCE.
BORN 17 DECEMBER 1778, AT PENZANCE.
DIED 28 MAY 1829, AT GENEVA,
WHERE HIS REMAINS ARE INTERRED.
The numerous scientific societies of which he was a member, will,
no doubt, consecrate his memory. An eloquent Eloge has been read
by Baron Cuvier before the Institute of France; but it has not
yet been published: I have obtained, however, a copy of a speech
delivered upon the same occasion, by H. C. Van der Boon Mesch,
before the Institute of the Netherlands.
Mr. Davies Gilbert, his early friend and patron, has likewise paid
to his memory a just and appropriate testimony of respect and
admiration, in an address from the chair of the Royal Society.
The inhabitants of Penzance and its neighbourhood, animated by
feelings of honourable pride and strong local attachment, will
shortly, it is understood, raise a pyramid of massive granite to
his memory, on one of those elevated spots of silence and solitude,
where he delighted in his boyish days to commune with the elements,
and where the Spirit of Nature moulded his genius in one of her
wildest moods.
As yet, no intention on the part of the Government to commemorate
this great philosopher, by the erection of a national monument,
has been manifested: for the credit, however, of an age which is
so continually distinguished as the most enlightened period in our
history, I do hope the disgrace of such an omission may pass from
us; although, I confess, it is rather to be wished than expected,
when it is remembered that not a niche has been graced by the
statue of Watt, while the giant iron children of his inventive
genius are serving mankind in every quarter of the civilized world.
A very erroneous impression would seem to exist with regard to the
object and importance of such monuments. They are not to honour
the dead, but to improve the living; not to give lustre to the
philosopher, but to afford a salutary incentive to the disciple;
not to perpetuate discoveries, for they can never be lost; but
to animate scientific genius, and to engage it upon objects that
may be useful to the commonwealth. Let it be remembered, that
the ardour of the Roman youth was kindled into active emulation,
whenever they beheld the images of their ancestors.
"Nam sæpe audivi, Q. Maximum, P. Scipionem, præterea civitatis
nostræ præclaros viros, solitos ita dicere, cùm majorum imagines
intuerentur, vehementissimè sibi animum ad virtutem accendi.
Scilicet non ceram illam, neque figuram tantam vim in sese habere;
sed memoriâ rerum gestarum eam flammam egregiis viris in pectore
crescere, neque prius sedari, quàm virtus eorum famam atque gloriam
adæquaverit."[130]
[130] Sallust. Bell. Jugurth.
The fame of such a philosopher as Davy can never be exalted by any
frail memorial which man can raise. His monument is in the great
Temple of Nature.[131] His chroniclers are Time and the Elements.
The destructive agents which reduce to dust the storied urn, the
marble statue, and the towering pyramid, were the ministers of his
power, and their work of decomposition is a perpetual memorial of
his intelligence.
[131] [Greek: Andrôn gar epiphanôn pasa gê taphos, kai ou
stêlôn monon en tê oikeia sêmainei epigraphê, alla kai en tê mê
prosêkousê agraphos mnêmê par' hekastô tês gnômês mallon ê tou
ergou endiaitatai.--Thucydides, B. 43.]
A SKETCH OF THE HISTORY OF CHEMICAL SCIENCE, WITH A VIEW TO EXHIBIT
THE REVOLUTIONS PRODUCED IN ITS DOCTRINES BY THE DISCOVERIES OF SIR
HUMPHRY DAVY.
The rapidity with which chemical opinions have risen into
notice, flourished for a while, and then fallen into disrepute,
to be succeeded by others equally precarious in their tenure
and ephemeral in their popularity, are circumstances which the
superficial reasoner has ever deplored, and the Sciolist as
constantly converted into arguments against the soundness of the
science which produced them. The leaves of a season will sprout,
expand, and wither; and the dry foliage will be pushed off by
the propulsion of new buds; but this last change is not effected
in them, until they have absorbed the light and dews of heaven
for the nourishment of the plant that bore them; and when even
they shall have fallen to the earth, they will farther supply its
spreading roots with fresh soil for its future growth and healthy
developement; and entering into new combinations, will re-appear in
the same tree under fresh forms of usefulness and symmetry. In like
manner, chemical theories are but for a season; they are nothing
more than general expressions of known facts; they may delight by
their ingenuity, as vegetable forms captivate by their beauty, but
their real and substantial use is to extend science; and as facts
accumulate under their operation, they must give way to others
better adapted to the increased growth and expansion of knowledge;
nor does the utility of theories cease with their rejection,--they
afford objects of analogy and comparison which assist the
philosopher in his progress to truth, while their elements furnish
materials for future arrangements. Were it otherwise, we should
behold science in its advancement as a shapeless mass, enlarging by
constant appositions, but without a single sign of growth or inward
sympathy.
If chemical theories have undergone more rapid and frequent
changes than those of other branches, the circumstance has arisen
from the rapid manner in which new and important facts have been
successively added to the general store.
Whatever may be the vices attributed to Chemistry on such
occasions, they have belonged to the philosophers engaged in its
pursuit, and are no evidence of the frailty of the science itself;
and here it must be admitted, that there exists in one portion of
mankind a self-love which cannot patiently submit to a change of
opinions of which they are either the authors or defenders, while
in another there predominates a timidity which naturally leads
them, amidst the storm of controversy, to cling to the wreck of
a shattered theory, rather than to trust themselves to a new and
untried bark.
In our review of the history of Science, we have frequently to
witness how the wisest philosopher has strained truth, for the
support of a favourite doctrine, and measured and accommodated
facts to theory, instead of adapting theories to facts--but this
vice does not belong exclusively to chemical philosophers. Huygens,
the celebrated Dutch Astronomer, from some imaginary property
in the number _six_, having discovered _one_ of Saturn's moons,
absolutely declined looking for any more, merely because that one,
when added to the four moons of Jupiter, and to the one belonging
to the Earth, made up the required number.
Such reflections naturally arise on viewing, with a philosophic
eye, the progress and modifications of chemical opinions; and
it is essential that they should be duly appreciated upon the
present occasion; for, before any just estimate can be formed of
the talents and services of Sir Humphry Davy, we must thoroughly
consider, in all their bearings and relations, the various
prejudices with which he had to contend in his efforts to modify
a gigantic theory, which enjoyed an unrestrained dominion in the
chemical world, and for many years continued to be the pride of
France and the admiration of Europe.
It would be quite foreign to the plan of this sketch,[132] which
the reader must consider as wholly subservient to the object that
has been announced, to enquire how far the ancients, in their
metallurgical processes, can be said to have exercised the arts
of chemistry. Equally vain would it be to enter into a history of
that system of delusion and imposture, so long practised under the
denomination of Alchymy. It is only necessary to consider Chemistry
in its dignified and purely scientific form; and we have only to
notice those commanding discoveries and opinions which led to the
developement of that system, which the genius of Davy was destined
to modify.
[132] This historical sketch has no pretensions to originality.
It is compiled from the best authors, and from the Introduction
to Sir H. Davy's Elements of Chemical Philosophy.
The origin of Chemistry, as a science, cannot be dated farther
back than about the middle of the seventeenth century; and
Beccher, the contemporary of Boyle, who was born at Spires in
1635, was unquestionably the first to construct any thing like a
general theory. He formed the bold idea of explaining the whole
system of the earth by the mutual agency and changes of a few
elements. And by supposing the existence of a vitrifiable, a
metallic, and an inflammable earth, he attempted to account for
the various productions of rocks, crystalline bodies, and metallic
veins, assuming a continual interchange of principles between
the atmosphere, the ocean, and the solid surface of the globe,
and considering the operations of nature as all capable of being
imitated by art.
Albertus Magnus had advanced the opinion that the metals were
earthy substances impregnated with a certain inflammable principle;
but Beccher supported the idea of this principle not only as the
cause of metallization, but likewise of combustibility. Stahl,
however, one of the most extraordinary men that Germany ever
produced, having adopted and amplified this theory, carried off the
entire credit of being its founder, and it is universally spoken of
as the _Stahlian Theory_.
This theory forms so important a feature in the history of
chemistry, and so long maintained its ascendency in the schools,
that it will be necessary to give the reader a short summary of
its principles. It assumed that all _combustible_ bodies are
compounds: one of the constituents being volatile, and therefore
easily dissipated during the act of combustion; while the other,
being fixed, constantly remained as the residue of the process.
This volatile principle, for which Stahl invented the term
_Phlogiston_, was considered as being identical in every species
of combustible matter; in short, it was supposed that there was
but one principle of combustibility in nature, and that was the
imaginary phantom Phlogiston, which for nearly a century possessed
the schools of Europe, and, like an evil spirit, crossed the
path of the philosopher at every step, and by its treacherous
glare allured him from the steady pursuit of truth; for, whether
a substance were combustible or not, its nature could never be
investigated without a reference to its supposed relations with
Phlogiston; its presence, or its absence, was supposed to stamp a
character upon all bodies, and to occasion all the changes which
they undergo. Hence chemistry and combustion came to be in some
measure identified; and a theory of combustion was considered the
same thing as a theory of chemistry.
The identity of Phlogiston in all combustible bodies was founded
upon observations and experiments of so decisive a nature, that
after the existence of the principle itself was admitted, they
could not fail to be satisfactory. When phosphorus is made to
burn, it gives out a strong flame, much heat is evolved, and the
phosphorus is dissipated in fumes, which, if properly collected,
will quickly absorb moisture from the atmosphere, and produce
an acid liquid known by the name of phosphoric acid. Phosphorus
then must consist, say the Stahlians, of Phlogiston and this acid.
Again--If this liquid be evaporated to a dry substance, mixed with
a quantity of charcoal powder, and then heated in a vessel from
which the external air is excluded, a _portion_, or the _whole_ of
the charcoal will disappear, and phosphorus will be reproduced,
possessing all the properties that it had before it was subjected
to combustion. In this case, it was supposed that the charcoal
restored the phlogiston. There was much plausibility in all this,
as well as in the reasoning which followed. Since we may employ,
with equal success, any kind of combustible body for the purpose
of changing phosphoric acid into phosphorus, such as lamp-black,
sugar, resin, or even several of the metals, it was concluded that
all such bodies contain a common principle which they communicate
to the phosphoric acid; and since the new body formed is in all
cases identical, the principle communicated must also be identical.
Hence combustible bodies contain an identical principle, and this
principle is Phlogiston.
The same theory applied with equal force to the burning of sulphur
and several of the metals, and to their reconversion by combustible
bodies.
When lead is kept nearly at a red-heat in the open air for some
time, it is converted into a pigment called _red lead_; this is a
calx of lead. To restore this calx again to metallic lead, it is
only necessary to heat it in contact with almost any combustible
matter; all these bodies therefore must contain one common
principle, which they communicated to the red lead, and by so doing
reconverted it to the state of metal. Metals then were regarded
as compounds of _calces_ and phlogiston. Thus far the theory
works glibly enough; but now comes a startling fact, which was
long unnoticed by the blind adherents of Stahl, or, if noticed,
intentionally overlooked. It was observed very early, that when a
metal was converted into a calx, its weight was increased. When
this difficulty first forced itself upon the attention of the
Phlogistians, it was necessary that they should either explain it,
or at once abandon their theory. They accordingly endeavoured to
evade the difficulty, not only by asserting that phlogiston had no
weight, but that it was actually endowed with a principle of levity.
It was not possible, however, that any rational notions should
have been entertained upon the subject of combustion, at a
period when the composition of the atmosphere even was unknown.
Let us therefore follow the stream of discovery, skimming the
surface merely, as it flowed onward towards quite a new field of
science--Pneumatic Chemistry.
Boyle and Hooke, who had improved the air-pump invented by
Otto de Guericke, of Madenburgh, first used this apparatus for
investigating the properties of air; and they concluded from their
experiments that air was absolutely necessary to combustion and
respiration, and that one part of it only was employed in these
processes; and Hooke formed the sagacious conclusion, that this
principle is the same as the substance fixed in nitre, and that
combustion is a chemical process, the solution of the burning body
in elastic fluid, or its union with this matter.
Mayow, of Oxford, in 1674, published his treatises on the
Nitro-aërial spirit, in which he advanced opinions similar to those
of Boyle and Hooke, and supported them by a number of original and
curious experiments.
Dr. Hales, about 1724, resumed the investigations commenced with
so much success by Boyle, Hooke, and Mayow; and endeavoured to
ascertain the chemical relations of air to other substances, and
to ascertain by statistical experiments the cases in nature, in
which it is absorbed or emitted. He obtained a number of curious
and important results; he disengaged elastic fluids from various
substances, and drew the conclusion, that air was a chemical
element in many compound bodies, and that flame resulted from the
action and reaction of aërial and sulphurous particles; but all
his reasonings were contaminated with the notion of one elementary
principle constituting elastic matter, and modified in its
properties by the effluvia of solid or fluid bodies.
The light of Pneumatic science which had dawned under Hooke, Mayow,
and Hales, burst forth in splendour under the ascendency of that
constellation of British science, Black, Cavendish, and Priestley.
In 1756, Dr. Black published his researches on calcareous,
magnesian, and alkaline substances, by which he proved the
existence of a gaseous body, perfectly distinct from the air of
the atmosphere. He showed, that quick-lime differed from marble
and chalk by not containing this substance, which he proved to be
a weak acid, capable of being expelled from alkaline and earthy
bodies by stronger acids.
As nothing is more instructive than to enquire into the
circumstances which have led to a great discovery, I quote with
pleasure the following passage from Dr. Thomson's History of
Chemistry.
"It was the good fortune of chemical science that, at this time
(1751), the opinions of professors were divided concerning the
manner in which certain lithonthriptic medicines, particularly
lime-water, acted in alleviating the excruciating pains of the
stone and gravel. The students usually partake of such differences
of opinion: they are thereby animated to more serious study, and
science gains by their emulation.
"All the medicines which were then in vogue as solvents of calculi
had a greater or less resemblance to caustic potash or soda;
substances so acrid, when in a concentrated state, that in a short
time they reduce the fleshy parts of the animal body to a mere
pulp. They all seemed to derive their efficacy from quick-lime,
which again derived its power from the fire. It was therefore very
natural for them to ascribe its power to igneous matter imbibed
from the fire, retained by the lime, and communicated by it to
alkalies which it renders powerfully acrid. It appears from Dr.
Black's note-books, that he originally entertained the opinion,
that caustic alkalies acquired igneous matter from quick-lime. In
one of them, he hints at some way of catching this matter as it
escapes from lime, while it becomes mild by exposure to the air;
but on the opposite blank page is written, 'Nothing escapes--the
cup rises considerably by absorbing air.' A few pages further on,
he compares the loss of weight sustained by an ounce of chalk when
calcined, with its loss while dissolved in muriatic acid.
"These experiments laid open the whole mystery, as appears by
another memorandum. 'When I precipitate lime by a common alkali,
there is no effervescence: the air quits the alkali for the lime;
but it is lime no longer, but c. c. c: it now effervesces, which
good lime will not.'--What a multitude of important consequences
naturally flowed from this discovery! He now knew to what the
causticity of alkalies is owing, and how to induce it, or remove
it, at pleasure. The common notion was entirely reversed. Lime
imparts nothing to the alkalies; it only removes from them a
peculiar kind of air (_carbonic acid gas_) with which they were
combined, and which prevented their natural caustic properties
from being developed. All the former mysteries disappear, and the
greatest simplicity appears in those operations of nature which
before appeared so intricate and obscure."
Dr. Thomson afterwards observes,--"The discovery which Dr. Black
had made, that marble is a combination of lime and a peculiar
substance, to which he gave the name of _fixed air_, began
gradually to attract the attention of chemists in other parts of
the world. It was natural, in the first place, to examine the
nature and properties of this fixed air, and the circumstances
under which it is generated. It may seem strange and unaccountable
that Dr. Black did not enter with ardour into this new career
which he had himself opened, and that he allowed others to reap
the corn after having himself sown the grain. Yet he did take
some steps towards ascertaining the properties of _fixed air_;
though I am not certain what progress he made. He knew that a
candle would not burn in it, and that it is destructive to life,
when any living animal attempts to breathe it. He knew that it is
formed in the lungs during the breathing of animals, and that it
is generated during the fermentation of wine and beer. Whether
he was aware that it possesses the properties of an acid, I do
not know; though with the knowledge which he possessed that it
combines with alkalies and alkaline earths, and neutralizes them,
or at least blunts and diminishes their alkaline properties,
the conclusion that it partook of acid properties was scarcely
avoidable. All these, and probably some other properties of _fixed
air_, he was in the constant habit of stating in his lectures
from the very commencement of his academical career; though, as
he never published any thing on the subject himself, it is not
possible to know exactly how far his knowledge of the properties of
_fixed air_ extended. The oldest manuscript copy of his lectures
that I have seen was taken down in writing in the year 1773; and
before that time Mr. Cavendish had published his paper on _fixed
air_ and _hydrogen gas_, and had detailed the properties of each.
It was impossible from the manuscript of Dr. Black's lectures, to
know which of the properties of _fixed air_ stated by him were
discovered by himself, and which were taken from Mr. Cavendish."
An idea so novel and important as that of an air possessing
properties quite different from that of the atmosphere, existing in
a fixed and solid state in various bodies, was not received without
doubt, and even opposition. Several German enquirers endeavoured
to controvert it. Meyer attempted to show that limestone became
caustic, not by the emission of elastic matter, but by combining
with a peculiar substance in the fire; the loss of weight, however,
was wholly inconsistent with such a view of the question: and
Bergman at Upsal, Macbride in Ireland, Keir at Birmingham, and
Cavendish in London, fully demonstrated the truth of the opinion of
Black, and a few years were sufficient to establish his theory upon
an immutable foundation, and to open a new road to most important
discoveries.
The knowledge of one elastic fluid, entirely different in its
properties from air, very naturally suggested the probability of
the existence of others. The processes of fermentation which had
been observed by the ancient chemists, and those by which Hales
had disengaged and collected elastic substances, were now regarded
under a novel point of view; and the consequence was, that a number
of new bodies, possessed of very extraordinary properties, were
discovered.
Mr. Cavendish, about the year 1765, invented an apparatus for
examining elastic fluids confined by water, which has since been
called the _hydro-pneumatic_ apparatus. He discovered inflammable
air, and described its properties; he ascertained the relative
weights of fixed air, inflammable air, and common air, and made a
number of beautiful and accurate experiments on the properties of
these elastic substances.
Dr. Priestley, in 1771, entered the same path of enquiry; and
principally by repeating the processes of Hales, added a number of
most important facts to this department of chemical philosophy. He
discovered nitrous air, nitrous oxide, and dephlogisticated air,
(oxygen) and by substituting mercury for water in the pneumatic
apparatus, ascertained the existence of several aëriform bodies
which are rapidly absorbable by water; such as muriatic acid gas,
sulphurous acid gas, and ammonia.
Scheele, independently of Priestley, also discovered several of the
aëriform bodies; he ascertained likewise the composition of the
atmosphere; he brought to light fluoric acid, prussic acid, and
the substance which he termed _dephlogisticated marine acid_, the
oxy-muriatic acid of the French school, and the chlorine of Davy.
Sir Humphry Davy, in the preface to his Chemical Philosophy,
observes that Black, Cavendish, Priestley, and Scheele, were
undoubtedly the greatest chemical discoverers of the eighteenth
century; and that their merits are distinct, peculiar, and of the
most exalted kind. He thus defines them:
"BLACK made a smaller number of original experiments than either of
the other philosophers; but being the first labourer in this new
department of the science, he had greater difficulties to overcome.
His methods are distinguished for their simplicity; his reasonings
are admirable for their precision; and his modest, clear, and
unaffected manner is well calculated to impress upon the mind a
conviction of the accuracy of his processes, and the truth and
candour of his researches.
"CAVENDISH was possessed of a minute knowledge of most of the
departments of Natural Philosophy: he carried into his chemical
researches a delicacy and precision, which have never been
exceeded: possessing depth and extent of mathematical knowledge,
he reasoned with the caution of a geometer upon the results of his
experiments; and it may be said of him, what, perhaps, can scarcely
be said of any other person, that whatever he accomplished, was
perfect at the moment of its production. His processes were all of
a finished nature; executed by the hand of a master, they required
no correction; the accuracy and beauty of his earliest labours even
have remained unimpaired amidst the progress of discovery, and
their merits have been illustrated by discussion and exalted by
time.
"DR. PRIESTLEY began his career of discovery without any general
knowledge of chemistry, and with a very imperfect apparatus. His
characteristics were ardent zeal and the most unwearied industry.
He exposed all the substances he could procure to chemical
agencies, and brought forward his results as they occurred, without
attempting logical method or scientific arrangement. His hypotheses
were usually founded upon a few loose analogies; but he changed
them with facility; and being framed without much effort, they
were relinquished with little regret. He possessed in the highest
degree ingenuousness and the love of truth. His manipulations,
though never very refined, were always simple, and often ingenious.
Chemistry owes to him some of her most important instruments of
research, and many of her most useful combinations; and no single
person ever discovered so many new and curious substances.
"SCHEELE possessed in the highest degree the faculty of invention;
all his labours were instituted with an object in view, and after
happy or bold analogies. He owed little to fortune or to accidental
circumstances: born in an obscure situation, occupied in the duties
of an irksome employment, nothing could damp the ardour of his
mind, or chill the fire of his genius; with very small means, he
accomplished very great things. No difficulties deterred him from
submitting his ideas to the test of experiment. Occasionally misled
in his views, in consequence of the imperfection of his apparatus,
or the infant state of the enquiry, he never hesitated to give
up his opinions the moment they were contradicted by facts. He
was eminently endowed with that candour which is characteristic
of great minds, and which induces them to rejoice as well in the
detection of their own errors, as in the discovery of truth. His
papers are admirable models of the manner in which experimental
research ought to be pursued; and they contain details on some of
the most important and brilliant phenomena of chemical philosophy."
The discovery of the gases, of a new class of bodies more active
than any others in most of the phenomena of nature and art, could
not fail to modify the whole theory of chemistry, and, under the
genius of Lavoisier, it ultimately led to the establishment of
those new doctrines, which it is the principal object of this
history to expound; but before this task can be accomplished, it
will be necessary to consider the rise and progress of opinion
concerning chemical attraction, and heat and light, since these
subjects are too intimately interwoven with the _anti-phlogistic_
system to be separated from any examination of its principles.
Boyle, says Sir Humphry Davy, was one of the most active
experimenters, and certainly the greatest chemist of his age. He
introduced the use of _tests_, or _re-agents_, active substances
for detecting the presence of other bodies: he overturned the ideas
which at that time were prevalent, that the results of operations
by fire were the real elements of things; and he ascertained a
number of important facts respecting inflammable bodies, and
alkalies, and the phenomena of combination; but neither he nor any
of his contemporaries endeavoured to account for the changes of
bodies by any fixed principles.
The solutions of the phenomena were attempted either on rude
mechanical notions, or by occult qualities, or peculiar subtile
spirits or ethers, supposed to exist in the different bodies. And
it is to the same great genius who developed the laws that regulate
the motions of the heavenly bodies, that chemistry owes the first
distinct philosophical elucidations of the powers which produce the
changes and apparent transmutations of the substances belonging to
the earth.
"Sugar dissolves in water, alkalies unite with acids, metals
dissolve in acids. Is not this," says Newton, "on account of an
attraction between their particles? Copper dissolved in aqua fortis
is thrown down by iron. Is not this because the particles of the
iron have a stronger attraction for the particles of the acid, than
those of copper; and do not different bodies attract each other
with different degrees of force?"
In 1719, Geoffroy endeavoured to ascertain the relative attractive
powers of bodies for each other, and to arrange them, under the
form of a table, in an order in which these forces, which he named
affinities, were expressed.
Concerning the nature of heat, there are two opinions which have
ever divided the chemical world. The one considers it merely as a
property of matter, and that it consists in an undefinable motion,
or vibration of its particles; the other, on the contrary, regards
it as a distinct and subtile substance, _sui generis_. Each of
these opinions has been supported by the greatest philosophers,
and for a long period the arguments on both sides appeared equally
plausible and forcible. The discovery of Dr. Black, however, gave a
preponderance to the scale in favour of its materiality.
"It was during his residence in Glasgow, between the year 1759
and 1763," says Dr. Thomson, "that he brought to maturity those
speculations concerning the combination of _heat_ with _matter_,
which had frequently occupied a portion of his thoughts."
Before Dr. Black's discovery, it was universally supposed that
solids were converted into liquids by a small addition of heat,
after they have been once raised to the melting point, and
that they returned again to the solid state on a very small
diminution of the quantity of heat necessary to keep them at
that temperature. An attentive view, however, of the phenomena
of liquefaction and solidification gradually led this sagacious
philosopher to a different conclusion. By observations which
it is unnecessary to detail, he became satisfied that when ice
is converted into water, it unites with a quantity of heat,
without having its temperature increased; and that when water
is frozen into ice, it gives out a quantity of heat without
having it diminished. The heat thus combined, then, is the cause
of the fluidity of the water; and as it is not sensible to the
thermometer, Dr. Black called it _latent heat_.
There is such an analogy between the cessation of thermometric
expansion during the liquefaction of ice, and during the conversion
of water into steam, that there could be no hesitation about
explaining both in the same way. Dr. Black, therefore, immediately
concluded that, as water is ice united to a certain quantity of
_latent_ heat, so steam is water united to a still greater quantity.
This beautiful theory enables us to understand phenomena in nature
which were previously quite inexplicable. We now comprehend how the
thaw which supervenes after intense frost, should so slowly melt
the wreaths of snow and beds of ice. Had, indeed, the transition
of water from its solid into its liquid state not been accompanied
by this great change in its relation to heat, every thaw would
have occasioned a frightful inundation, and a single night's frost
must have solidified our rivers and lakes. Neither animal nor
vegetable life could have subsisted under such sudden and violent
transitions. It would appear, then, that water, during the act of
freezing, is acted upon by two opposite powers: it is deprived of
heat by exposure to a medium whose temperature is below 32°; and
it is supplied with heat by the evolution of that principle from
itself, _viz._ of that portion which constituted its fluidity. As
these powers are exactly equal, the temperature of the water must
remain unchanged till the latent heat, necessary to its fluidity,
is all evolved.
Although these facts have been admitted by all, it has been
contended by many that the absorption of heat by bodies is the
necessary _effect_, and not the efficient _cause_, of change of
form,--the consequence of what has been called a change of their
_capacity_: thus ice, it is supposed, in becoming water, has its
capacity for heat increased, and the absorption of heat is a
consequence of such increased capacity. This theory, however, is
deficient, inasmuch as it fails to explain the cause of that change
of form, which is assumed to account for the increase of capacity.
Light, like heat, has been considered by some philosophers as a
subtile fluid filling space, and rendering bodies visible by the
undulations into which it is thrown; while others, with Newton at
their head, regard it as a substance consisting of small particles,
constantly separating from luminous bodies, moving in straight
lines, and rendering objects visible by passing from them and
entering the eye. The late experiments of Dr. Young would incline
us to prefer the undulatory to the corpuscular hypothesis.
By this preliminary sketch, the reader has been prepared for
viewing with advantage the theory of Lavoisier; in the construction
of which he will see little more than a happy generalization of
the several discoveries which have been enumerated. Indeed, this
observation will apply to all great systems of philosophy; facts,
developed by successive enquirers, go on accumulating, until, after
an interval, a happy genius arises who connects and links them
together; and thus generally receives that meed of praise which, in
stricter justice, would be apportioned and awarded to the separate
contributors. It is far from my intention to disparage the merits
of Lavoisier; but the materials of his system were undoubtedly
furnished by Black, Priestley, and Cavendish.
The most important modification of the phlogistic theory--for
there were several others--may be said to be that suggested by
Dr. Crawford. Dr. Priestley had found that the air in which
combustibles were suffered to burn till they were extinguished,
underwent a very remarkable change, for no combustible would
afterwards burn in it, and no animal could breathe it without
suffocation. Dr. Crawford, like many others, concluded, that this
change was owing to phlogiston; but he for the first time applied
Dr. Black's doctrine of _latent_ heat, for the explanation of the
origin of the heat and light which appear during the process.
According to this philosopher, the phlogiston of the combustible
combines, during combustion, with the air, and at the same time
separates the caloric and light with which that fluid had been
previously united. The heat and the light, then, which appear
during combustion, exist previously in the air. This theory was
very different from Stahl's, and certainly a great deal more
satisfactory; but still the question--_What is phlogiston?_
remained to be answered.
Mr. Kirwan attempted to answer it, and to prove that phlogiston is
no other than hydrogen.
This opinion, which Mr. Kirwan informs us was first suggested
by the discoveries of Dr. Priestley, met with a very favourable
reception from the chemical world, and was adopted, amongst many
others, by Mr. Cavendish. The object of Mr. Kirwan was to prove,
that hydrogen exists as a component part of every combustible body;
that during combustion it separates from the combustible body, and
combines with the oxygen of the air. At the same time, Lavoisier
was engaged in examining the experiment of Bayen, and those of
the British philosophers. Bayen, in 1774, had shown that mercury
converted into a calx, or earth, by the absorption of air, could
be revived without the addition of any inflammable substance; and
hence he concluded, that there was no necessity for supposing
the existence of any peculiar principle of inflammability, in
order to account for the calcination of metals; but he formed no
opinion respecting the nature of the air produced from the _calx_
of mercury. Lavoisier, in 1775, showed that it was an air, which
supported flame and respiration better than common air, which he
afterwards named oxygen: the same substance that Priestley and
Scheele had procured from other metallic bodies the year before,
and had particularly described.
Lavoisier also discovered that the same air is produced during the
revivification of metallic calces by charcoal, as that which is
emitted during the calcination of limestones; hence he concluded,
that this elastic fluid is composed of oxygen and charcoal: and
from his experiments on nitrous acid and oil of vitriol, he also
inferred that this gas entered into the composition of these
substances.
Lavoisier was now enabled to explain the phenomena of combustion,
without having recourse, to phlogiston: a principle merely supposed
to exist, because combustion could not be explained without it.
His new theory depends upon the two laws discovered by himself
and Dr. Black; _viz._ that when a combustible is raised to a
certain temperature, it begins to combine with the oxygen of the
atmosphere, and that this oxygen during its condensation lets go
the _latent_ caloric, and the light with which it was combined
while in the gaseous state. Hence their appearance during every
combustion. Hence also the change which the combustible undergoes
in consequence of combustion.
It followed from this view, that the metallic _calces_ were
combinations of metals with oxygen; and on examining the products
of certain inflammable bodies, and finding them to be acid, the
conclusion was extended by a plausible analogy to other acids whose
bases were unknown, and the general proposition was established
that oxygen was the universal principle of acidity; that acids
resulted from the union of a peculiar combustible base, called the
_radical_, with the common principle, oxygen, technically termed
the _acidifier_.
These views, regarding the phenomena of combustion and
acidification, may be considered as constituting what has been
termed the _Anti-phlogistic system_.
It was some time, however, after this system was promulgated,
before its author was able to gain a single convert, notwithstanding
his unwearied assiduity, and the great weight which his
talents, his reputation, his fortune, and his situation
naturally gave him.
At length, M. Berthollet, at a meeting of the Academy of Sciences
in 1785, solemnly renounced his old opinions, and declared himself
a convert. Fourcroy followed his example; and two years afterwards
Morveau, during a visit to Paris, was prevailed upon to embrace the
new doctrine.
The theory of Lavoisier, soon after it had been framed, received
an important confirmation from the two grand discoveries of Mr.
Cavendish, respecting the composition of water and nitric acid,
and the elaborate and beautiful investigations of Berthollet into
the nature of ammonia; by which, phenomena, before anomalous, were
shown to depend upon combinations of aëriform matter.
The notion of phlogiston, however, was still defended with
remarkable tenacity by many distinguished philosophers. Mr.
Kirwan, who considered hydrogen as the universal principle of
combustibility, undertook to prove that this element entered into
the composition of every body of the kind: a single exception, of
course, must necessarily prove fatal to the theory. Mr. Kirwan,
fortunately for the French chemists, founded his reasonings on the
inaccurate experiments of other chemists; and thus did he promote
the popularity of the anti-phlogistic system by the weakness of the
arguments by which he assailed it.
Lavoisier and his associates saw at once the important uses which
might be made of this essay: by refuting an hypothesis which had
been embraced by the most respectable chemists in Europe, their
cause would receive an _éclat_ which would make it irresistible.
The essay was accordingly translated into French, and each of the
sections into which it was divided was accompanied by a refutation.
Four of the sections were refuted by Lavoisier, three by
Berthollet, three by Fourcroy, two by Morveau, and one by Monge.
Mr. Cavendish, in a paper communicated to the Royal Society in
the year 1784, drew a comparison between the phlogistic and
anti-phlogistic theories, and showed that each of them was capable
of explaining the phenomena in a satisfactory manner; he however,
at the same time, gave the reasons which induced him to prefer the
earlier view. In the execution of this task, unlike Mr. Kirwan, he
never advanced a single opinion which he had not put to the test of
experiment; and he never suffered himself to go any farther than
his experiments would warrant. This paper, therefore, the French
chemists were unable to refute, and they were accordingly wise
enough to pass it over without notice. Had it been possible to have
preserved the phlogistic hypothesis, Mr. Cavendish would have saved
it--
"Si Pergama dextrâ
Defendi possent, etiam hâc defensa fuissent."
"Sooner or later," says Sir Humphry Davy, "that doctrine which
is an expression of facts, must prevail over that which is an
expression of opinion. The most important part of the theory of
Lavoisier was merely an arrangement of the facts relating to the
combinations of oxygen: the principle of reasoning which the French
school professed to adopt was, that every body which was not yet
decompounded, should be considered as simple; and though mistakes
were made with respect to the results of experiments on the nature
of bodies, yet this logical and truly philosophical principle was
not violated; and the systematic manner in which it was enforced
was of the greatest use in promoting the progress of science."
Till 1786, there had been no attempt to reform the nomenclature of
chemistry; the names applied by discoverers to the substances which
they made known were still employed. Some of these names, which
originated amongst the alchymists, were of the most barbarous kind;
few of them were sufficiently definite or precise, and most of them
were founded upon loose analogies, or upon false theoretical views.
"It was felt by many philosophers, particularly by the illustrious
Bergman, that an improvement in chemical nomenclature was
necessary; and in 1787, MM. Lavoisier, Morveau, Berthollet, and
Fourcroy, presented to the world a plan for an almost entire change
in the denomination of chemical substances, founded upon the idea
of calling simple bodies by some names characteristic of their
most striking qualities, and of naming compound bodies from the
elements which composed them." There was, besides, a secret feeling
in the breasts of the associated chemists, which, no doubt, had its
influence in suggesting and promoting such a scheme. The views of
Lavoisier had so changed the face of chemistry, as almost to have
rendered it a new science: by adopting a new nomenclature, they
identified, as it were, all the discoveries of the day with the new
theory, and thus appropriated to France the original and entire
merit of the system.
It is impossible to pass over this subject without a comment.
Lavoisier was unquestionably indebted to Dr. Black for the support,
if not for the suggestion, of the most brilliant part of his theory
of combustion; and yet he attempted even to conceal the name of the
discoverer of _latent heat_.
How far Lavoisier was really culpable, and whether he did not
intend to do full justice to all the claims of his predecessors,
cannot now be known; as he was cut off in the midst of his career,
while so many of his scientific projects remained unexecuted.
From the posthumous works of Lavoisier, there is some reason for
believing that, if he had lived, he would have done justice to
all parties; but there is no doubt that Dr. Black, in the mean
time, thought himself aggrieved by the publication of several
of Lavoisier's papers in the "Mémoires de l'Académie," and that
he formed the intention of doing himself justice, by publishing
an account of his own discoveries: this intention, however, was
unfortunately thwarted and prevented by bad health. But to return
to the subject of nomenclature. Sir H. Davy continues--"The
new nomenclature was speedily adopted in France; under some
modifications, it was received in Germany; and, after much
discussion and opposition, it became the language of a new and
rising generation of chemists in England. It materially assisted
the diffusion of the anti-phlogistic doctrine, and even facilitated
the general acquisition of the science; and many of its details
were contrived with much address, and were worthy of its celebrated
authors."
On the general adoption of this new theory of chemistry, it must be
admitted that its authors displayed an intemperate triumph wholly
unworthy of them. They held a festival, at which Madame Lavoisier,
in the habit of a priestess, burnt the works of Stahl on an altar
erected for the occasion, while solemn music played a requiem to
his departed system!
Sir Humphry Davy, in speaking of the merits of Lavoisier,
observes that "he must be regarded as one of the most sagacious
of the chemical philosophers of the last century; indeed, except
Cavendish, there is no other enquirer who can be compared to him
for precision of logic, extent of view, and sagacity of induction.
His discoveries are few, but he reasoned with extraordinary
correctness upon the labours of others. He introduced weight and
measure, and strict accuracy of manipulation into all chemical
processes. His mind was unbiassed by prejudice; his combinations
were of the most philosophical nature; and in his investigations
upon ponderable substances, he has entered the true path of
experiment with cautious steps, following just analogies, and
measuring hypotheses by their simple relations to facts."
It will be scarcely possible for a future generation of
philosophers to imagine with what an undisciplined ardour the
anti-phlogistic system, thus enhanced by a new and fascinating
nomenclature, was supported throughout Europe. Facts only were
appreciated in proportion to the evidence they furnished of its
truth; and a discovery even required the sanction of its authority
as the passport to notice and regard. The least expression of
doubt, as to the validity of any point in its doctrines, exposed
the sceptic to a host of assailants, and fortunate was he if he
escaped the fate of Peter Ramus, or of those who ventured to
question the infallibility of that great despot of another age,
Aristotle.
In no country of Europe did this feeling manifest itself to a
greater extent than in England. There was perhaps a political
prejudice co-operating upon the occasion: it is very difficult,
under any circumstances, to avoid connecting the man and his
works. The fate of Lavoisier[133] was truly affecting, and by a
species of retributive justice, he received the sympathy of the
world in the homage paid to his system; while the atrocity of
his assassination, on which every Englishman dwelt with horror,
appeared to be thus heightened by every praise bestowed upon his
merits.
[133] Lavoisier perished on the scaffold at the age of
fifty-one, during the sanguinary reign of Robespierre. The
fury of the revolutionary leaders of France was particularly
directed against the farmers-general of the revenue, who were
all executed, with the exception of a single individual, a M.
de Verdun. Sixty of them were guillotined at the same time,
in consequence of a report of Dupin, a frantic member of the
Convention. The revolutionary tribunal adopted a general formula,
as the ground of their condemnation, which is curious as applied
to Lavoisier, who was declared guilty of having "adulterated
snuff with water and ingredients destructive of the health of
the citizens." The unfortunate philosopher requested time to
complete some experiments on respiration. The reply of Coffinhal,
the President, was, that "the Republic did not want savans or
chemists, and that the course of justice could not be suspended."
It is not the least surprising circumstance in the history of
this system, that with such a blind and idolatrous admiration of
its principles, so few facts should have been distorted. It is
true that, from the belief that combustion could never take place
without the presence of oxygen, the elementary principle of Scheele
became, according to these views, a compound of oxygen and an acid;
and the name of _dephlogisticated marine acid_ was exchanged for
that of _oxy-muriatic acid_, a circumstance which spread a cloud
of error over the science, and perhaps retarded its progress in
a greater degree than is generally imagined. In like manner, the
chemist neglected to avail himself of the hint which, under other
impressions, would have proved an important clue to discovery,
_viz._ the acid properties of sulphuretted hydrogen.
We have now arrived at that stage in our history, when it may with
propriety and advantage be asked--WHAT HAS DAVY DONE IN CORRECTING
ERROR, OR IN ADVANCING TRUTH?
The answer to this question will be nothing more than a summary of
those discoveries which have been successively investigated during
the progress of the present work.
The new doctrines of chemistry were highly instrumental in
encouraging more extended investigations into all the different
productions of nature and art; and we may observe, that one of the
first efforts of Sir Humphry Davy was to improve our knowledge of
the nature and habitudes of the tanning and astringent principles
of vegetables,--an enquiry which had been commenced by Seguin and
Proust. In pursuing even the most beaten path, he was sure to
discover objects of novelty. Look at his early experiments on the
cane, and on the straw of wheat, barley, and hay, and we shall see
how magically he raised from their ashes a new flower of knowledge.
He soon, however, quitted the track of other experimentalists;
although we learn from the whole tenor of his researches, that he
could obey as well as he could command, and he could act in the
ranks, although he more frequently appeared as a general in the
field of science.
Sir Humphry Davy has observed, that "at the time when the
anti-phlogistic theory was established, electricity had little or
no relation to chemistry. The grand results of Franklin respecting
the cause of lightning, had led many philosophers to conjecture,
that certain chemical changes in the atmosphere might be connected
with electrical phenomena; and electrical discharges had been
employed by Cavendish, Priestley, and Van-Marum, for decomposing
and igniting bodies; but it was not till the era of the wonderful
discovery of Volta, in 1800, of a new electrical apparatus, that
any great progress was made in chemical investigation by means of
electrical combinations.
"Nothing tends so much to the advancement of knowledge as the
application of a new instrument. The native intellectual powers of
men in different times are not so much the causes of the different
success of their labours, as the peculiar nature of the means and
artificial resources in their possession. Independent of vessels of
glass, there could have been no accurate manipulations in common
chemistry: the air-pump was necessary for the investigation of the
properties of gaseous matter; and without the Voltaic apparatus,
there was no possibility of examining the relations of electrical
polarities to chemical attractions."
There is a candour in this statement which we cannot but admire.
Nor does the admission diminish the glory of him who, by the
application of such new instruments of research, was enabled to
penetrate into the hidden mysteries of Nature. What avails the
telescope, without the eye of the observer?
To Davy, the Voltaic apparatus was the _golden branch_, by which
he subdued the spirits that had opposed the advance of former
philosophers; but what would its possession have availed him, had
not his genius, like the ancient Sibyl, pointed out its use and
application?
It will be seen that he was thus enabled, not only to discover laws
which are in constant operation, modifying the forms of matter, and
influencing all the operations of chemistry, but, by applying them,
to determine the elements of the fixed alkalies to be oxygen and a
metallic base: a fact obviously opposed to the idea of oxygen being
the general principle of acidity; for here it was the principle
of alkalinity, if it may be so expressed. This was shaking the
corner-stone of the edifice, and his subsequent researches into
the nature of oxy-muriatic acid may be said to have overthrown it;
for if either of the elements of this body can be considered as
the acidifier, it is hydrogen. The consequences which flowed from
this truth were of the highest importance, not only in correcting
errors, which the progress of discovery, instead of rectifying,
was actually multiplying, but in leading to the developement of
new bodies. Iodine might have been recognised as an elementary
body; but its relations to oxygen and hydrogen would probably have
remained unknown, had not a knowledge of the true character of
chlorine assisted the enquiry.
The same observation will apply to the recently discovered body,
Bromine. In like manner has the chemist been led, by the chloridic
theory, to a more accurate acquaintance with the composition of
the fluoric, hydriodic, and hydrocyanic acids; while he has also
learnt that hydrogen alone can convert certain undecompounded bases
into well characterised acids, without the aid of oxygen. The same
discovery has completely changed all our opinions with regard to
a very important series of saline combinations, and developed the
existence of new compounds of a most interesting description.
Thus, then, has the _acidifying_ hypothesis of Lavoisier been
overturned, and a new theory constructed out of its ruins, which
acknowledges no distinct element as the one imparting to matter the
characters of an acid.
Equally complete has been the downfall of the theory of combustion.
The discovery of the true nature of chlorine was, in itself,
sufficient to show that bodies might combine, with the phenomena
of heat and light, without the presence of oxygen; but Davy has
brought a mass of evidence from other sources in proof of the
same truth. He has shown that, whenever the chemical forces which
determine either composition or decomposition are energetically
exercised, the phenomena of combustion, or incandescence, with a
change of properties, are displayed. He has therefore annulled the
distinction between supporters of combustion and combustibles,
since he has shown that, in fact, one substance frequently acts in
both capacities, being a supporter _apparently_ at one time, and a
combustible at another. But in both cases the heat and light depend
on the same cause, and merely indicate the energy and rapidity
with which reciprocal attractions are exerted. Thus sulphuretted
hydrogen is a combustible with oxygen and chlorine; a supporter
with potassium. Sulphur, with chlorine and oxygen, has been called
a combustible basis; with metals, it acts the part of a supporter.
In like manner, potassium unites so powerfully with arsenic and
tellurium, as to produce the phenomena of combustion. Nor can
we ascribe the appearances to the liberation of latent heat, in
consequence of condensation of volume. The protoxide of chlorine,
a body destitute of any combustible constituent, at the instant of
decomposition evolves light and heat with explosive violence; and
its volume becomes one-fifth greater. Chloride and iodide of azote,
compounds alike destitute of any inflammable matter, according to
the ordinary belief, are resolved into their respective elements
with tremendous force of inflammation; and the first expands
into more than six hundred times its bulk. Now, instead of heat
and light, a prodigious degree of _cold_ ought to accompany such
an expansion, according to the hypothesis of latent heat. Other
instances might be cited, and other arguments adduced on the same
subject, but time and space fail me.[134]
[134] The reader who wishes for further details, will consult
with advantage the article Combustion in Dr. Ure's Dictionary of
Chemistry; a work to which I acknowledge myself much indebted on
this and other occasions.
Such, then, are the facts developed by the experimental researches
of Sir Humphry Davy; from which it follows, that--
1. Combustion is not necessarily dependent on the agency of oxygen.
2. That it cannot be regarded as dependent upon any peculiar
principle or form of matter, but must be considered as a general
result of intense chemical action.
3. That the evolution of light and heat cannot be ascribed simply
to a gas parting with its latent store of those ethereal fluids.
4. That, since all bodies which act powerfully upon each other are
in the opposite electrical relations of positive and negative, the
evolution of heat and light may depend upon the annihilation of
these opposite states, which will happen whenever they combine.
Thus has Sir H. Davy, by refuting the opinions of the French
philosophers, respecting the relations of oxygen to the phenomena
of combustion, and the nature of its products, removed the pillars
on which the fabric of the anti-phlogistic rested, and reduced the
generalization of Lavoisier to isolated collections of facts; the
sound logic, however,--the pure candour, the numerical precision of
inference which characterise the labours of the French philosopher,
will cause his name to be held in everlasting admiration. The
downfall of his doctrine is the natural result of the progress of
truth; the same fate may attend our present systems, but the facts
discovered through their means are unchangeable and eternal; and
it is upon them alone that the fame of the chemist must ultimately
rest.
In sciences collateral to chemistry, the researches of Davy
have cast a reflected lustre. In geology, his discovery of the
composition of the earths, has opened a new path of investigation;
while his examination of the water and gaseous matter so frequently
enclosed in the cavities of quartz, has given no small degree of
support to the hypothesis of the Plutonists; above all, his results
connected with the decomposition and transfer of different elements
by Voltaic influence, has already explained many phenomena relating
to metallic veins; and the late researches of Mr. Fox must lead us
to the conclusion, that electric powers are still in operation in
the recesses of the earth; and that mineral veins are not only the
cabinets of Nature, but still her active laboratories.
These cursory observations upon the discoveries of Sir H. Davy
relate merely to the changes they have effected in the general
theory of chemistry. I might recapitulate the numerous researches
by which he has extended our knowledge upon particular subjects;
but I have so fully entered into the consideration of them in the
body of my work, that I consider such a tax upon the patience of my
reader would be both unfair and unnecessary.
I shall therefore _conclude_ my long and arduous labour,
by enumerating the different memoirs communicated by this
distinguished philosopher to the Royal Society; and also the
several works which he published at different periods of his
brilliant but too fleeting career.
1. An Account of some Galvanic Combinations, formed by single
metallic plates and fluids, analogous to the Galvanic Apparatus
of M. Volta.
_Read June 18, 1801._
2. An Account of some Experiments and Observations on the
constituent parts of certain Astringent Vegetables, and on
their operation in Tanning.
_February 24, 1803._
3. An Account of some Analytical Experiments on a Mineral
Production from Devonshire, consisting principally of Alumina
and Water.
_February 28, 1805._
4. On a Method of analysing Stones containing a fixed Alkali,
by means of Boracic acid.
_May 16, 1805_.
* _For the above papers, the Society awarded him the Copley
Medal._
5. THE BAKERIAN LECTURE.--On some Chemical agencies of
Electricity.
_November 20, 1806._
** _For this memoir, he received the prize of the French
Institute._
6. THE BAKERIAN LECTURE.--On some new Phenomena of Chemical
Changes produced by Electricity, particularly the Decomposition
of the Fixed Alkalies, and the exhibition of the new substances
which constitute their bases; and on the general nature of
Alkaline bodies. 3?
_Read November 19, 1807._
7. Electro-chemical Researches on the Decomposition of the
Earths; with Observations on the Metals obtained from the
Alkaline Earths; and on the Amalgam procured from Ammonia.
_June 30, 1808._
8. THE BAKERIAN LECTURE.--An Account of some new Analytical
Researches on the nature of certain bodies, particularly the
Alkalies, Phosphorus, Sulphur, Carbonaceous matter, and the
Acids hitherto uncompounded; with some general Observations on
Chemical Theory.
_December 15, 1808._
9. New Analytical Researches on the nature of certain bodies;
being an Appendix to the Bakerian Lecture for 1808.
_February 1809._
10. THE BAKERIAN LECTURE FOR 1809. On some new Electro-chemical
Researches on various objects, particularly the metallic bodies
from the Alkalies and Earths; and on some combinations of
Hydrogen.
_November 16, 1809._
11. Researches on the Oxy-muriatic Acid, its nature and
combinations; and on the elements of Muriatic Acid; with some
Experiments on Sulphur and Phosphorus, made in the Laboratory
of the Royal Institution.
_Read July 12, 1810._
12. THE BAKERIAN LECTURE FOR 1810. On some of the Combinations
of Oxy-muriatic Gas and Oxygen, and on the chemical relations
of those principles to inflammable bodies.
_November 15, 1810._
13. On a Combination of Oxy-muriatic Gas and Oxygen Gas.
_February 21, 1811._
14. On some Combinations of Phosphorus and Sulphur, and on some
other subjects of Chemical Enquiry.
_June 18, 1812._
15. On a new Detonating Compound; in a letter to Sir Joseph
Banks, Bart. F.R.S.
_November 5, 1812._
16. Some further Observations on a new Detonating substance.
_July 1, 1813._
17. Some Experiments and Observations on the Substances
produced in different chemical processes on Fluor Spar.
_July 8, 1813._
18. An Account of some New Experiments on the Fluoric
Compounds; with some Observations on other objects of Chemical
Enquiry.
_February 13, 1814._
19. Some Experiments and Observations on a new Substance, which
becomes a Violet-coloured Gas by heat.
_January 20, 1814._
20. Further Experiments and Observations on Iodine.
_Read June 16, 1814._
21. Some Experiments on the Combustion of the Diamond, and
other Carbonaceous Substances.
_June 23, 1814._
22. Some Experiments and Observations on the Colours used in
Painting by the Ancients.
_February 23, 1815._
23. Some Experiments on a solid Compound of Iodine and Oxygen,
and on its Chemical Agencies.
_April 20, 1815._
24. On the Action of Acid upon the Salts usually called
_Hyper-Oxymuriates_, and on the Gases produced from them.
_May 4, 1815._
25. On the _Fire-damp_ of Coal Mines, and on methods of
lighting the Mine, so as to prevent Explosion.
_November 19, 1815._
26. An Account of an Invention for giving Light in Explosive
Mixtures of _Fire-damp_ in Coal Mines, by consuming the
Fire-damp.
_January 11, 1816._
27. Further Experiments on the Combustion of Explosive Mixtures
confined by Wire Gauze, with some Observations on Flame.
_January 25, 1816._
28. Some Researches on Flame.
_January 16, 1817._
29. Some New Experiments and Observations on the Combustion of
Gaseous Mixtures; with an account of a method of preserving
a continued Light in Mixtures of inflammable Gases and Air,
without Flame.
_Read January 23, 1817._
*** _For the preceding five papers, the Rumford Medals were
awarded to him._
30. On the fallacy of Experiments in which Water is said to
have been formed by the decomposition of Chlorine.
_February 12, 1818._
31. New Experiments on some of the combinations of Phosphorus.
_April 9, 1818._
32. Some Observations on the formation of Mists in particular
situations.
_February 25, 1819._
33. On the Magnetic Phenomena produced by Electricity.
_November 16, 1820._
34. Some Observations and Experiments on the Papyri found in
the ruins of Herculaneum.
_March 15, 1821._
35. Further Researches on the Magnetic Phenomena produced by
Electricity; with some new Experiments on the properties of
Electrified bodies, in their relations to conducting powers and
temperature.
_July 5, 1821._
36. On the Electrical Phenomena exhibited _in vacuo_.
_December 20, 1821._
37. On the state of Water and Aëriform matter in cavities
found in certain Crystals.
_Read June 13, 1822._
38. On a new Phenomenon of Electro-Magnetism.
_March 6, 1823._
39. On the application of Liquids formed by the condensation of
Gases, as mechanical Agents.
_April 17, 1823._
40. On the changes of volume produced in Gases, in different
states of density, by Heat.
_May 1, 1823._
41. On the Corrosion of Copper Sheathing by sea-water; and on
methods of preventing this effect, and on their application to
ships of war and other ships.
_Jan. 24, 1824._
42. Additional Experiments and Observations on the application
of Electrical Combinations to the preservation of the Copper
Sheathing of ships, and to other purposes.
_June 17, 1824._
43. Further Researches on the preservation of Metals by
Electro-chemical means.
_June 9, 1825._
44. THE BAKERIAN LECTURE for 1826.--On the Relation of
Electrical and Chemical changes.
_June 3, 1826._
**** _For this memoir, the Royal Society conferred upon him the
Royal Medal._
45. On the Phenomena of Volcanoes.
_March 20, 1828._
46. Account of some Experiments on the Torpedo.
_November 20, 1828._
HIS PUBLISHED WORKS ARE,
"Experimental Essays on Heat, Light, and on the Combinations
of Light, with a new Theory of Respiration," &c. Published in
_Contributions to Physical and Medical Knowledge, by T. Beddoes,
M.D._ 1799.
"Researches Chemical and Philosophical, chiefly concerning Nitrous
Oxide, and its Respiration." 1800.
"A Syllabus of a Course of Lectures."
"An Introductory Lecture." 1801.
"Elements of Chemical Philosophy." 1812.
"Elements of Agricultural Chemistry." 1813.
"On the Safety Lamp for Coal Miners; with some Researches on
Flame." 1818. (Several Editions.)
"Salmonia; or Days of Fly-Fishing."
"Consolations in Travel; or the Last Days of a Philosopher."
APPENDIX.
APPENDIX.
EXTRACTED FROM THE REGISTRY OF THE PREROGATIVE COURT OF CANTERBURY.
A.
MY WILL.
This 3rd of January 1827 feeling more than usual symptoms of
mortality I make this my Will. First, I give my Brother John Davy
M.D. three hundred pounds a-year of money that I possess in the
Long Annuities and likewise four thousand pounds to be raised by
the sale of Securities I possess in the English or French funds
or annuities but I mean my said Brother to devote the interest
of three thousand pound of these last moneys to such purposes as
he may deem fitting for the benefit of my sisters particularly
my married one and I wish a part of the interest of these three
thousand pounds to be employed in educating and settling in life
my godson Humphrey Millett. I leave him Dr. Davy likewise all the
property devolving to me from my parents which has never been
divided to do what seems to him best for the benefit of my sisters
and my sister Millett's children and I leave my said brother my
Chemical Books and Chemical MSS. Apparatus _Sporting tackle_
Medals and the silver Venetian dish made from the Rumford Medal in
token of my affection. I leave £100 to each of these friends Dr.
Babington and Dr. Franck and £50 to Dr. Wilson Philip and to Mr.
Brodie surgeon to lay out in tokens of remembrance. I leave all my
other property whether in goods money chattels funded securities
annuities or plate to my wife (Lady) Jane Davy and I appoint her
the sole Executrix of this my Will. If my brother or his family
should not be in a condition at the time of her decease to use my
service of plate given for the safety lamp I wish it to be sold and
the same given to the Royal Society to provide an annual medal from
the interest for the best discovery made any where in chemistry and
I depend upon my dear wife to make such presents in seals or token
to such of my friends as she may think proper agreeably to their
and her feelings.
H. DAVY.
B.
Further explanatory Clause.
I leave to my wife Dame Jane Davy all my other property whether
funded or in government securities or in leases of houses or goods
&c. and I leave her my sole residuary legatee and sole Executrix.
I wish her to enjoy the use of my plate during her life and that
she will leave it to my brother in case he survive her and if not
to any child of his who may be capable of using it but if he be not
in a situation to use or enjoy it then I wish it to be melted and
given to the Royal Society to found a medal to be given annually
for the most important discovery in Chemistry any where made in
Europe or Anglo-America. Knowing the perfect understanding and love
of justice of my wife I leave to her all other arrangements which
may make my memory useful to the world and awaken the kind feelings
of my friends and I wish her and my brother and all my friends
every happiness this life can afford.
HUMPHRY DAVY.
C.
That is a Clause explanatory of my Will.
I wish seals not rings with a fish engraved upon them to be
given to some of my friends amongst whom I mention Mr Knight Dr
Babington Mr Pepys Mr Hatchett. And lest there should be any doubt
respecting the £3000 mentioned I mean my brother to be a trustee
for this and should he die without children I mean it to belong to
my sister Millett's children £2000 to Humphry Millett my godson
and the rest to be equally divided between the other children but
should my brother marry and have children I then mean after the
death of my sisters these £3000 to be divided between her child
or children and my sisters and £1000 to go to Humphry Millett
my godson and £500 to my sister's other children leaving the
arrangement to my brother.
H. D.
D.
Further explanatory Clause, Feb. 27th 1828.
I leave to my brother John Davy M.D. the proceeds of my
Agricultural Chemistry in the future editions and the profits of
my work on fishing and I give him the copyright. I leave my friend
Thomas Poole Esq. of Stowey fifty pounds to purchase some token of
remembrance.
H. D.
* * * * *
Rome Nov. 18th, 1828.
By this addition to my will I confirm all that I have willed in a
paper left in a brass box at Messrs. Drummond leaving Lady Davy
my sole Executrix and residuary legatee. I leave the copyright of
Salmonia to my brother John Davy wishing him to apply a part of the
profits of the sale of the editions of this work to the education
of my nephew Humphrey Millett in case he has no children of his
own. I leave the copy of my Vision in my writing desk to Lady
Davy to be published if my friends think it may give pleasure or
information to the public but I wish the profits of this work to be
applied to the use of my brothers and sisters. I leave to Josephine
Detela daughter of Mr. Detela of Laybach in Illyria innkeeper my
kind and affectionate nurse one hundred pounds or rather a sum
which shall equal a thousand florins to be paid out of the balance
at my banker's within three months after my decease. I beg Lady
Davy to be so good as to fulfill my engagements with the persons
who are travelling with me but without any favour as I have no
reason to praise either their attention or civilities within the
last two months but the kindness and attentions of Josephine Detela
during my illness at Laybach not only calls for the testimony I
have given but likewise my gratitude for which I give her the £100
or the 1000 florins.
H. DAVY.
* * * * *
Feb. 19th 1829.
I wish to be buried where I die _natura curat suas reliquias_.
I wish £100 to be given to George Whidby and I beg Lady Davy to
fulfill all my engagements and that if my friends should think my
Dialogues worthy of publication I beg that they may be published
and that Mr. Tobin may correct the press of them and I wish that
£150 may be given to him for this labour. There is a codicil to my
will in my writing desk. I beg Lady Davy to have the goodness to
attend to every thing mentioned in that. In addition to what I have
mentioned in that codicil I request that £50 or 500 florins may be
given to Josephine Dettela within five months after my decease and
I wish £50 to be presented to my friend Dr Morichini in remembrance
and memory of his great kindness to me.
H. D.
I wish one hundred to be given to my amanuensis.
* * * * *
For the purpose of explaining a Will that I made before I left
England and some papers that I have since added to it I write these
few words Rome, March 18, 1829.
I give the copyright of Salmonia my Dialogues and any other of
my works which my friends may think it proper to republish to my
brother John Davy M.D. to be published in the manner he may think
most fit and proper. I have already in my former testament left
Lady Davy my residuary legatee but I beg her in considering the
disposition of my property to regard £6000 as belonging to my
brother Dr. Davy in case there rests any doubt upon this subject
in my first will and I wish her the said Lady Davy to enjoy during
her life the use and property of the different services of plate
given to me whether by the Emperor of Russia or the different
coal _committees_ but I trust to her sense of justice that she
will leave them in the manner I have pointed out in my will to my
brother. With respect to any property at present in my banker's
hands or any thing I now carry with me I leave them entirely to my
brother Dr. Davy.
HUMPHRY DAVY.
At Rome March 18, 1829.
THE END.
LONDON:
PRINTED BY SAMUEL BENTLEY,
Dorset Street, Fleet Street.
Transcriber's note:
Minor spelling and punctuation inconsistencies, and hyphenated
words, have been harmonized. The formatting of the letters
has been regularized.
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