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Title: Scientific American Supplement, No. 286, June 25, 1881
Author: Various
Language: English
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*** Start of this LibraryBlog Digital Book "Scientific American Supplement, No. 286, June 25, 1881" ***
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SCIENTIFIC AMERICAN SUPPLEMENT NO. 286
NEW YORK, JUNE 25, 1881
Scientific American Supplement. Vol. XI, No. 286.
Scientific American established 1845
Scientific American Supplement, $5 a year.
Scientific American and Supplement, $7 a year.
* * * * *
TABLE OF CONTENTS.
I. ENGINEERING AND MECHANICS.--One Thousand Horse Power Corliss Engine.
5 figures, to scale, illustrating the construction of the new one
thousand horse power Corliss engine, by Hitch, Hargreaves & Co.
Opening of the New Workshop of the Stevens Institute of Technology.
Speech of Prof. R.W. Raymond, speech of Mr. Horatio Allen.
Light Steam Engine for Aeronautical Purposes. Constructed for Capt.
Mojoisky, of the Russian Navy.
Complete Prevention of Incrustation in Boilers. Arrangement for
purifying boiler water with lime and carbonate of soda.--The
purification of the water.--Examination of the purified
water.--Results of water purification.
Eddystone Lighthouse. Progress of the work.
Rolling Mill for Making Corrugated Iron. 1 figure. The new mill of
Schultz, Knaudt & Co., of Essen, Germany.
Railway Turntable in the Time of Louis XIV. 1 figure. Pleasure car.
Railway and turntable at Mary-le-Roy Chateau, France, in 1714.
New Signal Wire Compensator. Communication from A. Lyle, describing
compensators in use on the Nizam State Railway, East India.
Tangye's Hydraulic Hoist. 2 figures.
Power Loom for Delicate Fabrics. 1 figure.
How Veneering is Made.
II. TECHNOLOGY AND CHEMISTRY.--The Constituent Parts of Leather. The
composition of different leathers exhibited at the Paris
pounds of hides.--Percentage of tannin absorbed under different
methods of tanning.--Amounts of gelatine and tannin in leather of
different tonnages, etc.
Progress in American Pottery.
Photographic Notes.--Mr. Waruerke's New Discovery.--Method of
converting negatives directly into positives.--Experiments of Capt.
Bing on the sensitiveness of coal oil--Bitumen plates.--Method of
topographic engraving. By Commandant DE LA NOE.--Succinate of Iron
Developer.--Method of making friable hydro-cellulose.
Photo-Tracings in Black and Color.
Dyeing Reds with Artificial Alizarin. By M. MAURICE PRUD'HOMME.
III. ELECTRICITY, PHYSICAL SCIENCE, ETC.--On Faure's Secondary Battery.
Physical Science in Our Common Schools.--An exceptionally strong
argument for the teaching of physical science by the experimental
method in elementary schools, with an outline of the method and the
results of such teaching.
On the Law of Avogadro and Ampere. By E. VOGEL.
IV. GEOGRAPHY, GEOLOGY, ETC.--Petroleum and Coal in Venezuela.
Geographical Society of the Pacific.
The Behring's Straits Currents.--Proofs of their existence.
Experimental Geology.--Artificial production of calcareous pisolites
and oolites.--On crystals of anhydrous lime.--4 figures.
V. NATURAL HISTORY, ETC.--Coccidæ. By Dr. H. BEHR.--An important paper
read before the California Academy of Sciences.--The marvelous
fecundity of scale bugs.--Their uses.--Their ravages.--Methods of
destroying them.
Agricultural Items.
Timber Trees.
Blood Rains.
VI. MEDICINE AND HYGIENE.--Medical Uses of Figs.
Topical Medication in Phthisis.
VII. ARCHITECTURE, ETC.--Suggestions in Architecture.--Large
illustration.--The New High School for Girls, Oxford, England.
* * * * *
PETROLEUM AND COAL IN VENEZUELA.
MR. E. H. PLUMACHER, U. S. Consul at Maracaibo, sends to the State
Department the following information touching the wealth of coal and
petroleum probable in Venezuela:
The asphalt mines and petroleum fountains are most abundant in that part
of the country lying between the River Zulia and the River Catatumbo,
and the Cordilleras. The wonderful sand-bank is about seven kilometers
from the confluence of the Rivers Tara and Sardinarte. It is ten meters
high and thirty meters long. On its surface can be seen several round
holes, out of which rises the petroleum and water with a noise like that
made by steam vessels when blowing off steam, and above there ascends a
column of vapor. There is a dense forest around this sand-bank, and the
place has been called "El Inferno." Dr. Edward McGregor visited the
sand-bank, and reported to the Government that by experiment he had
ascertained that one of the fountains spurted petroleum and water at the
rate of 240 gallons per hour. Mr. Plumacher says that the petroleum is
of very good quality, its density being that which the British market
requires in petroleum imported from the United States. The river, up to
the junction of the Tara and Sardinarte, is navigable during the entire
year for flat-bottomed craft of forty or fifty tons.
Mr. Plumacher has been unable to discover that there are any deposits
of asphalt or petroleum in the upper part of the Department of Colon,
beyond the Zulia, but he has been told that the valleys of Cucuta and
the territories of the State of Tachira abound in coal mines. There are
coal mines near San Antonia, in a ravine called "La Carbonera," and
these supply coal for the smiths' forges in that place. Coal and asphalt
are also found in large quantities in the Department of Sucre. Mr.
Plumacher has seen, while residing in the State of Zulia, but one true
specimen of "lignite," which was given to him by a rich land-owner,
who is a Spanish subject. In the section where it was found there are
several fountains of a peculiar substance. It is a black liquid, of
little density, strongly impregnated with carbonic acid which it
transmits to the water which invariably accompanies it. Deposits of this
substance are found at the foot of the spurs of the Cordilleras, and are
believed to indicate the presence of great deposits of anthracite.
There are many petroleum wells of inferior quality between Escuque and
Bettijoque, in the town of Columbia. Laborers gather the petroleum in
handkerchiefs. After these become saturated, the oil is pressed out by
wringing. It is burned in the houses of the poor. The people thought, in
1824, that it was a substance unknown elsewhere, and they called it
the "oil of Columbia." At that time they hoped to establish a valuable
industry by working it, and they sent to England, France, and this
country samples which attracted much attention. But in those days no
method of refining the crude oil had been discovered, and therefore
these efforts to introduce petroleum to the world soon failed.
The plains of Ceniza abound in asphalt and petroleum. There is a large
lake of these substances about twelve kilometers east of St. Timoteo,
and from it some asphalt is taken to Maracaibo. Many deposits of asphalt
are found between these plains and the River Mene. The largest is that
of Cienega de Mene, which is shallow. At the bottom lies a compact
bed of asphalt, which is not used at present, except for painting
the bottoms of vessels to keep off the barnacles. There are wells of
petroleum in the State of Falcon.
Mr. Plumacher says that all the samples of coal submitted to him in
Venezuela for examination, with the exception of the "lignite" before
mentioned, were, in his opinion, asphalt in various degrees of
condensation. The sample which came from Tule he ranks with the coals
of the best quality. He believes that the innumerable fountains and
deposits of petroleum, bitumen, and asphalt that are apparent on the
surface of the region around Lake Maracaibo are proof of the existence
below of immense deposits of coal. These deposits have not been
uncovered because the territory remains for the most part as wild as it
was at the conquest.
* * * * *
ONE THOUSAND HORSE-POWER CORLISS ENGINE.
[Illustration: FIG. 1.
DIA. OF CYLINDER = 40''
STROKE = 10 ft.
REVS = 41
SCALE OF DIAGRAMS 40 LBS = 1 INCH
FIG. 2.]
We illustrate one of the largest Corliss engines ever constructed. It is
of the single cylinder, horizontal, condensing type, with one cylinder
40 inches diameter, and 10 feet stroke, and makes forty-five revolutions
per minute, corresponding to a piston speed of 900 feet per minute. At
mid stroke the velocity of the piston is 1,402 feet per minute nearly,
and its energy in foot pounds amounts to about 8.6 times its weight.
The cylinder is steam jacketed on the body and ends, and is fitted with
Corliss valves and Inglis & Spencer's automatic Corliss valve expansion
gear. Referring to the general drawing of the engine, it will be seen
that the cylinder is bolted directly to the end of the massive cast iron
frame, and the piston coupled direct to the crank by the steel piston
rod and crosshead and the connecting rod. The connecting rod is 28
feet long center to center, and 12 inches diameter at the middle. The
crankshaft is made of forged Bolton steel, and is 21 inches diameter at
the part where the fly-wheel is carried. The fly driving wheel is 35
feet in diameter, and grooved for twenty-seven ropes, which transmit the
power direct to the various line shafts in the mill. The rope grooves
are made on Hick, Hargreaves & Co.'s standard pattern of deep groove,
and the wheel, which is built up, is constructed on their improved plan
with separate arms and boss, and twelve segments in the rim with joints
planed to the true angle by a special machine designed and made by
themselves. The weight of the fly-wheel is about 60 tons. The condensing
apparatus is arranged below, so that there is complete drainage from the
cylinder to the condenser. The air pump, which is 36 inches diameter and
2 feet 6 inches stroke, is a vertical pump worked by wrought iron
plate levers and two side links, shown by dotted lines, from the main
crosshead. The engine is fenced off by neat railing, and a platform with
access from one side is fitted round the top of the cylinder for getting
conveniently to the valve spindles and lubricators. The above engraving,
which is a side elevation of the cylinder, shows the valve gear
complete. There are two central disk plates worked by separate
eccentrics, which give separate motion to the steam and exhaust valves.
The eccentrics are mounted on a small cross shaft, which is driven by a
line shaft and gear wheels. The piston rod passes out at the back end of
the cylinder and is carried by a shoe slide and guide bar, as shown more
fully in the detailed sectional elevation through the cylinder, showing
also the covers and jackets in section. The cylinder, made in four
pieces, is built up on Mr. W. Inglis's patent arrangement, with separate
liner and steam jacket casing and separate end valve chambers. This
arrangement simplifies the castings and secures good and sound ones. The
liner has face joints, which are carefully scraped up to bed truly to
the end valve chambers. The crosshead slides are each 3 feet 3 inches
long and I foot 3 inches wide. The engine was started last year, and
has worked beautifully from the first, without heating of bearings or
trouble of any kind, and it gives most uniform and steady turning. It is
worked now at forty-one revolutions per minute, or only 820 feet piston
speed, but will be worked regularly at the intended 900 feet piston
speed per minute when the spinning machinery is adapted for the increase
which the four extra revolutions per minute of the engine will give; the
load driven is over 1,000 horsepower, the steam pressure being 50 lb.
to 55 lb., which, however, will be increased when the existing boilers,
which are old, come to be replaced by new. Indicator diagrams from the
engines are given on page 309. The engine is very economical in steam
consumption, but no special trials or tests have been made with it. An
exactly similar engine, but of smaller size, with a cylinder 30 inches
diameter and 8 feet stroke, working at forty-five revolutions per
minute, made by Messrs. Hick, Hargreaves & Co. for Sir Titus Salt,
Sons & Co.'s mill at Saltaire, was tested about two years ago by Mr.
Fletcher, chief engineer of the Manchester Steam Users' Association, and
the results which are given below pretty fairly represent the results
obtained from this class of engine. Messrs. Hick, Hargreaves & Co. are
now constructing a single engine of the same type for 1,800 indicated
horse-power for a cotton mill at Bolton; and they have an order for a
pair of horizontal compound Corliss engines intended to indicate 3,000
horse-power. These engines will be the largest cotton mill engines in
the world.--_The Engineer_.
[Illustration: 1000 HORSE POWER CORLISS ENGINE.--BY HICK. HARGREAVES &
CO.]
_Result of Trials with Saltaire Horizontal Engine on February 14th and
15th, 1878. Trials made by Mr. L.E. Fletcher, Chief Engineer Steam
Users' Association, Manchester._
Engine single-cylinder, with Corliss valves. Inglis and Spencer's valve
gear. Diameter of cylinder. 30in.; stroke, 8ft.; 45 revolutions per
minute.
No. of trials
Total 1.H.P.
[MB] Mean boiler pressure.
[MP] Mean pressure on piston at beginning of stroke.
[ML] Mean loss between boiler pressure and cylinder.
[MA] Mean average pressure on piston.
[W] Water Per I.H.P. per hour.
[C] Coal per I.H.P. per hour.
No. of trials Total MB MP ML MA W C
I.H.P. lb lb lb lb lb lb
Trial No. 1. 301.89 46.6 44.11 2.53 21.23 18.373 2.699
Trial No. 2. 309.66 47.63 44.45 3.18 21.67 17.599 2.561
Means. 305.775 47.115 44.28 2.855 21.45 17.986 2.630
[Illustration: 1000 HORSE POWER CORLISS ENGINE.--BY HICK, HARGREAVES
& CO.] [Illustration: 1000 HORSE POWER CORLISS ENGINE.--BY HICK,
HARGREAVES & CO.]
* * * * *
OPENING OF THE NEW WORKSHOP OF THE STEVENS INSTITUTE OF TECHNOLOGY.
In our SUPPLEMENT No. 283 we gave reports of some of the addresses of
the distinguished speakers, and we now present the remarks of Prof.
Raymond and Horatio Allen, Esq.:
SPEECH OF PROF. R. W. RAYMOND.
A few years ago, at one of the meetings of our Society of Civil
Engineers we spent a day or so in discussing the proper mode of
educating young men so as to fit them for that profession. It is a
question that is reopened for us as soon as we arrive at the age when
we begin to consider what career to lay out for our sons. When we were
young, the only question with parents in the better walks of life was,
whether their sons should be lawyers, physicians, or ministers. Anything
less than a professional career was looked upon as a loss of caste, a
lowering in the social scale. These things have changed, now that we
engineers are beginning to hold up our heads, as we have every reason to
do; for the prosperity and well-being of the great nations of the world
are attributable, perhaps, more to our efforts than to those of any
other class. When, in the past, the man of letters, the poet, the
orator, succeeded, by some fit expression, by some winged word, to
engage the attention of the world concerning some subject he had at
heart, the highest praise his fellow man could bestow was to cry out
to him, "Well said, well said!" But now, when, by our achievements,
commerce and industry are increased to gigantic proportions, when the
remotest peoples are brought in ever closer communication with us, when
the progress of the human race has become a mighty torrent, rushing
onward with ever accelerating speed, we glory in the yet higher praise,
"Well done, well done!" Under these circumstances, the question how a
young man is best fitted for our profession has become one of increasing
importance, and three methods have been proposed for its solution.
Formerly the only point in debate was whether the candidate should go
first to the schools and then to the workshop, or first to the shop and
then to the schools. It was difficult to arrive at any decision; for of
the many who had risen to eminence as engineers, some had adopted
one order and some the other. There remained a third course, that of
combining the school and the shop and of pursuing simultaneously the
study of theory and the exercise of practical manipulation. Unforeseen
difficulties arose, however, in the attempt to carry out this, the most
promising method. The maintenance of the shop proved a heavy expense,
which it was found could not be lessened by the manufacture of salable
articles, because the work of students could not compete with that of
expert mechanics. It would require more time than could be allotted,
moreover, to convert students into skilled workmen. Various
modifications of this combination of theory and practice, including more
or less of the Russian system of instruction in shop-work, have been
tried in different schools of engineering, but never under so favorable
conditions as the present. With characteristic caution and good
judgment, President Morton has studied the operation of the scheme
of instruction adopted in the Stevens Institute, and, noting its
deficiencies, has now supplied them with munificent liberality, giving
to it a completeness that leaves seemingly nothing that could be
improved upon, even in a prayer or a dream. Still, no one will be more
ready to admit than he who has done all this, that it is not enough to
fit up a machine shop, be it never so complete, and light it with an
electric lamp. The decision as to its efficiency must come from the
students that are so fortunate as to be admitted to it. If such young
men, earnest, enthusiastic, with every incentive to exertion and every
advantage for improvement, here, where they can feel the throbbing of
the great heart of enterprise, within sight of bridges upon which their
services will be needed, within hearing of the whistles of a score of
railroads, and the bells of countless manufactories which will want
them; if such as these, trained under such instructors and amid such
surroundings, prove to be not fitted for the positions waiting for them
to fill, it will have been definitely demonstrated that the perfect
scheme is yet unknown.
SPEECH OF MR. HORATIO ALLEN.
Impressed with the very great step in advance which has been inaugurated
here this evening, I feel crowding upon me so many thoughts that I
cannot make sure that, in selecting from them, I may not leave unsaid
much that I should say, and say some things that I had better omit. Some
years ago, when asked by a wealthy gentleman to what machine-shop he had
best send his son, who was to become a mechanical engineer, I advised
him not to send him to any, but to fit up a shop for him where he could
go and work at what he pleased without the drudgery of apprenticeship,
to put him in the way of receiving such information as he needed, and
especially to let him go where he could see things break. Great, indeed,
are the advantages of those who have the opportunity of seeing things
break, of witnessing failures and profiting by them. When men have
enumerated the achievements of those most eminent in our profession the
thought has often struck me, "Ah! if we could only see that man's scrap
heap."
There are many who are able to construct a machine for a given purpose
so that it will work, but to do this so that it will not cost too much
is an entirely different problem. To know what to omit is a rare talent.
I once found a young man who could tell students what to store up in
their minds for immediate use, and what to skim over or omit; but I
could not keep him long, for more lucrative positions are always waiting
for such men.
The advice I gave my wealthy friend was given before the Stevens
Institute had developed in the direction it has now. The foundation of
this advice, namely, to combine a certain amount of judicious practice
with theory, is now in a fair way to be carried out, and although
things will probably not be permitted to break here, the students will
doubtless have opportunities for looking around them and supplementing
their systematic instruction here by observation abroad.
* * * * *
LIGHT STEAM ENGINE FOR BALLOONS.
We here illustrate one of a couple of compound engines designed and
constructed by Messrs. Ahrbecker, Son & Hamkens, of Stamford Street,
S.E., for Captain Mojaisky, of the Russian Imperial Navy, who intends
to use them for aeronautical purposes. The larger of these engines has
cylinders 3¾ in. and 7½ in. in diameter and 5 in. stroke, and when
making 300 revolutions per minute it develops 20 actual horse
power, while its weight is but 105 lbs. The smaller engine--the one
illustrated--has cylinders 2½ in. and 5 in. in diameter, and 3½ in.
stroke, and weighs 63 lbs., while when making 450 revolutions it
develops 10 actual horse power.
The two engines are identical in design, and are constructed of forged
steel with the exception of the bearings, connecting-rods, crossheads,
slide valves and pumps, which are of phosphor-bronze. The cylinders,
with the steam passages, etc., are shaped out of the solid. The
standards, as will be seen, are of very light T steel, the crankshafts
and pins are hollow, as are also the crosshead bolts and piston rods.
The small engine drives a single-acting air pump of the ordinary type by
a crank, not shown in the drawing. The condenser is formed of a series
of hollow gratings.
[Illustration: LIGHT STEAM ENGINE FOR AERONAUTICAL PURPOSES]
Steam is supplied to the two engines by one boiler of the Herreshoff
steam generator type, with certain modifications, introduced by the
designers, to insure the utmost certainty in working. It is of steel,
the outside dimensions being 22 in. in diameter, 25 in. high, and weighs
142 lb. The fuel used is petroleum, and the working pressure 190 lb. per
square inch.
The constructors consider the power developed by these engines very
moderate, on account of the low piston speed specified in this
particular case. In some small and light engines by the same makers
the piston speed is as high as 1000 ft. per minute. The engines now
illustrated form an interesting example of special designing, and
Messrs. Ahrbecker, Son, and Hamkens deserve much credit for the manner
in which the work has been turned out, the construction of such light
engines involving many practical difficulties,--_Engineering._
* * * * *
Mount Baker, Washington Territory, has shown slight symptoms of volcanic
activity for several years. An unmistakable eruption is now in progress.
* * * * *
COMPLETE PREVENTION OF INCRUSTATION IN BOILERS.
The chemical factory, Eisenbuettel, near Braunschweig, distributes the
following circular: "The principal generators of incrustation in boilers
are gypsum and the so-called bicarbonates of calcium and magnesium. If
these can be taken put of the water, before it enters the boiler, the
formation of incrustation is made impossible; all disturbances and
troubles, derived from these incrustations, are done away with, and
besides this, a considerable saving of fuel is possible, as clear iron
will conduct heat quicker than that which is covered with incrustation."
J. Kolb, according to _Dingler's Polyt. Journal_, says: "A boiler with
clear sides yielded with 1 kil. coal 7.5 kil. steam, after two months
only 6.4 kil. steam, or a decrease of 17 per cent. At the same time the
boiler had suffered by continual working."
Suppose a boiler free from inside crust would yield a saving of only
5 per cent. in fuel (and this figure is taken very low compared with
practical experiments) it would be at the same time a saving of 3c. per
cubic meter water. If the cleaning of one cubic meter water therefore
costs less than 3c., this alone would be an advantage.
Already, for a long time, efforts have been made to find some means for
this purpose, and we have reached good results with lime and chloride of
barium, as well as with magnesia preparations. But these preparations
have many disadvantages. Corrosion of the boiler-iron and muriatic acid
gas have been detected. (Accounts of the Magdeburg Association for
boiler management.)
Chloride of calcium, which is formed by using chloride of barium,
increases the boiling point considerably, and diminishes the elasticity
of steam; while the sulphate of soda, resulting from the use of
carbonate of soda, is completely ineffectual against the boiler iron.
It increases the boiling point of water less than all other salts, and
diminishes likewise the elasticity of steam (Wullner).
In using magnesia preparation, the precipitation is only very slowly and
incompletely effected--one part of the magnesia will be covered by the
mire and the formed carbonate of magnesia in such a way, that it can no
more dissolve in water and have any effect (_Dingler's Polyt. Journal_,
1877-78).
The use of carbonate of soda is also cheaper than all other above
mentioned substances.
One milligramme equivalent sulphate of lime, in 1 liter, = 68 grammes
sulphate of lime in 1 cubic meter, requiring for decomposition:
120 gr. (86-88 per cent.) chloride of barium of commerce--at $5.00 =
0.6c.
Or, 50 gr. magnesia preparation--at $10.00 = 0.5c.
Or, 55 gr. (96-98 per cent.) carbonate of soda--at $7.50 = 0.41c.
The proportions of cost by using chloride of barium, magnesia
preparation, carbonate of soda, will be 6 : 5 : 4.
ARRANGEMENT FOR PURIFYING BOILER-WATER WITH LIME AND CARBONATE OF SODA.
We need for carrying out these manipulations, according to the size
of the establishment, one or more reservoirs for precipitating the
impurities of the water, and one pure water reservoir, to take up the
purified water; from the latter reservoir the boilers are fed. The most
practical idea would be to arrange the precipitating reservoir in such
manner that the purified water can flow directly into the feeding
reservoir.
The water in the precipitating reservoir is heated either by adding
boiling water or letting in steam up to 60° C. at least. The
precipitating reservoirs (square iron vessels or horizontal
cylinders--old boilers) of no more than 4 or 4½ feet, having a faucet 6
inches above the bottom, through which the purified water is drawn off,
and another one at the bottom of the vessel, to let the precipitate off
and allow of a perfect cleaning. In a factory with six or seven boilers
of the usual size, making together 400 square meters heating surface,
two precipitating reservoirs, of ten cubic meters each, and one pure
water reservoir of ten or fifteen cubic meter capacity, are used.
In twenty-four hours about 240 cubic meters of water are evaporated; we
have, therefore, to purify twenty-four precipitating reservoirs at ten
cubic meters each day, or ten cubic meters each hour.
It is profitable to surround the reservoirs with inferior conductors of
heat, to avoid losses.
The contents of the precipitating reservoirs have to be stirred up very
well, and for this purpose we can either arrange a mechanical stirrer
or do it by hand, or the best would be a "Korting steam stirring and
blowing apparatus." In using the latter we only have to open the valve,
whereby in a very short time the air driven through the water stirs this
up and mixes it thoroughly with the precipitating ingredients. In a
factory where boilers of only 15 to 100 square meters heating surface
are, one precipitating reservoir of two to ten cubic meters and one pure
water reservoir of three to ten cubic meters capacity are required. For
locomobiles, two wooden tubs or barrels are sufficient.
THE PURIFICATION OF THE WATER.
After the required quantity of lime and carbonate of soda which is
necessary for a total precipitation has been figured out from the
analysis of the water, respectively verified by practical experiments
in the laboratory, the heated water in the reservoir is mixed with the
lime, in form of thin milk of lime, and stirred up; we have to add so
much lime, that slightly reddened litmus paper gives, after ¼ minute's
contact with this mixture, an alkaline reaction, i.e., turns blue; now
the solution of carbonate of soda is added and again stirred well.
After twenty or thirty minutes (the hotter the water, the quicker the
precipitation) the precipitate has settled in large flocks at the
bottom, and the clear water is drawn off into the pure water reservoir.
The precipitating and settling of the impurities can also take place in
cold water; it will require, however, a pretty long time.
In order to avoid the weighing and slaking of the lime, which is
necessary for each precipitation, we use an open barrel, in which a
known quantity of slaked lime is mixed with three and a half or four
times its weight of water, and then diluted to a thin paste, so that one
kilogramme slaked lime is diluted to twenty-five liters milk of lime.
Example.--If we use for ten cubic meters water, one kilogramme lime,
or in one day (in twenty-four hours), 240 cubic meters 24 kg. lime, a
vessel four or five feet high and about 700 liters capacity, in which
daily 24 kg. lime with about 100 liters water are slaked and then
diluted to the mark 600, constantly stirring, 25 liters of this mixture
contain exactly 1 kg. slaked lime.
Before using, this milk of lime has to be stirred up and allowed to
settle for a few seconds; and then we draw off the required quantity of
milk of lime (in our case 25 liters) through a faucet about 8 inches
above the bottom, or we can dip it off with a pail. For the first
precipitate we always need the exact amount of milk of lime, which we
have figured out, or rather some more, but for the next precipitates we
do not want the whole quantity, but always less, as that part of the
lime, which does not settle with the precipitate, will be good for use
in further precipitations. It is therefore important to control the
addition of milk of lime by the use of litmus paper. If we do not add
enough lime, it prevents the formation of the flocky precipitate, and,
besides, more carbonate of soda is used. By adding too much lime, we
also use more carbonate of soda in order to precipitate the excess of
lime. We can therefore add so much lime, that there is only a very small
excess of hydrous lime in the water, and that after well stirring, a red
litmus paper being placed in the water for twenty seconds, appears only
slightly blue. After a short time of practice, an attentive person can
always get the exact amount of lime which ought to be added. On adding
the milk of lime, we have to dissolve the required amount of pure
carbonate of soda in an iron kettle, in about six or eight parts hot
water with the assistance of steam; add this to the other liquid in the
precipitating reservoirs and stir up well. The water will get clear
after twenty-five or thirty minutes, and is then drawn off into the pure
water reservoir.
EXAMINATION OF WATER WHICH HAS BEEN PURIFIED BY MEANS OF MILK OF LIME
AND CARBONATE OF SODA.
In order to be convinced that the purification of the water has been
properly conducted, we try the water in the following manner. Take a
sample of the purified water into a small tumbler, and add a few
drops of a solution of oxalate of ammonia; this addition must neither
immediately nor after some minutes cause a milky appearance of the
water, but remain bright and clear. A white precipitate would indicate
that not enough carbonate of soda had been added. A new sample is taken
of the purified water and a solution of chloride of calcium added; a
milky appearance, especially after heating, would show that too much
carbonate of soda had been added.
RESULTS OF THIS WATER PURIFICATION.
1. The boilers do not need to be cleaned during a whole season, as they
remain entirely free from incrustation; it is only required to avoid a
collection of soluble salts in the boiler, and therefore it is partly
drawn off twice a week.
2. The iron is not touched by this purified water. The water does not
froth and does not stop up valves. The fillings in the joints of pipes,
etc., do not suffer so much, and therefore keep longer.
3. The steam is entirely free from sour gases.
4. The production of steam is easier and better.
5. A considerable saving of fuel can soon be perceived.
6. The cost of cleaning boilers from incrustation, and loss of time
caused by cleaning, is entirely done with. Old incrustations, which
could not be cleaned out before, get decomposed and break off in soft
pieces.
7. The cost of this purification is covered sufficiently by the above
advantages, and besides this, the method is cheaper and surer than any
other.
The chemical factory, Eisenbuettel, furnishes pure carbonate of soda in
single packages, which exactly correspond with the quantity, stated by
the analysis, of ten cubic meters of a certain water. The determination
of the quantities of lime and carbonate of soda necessary for a certain
kind of water, after sending in a sample, will be done without extra
charge.--_Neue Zeitung fur Ruebenzucker Industrie_.
* * * * *
EDDYSTONE LIGHTHOUSE.
The exterior work on the new Eddystone Lighthouse is about two thirds
done. In the latter part of April fifty-three courses of granite
masonry, rising to the height of seventy feet above high water, had been
laid, and thirty-six courses remained to be set. The old lighthouse had
been already overtopped. As the work advances toward completion the
question arises: What shall be done with John Smeaton's famous tower,
which has done such admirable service for 120 years? One proposition is
to take it down to the level of the top of the solid portion, and
leave the rest as a perpetual memorial of the great work which Smeaton
accomplished in the face of obstacles vastly greater than those which
confront the modern architect. The London _News_ says: "Were Smeaton's
beautiful tower to be literally consigned to the waves, we should regard
the act as a national calamity, not to say scandal; and, if public funds
are not available for its conservation, we trust that private zeal and
munificence may be relied on to save from destruction so interesting
a relic. It certainly could not cost much to convey the building in
sections to the mainland, and there, on some suitable spot, to re-erect
it as a national tribute to the genius of its great architect." When
the present lighthouse was built one of the chief difficulties was in
getting the building materials to the spot. They were conveyed from
Millbay in small sailing vessels, which often beat about for days before
they could effect a landing at the Eddystone rocks, so that each arrival
called out the special gratitude of Smeaton.
* * * * *
ROLLING-MILL FOR MAKING CORRUGATED IRON.
MESSRS. SCHULZ, KNAUDT & Co., of Essen, who are making an application
of corrugated iron in the construction of the interior flues of steam
boilers, have devised a new mill for the manufacture of this form of
iron plates, and which is represented in the accompanying cut, taken
from the _Deutsche Industrie Zeitung_. The supports of the two accessory
cylinders, F F, rest on two slides, G G, which move along the oblique
guides, H H. As a consequence of this arrangement, when the cylinders, F
F, are caused to approach the cylinder, D, both are raised at the same
instant.
When the cylinders, F, occupy the position represented in the engraving
by unbroken lines, the flat plate, O, is simply submitted to pressure
between the cylinders, D and P, the cylinders, F F, then merely acting
as guides. But when, while the plate is being thus flattened between the
principal cylinders, the accessory cylinders are caused to rise, the
plate is curved as shown by the dotted lines, O' O'. To obtain a
uniformity in the position of the two cylinders, F F, the following
mechanism is employed: Each cylinder has an axle, to which is affixed a
crank, Q, connected by means of a rod, R, with the slide, G. These axles
are also provided with toothed sectors, L L, which gear with two screws,
L L, whose threads run in opposite directions. These screws are mounted
on a shaft, N, which may be revolved by any suitable arrangement.
[Illustration: ROLLING MILL FOR MAKING CORRUGATED IRON]
* * * * *
RAILWAY TURN-TABLE IN THE TIME OF LOUIS XIV.
The small engraving which we reproduce herewith from _La Nature_ is
deposited at the Archives at Paris. It is catalogued in the documents
relating to Old Marly, 1714, under number 11,339, Vol. 1. The design
represents a diversion called the _Jeu de la Roulette_ which was
indulged in by the royal family at the sumptuous and magnificent chateau
of Mary-le-Roi.
[Illustration: PLEASURE CAR; RAILWAY AND TURN-TABLE OF THE TIME OF LOUIS
XIV.]
According to Alex. Guillaumot the apparatus consisted of a sort of
railway on which the car was moved by manual labor. In the car, which
was decorated with the royal colors, are seen seated the ladies and
children of the king's household, while the king himself stands in the
rear and seems to be directing operations. The remarkable peculiarity to
which we would direct the attention of the reader is that this document
shows that the car ran on rails very nearly like those used on the
railways of the present time, and that a turn-table served for changing
the direction to a right angle in order to place the car under the
shelter of a small building. The picture which we reproduce, and the
authenticity of which is certain, proves then that in the time of
Louis XIV. our present railway turn-tables had been thought of and
constructed--which is a historic fact worthy of being noted. It is well
known that the use of railways in mines is of very ancient date, but we
do not believe that there are on record any documents as precise as that
of the _Jeu de la Roulette_ as to the existence of turn-tables in former
ages.
* * * * *
NEW SIGNAL WIRE COMPENSATOR.
_To the Editor of the Scientific American_:
I send you a plate of my new railway signal wire compensator. Here
in India signal wires give more trouble, perhaps, than in America or
elsewhere, by expansion and contraction. What makes the difficulty more
here is the ignorance and indolence of the point and signalmen, who
are all natives. There have been numerous collisions, owing to signals
falling off by contraction. Many devices and systems have been tried,
but none have given the desired result. You will observe the signal wire
marked D is entirely separated and independent of the wire, E, leading
to lever. On the Great Indian and Peninsula Railway I work one of these
compensators, 1,160 yards from signal, which stands on a summit the
grade of which is 1 in 150; and on the Nizam State Railway I have one
working on a signal 800 yards. This signal had previously given so much
trouble that it was decided to do away with it altogether. It stands on
top of a high cutting and on a 1,600 foot curve.
[Illustration: Railway Signal Wire Comensator]
I have noted on the compensator fixed at 1,160 yards, 13¼ inches
contraction and expansion. The compensator is very simple and not at all
likely to get out of order. On new wire, when I fix my compensator, I
usually have an adjusting screw on the lead to lever. This I remove
when the wire has been stretched to its full tension. I have everything
removed from lever, so there can be no meddling or altering. When
once the wire is stretched so that no slack remains between lever and
trigger, no further adjustment is necessary.
A. LYLE,
Chief Maintenance Inspector, Permanent Way,
H.H. Nizam State Railway, E. India.
Secunderabad, India, 1881.
TANGYE'S HYDRAULIC HOIST.
[Illustration: TANGYE'S HYDRAULIC HOIST.]
The great merits of hydraulic hoists generally as regards safety and
readiness of control are too well known to need pointing out here.
We may, therefore, at once proceed to introduce to our readers the
apparatus of this class illustrated in the above engravings. This is
a hoist (Cherry's patent) manufactured by Messrs. Tangye Brothers, of
London and Birmingham, and which experience has proved to be a most
useful adjunct in warehouses, railway stations, hotels, and the like.
Fig. 1 of our engraving shows a perspective view of the hoist, Fig. 2
being a longitudinal section. It will be seen that this apparatus is of
very simple construction, the motion of the piston being transmitted
directly to the winding-drum shaft by means of a flexible steel rack.
Referring to Fig. 2, F is a piston working in the cylinder, G; E is
the flexible steel rack connected to the piston, F, and gearing with a
toothed wheel, B, which is inclosed in a watertight casing having cover,
D, for convenient access. The wheel, B, is keyed on a steel shaft, C,
which passes through stuffing-boxes in the casing, and has the winding
barrel, A, keyed on it outside the casing. H is a rectangular tube,
which guides the free end of the flexible steel rack, E. The hoist is
fitted with a stopping and starting valve, by means of which water
under pressure from any convenient source of supply may be admitted or
exhausted from the cylinder. The action in lifting is as follows: The
water pressure forces the piston toward the end of the cylinder. The
piston, by means of the flexible steel rack, causes the toothed wheel
to revolve. The winding barrel, being keyed on the same shaft as the
toothed wheel, also revolves, and winds up the weight by means of the
lifting chain. Two special advantages are obtained by this simple method
of construction. In the first place, twice the length of stroke can be
obtained in the same space as compared with the older types of hydraulic
hoist; and, from the directness of the action, the friction is reduced
to a minimum. This simple method of construction renders the hoist very
compact and easily fixed; and, from the directness with which the power
is conveyed from the piston to the winding drum, and the frictionless
nature of the mechanism, a smaller piston suffices than in the ordinary
hydraulic hoists, and a smaller quantity of water is required to work
them.--_Iron_.
* * * * *
POWER LOOM FOR DELICATE FABRICS.
The force with which the shuttle is thrown in an ordinary power
loom moving with a certain speed is always considerable, and, as a
consequence of the strain exerted on the thread, it is frequently
necessary to use a woof stronger than is desirable, in order that it may
have sufficient resistance. On another hand, when the woof must be very
fine and delicate the fabric is often advantageously woven on a hand
loom. In order to facilitate the manufacture of like tissues on the
power loom the celebrated Swiss manufacturer, Hanneger, has invented an
apparatus in which the shuttle is not thrown, but passed from one side
to the other by means of hooks, by a process analogous to weaving silk
by hand. A loom built on this principle was shown at work weaving silk
at the Paris Exhibition of 1878. This apparatus, represented in
the annexed figure, contains some arrangements which are new and
interesting. On each side of the woof in the heddle there is a carrier,
B. These carriers are provided with hooks, A A', having appendages,
_a a'_, which are fitted in the shuttle, O. The latter is of peculiar
construction. The upper ends of the hooks have fingers, _d d'_, which
holds the shuttle in position as long as the action of the springs, _e
e'_, continues. The distance that the shuttle has to travel includes the
breadth of the heddle, the length of the shuttle, and about four inches
in addition. The motion of the two carriers, which approach each other
and recede simultaneously, is effected by the levers, C, D, E, and C',
D', E'. The levers, E, E', are actuated by a piece, F, which receives
its motion from the main shaft, H, through the intervention of a
crank and a connecting rod, G, and makes a little more than a quarter
revolution. The levers, E, E', are articulated in such a way that
the motion transmitted by them is slackened toward the outer end and
quickened toward the middle of the loom. While the carriers, B B', are
receiving their alternate backward and forward motion, the shaft, I
(which revolves only half as fast as the main shaft), causes a lever, F
F', to swing, through the aid of a crank, J, and rod, K. Upon the two
carriers, B B', are firmly attached two hooks, M M', which move with
them. When the hook, M, approaches the extremity of the lever, F, the
latter raises it, pushes against the spring, E, and sets free the
shuttle, which, at the same moment, meets the opposite hook, _a'_, and,
being caught by it, is carried over to the other side. The same thing
happens when the carrier, B', is on its return travel, and the hook, M',
mounts the lever, F', which is then raised.
[Illustration: POWER LOOM FOR DELICATE FABRICS.]
As will be seen from this description, the woof does not undergo the
least strain, and may be drawn very gently from the shuttle. Neither
does this latter exert any friction on the chain, since it does not move
on it as in ordinary looms. In this apparatus, therefore, there may be
employed for the chain very delicate threads, which, in other looms,
would be injured by the shuttle passing over them. Looms constructed on
this plan have for some time been in very successful use in Switzerland.
* * * * *
HOW VENEERING IS MADE.
The process of manufacture is very interesting. The logs are delivered
in the mill yard in any suitable lengths as for ordinary lumber. A steam
drag saw cuts them into such lengths as may be required by the order
in hand; those being cut at the time of our visit were four feet long.
After cutting, the logs are placed in a large steam box, 15 feet wide,
22 feet long, and six feet high, built separate from the main building.
This box is divided into two compartments. When one is filled entirely
full, the doors are closed, and the steam, supplied by the engine in the
main building, is turned on. The logs remain in this box from three to
four hours, when they are ready for use. This steaming not only removes
the bark, but moistens and softens the entire log. From the steam box
the log goes to the veneer lathe. It is here raised, grasped at each end
by the lathe centers, and firmly held in position, beginning to slowly
revolve. Every turn brings it in contact with the knife, which is gauged
to a required thickness. As the log revolves the inequalities of its
surface of course first come in contact with the keen-edged knife, and
disappear in the shape of waste veneer, which is passed to the engine
room to be used as fuel. Soon, however, the unevenness of the log
disappears, and the now perfect veneer comes from beneath the knife in
a continuous sheet, and is received and passed on to the cutting table.
This continues until the log is reduced to about a seven inch core,
which is useless for the purpose. The veneer as it comes rolling off the
log presents all the diversity of colors and the beautiful grain and
rich marking that have perhaps for centuries been growing to perfection
in the silent depths of our great forests.
From the lathe, the veneer is passed to the cutting table, where it is
cut to lengths and widths as desired. It is then conveyed to the second
story, where it is placed in large dry rooms, air tight, except as the
air reaches them through the proper channels. The veneer is here placed
in crates, each piece separate and standing on edge. The hot air is then
turned on. This comes from the sheet iron furnace attached to the boiler
in the engine room below, and is conveyed through large pipes regulated
by dampers for putting on or taking off the heat. There is also a blower
attached which keeps the hot air in the dry rooms in constant motion,
the air as it cools passing off through an escape pipe in the roof,
while the freshly heated air takes its place from below. These rooms
are also provided with a net-work of hot air pipes near the floor. The
temperature is kept at about 165°, and so rapid is the drying process
that in the short space of four hours the green log from the steam box
is shaved, cut, dried, packed, and ready for shipment.
After leaving the dry rooms it is assorted, counted, and put up in
packages of one hundred each, and tied with cords like lath, when it is
ready for shipment. Bird's-eye maple veneer is much more valuable and
requires more care than almost any other, and this is packed in cases
instead of tied in bundles. The drying process is usually a slow one,
and conducted in open sheds simply exposed to the air. Mr. Densmore's
invention will revolutionize this process, and already gives his mill a
most decided advantage.
The mill will cut about 30,000 feet of veneer in a day, and this cut can
be increased to 40,000 if necessary. Mr. Densmore has already received
several large orders, and the rapidly increasing demand for this
material is likely to give the mill all the work it can do. The timber
used is principally curled and bird's-eye maple, beech, birch, cherry,
ash, and oak. These all grow in abundance in this vicinity, and the
beautifully marked and grained timber of our forests will find fitting
places in the ornamental uses these veneers will be put to.
* * * * *
THE CONSTITUENT PARTS OF LEATHER.
The constituent parts of leather seem to be but little understood. The
opinions of those engaged in the manufacture of leather differ widely on
this question.
Some think that tannin assimilates itself with the hide and becomes
fixed there by reason of a special affinity. Others regard the hide as
a chemical combination of gelatine and tannin. We know that the hide
contains some matters which are not ineradicable, but only need a slight
washing to detach them.
We deem it advisable, in order to examine the hide properly so-called,
to dispense with those eradicable substances which may be regarded, to
some extent, as not germain to it, and confine our attention to the raw
stock, freed from these imperfections.
It is well known that a large number of vegetable substances are
employed as tanning agents. Our researches have been directed to leather
tanned by means of the most important of these agents.
Many questions present themselves in the course of such an examination.
Among others, that most important one, from a practical point of view,
of the weight the tanning agent gives to the hide, that is to say, the
result in leather of weight given to the raw material. The degree of
tannage is also to be considered; the length of time during which the
tanning agent is to be left with the hide; in short, the influence upon
the leather of the substances used in its production. That is why we
have made the completest possible analysis of different leathers.
Besides ordinary oak bark there are used at present very different
substances, such as laurel, chestnut, hemlock, quebracho and pine bark,
sumac, etc.
Water is an element that exists in all hides, and it is necessary to
take it into consideration in the analysis. It is present in perceptible
quantity even in dry hides. This water cannot be entirely eradicated
without injuring the leather, which will lose in suppleness and
appearance. Water should then be considered as one of the elements of
leather, but it must be understood that if it exceeds certain limits,
say 12 to 14 per cent., it becomes useless and even injurious. Moreover,
if there is any excess over the normal quantity, it becomes deceptive
and dishonest, as in such a case one sells for hides that which is
nothing but water. Supposing that a hide, instead of only 14 per cent.,
contained 18 per cent. of water, it is evident that in buying 100 pounds
of such a hide one would pay for four pounds of water at the rate for
which he purchased the hide.
There are, also, some matters soluble in air, which are formed to a
large extent from fat arising as much from the hide as from tanning
substances. The air dissolves at the same time a certain amount of
organic acid and resinous products which the hide has absorbed. After
treating with air, alcohol is used, which dissolves principally the
coloring matters, tannin which has not become assimilated, bodies
analogous to resin, and some extractive substances.
That which remains after these methods have been pursued ought to be
regarded as the hide proper, that is to say, as the animal tissue
saturated with tannic acid. In this remainder one is able to estimate
with close precision that which belongs to the hide. The hide being an
elementary tissue of unchangeable form, it is easy, in determining the
elementary portion, to find the amount of real hide remaining in the
product. With these elements one can arrive at a solution of some of the
questions we are discussing.
We give below, according to this method, a table showing the composition
of the different leathers exhibited at the Paris Exposition of 1878.
They are the results of careful research, and we have based our work
upon them:
Matter Soluble Fixed
in Air Tannin
| |
| Matter Solu- |
| ble in Alcohol |
| | |
Moisture | | Gelatine |
--+-- --+-- --+-- --+-- --+--
Steer hide, hemlock tanned (heavy leather) 10.95 4.15 19.77 39.1 26.03
Sheepskins, sumac " (Hungarian) 10.8 10.3 12.1 40.3 26.5
Finished calf, pine bark tanned (Hungarian) 11.2 1.7 7.4 41.6 38.1
Steer hide, quebracho tanned (heavy leather) 11.7 1.6 11.2 43.1 32.4
" " chestnut " " " 13.5 0.29 1.99 45.46 38.76
Finished calfskins,
oak tanned (Chateau Renault) 12.4 0.33 3.59 46.74 36.94
Steer hide, laurel tanned (heavy leather) 12.4 1.05 7.95 47.47 31.13
" " oak tanned after three years in
the vats (heavy leather) 11.45 0.37 3.31 49.85 35.02
The following table shows the amount of leather produced by different
tannages of 100 pounds of hides:
Pounds.
Hemlock 255.7
Sumac 248.1
Pine 240.3
Quebracho 232
Chestnut 219.9
Oak 213.9
Laurel 210.6
Oak, lasting three years 206
It is important to mention here the large proportion of resinous matter
hemlock-tanned leather contains. This resin is a very beautiful red
substance, which communicates its peculiar color to the leather.
We should mention here that in these calculations we assume that the
hide is in a perfectly dry state, water being a changeable element which
does not allow one to arrive at a precise result.
These figures show the enormous differences resulting from diverse
methods of tanning. Hemlock, which threatens to flood the markets of
Europe, distinguishes itself above all. The high results attributable to
the large proportion of resin that the hide assimilates, explain in part
the lowness of its price, which renders it so formidable a competitor.
One is also surprised at the large return from sumac-tanned hides when
it is remembered in how short a time the tanning was accomplished,
which, in the present case, only occupied half an hour.
The figures show us that the greatest return is obtained by means of
those tanning substances which are richest in resin. In short, hemlock,
sumac, and pine, which give the greatest return, are those containing
the largest amount of resin. Thus, hemlock bark gives 10.58 per cent.
of it, and sumac leaves 22.7 per cent., besides the tannin which they
contain. We know also that pine bark is very rich in resin. There is,
then, advantage to the tanner, so far as the question of result is
concerned, in using these materials. There is, however, another side to
the question, as the leather thus surcharged with resin is of inferior
quality, generally has a lower commercial value, and is often of a color
but little esteemed.
The percentage of tannin absorbed by the different methods of tannages
appears in the following table:
Hemlock 64.2
Sumac 61.4
Pine 90.8
Quebracho 75.3
Chestnut 85.2
Oak 76.9
Laurel 64.8
Oak, three years in the vat 70.2
The subjoined is a statement of the gelatine and tannin in leather of
different tannages, and also shows the amount of azote or elementary
matter contained in each:
Gelatine. Tannin. Azote.
Hemlock 60.4 39.6 10.88
Sumac 60.4 39.6 11
Pine bark 52.5 47.5 9.56
Quebracho 57.1 42.9 10.4
Chestnut 53.97 46.03 9.79
Oak 55.87 44.13 10.24
Laurel 60.4 39.6 10.94
Oak, 3 years in vat 58.75 41.25 10.65
It is not pretended that these figures are absolutely correct, as they
often vary in certain limits even for similar products. They form,
however, a fair basis of calculation.
As to whether leather is a veritable combination, it seems to us that
this question should be answered affirmatively. In fact, the resistance
of leather properly so-called to neutral dissolvents, argues in favor of
this opinion.
Furthermore, the perceptible proportion of tannin remaining absorbed by
a like amount of hide is another powerful argument. It remains for us to
say here that the differences observable in the quantity of fixed tannin
ought to arise chiefly from the different natures of these tannins,
which have properties differing as do those of one plant from another,
and which really have but one property in common, that of assimilating
themselves with animal tissues and rendering them imputrescible.
In conclusion, these researches determine the functions of resinous
matters which frequently accompany tannin; they show a very simple
method for estimating the results of one's work, as well as the degree
of tannage.--_Muntz & Schoen, in La Halle aux Cuirs_.--_Shoe & Leather
Reporter_.
* * * * *
NEW HIGH SCHOOL FOR GIRLS, OXFORD.
The new High School for Girls at Oxford, built by Mr. T.G. Jackson, for
the Girls' Public Day School Company, Limited, was opened September 23,
1880, when the school was transferred from the temporary premises it had
occupied in St. Giles's. The new building stands in St. Giles's road,
East, to the north of Oxford, on land leased from University College,
and contains accommodation for about 270 pupils in 11 class-rooms, some
of which communicate by sliding doors, besides a residence for the
mistress, an office and waiting-room, a room for the teachers, cloak
rooms, kitchens, and other necessary offices, and a large hall, 50 ft.
by 30 ft., for the general assembling of the school together and for use
on speech-days and other public occasions. The principal front faces St.
Giles's road, and is shown in the accompanying illustration. The great
hall occupies the whole of the upper story of the front building, with
the office and cloak-rooms below it, and the principal entrance in the
center. The class-rooms are all placed in the rear of the building, to
secure quiet, and open on each floor into a corridor surrounding the
main staircase which occupies the center of the building. The walls
are built of Headington stone in rubble work, with dressings of brick,
between which the walling is plastered, and the front is enriched with
cornices and pilasters, and a hood over the entrance door, all of terra
cotta. The hinder part of the building is kept studiously simple and
plain on account of expense. Behind the school is a large playground,
which is provided with an asphalt tennis-court, and is picturesquely
shaded with apple-trees, the survivors of an old orchard. The builders
were Messrs. Symm & Co., of Oxford; and the terra cotta was made by
Messrs. Doulton, of Lambeth. Mr. E. Long was clerk of works.--_Building
News_.
[Illustration: SUGGESTIONS IN ARCHITECTURE--NEW HIGH SCHOOL, OXFORD]
* * * * *
PROGRESS IN AMERICAN POTTERY.
No advance in any industry has been more sure than in that of pottery
and chinaware, under the American tariff, or more rapid in the past
four or five years. It took Europe three centuries and the jealous
precautions of royal pottery proprietors to build up the great
protectorates that made their distinctive trade-marks of such value.
The earlier lusters of the Italian faience were guild privacies
or individual secrets, as was almost all the craft of the earlier
art-worker. Royal patronage in England was equivalent to a protective
tariff for Josiah Wedgwood; and everywhere the importance of guarding
the china nurseries has been understood. We have in this country
broadcast and in abundance every type of material needed for the
finest china ware, and for the finer glasses and enamels. The royal
manufactories in Europe were hard put to it sometimes for want of
discovering kaolin beds in their dominions, but the resources of the
United States in these particulars needed something more than to be
brought to light. The manipulation and washing of the clays to render
them immediately useful to the potteries depends entirely upon the
reliance of these establishments upon home materials. The Missouri
potteries have their supplies near home, but these supplies must be put
upon the market for other cities in condition to compete with the clays
of Europe. There are fine kaolin beds in Chester and Delaware counties
in this State; there are clay beds in New Jersey, and the recent needs
of Ohio potteries have uncovered fine clay in that State. This shows
that not only for the manufacture itself, but for the development of
material here, everything depends upon the stimulus that protection
gives.
Ohio china and Cincinnati pottery are known all over the country. The
Chelsea Works, near Boston, however, are as distinguished for their
clays and faience, and for lustrous tiles especially (to be used in
household decoration) can rival the rich show that the Doulton ware made
at the Centennial. Other New England potteries are eminent for terra
cotta and granite wares. On Long Island and in New York city there are
porcelain and terra cotta factories of established fame, and the first
porcelain work to succeed in home markets was made at the still busy
factories of Greenpoint. New Jersey potteries take the broad ground of
the useful, first of all, in their manufacture of excellent granite
and cream-colored ware for domestic use, but every year turn out more
beautiful forms and more artistic work. The Etruria Company especially
have succeeded in giving the warm flesh tints to the "Parian" for busts
and statuettes, now to be seen in many shop windows. These goods ought
always to be labeled and known as American--it adds to their value with
any true connoisseur. Some of these establishments, more than others,
have the enterprise to experiment in native clays, for which the whole
trade owes their acknowledgments.
The demand all through the country by skillful decorators for the
pottery forms to work upon, points to still greater extensions in this
business of making our own china, and to the employment and good pay of
more thousands than are now employed in it. A collection of American
china, terra cotta, etc., begun at this time and added to from year to
year, will soon be a most interesting cabinet. Both in the eastern
and western manufactories ingenious workers are rediscovering and
experimenting in pastes and glazes and colors, simply because there is a
large demand for all such, and they can be supplied at prices within the
reach of most buyers. It needs only to point out this flourishing state
of things, through the "let-alone" principle, which protection insures
to this industry, to exhibit the threatened damage of the attempt, under
cover of earthenware duties, to get a little free trade through at this
session.--_Philadelphia Public Ledger_.
* * * * *
PHOTOGRAPHIC NOTES.
_Mr. Warnerke's New Discovery_.--Very happily for our art, we are at the
present moment entering upon a stage of improvement which shows that
photography is advancing with vast strides toward a position that has
the possibility of a marvelous future. In England, especially, great
advances are being made. The recent experiments of our accomplished
colleague, Mr. Warnerke, on gelatine rendered insoluble by light, after
it has been sensitized by silver bromide and developed by pyrogallic
acid, have revealed to us a number of new facts whose valuable results
it is impossible at present to foretell. It seems, however, certain that
we shall thus be able to accomplish very nearly the same effects as
those obtained by bichromatized gelatine, but with the additional
advantage of a much greater rapidity in all the operations. In my own
experiments with the new process of phototypie, I hit upon the plan of
plunging the carbon image, from which all soluble gelatine had been
removed, into a bath of pyrogallic acid, in order to still further
render impermeable the substance forming the printing surface. I also
conceived the idea of afterward saturating this carbon image with a
solution of nitrate of silver, and of subsequently treating it with
pyrogallic acid, in order to still further render impermeable the
substance forming the printing surface. But the process described by Mr.
Warnerke is quite different; by means of it we shall be able to fix
the image taken in the camera, in the same way as we develop carbon
pictures, and afterward to employ them in any manner that may be
desirable. Thus the positive process of carbon printing would be
modified in such a manner that the mixtures containing the permanent
pigment should be sensitized with silver bromide in place of potassium
bichromate. In this way impressions could be very rapidly taken of
positive proofs, and enlargements made, which might be developed in hot
water, just as in the ordinary carbon process, and at least we should
have permanent images. Mr. Warnerke's highly interesting experiments
will no doubt open the way to many valuable applications, and will
realize a marked progress in the art of photography.
_Method for Converting Negatives Directly into Positives_.--Captain
Bing, who is employed in the topographic studios of the Ministry of
War, has devised a process for the direct conversion of negatives into
positives. The idea is not a new one; but several experimenters, and
notably the late Thomas Sutton, have pointed out the means of effecting
this conversion; it has never, however, so far as I know, been
introduced into actual practice, as is now the case. The process which
I am about to describe is now worked in the studios of the Topographic
Service. The negative image is developed in the ordinary way, but the
development is carried much further than if it were to be used as an
ordinary negative. After developing and thoroughly washing, the negative
is placed on a black cloth with the collodion side downward, and exposed
to diffuse light for a time, which varies from a few seconds to two or
three minutes, according to the intensity of the plate. Afterward the
conversion is effected by moistening the plate afresh, and then plunging
it into a bath which is thus composed:
Water 700 cub. cents.
Potassium bichromate 30 grams.
Pure nitric acid 300 cub. cents.
In a few minutes this solution will dissolve all the reduced silver
forming the negative; the negative image is therefore entirely
destroyed; but it has served to impress on the sensitive film beneath
it a positive image, which is still in a latent condition. It must,
therefore, be developed, and to do this, the film is treated with a
solution of--
Water 1,000 grams
Pyrogallic acid 25 "
Citric acid 20 "
Alcohol of 36° 50 cub. cents.
The process is carried on exactly as if developing an ordinary negative;
but the action of the developer is stopped at the precise moment when
the positive has acquired intensity sufficient for the purpose for which
it is to be used. Fixing, varnishing, etc., are then carried on the
usual way. The great advantage of this process consists in the fact of
its rendering positives of much greater delicacy than those that are
taken by contact; and, on the other hand, by means of it we are able to
avoid two distinct operations, when for certain kinds of work we require
positive plates where a negative would be of no service. M. V. Rau,
the assistant who has carried out this process under the direction of
Captain Bing, has described it in a work which has just been published
by M. Gauthier-Villars.
_Experiments of Captain Bing on the Sensitiveness of Coal Oil_.--The
same Captain of Engineers has undertaken a series of very interesting
experiments on the sensitiveness to light of one or two substances to
which bitumen probably owes its sensitiveness, but which, contrary to
what takes place with bitumen, are capable of rendering very beautiful
half tones, both on polished zinc and on albumenized paper. These
sensitive substances are extracted by dissolving marine glue or coal-tar
in benzine. By exposure to light, both marine-glue and coal-tar turn of
a sepia color, and, in a printing-frame, they render a visible image,
which is not the case with bitumen; their solvents are in the order of
their energy; chloroform, ether, benzine, turpentine, petroleum spirit,
and alcohol. Of these solvents, benzine is the best adapted for reducing
the substances to a fluid state, so as to enable them to flow over the
zinc. The images obtained, which are permanent, and which are very much
like those of the Daguerreotype, are fixed by means of the turpentine
and petroleum spirit. They are washed with water, and then carefully
dried. It is possible to obtain prints with half-tones in fatty ink by
means of plates of zinc coated with marine-glue. Some attempts in this
direction were shown to me, which promised very well in this respect. We
are, therefore, in the right road, not only for economically producing
permanent prints on paper, but also for making zinc plates in which the
phototype film of bichromatized gelatine is replaced by a solution of
marine-glue and benzine. The substance known in commerce under the name
of pitch or coal-tar will produce the same results.
_Bitumen Plates_.--A new method of making bitumen plates by contact has
also been introduced into the topographical studios. The plan, or the
original drawing, is placed against a glass plate, coated with a mixture
of bitumen and of marine-glue dissolved in benzine. The marine-glue
gives the bitumen greater pliancy, and prevents it from scaling off when
rubbed, particularly when the plate is retouched with a dry point.
These bitumen plates are so thoroughly opaque to the penetration of the
actinic rays, that the printing-frame may be left for any time in full
sunlight without any fear of fog being produced on the zinc plate from
which the prints are to be taken.
_Method for Topographic Engraving by Commandant de la Noë_.--Before
leaving the interesting studios of which I have been speaking, I ought
to mention a very ingenious application which has been made of a process
called _topogravure_, invented by Commandant de la Noë, who is the
director of this important department. A plate of polished zinc is
coated with bitumen in the usual way, and then exposed directly to the
light under an original drawing, or even under a printed plan. So soon
as the light has sufficiently acted, which may be seen by means of
photometric bands equally transparent at the plate, all the bitumen not
acted upon is dissolved. As it is a positive which has acted as matrix,
the uncovered zinc indicates the design, and the ground remains coated
with insoluble bitumen. The plate is then etched with a weak solution
of nitric acid in water, and the lines of the design are thus slightly
engraved; the surface is then re-coated with another layer of bitumen,
which fills up all the hollows, and is then rubbed down with charcoal.
All the surface is thus cleaned off, and the only bitumen which remains
is that in the lines, which, though not deep, are sufficiently so to
protect the substance from the rubbing of the charcoal. When this
is done we have an engraved plate which can be printed from, like a
lithographic stone; it is gummed and wetted in the usual way, and it
gives prints of much greater delicacy and purity than those taken
directly from the bitumen. The ink is retained by the slight projection
of the surface beyond the line, so that it cannot spread, and a kind of
copper plate engraving is taken by lithographic printing. Besides, in
arriving at this result, there is the advantage of being able to use
directly the original plans and drawings, without being obliged to have
recourse to a plate taken in the camera; the latter is indispensable
for printing in the usual way on bitumen where the impression on the
sensitive film is obtained by means of a negative. It will be seen that
this process is exceedingly ingenious, and not only is its application
very easy, but all its details are essentially practical.
_Succinate of Iron Developer_.--I have received a letter from M.
Borlinetto, in which he states that he has been induced by the analogy
which exists between oxalic and succinic acids to try whether succinate
of iron can be substituted for oxalate of iron as a developer. To prove
this he prepared some proto-succinate of iron from the succinate of
potassium and proto-sulphate of iron, following the method given by Dr.
Eder for the preparation of his ferrous oxalate developer. He carried
out the development in the same way as is done by the oxalate, and
he found that the succinate of iron is even more energetic than the
oxalate. The plate develops regularly with much delicacy, and gives a
peculiar tone. It is necessary to take some fresh solution at every
operation, on account of the proto-succinate of iron being rapidly
converted into per-succinate by contact with the air.
_Method of Making Friable Hydro-Cellulose_.--At the meeting of the
Photographic Society of France, M. Girard showed his method of preparing
cellulose in a state of powder, specially adapted for the production of
pyroxyline for making collodion. Carded cotton-wool is placed in water,
acidulated with 3 per cent. of sulphuric or nitric acid, and is left
there from five to fifteen seconds; it is then taken out and laid on a
linen cloth, which is then wrung so as to extract most of the liquid. In
this condition there still remains from 30 to 40 per cent. of acidulated
water; the cotton is divided into parcels and allowed to dry in the open
air until it feels dry to the touch, though in this condition it still
contains 20 per cent. of water. It is next inclosed in a covered jar,
which is heated to a temperature of 65° C.; the desiccation therefore
takes place in the closed space, and the conversion of the material
is completed in about two or three hours. In this way a very perfect
hydro-cellulose is obtained, and in the best form for producing
excellent pyroxyline.--_Corresp. Photo Mews_.
* * * * *
PHOTO TRACINGS IN BLACK AND COLOR.
Two new processes for taking photo tracings in black and color have
recently been published--"Nigrography" and "Anthrakotype"--both of which
represent a real advance in photographic art. By these two processes we
are enabled for the first time to accomplish the rapid production of
positive copies in black of plans and other line drawings. Each of
these new methods has its own sphere of action; both, therefore, should
deserve equally descriptive notices.
For large plans, drawn with lines of even breadth, and showing no
gradated lines, or such as shade into gray, the process styled
"nigrography," invented by Itterbeim, of Vienna, and patented both
in Germany and Austria, will be found best adapted. The base of this
process is a solution of gum, with which large sheets of paper can be
more readily coated than with one of gelatine; it is, therefore, very
suitable for the preparation of tracings of the largest size. The paper
used must be the best drawing paper, thoroughly sized, and on this the
solution, consisting of 25 parts of gum arabic dissolved in 100 parts of
water, to which are added 7 parts of potassium bichromate and I part of
alcohol, is spread with a broad, flat brush. It is then dried, and if
placed in a cool, dark place will keep good for a long time. When used,
it is placed under the plan to be reproduced, and exposed to diffused
light for from five to ten minutes--that is to say, to about 14° of
Vogel's photometer; it is then removed and placed for twenty minutes in
cold water, in order to wash out all the chromated gum which has not
been affected by light. By pressing between two sheets of blotting-paper
the water is then got rid of, and if the exposure has been correctly
judged the drawing will appear as dull lines on a shiny ground. After
the paper has been completely dried it is ready for the black color.
This consists of 5 parts of shellac, 100 parts of alcohol, and 15 parts
of finely-powdered vine-black. A sponge is used to distribute the color
over the paper, and the latter is then laid in a 2 to 3 per cent. bath
of sulphuric acid, where it must remain until the black color can be
easily removed by means of a stiff brush. All the lines of the drawing
will then appear in black on a white ground. These nigrographic tracings
are very fine, but they only appear in complete perfection when the
original drawings are perfectly opaque. Half-tone lines, or the marks
of a red pencil on the original, are not reproduced in the nigrographic
copy.
"Anthrakotype" is a kind of dusting-on process. It was invented by Dr.
Sobacchi, in the year 1879, and has been lately more fully described by
Captain Pizzighelli. This process--called also "Photanthrakography"--is
founded on the property of chromated gelatine which has not been acted
on by light to swell up in lukewarm water, and to become tacky, so that
in this condition it can retain powdered color which had been dusted
on it. Wherever, however, the chromated gelatine has been acted on by
light, the surface becomes horny, undergoes no change in warm water, and
loses all sign of tackiness. In this process absolute opacity in
the lines of the original drawing is by no means necessary, for it
reproduces gray, half-tone lines just as well as it does black ones.
Pencil drawings can also be copied, and in this lies one great advantage
of the process over other photo-tracing methods, for, to a certain
extent, even half-tones can be produced.
For the paper for anthrakotype an ordinary strong, well-sized paper must
be selected. This must be coated with a gelatine solution (gelatine 1,
water 30 parts), either by floating the paper on the solution, or by
flowing the solution over the paper. In the latter case the paper is
softened by soaking in water, is then pressed on to a glass plate placed
in a horizontal position, the edges are turned up, and the gelatine
solution is poured into the trough thus formed. To sensitize the
paper, it is dipped for a couple of minutes in a solution of potassium
bichromate (1 in 25), then taken out and dried in the dark.
The paper is now placed beneath the drawing in a copying-frame, and
exposed for several minutes to the light; it is afterward laid in cold
water in order to remove all excess of chromate. A copy of the original
drawing now exists in relief on the swollen gelatine, and, in order to
make this relief sticky, the paper is next dipped for a short time in
water, at a temperature of about 28° or 30° C. It is then laid on a
smooth glass plate, superficially dried by means of blotting-paper, and
lamp-black or soot evenly dusted on over the whole surface by means of
a fine sieve. Although lamp-black is so inexpensive and so easily
obtained, as material it answers the present purpose better than any
other black coloring substance. If now the color be evenly distributed
with a broad brush, the whole surface of the paper will appear to be
thoroughly black. In order to fix the color on the tacky parts of the
gelatine, the paper must next be dried by artificial heat--say, by
placing it near a stove--and this has the advantage of still further
increasing the stickiness of the gelatine in the parts which have not
been acted upon by light, so that the coloring matter adheres even more
firmly to the gelatine. When the paper is thoroughly dry, place it in
water, and let it be played on by a strong jet; this removes all the
color from the parts which have been exposed to the light, and so
develops the picture. By a little gentle friction with a wet sponge, the
development will be materially promoted.
A highly interesting peculiarity of this anthrakotype process is the
fact that a copy, though it may have been incorrectly exposed, can
still be saved. For instance, if the image does not seem to be vigorous
enough, it can be intensified in the simplest way; it is only necessary
to soak the paper afresh, then dust on more color, etc.; in short,
repeat the developing process as above described. In difficult cases the
dusting-on may be repeated five or six times, till at last the desired
intensity is obtained.
By this process, therefore, we get a positive copy of a positive
original in black lines on a white ground. Of course, any other coloring
material in a state of powder may be used instead of soot, and then a
colored drawing on a white ground is obtained. Very pretty variations of
the process may be made by using gold or silver paper, and dusting-on
with different colors; or a picture may be taken in gold bronze powder
on a white ground. In this way colored drawings may be taken on a gold
or a silver ground, and very bright photo tracings will be the result.
Some examples of this kind, that have been sent us from Vienna, are
exceedingly beautiful.
Summing up the respective advantages of the two processes we have above
described, we may say that "nigrography" is best adapted for
copying drawings of a large size; the copies can with difficulty be
distinguished from good autographs, and they do not possess the bad
quality of gelatine papers--the tendency to roll up and crack. Drawings,
however, which have shadow or gradated lines cannot be well produced by
this process; in such cases it is better to adopt "anthrakotype," with
which good results will be obtained.--_Photographic News_.
* * * * *
ON M. C. FAURE'S SECONDARY BATTERY.
The researches of M. Gaston Planté on the polarization of voltameters
led to his invention of the secondary cell, composed of two strips of
lead immersed in acidulated water. These cells accumulate, and, so to
speak, store up the electricity passed into them from some outside
generator. When the two electrodes are connected with any source of
electricity the surfaces of the two strips of lead undergo certain
modifications. Thus, the positive pole retains oxygen and becomes
covered with a thin coating of peroxide of lead, while the negative pole
becomes reduced to a clean metallic state.
Now, if the secondary cell is separated from the primary one, we have a
veritable voltaic battery, for the symmetry of the poles is upset, and
one is ready to give up oxygen and the other eager to receive it. When
the poles are connected, an intense electric current is obtained, but
it is of short duration. Such a cell, having half a square meter of
surface, can store up enough electricity to keep a platinum wire 1
millim. in diameter and 8 centims. long, red-hot for ten minutes. M.
Planté has succeeded in increasing the duration of the current by
alternately charging and discharging the cell, so as alternately to
form layers of reduced metal and peroxide of lead on the surface of the
strip. It was seen that this cell would afford an excellent means for
the conveyance of electricity from place to place, the great drawback,
however, being that the storing capacity was not sufficient as compared
with the weight and size of the cell. This difficulty has now been
overcome by M. Faure; the cell as he has improved it is made in the
following manner:
The two strips of lead are separately covered with minium or some other
insoluble oxide of lead, then covered with an envelope of felt, firmly
attached by rivets of lead. These two electrodes are then placed near
each other in water acidulated with sulphuric acid, as in the Planté
cell. The cell is then attached to a battery so as to allow a current
of electricity to pass through it, and the minium is thereby reduced to
metallic spongy lead on the negative pole, and oxidized to peroxide of
lead on the positive pole; when the cell is discharged the reduced lead
becomes oxidized, and the peroxide of lead is reduced until the cell
becomes inert.
The improvement consists, as will be seen, in substituting for strips
of lead masses of spongy lead; for, in the Planté cell, the action is
restricted to the surface, while in Faure's modification the action is
almost unlimited. A battery composed of Faure's cells, and weighing 150
lb., is capable of storing up a quantity of electricity equivalent to
one horsepower during one hour, and calculations based on facts in
thermal chemistry show that this weight could be greatly decreased. A
battery of 24 cells, each weighing 14 lb., will keep a strip of platinum
five-eighths of an inch wide, one-thirty-second of an inch thick, and 9
ft. 10 in. long, red-hot for a long time.
The loss resulting from the charging and discharging of this battery is
not great; for example, if a certain quantity of energy is expended in
charging the cells, 80 per cent. of that energy can be reproduced by the
electricity resulting from the discharge of the cells; moreover, the
battery can be carried from one place to another without injury. A
battery was lately charged in Paris, then taken to Brussels, where it
was used the next day without recharging. The cost is also said to be
very low. A quantity of electricity equal to one horse power during an
hour can be produced, stored, and delivered at any distance within 3
miles of the works for 1½d. Therefore these batteries may become useful
in producing the electric light in private houses. A 1,250 horsepower
engine, working dynamo-machines giving a continuous current, will in one
hour produce 1,000 horse-power of effective electricity, that is to
say 80 per cent. of the initial force. The cost of the machines,
establishment, and construction will not be more than £40,000, and the
quantity of coal burnt will be 2 lb. per hour per effective horse-power,
which will cost (say) ½d. The apparatus necessary to store up the force
of 1,000 horses for twenty-four hours will cost £48,000, and will weigh
1,500 tons. This price and these weights may become much less after a
time. The expense for wages and repairs will be less than ¼d. per hour
per horse-power, which would be £24 a day, or £8,800 a year; thus the
total cost of one horse-power for an hour stored up at the works is
¾d. Allowing that the carriage will cost as much as the production and
storing, we have what is stated above, viz., that the total cost within
3 miles of the works is 1½d. per horse-power per hour. This quantity of
electricity will produce a light, according to the amount of division,
equivalent to from 5 to 30 gas burners, which is much cheaper than
gas.--_Chemical News_.
* * * * *
PHYSICAL SCIENCE IN OUR COMMON SCHOOLS.
[Footnote: Read before the State Normal Institute at Winona, Minnesota,
April 28, 1881, by Clarence M. Boutelle, Professor of Mathematics and
Physical Science in the State Normal School.]
Very little, perhaps, which is new can be said regarding the teaching
of physical science by the experimental method. Special schools for
scientific education, with large and costly laboratories, are by no
means few nor poorly attended; scientific books and periodicals are
widely read; scientific lectures are popular. But, while in many schools
of advanced grade, science is taught in a scientific way, in many others
the work is confined to the mere study of books, and in only a few of
our common district schools is it taught at all.
I shall advocate, and I believe with good reason, the use of apparatus
and experiments to supplement the knowledge gained from books in schools
where books are used, the giving of lessons to younger children who do
not use books, and the giving of these lessons to some extent in all
our schools. And the facts which I have gathered together regarding the
teaching of science will be used with all these ends in view.
Physics--using the term in its broadest sense--has been defined as the
science which has for its object the study of the material world, the
phenomena which it presents to us, the laws which govern (or account
for) these phenomena, and the applications which can be made of either
classes of related phenomena, or of laws, to the wants of man. Thus
broadly defined, physics would be one of two great subjects covering the
whole domain of knowledge. The entire world of matter, as distinguished
from the world of mind, would be presented to us in a comprehensive
study of physics.
I shall consider in this discussion only a limited part of this great
subject. Phenomena modified by the action of the vital force, either in
plants or in animals, will be excluded; I shall not, therefore, consider
such subjects as botany or zoölogy. Geology and related branches will
also be omitted by restricting our study to phenomena which take place
in short, definite, measurable periods of time. And lastly, those
subjects in which, as in astronomy, the phenomena take place beyond
the control of student and teacher, and in which their repetition at
pleasure is impossible, will not be considered. Natural philosophy, or
physics, as this term is generally used, and chemistry, will, therefore,
be the subjects which we will consider as sources from which to draw
matter for lessons for the children in our schools.
The child's mind has the receptive side, the sensibility, the most
prominent. His senses are alert. He handles and examines objects about
him. He sees more, and he learns more from the seeing, than he will in
later years unless his perceptive powers are definitely trained and
observation made a habit. His judgment and his will are weak. He reasons
imperfectly. He chooses without appropriate motives. He needs the
building up and development given by educational training. _Nature
points out the method._
Sensibility being the characteristic of his mind, we must appeal to him
through his senses. We must use the concrete; through it we must act
upon his weak will and immature judgment. From his natural curiosity we
must develop attention. His naturally strong perceptive powers must be
made yet stronger; they must be led in proper directions and fixed upon
appropriate objects. He must be led to appreciate the relation between
cause and effects--to associate together related facts--and to state
what he knows in a definite, clear, and forcible manner.
Object lessons, conversational lessons, lessons on animals, lessons
based on pictures and other devices, have been used to meet this demand
of the child's mental make up. Good in many respects, and vastly better
than mere book work, they have faults which I shall point out in
connection with the corresponding advantages of easy lessons in the
elements of science. I shall not quibble over definitions. Object
lessons may, perhaps, properly be said to include lessons such as it
seems to me should be given--lessons drawn from natural philosophy or
chemistry--but I use the term here in the sense in which it is often
used, as meaning lessons based upon some object. A thimble, a knife, a
watch, for instance, each of these being a favorite with a certain class
of object teachers, may be taken.
The objections are:
1. Little new knowledge can be given which is simple and appropriate.
Most children already know the names of such objects as are chosen,
the names of the most prominent parts, the materials of which they are
composed and their uses. Much that is often given should be omitted
altogether if we fairly regard the economy of the child's time and
mental strength. It doesn't pay to teach children that which isn't worth
remembering, and which we don't care to have them remember.
2. Study of the qualities of materials is a prominent part of lessons on
objects. Such study is really the study of physical science, but with
objects such as are usually selected is a very difficult part to give
to young children. Ask the student who has taken a course in chemistry
whether the study of the qualities of metals and their alloys is easy
work. Ask him how much can readily be shown, and how much must be taken
on authority. Have him tell you how much or how little the thing itself
suggests, and how much must he memorized from the mere book statement
and with difficulty. Study of materials is good to a certain extent, but
it is often carried much too far.
Consider a conversational lesson on some animal. Lessons are sometimes
given on cats. As an element in a reading lesson--to arouse interest--to
hold the attention--to secure correct emphasis and inflection--to make
sure of the reading being good: such work is appropriate. But let us see
what the effect upon the pupil is as regards the knowledge he gains
of the cat, and the effect upon his habits of thought and study. The
student gives some statement as to the appearance--the size--or some
act of his cat. It is usually an imperfect statement drawn from the
imperfect memory of an imperfect observation. And the teacher, having
only a _general knowledge_ of the habits of cats, can correct in only
a general way. Thus habits of faulty and incorrect observation and
inaccurate memory are fastened upon the child. It is no less by the
correction of the false than by the presenting of the true, that we
educate properly.
Besides this there is the fact that traits, habits, and peculiarities
of animals are not always manifested when we wish them to be. Suppose
a teacher asks a child to notice the way in which a dog drinks, for
example; the child may have to wait until long after all the associated
facts, the reasons why this thing was to be observed--the lesson as a
whole of which this formed a part--have all grown dim in the memory,
before the chance for the observation occurs.
Pictures are less valuable as educational aids than objects; at best
they are but partially and imperfectly concrete. The study of pictures
tends to cultivate the imagination and taste, but observation and
judgment are but little exercised.
A comparison of the kind of knowledge gained in either of the above ways
with that gained by a study of science as such, will make some of the
advantages of the latter evident. An act of complete knowledge consists
in the identifying of an attribute with a subject. Attributes of
quality--of condition--of relation, may be gained from lessons in which
objects or pictures are used. Attributes of action which are unregulated
by the observer may be learned from the study of animals. But very
little of actions and changes which can be made to take place under
specified conditions, and with uniformity of result, can be learned
until physical science is drawn upon.
And yet consider the importance of such study. Changes around him appeal
most strongly to the child. "Why _does_ this thing _do_ as it _does_?"
is more frequent than "Why _is_ this thing as it _is_?" He sees changes
of place, of form, of size, of composition, taking place; his curiosity
is aroused; and he is ready to study with avidity, and in a systematic
manner, the changes which his teacher may present to him. Consider
the peculiarities belonging to the study of changes of any sort. The
interest is held, for the mind is constantly gaining the new. The
attention cannot be divided--all parts of the change, all phases of the
action, must be known, and to be known must be _observed_; while in
other forms of lessons the attention may be diverted for a moment to
return to the consideration of exactly what was being observed before.
It goes without saying that in one case quick and accurate observation,
a retentive memory, and the association of causes and effects follow,
and that in the other they do not.
I advocate, therefore, the teaching of physical science in our
schools--_in all our schools_. Physical science taught by the
experimental method.
An experiment has been defined as a question put to Nature, a question
asked in _things_ rather than in _words_, and so conditioned that no
uncertain answer can be given. Nature says that all matter gravitates,
not in words, but in the swing of planets around the sun, and in the
leap of the avalanche. And men have devised ingenious machines through
which Nature may tell us the invariable laws of gravitation, and give
some hint as to why it is true.
There are two kinds of experiments, and two corresponding kinds of
investigators.
I. In original investigation there are the following elements:
1. The careful determination of all the conditions under which the
experiment takes place.
2. The observation of exactly what happens, with a painstaking
elimination of all previous notions as to what ought to happen.
3. The change of conditions, one at a time, with a comparison of the
results obtained with the changes made, in order to determine that each
condition has been given just its appropriate weight in the experiment.
4. The classification and explanation of the result.
5. The extension of the knowledge gained by turning it to investigations
suggested by what has already been learned.
6. The practical application of the knowledge gained.
II. In ordinary experiments for educational purposes the experimenter
follows in a general way in the footsteps of the original investigator.
There are the following elements to be considered:
1. The arrangement of conditions in general imitation of the original
investigator. This arrangement needs only to be general. For example, if
an original investigation were undertaken to determine the composition
of a metallic oxide, the metal and the oxygen would both be carefully
saved to be measured and weighed and fully tested. The ordinary
experiment would be considered successful if oxygen and the metal were
shown to result.
2. The careful consideration of what should happen.
3 The determination that the expected either does or does not happen,
with examination of reasons and elimination of disturbing causes in the
latter case.
4. The accepting as true of the classification and explanation already
given. Theories, explanations, and laws are thus accepted every day by
minds which could never have originated either them or the experiments
from which they were derived.
The method of original investigation, strictly considered, presents
many difficulties. A long course of preliminary training--a thorough
knowledge of what has been done in a given field already--a quick
imagination--a genius for devising forms of apparatus which will enable
him to work well under particular conditions in the most simple and
effective way--the faculty of suspending judgment, and of seeing
what happens, all that happens, and just how it
happens--patience--caution--courage--quick judgment when a completed
experiment presses for an explanation--these are some of the
characteristics which must belong to the original worker.
Were we all capable of doing such work there would be these advantages,
among others, of studying for ourselves:
1. What we find out for ourselves we remember longer and recall more
readily than what we acquire in any other way. This advantage holds true
whether the facts learned are entirely new or only new to us. Almost
every man whose life has been spent in study has a store of facts which
he discovered, and on which he built hopes of future greatness until
he found out later that they were old to the knowledge of the world he
lived in. And these things are among those which will remain longest in
his memory.
2. Associated facts would be learned in studying in this way which would
remain unknown otherwise.
But all the advantages would be associated with disadvantages too. Long
periods of time would have to be given for comparatively small results.
The history of science is full of instances in which years were spent in
the elaboration of some law, or principle, or theory which the school
boy of to-day learns in an hour and recites in a breath. Why does water
rise in a pump? Do all bodies, large and small, fall equally fast? The
principles which answer and explain such questions can be made so clear
and evident to the mind of a pupil that he would almost fancy they must
have been known from the first instead of having waited for the hard,
earnest labor of intellectual giants. And science has gone on, and
for us and for our pupils would still go on, only as accompanied with
numerous mistakes and disappointments.
What method shall we adopt in the teaching of science? It must
differ according to the age and capacity of the pupils. An excellent
modification of the method of original investigation may be arranged as
follows:
The children are put in possession of all facts relating to conditions,
the teacher explaining them as much as may be necessary. The experiment
is performed, the pupils being required to observe exactly what takes
place, the experiments selected being of such a nature that any previous
judgment as to what ought to occur is as nearly impossible as may be. We
predict from knowledge, real or supposed, of facts which are associated
in our minds with any new subject under consideration. Children often
know in a general, vague, and indefinite way that which, for the sake of
a full and systematic knowledge, we may desire them to study. What
they know will unconsciously modify their expectations, and their
expectations in turn may modify their observations. We are apt to
believe that happens which we expect will happen. There ought to be no
difficulty, however, in finding simple and appropriate experiments with
which the child is entirely unacquainted, and in which anything beyond
the wildest guess work is, for him, impossible. The principal use which
can be made of this method is in the mere observation of what takes
place. Nothing which the child notices correctly need be rejected,
no matter how far removed from the chief event on the object of the
experiment. Care that the pupil shall see all, and separate the
essential from the accidental, is all that is necessary.
But the original investigator assigns reasons, and with care the
children may be allowed to attempt that. This, however, should not be
carried far; incorrect explanations should be criticised; and the class
should at length be given all the elements of the correct explanation
which they have not determined for themselves. Later, pupils should be
encouraged to name related phenomena, to mention things which they
have seen happen which are due to associated causes, and to suggest
variations for the experiment and tests for its explanation. Good
results may be made to follow this kind of work even with very young
pupils. A child grows in mental strength by using the powers he has, and
mistakes seen to be such are not only steps toward a correct view of the
subject under consideration, but are steps toward that habit of mind
which spontaneously presents correct views at once in study which comes
later in life.
Another method is this: The pupil may know what is expected to happen,
as well as the conditions given, and held responsible for an observation
of what does happen and a comparison of what he really observes with
what he expects to observe. Explanations are usually given a class,
often in books with which they are furnished, instead of being drawn
from them, in whole or in part, by questioning, when physical science is
studied in this way. Indeed, this method is a necessity when text books
are used, unless experiments from some outside source are introduced.
Who shall perform the experiments? With young pupils everywhere, and
in most of our common, and even in many of our graded schools, the
experiments must be performed by the teacher. With young pupils the time
is too limited, and the responsibility and necessary care too great to
permit of any other plan being practical. In many of our schools the
small supply of apparatus renders this necessary even with larger
pupils. Added to the reasons already given is the important one that in
no other way--by no other plan--can the teacher be as readily sure that
his pupils observe and reason fully for themselves. In this normal
school a course in physics, in which the experiments are all performed
in the class room by the teacher, is followed by a course in chemistry,
in which the members of the class perform the experiments for themselves
in the laboratory. And, notwithstanding the age, maturity, and previous
observation of the pupils, a great deal must be done both in the
laboratory and in the recitation room to be sure that all that happens
is seen--that the purpose is clearly held in the mind--that the reason
is fully understood.
With older pupils and greater facilities, however, the experiments
should be performed by the pupils themselves. Constant watchfulness is
necessary, it is true, to insure to the pupil the full educational
value of the experiment. With this watchfulness it can be done, and the
advantages are numerous. Among them are:
1. The learning of the use and care of apparatus.
2. The learning of methods of actual construction, from materials at
hand, of some of the simpler kinds of apparatus.
3. The learning of the importance of careful preparation. An experiment
may be performed in a few minutes before a class which has taken an hour
or more of time in its preparation. The pupil fully appreciates its
importance, and is in the best condition to remember it only when he
has had a part of the hard work attending that preparation. Again,
conditions under which an experiment is successfully performed are often
not appreciated when merely stated in words. "To prepare hydrogen gas,
pass a thistle tube and a delivery tube through a cork which fit tightly
in the neck of a bottle," etc., is simple enough. Let a pupil try with a
cork which does not fit tightly and he will never forget that condition.
4. The learning of the importance of following directions. Chemistry,
especially, is full of those cases where this means everything.
Sometimes, not often in experiments performed in school, however, it may
mean even life or death.
The time for experiments should be carefully considered. When performed
by the teacher they should be taken up during the recitation:
1. If used as a foundation to build upon, at the beginning of the
lesson.
2. If used as a summary, at the close.
3. They should be closely connected with the points which they
illustrate.
4. When very short, or when so difficult as to demand the whole
attention of the teacher, they may be given and afterward discussed. If
long or easy, they may be discussed while the work is going on. Changes
which take place slowly, as those which are brought about by the gradual
action of heat, for instance, are best taken up in this latter way.
5. Exceptions may be necessary, as when experiments which demand special
preparation immediately before they are presented are given when the
recitation begins, or cases in which experiments are kept until near the
close of a recitation, when the teacher finds that attention flags and
the lesson seems to have lost its interest to the pupils as soon as the
experiments have been given.
When performed by the pupils themselves, experiments should come before
the recitation as a part of the preparation for the work of the class
room.
Even in those cases in which the teacher performs the work, opportunity
should be given, from time to time, for the performing of the experiment
by the pupils themselves. This can be done in several ways. During the
course in physics here I am in the habit of leaving apparatus on the
table in my room for at least one day, often for a longer time, and of
giving permission to my class to perform the experiments for themselves
when their time permits and the nature of the experiment makes it an
advantage to get a nearer view than was possible in the class work. I
leave it to them to decide when to perform the experiments, or whether
it is to their advantage to take the time to perform them at all. I make
no attempt to watch either pupils or apparatus, although I would
often assist or explain at intermissions or during the afternoon. The
apparatus was largely used, and the effect on recitations was a good
one. For advanced pupils, and those who can be fully trusted, the plan
is a good one. The only question is the safety of the apparatus; each
teacher can decide for himself regarding the advisability of the plan
for his own school.
With smaller pupils their own safety may render it best to keep
apparatus out of their hands, except under the immediate direction of
the teacher. With all pupils that is, doubtless, the best plan where
chemicals are concerned.
Another method is to allow pupils to assist the teacher in the
preparation of experiments, to call occasionally upon members of the
class to come forward and give the experiment in the place of the
teacher, and to encourage home work relating to experiments. This latter
is often spontaneous on the part of older pupils, and can be brought
about with the smaller ones by the use of a little tact; many of the
toys of the present day have some scientific principle at bottom; let
the teacher find out what toys his young pupils have, and encourage them
to use them in a scientific way.
In whatever ways experiments be used, the class should be made to
consider the following elements as important in every case:
1. The purpose of the experiment. The same experiment may be performed
at one time for one purpose, at another time for another. The purpose
intended should be made the prominent thing, all others being
subordinated to it. Many chemical reactions, for instance, can be made
to yield either one of two or more substances for study or examination,
or use, while it may be the purpose of the experiment to close only one
of them.
2 The apparatus. All elements should be considered. The necessary should
be separated from that which may vary. In cases where the various parts
must have some definite relation to the others as regards size or
position, all that should be considered with care. In complex apparatus
the exact office of each part should be understood.
3. A clear understanding of what happens. To this I have already
referred.
4. Why it happens.
5. In what other way it might be made to happen. In chemistry almost
every substance can be prepared in several different ways. The common
method is in most cases made so by some consideration of convenience,
cheapness, or safety. Often only one method is considered in one place
in a text book. In a review, however, several methods can be associated
together. Tests, uses, etc., will vary, too, and should be studied with
that fact in view. In physics phenomena illustrating a given principle
can usually be made to take place in several different ways. Often very
simple apparatus will do to illustrate some fact for which complex and
costly apparatus would be convenient. In such case the study of the
experiment with that fact in view becomes important to us who need to
simplify apparatus as much as possible.
6. Special precautions which may be necessary. Some experiments always
work well, even in the hands of those not used to the work. Others are
successful--sometimes safe, even--only when the greatest care is taken.
Substances are used constantly in work in chemistry which are deadly
poisons, others which are gaseous and will pass through the smallest
holes. In physics the experiments usually present fewer difficulties of
this sort. But special care is necessary to complete success here.
7. Other things shown by the experiment. While the main object should
be kept in most prominent view in all experimental work, the fullest
educational value will come only when all that can be learned by the use
of an experiment is carefully considered.
In selecting just the work to be taken up with a given class of
children, attention must be paid to the selection of the appropriate
matter to be presented and the well adapted method of presenting it. The
following points should be carefully considered:
1. The matter must be adapted to the capacity of the child. This must be
true both as regards the quality and the quantity. The tendency will be
to teach too much when the matter presented is entirely new, but too
little in many cases where the pupil already knows the subject in a
general way. Matter is valuable only when given slowly enough to permit
of its being fully understood and memorized, while on the other hand
method is valuable only when it secures the development of attention and
the various faculties of the child's mind by presenting a sufficient
amount of the new.
2. The work must be based on what is already known. This, one of the
best known of the principles of teaching, is of at least as great
importance in physical science as in any other department of knowledge.
It seems to me in many cases to be more important here than elsewhere.
It is not necessary to reach each point by passing over every other
point usually considered. Lessons in electricity or sound, for instance,
can be given to children who have done nothing with other parts of
science. But a natural beginning must be made, and an orderly sequence
of lessons adopted. Children will not do what adults would find almost
impossible in covering gaps between lessons.
Science may be compared to a great temple. Pillars, each built of many
curiously joined stones, standing at the very entrance, represent the
departments of science so far as man has studied them. We need not dig
down and study the foundations with the children; we need not study
every pillar nor choose any particular one rather than some other; but
we must learn something of every stone--of each great fact--in the
pillar we select, be it ever so little. The original investigator climbs
to stones never before reached, or boldly ventures away into the dim
recesses beyond the entrance to bring back hints of what may be known
and believed a hundred years hence, perhaps. The exact investigator
measures each stone. Patiently and toilsomely scientific men examine
them with glass and reagent. We need not do this, but we must omit none
of the stones.
3. The work must be continuous. To continue the figure, the stones must
be considered in some regular order. One lesson in electricity, one in
sound, then one in some other department is injurious. We remember best
by associated facts, and, while with the child this is less so than with
the man, one great object of this work is to teach him to remember in
that way.
4. Experiments should never be performed for mere show. Of two
experiments which illustrate a fact equally well it is often best to
select the most striking and brilliant one. The attention and interest
of the child will be gained in this way when they would not be to so
great an extent in any other. The point of the experiment, however,
should never be lost sight of in attention to the merely wonderful in
it.
With older pupils, and especially with those who use books for
themselves and perform the experiments there considered, the fact that
experiments demand work, downright hard work, with care, and patience,
and perseverance, and courage, cannot be kept too prominently before
them.
5. Every lesson should have a definite object. Not the general value of
the experiment, but some _one thing_ which it shows should be the object
considered.
6. Each experiment should be associated with some truth expressed in
words. The experiment should be remembered in connection with a definite
statement in each case. The memory of either the experiment, or the
principle apart from the experiment, is a species of half knowledge
which should be avoided. An unillustrated principle must, when the
necessity arises, be stored in the memory; and in the systematic study
of books this necessity will often come. But we should never crowd this
abstract work on the memory unassisted by the suggestive concrete, when
the concrete aid is possible.
7. All that is taught should be true. It is not necessary to attempt to
exhaust a subject, nor to attempt to teach minute details regarding it
to the pupils in our schools, but it is necessary that every statement
given to the pupil to be learned and remembered should contain no
element of falsehood.
The student in mathematics experiences a feeling of growing strength and
power when he finds, in algebra, that the formula he used in arithmetic
in extracting a square root has grown in importance by leading
indirectly to a theorem of which it is only one particular case--a
theorem with a more definite proof, and a larger capability for use than
he had thought possible. When he finds a still simpler proof for the
binomial theorem in his study of the calculus, his feeling of increasing
power and the desire for still greater results deepens and intensifies.
Were he to find, on the contrary, that from a false notion of the means
to be used in making a thing simple, his teacher in arithmetic had
taught him what is false, we should approve his feeling of disgust and
disappointment. Early impressions are the most lasting, and the hardest
part of school work for the teacher is the unteaching of false ideas,
and the correcting of imperfectly formed and partially understood ideas.
I took a case from mathematics, the exact science, to illustrate this
point. But I must not neglect to notice the difference between that
subject and physical science. The latter consists of theories,
hypotheses, and so-called laws, supported by _observed facts_. The facts
remain, but time has overthrown many of the hypotheses and theories, and
it will doubtless overthrow more and give us something better and truer
in their place. While a careful distinction between what is known and
what is believed is necessary, I should always class the teaching of
accepted theories and hypotheses with the teaching of the true.
But teachers, with more of imagination than good sense, teach
distinctions which do not exist, generalizations which do not
generalize, and do incalculable mischief by so doing.
8. Experimental work should be thoroughly honest as to conditions and
results. If an experiment is not the success you expected it would be,
say so honestly, and if you know why, explain it. The pupil should be
taught to know just what _is_, theory or expectation to the contrary
notwithstanding. Discoveries in physical science have often originated
in a search for the reason for some unexpected thing.
The relation of the study of science to books on science should be
considered. For the work done with pupils before they are given books to
use for themselves, any attempt to follow a text book is to be deplored.
The study of the properties of matter, for instance, would be a fearful
and wonderful thing to set a class of little ones at as a beginning in
scientific work. Just what matter, and force, and molecules, and atoms
are may be well enough for the student who is old enough to begin to use
a book, but they would be but dry husks to a younger child. Many of the
careful classifications and analyses of topics in text books had far
better be used as summaries than in any other way; and a definition is
better when the pupil knows it is true than when he is about to find out
whether it is or not.
An ideal course in science would be one in which nothing should be
learned but that found out by the observation of the pupil himself under
the guidance of the teacher, necessary terms being given, but only when
the thing to be named had been considered, and the mind demanded the
term because of a felt need. Practically such a method is impossible in
its fullest sense, but a closer approach to it will be an advantage.
Among the numerous good results which will follow the study of physical
science are the following:
1. The cultivation of all the faculties of the child in a natural order,
thus making him grow into a ready, quick, and observing man. Education
in schools is too often shaped so as to repress instead of cultivate the
instinctive desire for the _knowledge of things_ which is found in every
child.
2. The mechanical skill which comes from the preparation and use of
apparatus.
3. The ability to follow directions.
4. The belief in stated scientific facts, the understanding of
descriptions, diagrams, etc.
5. The habitual scientific use of events which happen around us.
6. The study of the old to find the new. The principle of the telephone,
for instance, is as old as spoken language. The mere[1] pulses in the
air--carrying all the characteristics of what you say--may set in
vibration either the drum of my ear, or a disk of metal. How simple--and
how simple all true science is--when we understand it.
[Transcribers note 1: corrected from 'more']
8. The cultivation of the scientific judgment, and the inventive powers
of the mind. One great original investigator, made such by the direction
given his mind in one of our common schools, would be cheaply bought at
the price of all that the study of science in our schools will cost for
the next quarter of a century.
8. Honesty. If there is a study whose every tendency is more in the
direction of honesty and truthfulness--both with ourselves and with
others--than is the study of experimental science, I do not know what it
is.
Physical science, then, will help in making men and women out of our
boys and girls. It is worthy of a fair, earnest trial everywhere.
A few minutes each day in which a class or a school study science in
some of the ways I have indicated will give a knowledge at the end of a
term or a year of no mean value. The time thus spent will have rested
the pupils from their books, to which they will return refreshed, and
instead of being time lost from other study the work will have been made
enough more earnest and intense to make it again.
Apparatus for illustrating many of the ordinary facts of physics can be
devised from materials always at hand. Many more can be made by any
one skilled in the use of tools. In chemistry, the simplicity of the
apparatus, and comparative cheapness of ordinary chemicals, make the use
of a large number of beautiful and instructive experiments both easy and
cheap.
A nation is what its trades and manufactures--its inventions and
discoveries--make it; and these depend on its trained scientific men.
Boys become men. Their growing minds are waiting for what I urge you
to offer. Science has never advanced without carrying practical
civilization with it--but it has never truly advanced save by the use of
the experimental method. _And it never will_.
Let us then look forward to the time when our boys and young men--our
girls and young women--shall extend the boundaries of human knowledge by
its use, fitted so to do by what we may have done for them.
* * * * *
GEOGRAPHICAL SOCIETY OF THE PACIFIC.
This society is a recent organization, the objects of which are to
encourage geographical exploration and discovery; to investigate and
disseminate geographical information by discussion, lectures, and
publications; to establish in this, the chief maritime city of the
Western States, for the benefit of commerce, navigation, and the
industrial and material interests of the Pacific slope, a place where
the means will be afforded of obtaining accurate information not only of
the countries bordering on the Pacific ocean, but of every part of the
habitable globe; to accumulate a library of the best books on geography,
history, and statistics; to make a collection of the most recent maps
and charts--especially those which relate to the Pacific coast, the
islands of the Pacific and the Pacific ocean--and to enter into
correspondence with scientific and learned societies whose objects
include or sympathize with geography.
The society will publish a bulletin and an annual journal, which will
interchange with geographical and other societies. Monthly meetings are
to be held, at which original papers will be read or lectures be
given; and to which, as well as to the entertainments to distinguished
travelers, to the conversazioni, and to the informal evenings, the
fellows of the society will have the privilege of introducing their
friends. The initiation fee to the society is $10; monthly dues $1; life
fellowship $100.
At a meeting held at the Palace Hotel on the 12th May, the following
gentlemen were elected for the ensuing year: President, Geo. Davidson;
Vice-Presidents, Hon. Ogden Hoffman, Wm. Lane Booker, H.B.M. Consul, and
John R. Jarboe; Foreign Corresponding Sec., Francis Berton; Home Cor.
Sec., James P. Cox; Treas., Gen. C. I. Hutchinson; Sec'y, C. Mitchell
Grant, F.R.G.S. The council is composed of the following: Hon. Joseph W.
Winans, Hon. J.F. Sullivan, Ralph C. Harrison, A.S. Hallidie, Thos. E.
Stevin, F.A.G.S., W.W. Crane, Jr., W.J. Shaw, C.P. Murphy, Thos. Brice,
Edward L.G. Steele, Gerrit L. Lansing, Joseph D. Redding. The Trustees
are Geo. Davidson, Wm. Lane Booker, Hon. Jno. S. Hager, Geo. Chismore,
M.D., Selim Franklin.
* * * * *
THE BEHRING'S STRAITS CURRENTS.
It will be remembered that a short time since we mentioned the fact that
W.H. Dall, of the U. S. Coast Survey, who has passed a number of years
in Alaskan waters, on Coast Survey duty, denied the existence of any
branch of the Kuro Shiwo, or Japanese warm stream, in Behring's Straits.
That is, he failed to find evidence of the existence of any such
current, although he had made careful observations. At the islands in
Behring's Straits, his vessel had sailed in opposite directions with ebb
and flood tide, and he thought the only currents there were tidal in
their nature. The existence or non-existence of this current is an
important point in Arctic research on this side of the continent.
At the last meeting of the Academy of Sciences, Prof. Davidson, of the
U. S. Coast Survey, author of the "Alaska Coast Pilot," refuted Dr.
Dall's opinion of the non-existence of a branch of the Kuro Shiwo, or
Japanese warm stream, from the north Pacific into the Arctic Ocean,
through Behring's Straits. He said that in 1857 he gave to the Academy
his own observations, and recently he had conferred with Capt. C.L.
Hooper, who commanded the U. S. steamer Thomas Corwin, employed as a
revenue steam cruiser in the Arctic and around the coast of Alaska.
Capt. Hooper confirms the opinions of all previous navigators, every one
of which, except Dr. Dall, say that a branch of this warm stream passed
northward into the Arctic through Behring's Strait. It is partly
deflected by St. Lawrence Island, and closely follows the coast on the
Alaskan side, while a cold current comes out south, past East Cape
in Siberia, skirting the Asiatic shore past Kamschatka, and thence
continues down the coast of China. He said ice often extended several
miles seaward, from East Cape on the Asiatic side of Behring Strait,
making what seamen call a false cape, and indicating cold water, while
no such formation makes off on the American side, where the water is
12 degrees warmer than on the Asiatic shore off the Diomede islands,
situated in the middle of Behring's Strait, the current varies in
intensity according to the wind.
Frequently it is almost nothing for several days, when after a series of
southerly winds the shallow Arctic basin has been filled, under a heavy
pressure, with an unusual volume of water, and a sudden change to
northerly winds, makes even a small current setting southward for a few
days, just as at times the surface currents set out our Golden Gate
continuously for 24 and 48 hours, as shown by the United States Coast
Survey tide gauges. Whalers report that the incoming water then flows
in, under the temporary outflowing stream.
Old trees, of a variety known to grow in tropical Japan, are floated
into the Arctic basin as far as past Point Barrow, on the American side,
but none are found on the Asiatic side, or near Wrangell Land, where a
cold stream exists, and ice remains late in the season. On the northern
side of the Aleutian islands are found cocoanut husks and other tropical
productions stranded along the beaches. The American coast of Alaska
has a much warmer climate than the Asiatic coast of Siberia, and the
American timber line extends very far north. The ice opens early in the
season on the American side, and invariably late on the Asiatic.
Capt. C. L. Hooper says that when just north of Behring's Strait, off
the American coast, in the Arctic basin, the U.S. steamer Thomas Corwin,
when becalmed for 24 hours, drifted 40 miles to the northward. From
all these, and other facts, and the unanimous testimony of American
whalemen, who have for years spent many months annually in the Arctic,
and from his own observations, he argued that a branch of the Kuro-Shiwo
or Japanese warm stream, unquestionably runs northward through Behring's
Strait into the Arctic basin along the northwestern coast of Alaska.
Prof. Davidson then called to mind the testimony in regard to the
existence of Plover Island, between Herald Island and Wrangell Land,
which he said was first made public through this academy. The evidence
of Capts. Williams and Thomas Long were recited and highly praised. One
of the officers of Admiral Rodgers' expedition climbed to near the top
of Herald Island, at a time of great refraction, when probably a false
horizon existed, and hence did not see Plover Island, although Wrangell
Land was in sight.
Prof. Davidson thinks all the authorities are against Dr. Dall, who
attributes the warm current he observed on the American coast to water
from the Yukon River and to the large expanse of shallow water exposed
to the sun's rays. As Dall's observations only covered a few days of
possibly exceptional weather, and the whalers and Captain Hooper's cover
vastly longer periods, and whalers all say it is a pretty hard thing to
beat southward through Behring's Strait, owing to the northerly current
setting into the Arctic, we are forced to the conclusion that Dr.
Dall has mistaken the exception for the rule, and his conclusions are
therefore erroneous. When, in 1824, Wrangell went north, he, like
others, always found broken ice and considerable open water. In 1867,
when Capt. Thomas Long made his memorable survey of the coast of
Wrangell Land, the season was an exceptionally open one, and in
California we had heavy rains, extending into July.
* * * * *
EXPERIMENTAL GEOLOGY.
ARTIFICIAL PRODUCTION OF CALCAREOUS PISOLITES AND OOLITES.
Mr. Stanislas Meunier communicates to _Le Nature_ an account of some
interesting specimens of globular calcareous matter, resembling
pisolites or peastones both in appearance and structure, which were
accidentally formed as follows: The Northern Railway Company, France,
desiring to purify some calciferous water designed for use in steam
boilers, hit upon the ingenious expedient of treating it with lime water
whose concentration was calculated exactly from the amount of lime
held in the liquid to be purified. The liquids were mixed in a vast
reservoir, to which they were led by parallel pipes, and by which they
were given a rapid eddying motion. The transformation of the
bicarbonate into neutral carbonate of lime being thus effected with
the accompaniment of a circling motion, the insoluble salt which
precipitated, instead of being deposited in an amorphous state, hardened
into globules, the sizes of which were strictly regulated by the
velocity of the currents. Those that have been formed at one and the
same operation are uniform, but those formed at different times vary
greatly--their diameters varying by at least one millimeter to one and
a half centimeters. The surface of the smaller globules is smooth, but
that of the larger ones is rough. Even by the naked eye, it may be
seen that both the large and small globules are formed of regularly
superposed concentric layers. If an extremely thin section be made
through one of them it is found that the number of layers is very great
and that they are remarkably regular (A). By the microscope, it has been
ascertained that each layer is about 0.007 of a millimeter in thickness.
On observing it under polarized light the calcareous substance is
discovered to be everywhere crystallized, and this suggests the question
whether the carbonate has here taken the form of aragonite or of
calcite. Examination has shown it to be the latter. The density of the
globules (2.58) is similar to that of ordinary varieties of calcite. It
is probable that if the operation were to take place under the influence
of heat, under the conditions above mentioned, aragonite would be
formed. It is hardly necessary to dwell upon the possible geological
applications of this mode of forming calcareous oolites and pisolites.
ON CRYSTALS OF ANHYDROUS LIME.
Some time ago it was discovered that some limestone, which had been
submitted for eighteen months to a heat of nearly 1,000 degrees in
the smelting furnaces of Leroy-Descloges (France), had given rise to
perfectly crystallized anhydrous lime. Figure C shows three of these
crystals magnified 300 diameters. It will be noticed that they have a
striking analogy with grains of common salt. They are, in fact, cubes
(often imperfect), but do not polarize light, as a substance of the
first crystalline system should. However, it is rarely the case that the
crystals do not have _some_ action on light. Most usually, when the two
Nicol prisms are crossed so as to cause extinction, the crystals present
the appearance shown at D. That is to say, while the central portion
is totally inactive there are seen on the margins zones which greatly
brighten the light.
[Illustration]
A and B.--Calcareous Pisolites and Oolites produced artificially.
A.--External aspect and section of a Pisolite. B.--Details of internal
structure as seen by the microscope.
C and D.--Crystals of anhydrous Lime obtained artificially. C.--Crystals
seen under the microscope in the natural light. D.--Crystals seen under
the microscope in polarized light.
The phenomenon is explained by the slow carbonization of the anhydrous
lime under the influence of the air; the external layers passing to the
state of carbonate of lime or Iceland spar, which, as well known, has
great influence on polarized light. This transformation, which takes
place without disturbing the crystalline state, does not lead to any
general modification of the form of the crystals, and the final product
of carbonization is a cubic form known in mineralogical language as
_epigene_. As the molecule of spar is entirely different in form
from the molecule of lime, the form of the crystal is not absolutely
preserved, and there are observed on the edges of the epigene crystal
certain grooves which correspond with a loss of substance. These grooves
are quite visible, for example, on the crystal to the left in Fig. D.
Up to the present time anhydrous lime has been known only in an
amorphous state. The experiment which has produced it in the form noted
above would doubtless give rise to crystallized states of other earthy
oxides likewise, and even of alkalino-earthy oxides.
COCCIDÆ.
[Footnote: A paper recently read before the California Academy of
Sciences.]
By DR. H. BEHR.
With the exception of Hymenoptera there is no group of insects that
interfere in so many ways in good and evil with our own interests, as
that group of Homoptera called Coccidæ.
But while the Hymenoptera command our respect by an intellect that
approaches the human, the Coccus tribe possesses only the lowest kind of
instinct, and its females even pass the greater part of their lives in
a mere vegetation state, without the power of locomotion or perception,
like a plant, exhibiting only organs of assimilation and reproduction.
But strange to say, these two groups, otherwise so very dissimilar,
exhibit again a resemblance in their product. Both produce honey and
wax.
It is true, the honey of this tribe is almost exclusively used by the
ants. But I have tasted the honey-like secretion of an Australian
lecanium living; on the leaves of Eucalyptus dumosus; and the manna
mentioned in Scripture is considered the secretion of Coccus manniparus
(Ehrenberg) that feeds on a tamarix, and whose product is still used by
the native tribes round Mount Sinai.
Several species of Coccides are used for the production of wax; many
more, among which the Cochenill, for dyes.
All these substances can be obtained in other ways, even the Cochenill
is to a great extent superseded by aniline dyes, but in regard to one
production, indispensable to a great extent, we are entirely dependent
on some insects of this family; it is the Shellac, lately also found in
the desert regions around the Gila and Colorado on the Larrea Mexicana.
You will remember that excellent treatise on this variety of Shellac,
written by Professor J.M. Stillman at Berkeley, on its chemical
peculiarities.
But all these different forms of utility fall very lightly in weight,
and can not even be counted as an extenuating circumstance, when we
compare them to the enormous evils brought on farmer and gardener by the
hosts of those Coccides that visit plantations, hothouses, and orchards.
To combat successfully against these insect-pests we have first to study
their habits and then adapt to them our remedies, which you will see
are more effective when well administered than those which we possess
against insect pests of other classes.
I give here only the outlines of their natural history, peculiarities
that are common to all, for it would be impossible to go into detail.
Where there are exceptions of practical importance I will mention them.
In countries with a well defined winter the winged males appear as
soon as white frosts are no more usual, and copulate with the unwieldy
limbless female, that looks more like a gall or morbid excrescence, than
a living animal. Shortly after the young ones are perceptible near the
withered body of their mother, covered by waxy secretions that look
somewhat like a feathery down.
These young ones are lively enough, they move about with agility, and
it is not till high summer that they fasten themselves permanently, and
lose feet and antennae, organs of locomotion and perception that are no
more of any use to them. (There is a slight difference in this regard
between different genera, as for instance, Coccus and Dorthesia retain
these organs in different degrees of imperfection, Lecanium and
Aspidiotus losing every trace of them.)
In this limbless, senseless state the females remain fall and winter.
Toward the end of winter these animated galls begin to swell, and those
containing males enter the state of the chrysalis, from which the males
emerge at the beginning of the warm season and fecundate the gall-like
females, which undergo neither chrysalis state nor any other change, but
die, or we may call it dissolve into their offspring, for there scarcely
remains anything of them, except a pruinous kind of down, after having
given birth to the young ones.
Now we come to the practical deduction from these facts. It is clear
that the only time when the scalebug can emigrate and infest a new
tree is the time when it is a larva, that is, when it has the power of
locomotion. In countries with a pronounced winter this time begins
much later than with us, but it ends about the same time, that is, the
beginning of August. I have seen the male of Aspidiotus in February, so
that the active larva may be expected in March, and the active Lecanium
Hesperidum I have seen last year, June 27, at Colonel Hooper's ranch in
Sonoma County. We may safely fix the time of the active scalebug from
March to August.
Notwithstanding the agility of the young scalebug, the voyage from one
tree to another, considering the minute size of the traveler, is an
undertaking but seldom succeeding, but one female bug, if we take
into account its enormous fertility, is sufficient to cover with its
grandchildren next year a tree of moderate size.
Besides there is another and much more effective way of transmigration
by the kind assistance of the ant who colonizes the scalebug as well for
its wax as it colonizes the Aphis for its honey. Birds on their feathers
and the gardener himself on his dress contribute to spread them.
But even the ant can not transplant the scalebug when it is once firmly
fixed by its rostrum.
It is evident, therefore, that the time for the application of
insecticides is the time when all the scalebugs are fixed, that is about
the end of July or beginning of August. All previous application will
clean the tree or plant only for a time, and does not prevent a more or
less numerous immigration from the neighboring vegetation, especially if
an ant-hill is not far off.
As to the insecticide, there are to be applied two very effective ones,
each with its advantages and disadvantages.
1. Petroleum and its different preparations.
2. Lye or soap.
The petroleum is the best disinfectant. It can safely be applied to any
cutting or stem, as long as it is not planted, but is one of the most
invidious substances when applied to vegetation in the garden, or
fields. If effectively applied, it can not be prevented from running
down the bark of the tree and entering the ground, where every drop
binds a certain amount of earth to an insoluble substance, in which
state it remains for ever. With every application the quantity of these
insoluble compounds is augmented and sterility added.
If I am not mistaken, it was near Antwerp--at least I am certain it was
in Belgium--where the first experience of this kind is recorded.
In France, preparations of coal tar have been recommended and have
been lately used in the form of a paint. May be that in this form the
substance is not so apt to enter into combinations with the soil. At any
rate, the method is of too recent a date to permit any conclusions about
the final result of these applications, as the invidious nature of the
substance produces, by gradual accumulation, its effects, which are not
perceived until they are irreparable.
2. Lye or soap. The application of these insecticides requires more
care, and is therefore more troublesome. But instead of attracting
fertility from the soil, they add to it. In Southern Europe soap
and water has been for many years the remedy against the Lecanium
Hesperidum. The method applied by the farmers in Portugal, as described
to me by Dr. Bleasdale, is perhaps the most perfect one. The Portuguese
have very well observed that the colonization of scalebugs always begins
at the lowest end of the trunk and pretend, therefore, that the scalebug
comes out of the ground. This, of course, is not the case, but may their
interpretation be an error, they have been practical enough in utilizing
their observation about the invasion beginning near the roots. They
knead a ring of clay round the tree, in which ring the soap water runs
when they wash the tree, and besides, they fill frequently the little
ditch formed by this ring.
This arrangement of course is only possible in climates of a rainy
summer.
As it is our object to make our knowledge as available as possible for
practical purposes, I repeat for the benefit of cultivators the advice,
without repeating the reasoning:
1. Use the petroleum for disinfecting imported trees and cuttings:
2. Use soap for cleaning trees planted in your orchard.
3. If you must use the petroleum in your garden, use it in August, when
a single application is sufficient.
* * * * *
AGRICULTURAL ITEMS.
The exportation of dried apples from this country to France has greatly
increased of late years, and now it is said that a large part of this
useful product comes back in the shape of Normandy cider and light
claret.
A.B. Goodsell says in the _New York Tribune_: "Put your hen feed around
the currants. I did this twice a week during May and June, and not a
currant worm was seen, while every leaf was eaten off other bushes 150
feet distant, and not so treated."
Buckwheat may be made profitable upon a piece of rough or newly cleared
ground: No other crop is so effective in mellowing rough, cloddy land.
The seed in northern localities should be sown before July 12; otherwise
early frosts may catch the crops. Grass and clover may sometimes be sown
successfully with buckwheat.
The London News says: "Of all poultry breeding, the rearing of the goose
in favorable situations is said to be the least troublesome and most
profitable. It is not surprising, therefore, that the trade has of late
years been enormously developed. Geese will live, and, to a certain
extent, thrive on the coarsest of grasses."
When a cow has a depraved appetite, and chews coarse, indigestible
things, or licks the ground, it indicates indigestion, and she should
have some physic. Give one pint and a half of linseed oil, one pound of
Epsom salts, and afterward give in some bran one ounce of salt and the
same of ground ginger twice a week.
Asiatic breeds of fowl lay eggs from deep chocolate through every shade
of coffee color, while the Spanish, Hamburg, and Italian breeds are
known for the pure white of the eggshell. A cross, however remote, with
Asiatics, will cause even the last-named breeds to lay an egg slightly
tinted.
In setting out currant bushes care should be exercised not to place any
buds under ground, or they will push out as so many suckers. Currants
are great feeders, and should be highly manured. To destroy the worm,
steep one table-spoonful of hellebore in a pint of water, and sprinkle
the bushes. Two or three sprinklings are sufficient for one season.
Mr. Joseph Harris, of Rochester, makes a handy box for protecting melons
and cucumbers from insect enemies. Take two strips of board of the
required size, and fasten them together with a piece of muslin, so the
muslin will form the top and two sides of the box. Then stretch into
box form by inserting a small strip of wood as a brace between the two
boards. This makes a good, serviceable box, and, when done with for the
season, it can be packed into a very small space, by simply removing the
brace and bringing the two board sides together. As there is no patent
on the contrivance, anybody can make the boxes for himself.
Mr. C. S. Read recently said before the London Fanners' Club: "American
agriculturists get up earlier, are better educated, breed their stock
more scientifically, use more machinery, and generally bring more
brains to bear upon their work than the English farmer. The practical
conclusion is, that if farmers in England worked hard, lived frugally,
were clad as meanly as those of the States, were content to drink filthy
tea three times a day, read more and hunted less, the majority of them
may continue to live in the old country."--_N. E. Farmer_.
* * * * *
TIMBER TREES.
A paper was read by Sir R. Christison at the last meeting of the
Edinburgh Botanical Society upon the "Growth of Wood in 1880." In a
former paper, he said, he endeavored to show that, in the unfavorable
season of 1879, the growth of wood of all kinds of trees was materially
less than in the comparatively favorable season of 1878. He had now to
state results of measurements of the same trees for the recent favorable
season of 1880. The previous autumn was unfavorable for the ripening of
young wood, and the trees in an unprepared condition were exposed during
a great part of December, 1879, to an asperity of climate unprecedented
in this latitude. This might have led one to expect a falling off in the
growth of wood, and it appeared, from comparison of measurements, that,
with very few exceptions, the growth of wood last year was even more
below the average of favorable years than that of the bad year, 1879.
Thus, in fifteen leaf-shedding trees of various species, exclusive of
the oak, the average growth of trunk girth in three successive years
was: 1878, 8-10ths; 1879, 45-100ths; 1880, 3-10ths and a half. In
four specimens of the oak tribe, the growth was: 1878, 8-10ths; 1879,
77-100ths; 1880, 54-100ths. In twenty specimens of the evergreen
Pinaceae the growth was: 1878, 8-10ths; 1879, 7-10ths; 1880, 6-10ths and
a half. After giving details in regard to particular trees, Sir Robert
stated, as general deductions from his observations, that leaf-shedding
trees, exclusive of the oak, suffered most; that the evergreen Pinaceae
suffered least; and that there was some power of resistance on the part
of the oak tribe which was remarkable, the power of resistance of the
Hungary oak being particularly deserving of attention. In another
communication on the "extent of the season of growth," Sir Robert
stated, as the result of observations on five leaf-shedding and five
evergreen trees, that in the case of the former, even in a fine year,
the growth of wood was confined very nearly, if not entirely, to the
months of June, July, and August; while in the case of the latter growth
commenced a month sooner, terminating, however, about the same time. Mr.
A. Buchan said it was proposed that the inquiry should be taken up more
extensively over Scotland.
* * * * *
MEDICAL USES OF FIGS.--Prof. Bouchut speaks (_Comptes Rendus_) of some
experiments he has made, going to show that the milky juice of the
fig-tree possesses a digestive power. He also observed that, when some
of this preparation was mixed with animal tissue, it preserved it
it from decay for a long time. This fact, in connection with Prof.
Billroth's case of cancer of the breast, which was so excessively foul
smelling that all his deodorizers failed, but which, on applying a
poultice made of dried figs cooked in milk, the previously unbearable
odor was entirely done away with, gives an importance to this homely
remedy not to be denied.--_Medical Press and Circ._
* * * * *
BLOOD RAIN.
The sensibilities of ignorant or superstitious people have at various
times been alarmed by the different phenomena of so-called blood, ink,
or sulphur rains. Ehrenberg very patiently collected records of the most
prominent instances of these, and published them in his treatise on the
dust of trade winds. Some, it is known, are due to soot; others, to
pollen of conifers or willows; others, to the production of fungi and
algae.
Many of the tales of the descent of showers of blood from the clouds
which are so common in old chronicles, depends, says Mr. Berkeley, the
mycologist, upon the multitudinous production of infusorial insects or
some of the lower algae. To this category belongs the phenomenon known
under the name of "red snow." One of the most peculiar and remarkable
form, which is apparently virulent only in very hot seasons, is caused
by the rapid production of little blood-red spots on cooked vegetables
or decaying fungi, so that provisions which were dressed only the
previous day are covered with a bright scarlet coat, which sometimes
penetrates deeply into their substance. This depends upon the growth of
a little plant which has been referred to the algae, under the name
of _Palmellae prodigiosa_. The rapidity with which this little plant
spreads over meat and vegetables is quite astonishing, making them
appear precisely as if spotted with arterial blood; and what increases
the illusion is, that there are little detached specks, exactly as if
they had been squirted from a small artery. The particles of which the
substance is composed have an active molecular motion, but the morphosis
of the production has not yet been properly observed. The color of the
so-called "blood rain" is so beautiful that attempts have been made
to use it as a dye, and with some success; and could the plant be
reproduced with any constancy, there seems little doubt that the color
would stand. On the same paste with the "blood-rain" there have been
observed white, blue, and yellow spots, which were not distinguishable
in structure and character.
* * * * *
TOPICAL MEDICATION IN PHTHISIS.
Dr. G.H. Mackenzie reports in the _Lancet_ an acute case of phthisis
which was successfully treated by him by causing the patient to respire
as continuously as possible, through a respirator devised for the
purpose, an antiseptic atmosphere. The result obtained appears to bear
out the experiments of Schüller of Greifswald, who found that animals
rendered artificially tuberculous were cured by being made to inhale
creosote water for lengthened periods. Intermittent spraying or inhaling
does not produce the same result. In order to insure success the
application to the lungs must be made _continuously_. For this purpose
Dr. Mackenzie has used various volatile antiseptics, such as creosote,
carbolic acid, and thymol. The latter, however, he has discarded
as being too irritating and inefficient. Carbolic acid seems to be
absorbed, for it has been detected freely in the urine after it had been
inhaled; but this does not happen with creosote. As absorption of the
particular drug employed is not necessary, and therefore not to be
desired, Dr. Mackenzie now uses creosote only, either pure or dissolved
in one to three parts of rectified spirits. "Whether," says he, "the
success so far attained is due to the antidotal action of creosote and
carbolic acid on a specific tubercular neoplasm, or to their action as
preventives of septic poisoning from the local center in the lungs,
it is certain that their continuous, steady use in the manner just
described has a decidedly curative action in acute phthisis, and is
therefore, worthy of an extended trial."
* * * * *
ON THE LAW OF AVOGADRO AND AMPERE.
The Scientific American Supplement of May 14,1881, contains, under this
head, Mr. Wm. H. Greene's objections to my demonstration (in No. 270
of the same paper) of the error of Avogadro's hypothesis. The most
important part of my argument is based on the evidence afforded by the
compound cyanogen; and Mr. Greene, directing his attention to this
subject in the first place, states that because cyanogen combines
with hydrogen or with chlorine, without diminution of volumes, I have
concluded that the hypothesis falls to the ground. This statement has
impressed me with the conviction that Mr. Greene has failed to perceive
the difficulty which is at the bottom of the question, and I will,
therefore, present the subject more fully and comprehensively.
The molecule of any elementary body is, on the ground of the hypothesis,
assumed to be a compound of two atoms, and the molecule of carbon
consequently C_2=24; that of nitrogen N_2=28. Combination of the two,
according to the same hypothesis, takes place by substitution; the
atoms are supposed to be set free and to exchange places, forming a
new compound different from the original only in this: that each new
particle contains an atom of each of the two different substances, while
each original particle consists of two identical atoms. The product is,
therefore, assumed to be, and can, under the circumstances, be no other
than particles of the composition CN and weight 26. These particles are
molecules, according to the definition laid down, just as C_2 and N_2;
but there is this essential difference, that the specific gravity of
cyanogen gas, 26, coincides with the molecular weight, while the assumed
molecular weight, N_2=28, is twice as great as the specific gravity of
the gas, N=14.
In using the term molecular weight, it is to be remembered that it does
not express the weight of single molecules, but only their relative
weight, millions of millions molecules being contained in the unit of
volume. But on the hypothesis that there is the same number of molecules
in the same volume of any gas, the specific gravities of gases can be,
and are, identified with their molecular weights, and, on the ground of
the hypothesis again, the unit of the numbers which enter into every
chemical reaction and constitute the molecular weight, is stipulated to
be that contained in two volumes.
The impossibility of the correctness of the hypothesis is now revealed
by the fact just demonstrated, that in the case of nitrogen the specific
gravity does not coincide with the molecular weight. If equal volumes
contain the same number of molecules, the specific gravities and the
molecular weights must be the same; and if the specific gravities and
molecular weights are not the same, equal volumes cannot contain the
same number of molecules. The assumed molecular weight of nitrogen is
twice as great as the specific gravity, but the molecular weight and
the specific gravity of cyanogen are identical; the number of molecules
contained in one volume of cyanogen must, therefore, necessarily be
twice as great as the number contained in one of nitrogen, and this is
fully and completely borne out by the chemical facts.
In saying that when cyanogen combines with chlorine there is naturally
no condensation, Mr. Greene has no idea that this natural law is fatal
to his artificial law of Avogadro and Ampere; "for," continues he, "the
theory is fulfilled by the actual reaction." It is not. The theory
requires two vols. of cyanogen and two vols. of chlorine, that is, the
unit of numbers, to enter into reaction and to produce two vols. of
the compound. But they produce four vols., and the non-condensation is
therefore in opposition to the theory. It is true beyond doubt that the
molecular weight of cyanogen chloride is contained in two volumes, in
spite of the hypothesis, not on the ground of it; two vols. + two vols.,
producing four vols.; two vols. could, theoretically, contain only half
the unit of numbers, and there seems to be no escape from the following
general conclusions:
1. Two vols. of CNCl, representing the unit of numbers, the constituent
weights, C=12, N=14, Cl=35.5, must each, likewise, represent the same
number; the molecular weight is, therefore, contained in one vol. of N
or Cl, but in two of CNCl and equal numbers are not contained in equal
volumes.
2. The weights N=14, Cl=35.5 occupy in the free state one volume, but
in the combination, CNCl, two volumes; their specific gravity is,
therefore, by chemical action reduced to one half. The fact thus
elicited of the variability and variation of the specific gravity is of
fundamental importance and involves the irrelevancy of the mathematical
demonstration of the hypothesis. In this demonstration the specific
gravity is assumed to be constant, and this assumption not holding good,
and the number of molecules in unit of volume being reduced to one half
when the specific gravity is reduced to the same extent by chemical
action, it is obvious that the mathematical proof must fail. Mr. Greene
states that I have proceeded to demolish C. Clerk Maxwell's conclusion
from mathematical reasoning. This is incorrect; I have found no fault
with the conclusion of the celebrated mathematician, and consider his
reasoning unimpeachable. I am also of opinion that he is entitled to
great credit and respect for the prominent part he has taken in the
development of the kinetic theory, and further think that it was for
the chemists to produce the fact of the variability of the specific
gravities, which they would probably not have failed to do but for the
prevalence of Avogadro's hypothesis, which is virtually the assertion of
the constancy of the specific gravities.
3. The unit of numbers being represented by Cl=35.5, it is likewise
represented by H=1, and as the product of the union of the two elements
is HCl, 36.5 = two vols., combination takes place by addition and not by
substitution; consequently are
4. The elementary molecules not compounds of atoms? And the distinction
between atoms and molecules is an artificial one, not justified by the
natural facts.
5. Is the molecular weight not in every instance = two volumes?
These conclusions overthrow all the fundamental assumptions on which the
hypothesis rests, and leave it, in the full meaning of the term, without
support. Though Mr. Greene states that my arguments are based upon
entirely erroneous premises, he has not even attempted to invalidate a
single one of my premises.
As he considers the non-condensation to be natural in the case of
cyanogen and chlorine, the condensation of two vols. of HCl + two vols.
of H_3N to two vols. of NH_4Cl ought to appear to him unnatural. He,
however, contends for it, and tries, on this solitary occasion, to
strengthen his opinion by authority, though the proof, if it could be
given, that ammonium chloride at the temperature of volatilization is
decomposed into its two constituents, would be insufficient to uphold
the theory.
The ground on which Mr. Greene assumes a partial decomposition at 350°
C. is the slight excess of the observed density (14.43) over that
corresponding to four vols. (13.375). There is, however, a similar
slight excess in the case of the vapor of ammonium cyanide, the same
values being respectively 11.4 and 11; and as this compound is volatile
at 100° C and, at the same time, is capable to exist at a very high
temperature, being formed by the union of carbon with ammonia, nobody
has ever, as far as I am aware, maintained that it is completely or
partially decomposed at volatilization. The excess of weight not being
due, therefore, to such cause in this case, it cannot be due to it in
the other.
The question being whether the molecular weight of ammonium chloride
is two vols. or four vols., an idea of the magnitude of the assumed
decomposition is conveyed by the proportion of the volume of the
decomposed salt to the volume of the non-decomposed, and Mr. Greene's
quotation of the percentage of weight is irrelevant and misleading, and
his number not even correct. A mixture containing
1.055 vols. of spec. gr. 26.75 = 28.22 and
12.32 " " " " 13.375 = 164.78
------ ------
13.375 " 193
has the spec. gr. 193 / 13.375 = 14.43. The proportion in one vol. of
the undecomposed to the decomposed salt is, therefore, as 1 to 11.68 and
the percentage of volume of the former 0.0789, and that of weight 28.22
/ 193 = 0.146, and not 0.16.
It is not easy to imagine why a small fraction of the heavy molecules
should be volatilized undecomposed, the temperature being sufficient
to decompose the great bulk. Marignac assumes, indeed, partial
decomposition, but the difficulties which he encountered in making the
experiments, on the results of which his opinion rests, were so great
that he himself accords to the numbers obtained by him only the value of
a rough approximation.
The heat absorbed in volatilization will comprise the heat of
combination as well as of aggregation, if decomposition takes place, and
will therefore be the same as that set free at combination. Favre and
Silbermann found this to be 743.5 at ordinary temperature, from which
Marignac concludes that it would be 715 for the temperature 350°; he
found as the heat of volatilization 706, but considers the probable
exact value to be between 617 and 818.[1]
[Footnote 1: See _Comptes Rendus_, t. lxvii., p. 877.]
An uncertainty within so wide a range does not justify the confidence
of Mr. Greene which he expresses in these words: "It is, therefore,
extremely probable that ammonium chloride is almost entirely
dissociated, even at the temperature of volatilization." By Boettinger's
apparatus a decomposition may possibly have been demonstrated, but it
remains to be seen whether it is not due to some special cause.
When Mr. Greene says that the relations between the physical properties
of solids and liquids and their molecular composition can in no
manner affect the laws of gases, nobody is likely to dissent; but the
conclusion that their discussion is foreign to the question of the
number of molecules in unit of volume does by no means follow. If the
specific gravity of a solid or the weight of unit of volume represents
a certain number of molecules, and is found to occupy two volumes in a
compound of the solid with another solid, the number of molecules in one
volume is reduced to one half. This I have shown to be the case in a
number of compounds, and the decrease of the specific gravity with
increase of the complexity of composition appears to be a general law,
as may be concluded from the very low specific gravity of the most
highly organized compounds, for instance the fatty bodies, the molecules
of which, being composed of very many constituents, are of heavy weight;
and likewise the compounds which occur in combination with water and
without it, the simpler compound having invariably a greater specific
gravity than the one combined with water; for instance:
BaH_2O_2 sp. gr. 4.495
" " + 8H_2O " 1.656
S_2H_2O_2 " 3.625
" " + 8H_2O " 1.396
FeSO_4 " 3.138
" + 7H_2O " 1.857
and so in every other case. This is now a recurrence of what takes
place in gases, and proves the fallacy of the hypothesis; for if these
compounds could be volatilized the vapor densities would necessarily
vary in the inverse proportion of the degree of composition.
The reproach that Berthelot has been endeavoring for nearly a quarter of
a century to hold back the progress of scientific chemistry, is a great
and unjustifiable misrepresentation of the distinguished chemist
and member of the Institute of France, who has done so much for
thermo-chemistry, and the more unfortunate as it seems to serve only the
purpose of a prelude to the following sentences: "But Mr. Vogel cannot
claim, as can Mr. Berthelot, any real work or experiment, however
roughly performed, suggested by the desire to prove the truth of his
own views. Let him not, then, bring forth old and long since explained
discrepancies, ... but when he will have discovered new or overlooked
facts ... chemists will gladly listen." ... Mr. Greene is here no longer
occupied to investigate whether what I have said concerning Avogadro's
hypothesis is true or false, but with myself he has become personal, and
in noticing his remarks my sole object is to contend against an error
which is much prevalent. If, according to Mr. Greene, the real work of
science consists in experimenting, and conclusions unsupported by our
own experiments have no value, it does not appear for what purpose he
has published his answer to my paper; an experiment of his, settling
Marignac's uncertain results, would have justified the reliance he
places on them. The ground he takes is utterly untenable. Experiments
are necessary to establish facts; without them there could be no
science, and the highest credit is due to those who perform successfully
difficult or costly experiments. Experimenting is, however, not the
aim and object of science, but the means to arrive at the truth; and
discoveries derived from accumulated and generally accepted facts are
not the less valuable on account of not having been derived from new and
special experiment.
It is, further, far from true that the real work of science consists
in experimenting; mental work is not less required, and the greatest
results have not been obtained by experimenters, but by the mental labor
of those who have, from the study of established facts, arrived at
conclusions which the experimenters had failed to draw. This is
naturally so, because a great generalization must explain all the facts
involved, and can be derived only from their study; but the attention
of the experimenter is necessarily absorbed by the special work he
undertakes. I refer to the three greatest events in science: the
discovery of the Copernican system, the three laws of Kepler, and
Newton's law of gravitation, none of which is due to direct and special
experimentation. Copernicus was an astronomer, but the discovery of his
system is due chiefly to his study of the complications of the Ptolemaic
system. Kepler is a memorable witness of what can be accomplished by
skillful and persistent mental labor. "His discoveries were secrets
extorted from nature by the most profound and laborious research." The
discovery of his third law is said to have occupied him seventeen years.
Newton's great discovery is likewise the result of mental labor; he was
enabled to accomplish it by means of the laws of Kepler, the laws of
falling bodies established by Galileo, and Picard's exact measurement of
a degree of a meridian.
If, then, mental work is as indispensable as experimental, it is not
less true that there are men more specially fitted for the one, others
for the other, and the best interests of science will be served when
experiments are made by those specially adapted, skillful, and favorably
situated, and the possibly greatest number of men, able and willing to
do mental work, engage in extracting from the accumulated treasures of
experimental science all the results which they are capable to yield.
Any truth discovered by this means is clear gain, and saves the waste
of time, labor, and money spent in unnecessary experiment. Mr. Greene's
zeal for experiment and depreciation of mental work would be in order,
if ways and means were to be found to render the advancement of science
as difficult and slow as possible; they are decidedly not in the
interest of science, and can not have been inspired by a desire for its
promotion.
As the evidence of the specific heats of the fallacy of Avogadro's
hypothesis involves lengthy explanations, the subject is reserved for
another paper.
San Francisco, Cal., May, 1881.
E. VOGEL.
* * * * *
DYEING REDS WITH ARTIFICIAL ALIZARIN.
By M. MAURICE PRUD'HOMME.
Since several years, the methods of madder dyeing have undergone a
complete revolution, the origin of which we will seek to point out. When
artificial alizarin, thanks to the beautiful researches of Graebe and
Liebermann, made its industrial appearance in 1869, it was soon found
that the commercial product, though yielding beautiful purples, was
incapable of producing brilliant reds (C. Koechlin). While admitting
that the new product was identical with the alizarin extracted from
madder, we were led to conclude that in order to produce fine Turkey
reds, the coloring matters which accompany alizarin must play an
important part. This was the idea propounded by Kuhlmann as far back as
1828 (_Soc. Ind. de Mulhouse_, 49, p. 86). According to the researches
of MM. Schützenberger and Schiffert, the coloring matters of madder
are alizarin, purpurin, pseudopurpurin, purpuroxanthin, and an orange
matter, which M. Rosenstiehl considers identical with hydrated purpurin.
Subsequently, there have been added to the list an orange body,
purpuroxantho-carbonic acid of Schunck and Roemer, identical with the
munjistin found by Stenhouse in the madder of India. It was known
that purpuroxanthin does not dye; that pseudopurpurin is very easily
transformed into purpurin, and the uncertainty which was felt concerning
hydrated purpurin left room merely for the hypothesis that Turkey-red
is obtained by the concurrent action of alizarin and purpurin. In the
meantime, the manufacture of artificial alizarin became extended, and a
compound was sold as "alizarin for reds." It is now known, thanks to the
researches of Perkin, Schunck, Roemer, Graebe, and Liebermann, that in
the manufacture of artificial alizarin there are produced three distinct
coloring matters--alizarin, iso or anthrapurpurin, and flavopurpurin,
the two latter being isomers of purpurin. We may remark that purpurin
has not been obtained by direct synthesis. M. de Lalande has produced
it by the oxidation of alizarin. Alizarin is derived from
monosulphanthraquinonic acid, on melting with the hydrate of potassa or
soda. It is a dioxyanthraquinone.
Anthrapurpurin and flavopurpurin are obtained from two isomeric
disulphanthraquinonic acids, improperly named isoanthraflavic and
anthraflavic acids, which are converted into anthrapurpurin and
flavopurpurin by a more profound action of potassa. These two bodies are
trioxyanthraquinones.
We call to mind that alizarin dyes reds of a violet tone, free from
yellow; roses with a blue cast and beautiful purples. Anthrapurpurin and
flavopurpurin differ little from each other, though the shades dyed
with the latter are more yellow. The reds produced with these coloring
matters have a very bright yellowish reflection, but the roses are too
yellow and the purples incline to a dull gray.
Experience with the madder colors shows that a mixture of alizarin and
purpurin yields the most beautiful roses in the steam style, but it is
not the same in dyeing, where the roses got with fleur de garance have
never been equaled.
"Alizarins for reds" all contain more or less of alizarin properly
so-called, from 1 to 10 per cent., along with anthrapurpurin and
flavopurpurin. This proportion does not affect the tone of the reds
obtained further than by preventing them by having too yellow a tone.
The first use of the alizarins for reds was for application of styles,
that is colors containing at once the mordant and the coloring matter
and fixed upon the cloth by the action of steam. Good steam-reds were
easily obtained by using receipts originally designed for extracts of
madder (mixtures of alizarin and purpurin). On the other hand, the first
attempts at dyeing red grounds and red pieces were not successful. The
custom of dyeing up to a brown with fleur and then lightening the shade
by a succession of soapings and cleanings had much to do with this
failure. Goods, mordanted with alumina and dyed with alizarin for reds
up to saturation, never reach the brown tone given by fleur or garancin.
This tone is due in great part to the presence of fawn colored matters,
which the cleanings and soapings served to destroy or remove. The same
operations have also another end--to transform the purpurin into its
hydrate, which is brighter and more solid. The shade, in a word, loses
in depth and gains in brightness. With alizarins for reds, the case is
quite different; they contain no impurities to remove and no bodies
which may gain brightness in consequence of chemical changes under the
influence of the clearings and soapings. These have only one result, in
addition to the formation of a lake of fatty acid, that is to make the
shades lose in intensity. The method of subjecting reds got up with
alizarin to the same treatment as madder-reds was faulty.
There appeared next a method of dyeing bases upon different
principles. The work of M. Schützenberger (1864) speaks of the use of
sulpho-conjugated fatty acids for the fixation of aniline colors. In
England, for a number of years, dyed-reds had been padded in soap-baths
and afterwards steamed to brighten the red. In 1867, Braun and Cordier,
of Rouen, exhibited Turkey reds dyed in five days. The pieces were
passed through aluminate of soda at 18° B., then through ammonium
chloride, washed, dyed with garancin, taken through an oil-bath, dried
and steamed for an hour, and were finally cleared in the ordinary manner
for Turkey-reds. The oil-bath was prepared by treating olive-oil with
nitric acid. This preparation, invented by Hirn, was applied since 1846
by Braun (Braun and Cordier). Since 1849, Gros, Roman, and Marozeau,
of Wesserling, printed fine furniture styles by block upon pieces
previously taken through sulpholeic acid. When the pieces were steamed
and washed the reds and roses were superior to the old dyed reds and
roses produced at the cost of many sourings and soapings. Certain makers
of aniline colors sold mixtures ready prepared for printing which were
known to contain sulpholeic acids. There was thus an idea in the air
that sulpholeic acid, under the influence of steam, formed brilliant and
solid lakes with coloring matters. These facts detract in nothing from
the merit of M. Horace Koechlin, who combined these scattered data
into a true discovery. The original process may be summed up under the
following heads: Printing or padding with an aluminous mordant, which is
fixed and cleaned in the usual manner; dyeing in alizarin for reds with
addition of calcium acetate; padding in sulpholeic acid and drying;
steaming and soaping. The process was next introduced into England,
whence it returned with the following modifications; in place of
olive-oil or oleic acid, castor oil was used, as cheaper, and the number
of operations was reduced. Castor oil, modified by sulphuric acid, can
be introduced at once into the dye-beck, so that the fixation of the
coloring matter as the lake of a fatty acid is effected in a single
operation. The dyeing was then followed by steaming and soaping.
For red on white grounds and for red grounds, a mordant of red liquor at
5° to 6° B. is printed on, with a little salt of tin or nitro-muriate of
tin. It is fixed by oxidation at 30° to 35° C., and dunged with cow-dung
and chalk. The pieces are then dyed with 1 part alizarin for reds at 10
per cent., ¼ to ½ oil for reds (containing 50 per cent.), 1-6th part
acetate of lime at 15° B., giving an hour at 70° and half an hour at the
same heat. Wash, pad in oil (50 to 100 grms. per liter of water), dry on
the drum, or better, in the hot flue, and steam for three-quarters to an
hour and a half. The padding in oil is needless, if sufficient oil has
been used in dyeing, and the pieces may be at once dried and steamed.
Wash and soap for three-quarters of an hour at 60°. Give a second
soaping if necessary. If there is no fear of soiling the whites, dye at
a boil for the last half-hour, which is in part equal to steaming.
Red pieces and yarns may be dyed by the process just given for red
grounds; or, prepare in neutral red oil, in the proportion of 150 grms.
per liter of water for pieces and 15 kilos for 100 kilos of yarns. For
pieces, pad with an ordinary machine with rollers covered with
calico. Dry the pieces in the drum, and the yarn in the stove. Steam
three-quarters of an hour at 1½ atmosphere. Mordant in pyrolignite of
alumina at 10° B., and wash thoroughly. Dye for an hour at 70°, and half
an hour longer at the same heat, using for 100 kilos of cloth or yarn 20
kilos alizarin at 10 per cent., 10 kilos acetate of lime at 18° B., and
5 kilos sulpholeic acid. Steam for an hour. Soap for a longer or shorter
time, with or without the addition of soda crystals. There may be added
to the aluminous mordant a little salt of tin to raise the tone. Lastly,
aluminate of soda may be used as a mordant in place of red liquor or
sulphate of alumina.
Certain firms employ a so-called continuous process. The pieces are
passed into a cistern 6 meters long and fitted with rollers. This
dye-bath contains, from 3 to 5 grms. of alizarin per liter of water, and
is heated to 98°. The pieces take 5 minutes to traverse this cistern,
and, owing to the high temperature and the concentration of the dye
liquor, they come out perfectly dyed. Two pieces may even be passed
through at once, one above the other. As the dye-bath becomes exhausted,
it must be recruited from time to time with fresh quantities of
alizarin. The great advantage of this method is that it economizes not
merely time but coloring matter.
The quantity of acetate of lime to be employed in dyeing varies with the
composition of the mordant and with that of the water. Schlumberger has
shown that Turkey-red contains 4 molecules of alumina to 3 of lime.
Rosenstiehl has shown that alumina mordants are properly saturated if
two equivalents of lime are used for each equivalent of alizarin, if the
dyeing is done without oil. These figures require to be modified when
the oil is put into the dye beck, as it precipitates the lime. Acetate
of lime at 15° B., obtained by saturating acetic acid with chalk and
adding a slight excess of acetic acid, contains about ¼ mol. acetate of
lime.--_Bulletin de la Société Chimique de Paris._
* * * * *
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