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Title: Experiments and Considerations Touching Colours (1664)
Author: Boyle, Robert
Language: English
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EXPERIMENTS
AND
CONSIDERATIONS
Touching
COLOURS.
First occasionally Written, among some other
_Essays_, to a Friend; and now suffer'd to
come abroad as
THE
BEGINNING
Of An
Experimental History
OF
COLOURS.
By the Honourable ROBERT BOYLE,
Fellow of the ROYAL SOCIETY.
_Non fingendum, aut excogitandum, sed inveniendum,
quid Natura faciat, aut ferat._ Bacon.
_LONDON._
Printed for _Henry Herringman_ at the
_Anchor_ on the Lower walk of the _New
Exchange._ MDCLXIV.
* * * * *
THE
PREFACE.
Having in convenient places of the following Treatise, mention'd the
Motives, that induc'd me to write it, and the Scope I propos'd to my self
in it; I think it superfluous to entertain the Reader now, with what he
will meet with hereafter. And I should judge it needless, to trouble
others, or my self, with any thing of Preface: were it not that I can
scarce doubt, but this Book will fall into the hands of some Readers, who
being unacquainted with the difficulty of attempts of this nature, will
think itn strange that I should publish any thing about Colours, without a
particular Theory of them. But I dare expect that Intelligent and Equitable
Readers will consider on my behalf: That the professed Design of this
Treatise is to deliver things rather _Historical_ than _Dogmatical_, and
consequently if I have added divers new _speculative_ Considerations and
hints, which perhaps may afford no despicable Assistance, towards the
framing of a solid and comprehensive Hypothesis, I have done at least as
much as I promis'd, or as the nature of my undertaking exacted. But another
thing there is, which if it should be objected, I fear I should not be able
so easily to answer it, and that is; That in the following treatise
(especially in the Third part of it) the Experiments might have been better
Marshall'd, and some of them deliver'd in fewer words. For I must confess
that this Essay was written to a private Friend, and that too, by snatches,
at several times, and places, and (after my manner) in loose sheets, of
which I oftentimes had not all by me that I had already written, when I was
writing more, so that it needs be no wonder if all the Experiments be not
rang'd to the best Advantage, and if some connections and consecutions of
them might easily have been mended. Especially since having carelessly laid
by the loose Papers, for several years after they were written, when I came
to put them together to dispatch them to the Press, I found some of those I
reckon'd upon, to be very unseasonably wanting. And to make any great
change in the order of the rest, was more than the Printers importunity,
and that, of my own avocations (and perhaps also considerabler
solicitations) would permit. But though some few preambles of the
particular Experiments might have (perchance) been spar'd, or shorten'd, if
I had had all my Papers under my View at once; Yet in the most of those
Introductory passages, the Reader will (I hope) find hints, or
Advertisements, as well as Transitions. If I sometimes seem to insist long
upon the circumstances of a Tryall, I hope I shall be easily excused by
those that both know, how nice divers experiments of Colours are, and
consider that I was not barely to _relate_ them, but so as to teach a young
Gentleman to make them. And if I was not sollicitous, to make a nicer
division of the whole Treatise, than into three parts, whereof the One
contains some Considerations about Colours in general. The Other exhibits a
specimen of an Account of particular Colours, Exemplifi'd in Whiteness and
Blackness. And the Third promiscuous Experiments about the remaining
Colours (especially Red) in order to a Theory of them. If, I say, I
contented my self with this easie Division of my Discourse, it was perhaps
because I did not think it so necessary to be Curious about the Method or
Contrivance of a Treatise, wherein I do not pretend to present my Reader
with a compleat Fabrick, or so much as Modell; but only to bring in
Materials proper for the Building; And if I did not well know how Ingenious
the Curiosity and Civility of Friends makes them, to perswade Men by
specious allegations, to gratifie their desires; I should have been made to
believe by persons very well qualify'd to judge of matters of this nature,
that the following Experiments will not need the addition of accurate
Method and speculative Notions to procure Acceptance for the Treatise that
contains them: For it hath been represented, That in most of them, as the
Novelty will make them surprizing, and the Quickness of performance, keep
them from being tedious; so the sensible changes, that are effected by
them, are so manifest, so great, and so sudden, that scarce any will be
displeased to see them, and those that are any thing Curious will scarce be
able to see them, without finding themselves excited, to make Reflexions
upon Them. But though with me, who love to measure Physical things by
their _use_, not their _strangeness_, or _prettiness_, the partiality of
others prevails not to make me over value these, or look upon them in
themselves as other than Trifles: Yet I confess, that ever since I did
divers years ago shew some of them to a Learned Company of _Virtuosi_: so
many persons of differing Conditions, and ev'n Sexes, have been Curious to
see them, and pleas'd not to Dislike them, that I cannot Despair, but that
by complying with those that urge the Publication of them, I may both
gratifie and excite the Curious, and lay perhaps a Foundation whereon
either others or my self may in time superstruct a substantial theory of
Colours. And if _Aristotle_, after his Master _Plato_, have rightly
observ'd Admiration to be the _Parent of Philosophy_, the wonder, some of
these Trifles have been wont to produce in all sorts of Beholders, and the
access they have sometimes gain'd ev'n to the Closets of Ladies, seem to
promise, that since the subject is so pleasing, that the Speculation
appears as Delightful! as Difficult, such easie and recreative Experiments,
which require but little time, or charge, or trouble in the making, and
when made are sensible and surprizing enough, may contribute more than
others, (far more important but as much more difficult) to recommend those
parts of Learning (Chymistry and Corpuscular Philosophy) by which they have
been produc'd, and to which they give Testimony ev'n to such kind of
persons, as value a pretty Trick more than a true Notion, and would scarce
admit Philosophy, if it approach'd them in another Dress: without the
strangeness or endearments of pleasantness to recommend it. I know that I
do but ill consult my own Advantage in the consenting to the Publication of
the following Treatise: For those things, which, whilst men knew not how
they were perform'd, appear'd so strange, will, when the way of making
them, and the Grounds on which I devis'd them, shall be Publick, quickly
lose all that their being _Rarityes_, and their _being thought Mysteries_,
contributed to recommend them. But 'tis fitter for Mountebancks than
Naturalis to desire to have their discoverys rather admir'd than
understood, and for my part I had much rather deserve the thanks of the
Ingenious, than enjoy the Applause of the Ignorant. And if I can so farr
contribute to the discovery of the nature of Colours, as to help the
Curious to it, I shall have reach'd my End, and sav'd my self some Labour
which else I may chance be tempted to undergo in prosecuting that subect,
and Adding to this Treatise, which I therefore call a _History_, because it
chiefly contains matters of fact, and which History the Title declares me
to look upon but as _Begun_: Because though that above a hundred, not to
say a hundred and fifty Experiments, (some loose, and others interwoven
amongst the discourses themselves) may suffice to give a _Beginning_ to a
History not hitherto, that I know, begun, by any; yet the subject is so
fruitfull, and so worthy, that those that are Curious of these Matters will
be farr more wanting to themselves than I can suspect, if what I now
publish prove any more than a _Beginning_. For, as I hope my Endeavours may
afford them some assistance towards this work, so those Endeavours are much
too Vnfinish'd to give them any discouragement, as if there were little
left for others to do towards the History of Colours.
For (first) I have been willing to leave unmention'd the _most part_ of
those Phænomena of Colours, that Nature presents us of her own accord,
(that is, without being guided or over-ruld by man) such as the different
Colours that several sorts of Fruites pass through before they are
perfectly ripe, and those that appear upon the fading of flowers and
leaves, and the putrifaction (and its several degrees) of fruits, &c.
together with a thousand other obvious Instances of the changes of colours.
Nor have I _much_ medled with those familiar Phænomena wherein man is not
an Idle spectator; such as the Greenness produc'd by salt in Beef much
powder'd, and the Redness produc'd in the shells of Lobsters upon the
boyling of those fishes; For I was willing to leave the _gathering_ of
_Observations_ to those that have not the Opportunity to _make
Experiments_. And for the same Reasons, among others, I did purposly omit
the Lucriferous practise of Trades-men about colours; as the ways of
making Pigments, of Bleanching wax, of dying Scarlet, &c. though to divers
of them I be not a stranger, and of some I have myself made Tryall.
Next; I did purposely pass by divers Experiments of other Writers that I
had made Tryall of (and that not without registring some of their Events)
unless I could some way or other improve them, because I wanted leasure to
insert them, and had thoughts of prosecuting the work once begun of laying
together those I had examin'd by themselves in case of my not being
prevented by others diligence. So that there remains not a little, among
the things that are already published, to imploy those that have a mind to
exercise themselves in repeating and examining them. And I will not
undertake, that _none_ of the things deliver'd, ev'n in this Treatise,
though never so faithfully set down, may not prove to be thus farr of this
Sort, as to afford the Curious somewhat to add about them. For I remember
that I have somewhere in the Book it self acknowledged, that having written
it by snatches, partly in the Counntrey, and partly at unseasonable times
of the year, when the want of fit Instruments, and of a competent variety
of flowers, salts, Pigments, and other materials made me leave some of the
following Experiments, (especialy those about Emphatical Colours) far more
unfinish'd than they should have been, if it had been as easie for me to
_supply_ what was wanting to compleat them, as to _discern_. Thirdly to
avoyd discouraging the young Gentleman I call Pyrophilus, whom the less
Familiar, and more Laborious operations of Chymistry would probably have
frighted, I purposely declin'd in what I writ to him, the setting down any
Number of such Chymicall Experiments, as, by being very elaborate or
tedious, would either require much skill, or exercise his patience. And yet
that this sort of Experiments is exceedingly Numerous, and might more than
a little inrich the History of Colours, those that are vers'd in Chymical
processes, will, I presume, easily allow me.
And (Lastly) for as much as I have occasion more than once in my several
Writings to treat either porposely or incidentally of matters relating to
Colours; I did not, perhaps, conceive my self oblig'd, to deliver in one
Treatise _all_ that I would say concerning that subject.
But to conclude, by summing up what I would say concerning what I _have_
and what I _have not_ done, in the following Papers; I shall not (_on the
one side_) deny, that considering that I pretended not to write an accurate
Treatise of Colours, but an Occasional Essay to acquaint a private friend
with what then occurrd to me of the things I had thought or try'd
concerning them; I might presume I did enough for once, if I did clearly
and faithfully set down, though not _all_ the Experiments I could, yet at
least such a variety of them, that an attentive Reader that shall consider
the Grounds on which they have been made, and the hints that are purposely
(though dispersedly) couched in them, may easily _compound_ them, and
otherwise _vary_ them, so as very much to increase their Number. And yet
(_on the other side_) I am so sensible both of how much I have, either out
of necessity or choice, left undone, and of the fruitfullness of the
subject I have begun to handle; that though I had performed far more then
'tis like many Readers will judge I have, I should yet be very free to let
them apply to my Attempts that of _Seneca_, where having spoken of the
Study of Natures Mysteries, and Particularly of the Cause of Earth-Quakes,
he subjoins.[1] _Nulla res consummata est dum incipit. Nec in hac tantum re
omnium maxima ac involutissimá, in quâ etiam cum multum actum erit, omnis
ætas, quod agat inveniet; sed in omni alio Negotio, longè semper à perfecto
fuere Principia._
[1] L. Annæ Senecæ Natur. Quest. l. 6. c. 5.
* * * * *
_The Publisher to the_
READER.
_Friendly Reader,_
Here is presented to thy view one of the Abstrusest as well as the
Gentilest Subjects of Natural Philosophy, the _Experimentall History of
Colours_; which though the Noble Author be pleased to think but _Begun_,
yet I must take leave to say, that I think it so well begun, that the work
is more than half dispatcht. Concerning which I cannot but give this
advertisement to the Reader, that I have heard the Author express himself,
that it would not surprise him, if it should happen to be objected, that
some of these Experiments have been already published, partly by Chymists,
and partly by two or three very fresh Writers upon other Subjects. And
though the number of these Experiments be but very small, and though they
be none of the considerablest, yet it may on this occasion be further
represented, that it is easie for our Author to name several men, (of whose
number I can truly name my self) who remember either their having seen him
make, or their having read, his Accounts of the Experiments delivered in
the following Tract several years since, and long before the publication of
the Books, wherein they are mentioned. Nay in divers passages (where he
could do it without any great inconvenience) he hath struck out
Experiments, which he had tryed many years ago, because he since found them
divulged by persons from whom he had not the least hint of them; which yet
is not touched, with design to reflect upon any Ingenious Man, as if he
were a Plagiary: For, though our Generous Author were not reserved enough
in showing his Experiments to those that expressed a Curiosity to see them
(amongst whom a very Learned Man hath been pleased publickly to acknowledge
it several years ago[2]; yet the same thing may be well enough lighted on
by persons that know nothing of one another. And especially Chymical
Laboratories may many times afford the same _Phænomenon_ about Colours to
several persons at the same or differing times. And as for the few
_Phænomena_ mentioned in the same Chymical writers, as well as in the
following Treatise, our Author hath given an account, why he did not
decline rejecting them, in the Anotations upon the 47th Experiment of the
third part. Not here to mention, what he elsewhere saith, to shew what use
may be Justifiably made of Experiments not of his own devising by a writer
of Natural History, if, what he employes of others mens, be well examined
or verified by himself.
[2] He that desires more instances of this kind and matter, that
according to this doctrine may much help the Theory of colours, and
particularly the force both of Sulphureous and volatile, is likewise of
Alcalizate and Acid Salts, and in what particulars, Colours likely depend
not in the causation from any Salt at all, may beg his information from
M. Boyle who hath some while since honoured me with the sight of his
papers concerning this subject, containing many excellent experiments,
made by him for the Elucidation of this doctrine, &c Dr. R. Sharrock in
his ingenious and usefull History of the Propagation and Improvement of
Vegetables, published in the yeare 1660.
In the mean time, this Treatise is such, that there needs no other
invitation to peruse it, but that tis composed by one of the Deepest & Most
indefatigable searchers of Nature, which, I think the World, as far as I
know it, affords. For mine own part, I feel a Secret Joy within me, to see
such beginings upon such _Themes_, it being demonstratively true, _Mota
facilius moveri_, which causeth me to entertain strong hopes, that this
Illustrious _Virtuoso_ and Restless Inquirer into Nature's Secrets will not
stop here, but go on and prosper in the Disquisition or the other principal
Colours, _Green, Red_, and _Yellow_. The Reasoning faculty set once afloat,
will be carried on, and that with ease, especially, when the productions
thereof meet, as they do here, with so greedy an Entertainment at home and
abroad. I am confident, that the ROYAL SOCIETY, lately constituted by his
MOST EXCELLENT MAJESTY _for improving Natural knowledge_, will Judge it
their interest to exhort our Author to the prosecution of this Argument,
considering, how much it is their design and business to accumulate a good
stock of such accurate Observations and Experiments, as may afford them and
their Offpring genuine Matter to raise a Masculine Philosophy upon, whereby
the Mind of Man may be enobled with the Knowledge of solid Truths, and the
Life of Man benefited with ampler accommodations, than it hath been
hitherto.
Our Great Author, one of the Pillars of that Illustrious Corporation, is
constantly furnishing large _Symbola_'s to this work, and is now falln, as
you see, upon so comprehensive and important a theme, as will, if insisted
on and compleated, prove one of the considerablest peeces of that
structure. To which, if he shall please to add his Treatise of _Heat_ and
_Flame_, as he is ready to publish his Experimental Accounts of _Cold_, I
esteem, the World will be obliged to Him for having shewed them both the
_Right_ and _Left Hand_ of Nature, and the Operations thereof.
The considering Reader will by this very Treatise see abundant cause to
sollicit the Author for more; sure I am, that of whatever of the
Productions of his Ingeny comes into _Forein parts_ (where I am happy in
the acquaintance of many intelligent friends) is highly valued; And to my
knowledge, there are those among the French, that have lately begun to
learn English, on purpose to enable themselves to read his Books, being
impatient of their Traduction into Latin. If I durst say all, I know of the
Elogies received by me from abroad concerning Him, I should perhaps make
this Preamble too prolix, and certainly offend the modesty of our Author.
Wherefore I shall leave this, and conclude with desiring the Reader, that
if he meet with other faults besides those, that the Errata take notice of
(as I believe he may) he will please to consider both the weakness of the
Authors eyes, for not reviewing, and the manifold Avocations of the
Publisher for not doing his part; who taketh his leave with inviting those,
that have also considered this Nice subject experimentally, to follow the
Example of our Noble Author, and impart such and the like performances to
the now very inquisitive world. _Farewell._
_H. O._
* * * * *
THE
CONTENTS.
* * * * *
CHAP. I.
_The Author shews the Reason, first of his Writing on this Subject_ (1.)
_Next of his present manner of Handling it, and why he partly declines a
Methodical way_ (2.) _and why he has partly made use of it in the History
of_ Whiteness _and_ Blackness. (3.)
Chap. 2. _Some general Considerations are premis'd, first of the
Insignificancy of the Observasion of Colours in many Bodies_ (4, 5.) _and
the Importance of it in others_ (5.) _as particularly in the Tempering of
Steel_ (6, 7, 8.) _The reason why other particular Instances are in that
place omitted_ (9) _A necessary distinction about Colour premis'd_ (10,
11.) _That Colour is not Inherent in the Object_ (11.) _prov'd first by the
Phantasms of Colours to_ Dreaming _men, and_ Lunaticks; _Secondly by the
sensation or apparition of Light upon a Blow given the Eye or the Distemper
of the Brain from internal Vapours_ (12.) _The Author recites a particular
Instance in himself; another that hapn'd to an Excellent Person related to
him_ (13.) _and a third told him by an Ingenious Physician_ (14, 15.)
_Thirdly, from the change of Colours made by the Sensory Disaffected_ (15,
16.) _Some Instances of this are related by the Author, observ'd in
himself_ (16, 17.) _others told him by a Lady of known Veracity_ (18.) _And
others told him by a very Eminent Man_ (19.) _But the strange Instances
afforded by such as are Bit by the_ Tarantula _are omitted, as more
properly deliver'd in another place_. (20.)
Chap. 3. _That the Colour of Bodies depends chiefly on the disposition of
the Superficial parts, and partly upon the Variety of the Texture of the
Object_ (21.) _The former of these are confirm'd by several Persons_ (22.)
_and two Instances, the first of the Steel mention'd before, the second of
melted Lead_ (23, 24.) _of which last several Observables are noted_ (25.)
_A third Instance is added of the Porousness of the appearing smooth
Surface of Cork_ (26, 27.) _And that the same kind of Porousness may be
also in the other Colour'd Bodies; And of what kind of Figures, the
Superficial reflecting Particles of them may be_ (28.) _and of what Bulks,
and closeness of Position_ (29.) _How much these may conduce to the
Generation of Colour instanc'd in the Whiteness of Froth, and in the
mixtures of Dry colour'd Powders_ (30.) _A further explication of the
Variety that may be in the Superficial parts of Colour'd Bodies, that may
cause that Effect, by an example drawn from the Surface of the Earth_ (31.)
_An Apology for that gross Comparison_ (32.) _That the appearances of the
Superficial asperities may be Varied from the position of the Eye, and
several Instances given of such appearances_ (33, 34, 35.) _That the
appearance of the Superficial particles may be Varied also by their Motion,
confirm'd by an Instance of the smoaking Liquor_ (35.) _especially if the
Superficial parts be of such a Nature as to appear divers in several
Postures, explain'd by the variety of Colours exhibited by the shaken
Leaves of some Plants_ (36.) _and by changeable Taffities_ (37, 38, 39.)
_The Authors wish that the Variety of Colours in Mother of Pearl were
examin'd with a_ Microscope (40.) _And his Conjectures, that possibly good_
Microscopes _might discover those Superficial inequalities to be Real,
which we now only imagine with his reasons drawn partly from the
Discoveries of the_ Telescope, _and_ Microscope (41.) _And partly also from
the Prodigiously strange example of a Blind man that could feel Colours_
(42.) _whose History is Related_ (43, 44, 45.) _The Authors conjecture and
thoughts of it_ (46, 47, 48, 49.) _and several Conclusions and Corollaries
drawn from it about the Nature of Blackness and Black Bodies_ (50, 51, 52.)
_and about the Asperities of several other Colour'd Bodies_ (53.) _And from
these, and some premis'd Considerations, are propos'd some Conjectures;
That the reason of the several Phænomena of Colours, afterwards to be met
with, depends upon the Disposition of the Seen parts of the Object_ (54.)
_That Liquors may alter the Colours of each other, and of other Bodies,
first by their Insinuating themselves into the Pores, and filling them,
whence the Asperity of the Surface of a Body becomes alter'd, explicated
with some Instances_ (55, 56.) _Next by removing those Bodies, which before
hindred the appearance of the Genuine Colour, confirm'd by several
examples_ (57) _Thirdly, by making a Fissure or Separation either in the
Contiguous or Continued Particles of a Body_ (58.) _Fourthly, by a Union or
Conjunction of the formerly separated Particles; Illustrated with divers
Instances of precipitated Bodies_ (59.) _Fifthly, by Dislocating the parts,
and putting them both into other Orders and Postures, which is Illustrated
with Instances_ (60, 61.) _Sixthly, by Motion, which is explain'd_ (62.)
_And lastly, and chiefly, by the Union of the Saline Bodies, with the
Superficial parts of another Body, whereby both their Bigness and Shape
must necessarily be alter'd_ (63, 64.) _Explain'd by Experiments_ (65, 66.)
_That the Colour of Bodies may be Chang'd by the concurrence of two or more
of these ways_ (67.) _And besides all these, Eight Reflective causes of
Colours, there may be in Transparent Bodies several Refractive_ (68, 69)
_Why the Author thinks the Nature of Colours deserves yet a further
Inquiry_ (69.) _First for that the little Motes of Dust exhibited very
lovely Colours in a darkned Room, whilst in a convenient posture to the
Eye, which in other Postures and Lights they did not_ (70.) _And that
though the smaller Parts of some Colour'd Bodies are Transparent, yet of
others they are not, so that the first Doubt's, whether the Superficial
parts create those Colours, and the second, whether there be any Refraction
at all in the later_ (71, 72, 73.) _A famous Controversie among
Philosophers, about the Nature of Colour decided_. (74. 75.)
Chap. 4. _The controversie stated about Real and Emphatical Colours_ (75,
76.) _That the great Disparity between them seems to be, partly their
Duration in the same state, and partly, that Genuine Colours are produc'd
in Opacous Bodies by Reflection, and Emphatical in Transparent by
Refraction_ (78.) _but that this is not to be taken in too large a Sense,
the Cautionary instance of Froth is alleged and insisted on_ (78, 79.)
_That the Duration is not a sufficient Characteristick, exemplify'd by the
duration of Froth, and other Emphatical Colours, and the suddain fading of
Flowers, and other Bodies of Real ones_ (80.) _That the position of the Eye
is not necessary to the discerning Emphatical Colours, shew'd by the seeing
white Froth, or an Iris cast on the Wall by a Prism, in what place of the
Room soever the Eye be_ (81.) _which proceeds from the specular Reflection
of the Wall_ (82.) _that Emphatical Colours may be Compounded, and that the
present Discourse is not much concern'd, whether there be, or be not made a
distinction between Real and Emphatical Colours_. (83.)
Chap. 5. _Six Hypotheses about Colour recited_ (84, 85) _Why the Author
cannot more fully Speak of any of these_ (86.) _nor Acquiesce in them_ (87,
88.) _What_ Pyrophilus _is to expect in this Treatise_ (88, 89.) _What
Hypothesis of Light and Colour the Author most inclines too_ (90.) _Why he
thinks neither that nor any other sufficient; and what his Difficulties
are, that make him decline all Hypotheses, and to think it very difficult
to stick to any._ (91, 92.)
* * * * *
Part the Second.
_Of the Nature of Whiteness and Blackness,_
CHAP. I.
_The reason why the Author chose the Explication of Whiteness and
Blackness_ (93.) _Wherein_ Democritus _thought amiss of these_ (94.)
Gassendus _his Opinion about them_ (95.) _What the Author approves, and a
more full Explication of White, makinig it a Multiplicity of Light or
Reflections_ (96, 97.) _Confirm'd first by the Whiteness of the_ Meridian
_Sun, observ'd in Water_ (98.) _and of a piece of Iron glowing Hot_ (99.)
_Secondly, by the Offensiveness of Snow to the Travellers eyes, confirm'd
by an example of a Person that has Travell'd much in Russia_ (100.) _and by
an Observation out of_ Olaus Magnus (100.) _and that the Snow does
inlighten and clear the Air in the Night, confirm'd by the Mosco Physician,
and Captain_ James (101.) _But that Snow has no inherent Light, prov'd by
Experience_ (102.) _Thirdly, by the great store of Reflections, from white
Bodies observ'd in a darkned Room, and by their unaptness to be Kindled by
a Burning-glass_ (103.) _Fourthly, the Specularness of White Bodies is
confirm'd by the Reflections in a dark Room from other Bodies_ (104.) _and
by the appearance of a River, which both to the Eye and in a darkned Room
appear'd White_ (105, 106.) _Fifthly, by the Whiteness of distill'd_
Mercury, _and that of the_ Galaxie (107, 108.) _and by the Whiteness of
Froth, rais'd from whites of Eggs beaten; that this Whiteness comes not
from the Air, shew'd by Experiments_ (109, 110.) _where occasionally the
Whiteness of Distill'd Oyls, Hot water, &c. are shew'd_ (111.) _That it
seems not necessary the Reflecting Surfaces should be Sphærical, confirm'd
by Experiments_ (112, 113.) _Sixthly, by the Whiteness of the Powders of
transparent Bodies_ (114.) _Seventhly, by the Experiment of Whitening and
Burnishing Silver._ (115, 116.)
Chap. 2. _A Recital of some Opinions about Blackness, and which the Author
inclines to_ (117.) _which he further insists on and explicates_ (118,
119.) _and shews for what reasons he imbrac'd that Hypothesis_ (120.)
_First, from the contrary Nature of Whiteness and Blackness, White
reflecting most Beams outwards, Black should reflect most inward_ (120.)
_Next, from the Black appearance of all Bodies, when Shadow'd; And the
manner how this paucity of Reflection outwards is caus'd, is further
explicated, by shewing that the Superficial parts may be Conical and
Pyramical_ (121.) _This and other Considerations formerly deliver'd,
Illustrated by Experiments with black and white Marble_ (122, 123.)
_Thirdly, from the Black appearance of Holes in white Linnen, and from the
appearance of Velvet stroak'd several ways, and from an Observation of
Carrots_ (124, 125.) _Fourthly, from the small Reflection from Black in a
darkned Room_ (125, 126.) _Fifthly, from the Experiment of a Checker'd Tile
expos'd to the Sun-beams_ (127.) _which is to be preferr'd before a Similar
Experiment try'd in_ Italy, _with black and white Marble_ (128.) _Some
other congruous Observations_ (129.) _Sixthly, from the Roasting black'd
Eggs in the Sun_ (130.) _Seventhly, by the Observation of the Blind man
lately mention'd, and of another mention'd by_ Bartholine (130.) _That
notwithstanding all these Reasons, the Author is not absolutely Positive,
but remains yet a Seeker after the true Nature of Whiteness and Blackness._
(131, 132.)
Experiments _in Consort, touching_ Whiteness _and_ Blackness.
_The first_ Experiment, _with a Solution of Sublimate, made White with
Spirit of Urine_, &c. (133, 134.)
_The second_ Experiment, _with an Infusion of Galls, made Black with
Vitriol_, &c. (135, 136.) _further Discours'd of_ (137.)
_The third_ Experiment, _of the Blacking of Hartshorn, and Ivory, and
Tartar, and by a further Calcination making them White_ (138, 139.)
_The fourth_ Experiment, _limiting the_ Chymist's _principle_, Adusta nigra
sed perusta alba, _by several Instances of Calcin'd Alabaster, Lead,
Antimony, Vitriol, and by the Testimony of_ Bellonius, _about the white
Charcoles of_ Oxy-cædar, _and by that of_ Camphire. (140, 141, 142.) _That
which follows about Inks was misplac'd by an Errour of the Printer, for it
belongs to what has been formerly said of Galls_ (142, 143.)
_The fifth_ Experiment, _of the black Smoak of Camphire_ (144.)
_The sixth_ Experiment, _of a black_ Caput Mortuum, _of Oyl of Vitriol,
with Oyl of Worm-word, and also with Oyl of Winter-Savory_ (145.)
_The seventh_ Experiment, _of whitening Wax_ (146.)
_The eighth_ Experiment, _with Tin-glass, and Sublimate_ (147, 148.)
_The ninth_ Experiment, _of a Black powder of Gold in the bottom of_
Aqua-fortis, _and of the Blacking of Refin'd Gold and Silver_ (148, 149.)
_The tenth_ Experiment, _of the staining Hair, Skin, Ivory_, &c. _Black,
with Crystals of Silver_ (150, 151.)
_The eleventh_ Experiment, _about the Blackness of the Skin, and Hair of_
Negroes, _and Inhabitants of Hot Climates. Several Objections are made, and
the whole Matter more fully discours'd and stated from several notable
Histories and Observations_ (from the 151 to the 167.)
_The twelfth_ Experiment, _of the white Powders, afforded by Precipitating
several Bodies, as Crabs Eyes, Minium, Coral, Silver, Lead, Tin,
Quick-silver, Tin-glass, Antimony, Benzoin, and Resinous Gumms out of
Spirit of Wine_, &c. _but this is not Universal, since other Bodies, as
Gold, Antimony, Quick-silver_, &c. _may be Precipitated of other Colours_
(168, 169, 170.)
_The thirteenth_ Experiment, _of Changing the Blackness of some Bodies into
other Colours_ (171, 172.) _and of Whitening what would be Minium, and
Copper, with Tin, and of Copper with Arsnick, which with Coppilling again
Vanishes; of covering the Colour of that of_ 1/3 _of Gold with_ 2/3 _of
Silver melted in a Mass together_ (173, 174)
_The fourteenth_ Experiment, _of turning the black Body of Horn into a
White immediately with Scraping, without changing the Substantial form, or
without the Intervention of Salt, Sulphur, or Mercury_ (176.)
_The fifteenth_ Experiment, _contains several Instances against the Opinion
of the_ Chymists _that Sulphur_ Adust _is the cause of Blackness, and the
whole Matter is fully discuss'd and stated_ (from 176 to 184)
Part the Third.
_Concerning Promiscuous Experiments about Colours_.
Experiment the First.
_IN confirmation of a former Conjecture about the Generation of Colours
from diversity of Reflections are set down several Observations made in a
Darkned room_ (186, 187.)
Experiment _the second, That white Linnen seem'd Ting'd with the Red of
Silk plac'd near it in a light Room_ (188,189.)
Experiment _the third, Of the Trajection of Light through Colour'd Papers_
(189, 190.)
Experiment _the fourth, Observations of a Prism in a dark Room_ (191, 192.)
Experiment _the fifth, Of the Refracting and Reflecting Prismatical Colours
in a light Room_ (193.)
Experiment _the sixth, On the Vanishing of the_ Iris _of the Prism, upon
the access of a greater adventitious Light_ (194.)
Experiment _the seventh, Of the appearances of the same Colour'd Papers by
Candle-light_ (195, 196).
Experiment _the eighth, Of the Yellowness of the Flame of a Candle_ (197).
Experiment _the ninth, Of the Greenish Blew transparency of Leaf Gold_
(198).
Experiment _the tenth, Of the curious Tinctures afforded by_ Lignum
Nephriticum (from 199 to 203). _Several trials for the Investigation of the
Nature of it_ (from 204 to 206.) Kircher's _relation of this Wood set down,
and examin'd_ (from 206 to 212). _A Corollary on this tenth_ Experiment,
_shewing how it may be applicable for the Discovering, whether any Salt be
of an Acid, or a Sulphureous, and Alcalizate Nature_ (from 213 to 216).
_The eleventh_ Experiment, _Of certain pieces of Glass that afforded this
Variety of Colours; And of the way of so Tinging any Plate of Glass with
Silver_ (from 216 to 219).
_The twelfth_ Experiment, _Of the Mixing and Tempering of Painters
Pigments_ (219, 220, 221).
_The thirteenth_ Experiment, _Of compounding several Colours by Trajecting
the Sun-beams through Ting'd Glasses_ (from 221 to 224).
_The fourteenth_ Experiment, _Of the Compounding of Real and Phantastical
Colours, and the Results_ (224, 225, 226.) _as also the same of
Phantastical Colours_ (226, 227.)
_The fifteenth_ Experiment, _Of Varying the Trajected_ Iris _by a Colour'd
Prism_ (228, 229.)
_The sixteenth_ Experiment, _Of the Red fumes of Spirit of_ Nitre, _and,
the resembling Redness of the Horizontal Sun-beams_ (230, 231.)
_The seventeenth_ Experiment, _Of making a Green by nine Kinds of
Compositions_ (from 231 to 236.) _And some Deductions from them against the
necessity of recurring to Substantial forms and Hypostatical principles for
the production of Colours_ (from 237 to 240.)
_The eighteenth_ Experiment, _Of several Compositions of Blew and Yellow
which produce not a Green, and of the production of a Green by other
Colours_ (241, 242.)
_The nineteenth_ Experiment, _contains several instances of producing
Colours, without the alteration of any Hypostatical principle, by the
Prism, Bubbles, and Feathers_ ( from 242 to 245.)
_The twentieth_ Experiment _Of turning the Blew of Violets into a Red by
Acid Salts, and to a Green by Alcalizate (245, 246.) and the use of it for
Investigating the Nature of Salts_ (247, 248.)
_The one and twentieth_ Experiment, _of the same Changes effected by the
same means on the Blew Tinctures of Corn-flowers_ (249, 250.) _And some
Restrictions to shew it not to be so general a propriety as one might
imagine_ (251.)
_The twenty second_ Experiment, _of turning a Solution of Verdigrease into
a Blew, with Alcalizate and Urinous Salts_ (252, 253, 254.)
_The twenty third_ Experiment, _of taking away the Colour of Roses with the
Steams of Sulphur, and heightning them with the Steams Condens'd into Oyl
of Sulphur_ per Campanam (254, 255.)
_The twenty fourth_ Experiment, _of Tinging a great quantity of Liquor with
a very little Ting'd Substance, Instanced in_ Cochineel (from 255 to 257.)
_The twenty fifth_ Experiment, _of the more general use of Alcalizate and
Sulphureous Salts in the Tinctures of Vegetables, further Instanced in the
Tincture of Privet Berries, and of the Flowers of Mesereon and Pease_ (from
257 to 259.) _An_ Annotation, _shewing that of the three Hypostatical
principles, Salt according to_ Paracelsus _is the most active about
Colours_ (from 259 to 261.) _Some things Precursory premis'd to three
several Instances next following, against the fore-mention'd Operations of
Salts_ (261, 262.)
_The twenty sixth_ Experiment, _containing Trials with Acid and Sulphureous
Salts on the Red Tinctures of Clove-july-flowers, Buckthorn Berries,
Red-Roses, Brasil_, &c. (262, 263.)
_The twenty seventh_ Experiment, _of the changes of the Colour of Jasmin
flowers, and Snow drops, by Alcalizate and Sulphureous Salts_ (263, 264.)
_The twenty eighth_ Experiment, _of other differing Effects on Mary-golds,
Prim-roses, and fresh Madder_ (265.) _with an Admonition, that these Salts
may have differing Effects in the changing of the tinctures of divers other
Vegetables_ (266, 267.)
_The twenty ninth_ Experiment, _of the differing Effects of these Salts on
Ripe and Unripe Juices, instanced in Black-berries, and the Juices of
Roses_ (from 267 to 270.) _Two reasons, why the Author added this twenty
ninth_ Experiment, _the last of which is confirm'd by an Instance of Mr._
Parkinson, _consonant to the Confession of the Makers of such Colours_
(272.)
_The thirtieth_ Experiment, _of several changes in Colours by Digestion,
exemplify'd by an_ Amalgam _of_ Gold _and_ Mercury _and by Spirit of
Harts-horn. And (to such as believe it) by the changes of the_ Elixir.
_The thirty first_ Experiment, _shewing that most Tinctures drawn by
Digestion Incline to a Red, instanc'd in_ Jalap, Guaicum, _Amber, Benzoin,
Sulphur, Antimony_, &c. (276, 277.)
_The thirty second_ Experiment, _That some Reds with Diluting turn Yellow,
others not, exemplify'd by the Tincture of_ Cochineel, _and by Balsam of_
Sulphur, _Tinctures of_ Amber, &c. (277, 278, 279.)
_The thirty third_ Experiment, _of a Red Tincture of_ Saccarum Saturni _and
Oyl of_ Turpentine _made by Digestion_ (279.)
_The thirty fourth_ Experiment, _of drawing a Volatile red Tincture of
Mercury_, _whose Steams were white, but it would Tinge the Skin black_
(279, 280.)
_The thirty fifth_ Experiment, _of a suddain way of making a Blood red
Colour with Oyl of_ Vitriol, _and Oyl of_ Anniseeds, _two transparent
Liquors_ (280, 281.)
_The thirty sixth_ Experiment, _of the Degenerating of several Colours
exemplify'd in the last mention'd Blood red, and by Mr._ Parkinsons
_relation of_ Turnsol, _by some Trials with the Juice of Buck-thorn
Berries, and other Vegetables, to which several notable Considerations and
Advertisements back'd with_ Experiments _are adjoyn'd_ (from 281 to 288.)
_The thirty seventh_ Experiment, _Of Varying the Colour of the Tinctures
of_ Cochineel, _Red-cherries, and Brasil, with Acid and Sulphureous Salts,
and divers Considerations thereon_ (from 288 to 290.)
_The thirty eighth_ Experiment, _About the Red fumes of some, and White of
other distill'd Bodies, and of their Coalition for the most part into a
transparent Liquor_ (290, 291.) _And of the various Colours of dry
Sublimations, exemplify'd with several_ Experiments (292, 293, 294.)
_The thirty ninth_ Experiment, _Of Varying the Decoction of_ Balaustiums
_with Acid and Urinous Salts_ (294, 295.) _Some_ Annotations _wherein two_
Experiments _of_ Gassendus _are Related, Examined, and Improv'd_ (from 295
to 302.)
_The fortieth_ Experiment, _Of the no less Strange than Pleasant changes
made with a Solution of Sublimate_ (from 301 to 306.) _The difference
between a Chymical axd Philosophical Solution of a_ Phænomenon (307, 308.)
_The Authors Chymical Explication of the_ Phænomena, _confirm d by several_
Experiments _made on_ Mercury, _with several Saline Liquors_ (from 308 to
310.) _An Improvement of the fortieth_ Experiment, _by a fresh Decoction
of_ Antimony _in a_ Lixivium (311, 312, 313.) _Reflections on the tenth,
twentieth, and fortieth_ Experiments, _compar'd together, shewing a way
with this Tincture of Sublimate to distinguish whether any Saline Body to
be examin'd be of a Urinous or Alcalizate Nature_ (from 314 to 317.) _The
Examination of Spirit of_ Sal-armoniack, _and Spirit of_ Oak _by these
Principles_ (from 316 to 319.) _That the Author knows ways of making highly
Operative Saline bodies, that produce none of the before mention'd effects_
(319, 320.) _Some notable_ Experiments _about Solutions and Precipitations
of Gold and Silver_ (320, 321.)
_The one and fortieth_ Experiment, _Of Depriving a deep Blew Solution of
Copper of its Colour_ (322.) _to which is adjoyn'd the Discolouring or
making Transparent a Solution of Verdigrease, &c. and another of Restoring
or Increasing it_ (322, 323.)
_The forty second_ Experiment, _Of changing a Milk white Precipitate of_
Mercury _into a Yellow, by Affusion of fair Water, with several
Considerations thereon_ (from 323 to 326.)
_The forty third_ Experiment, _Of Extracting a Green Solution with fair
Water out of imperfectly Calcin'd Vitriol_ (327.)
_The forty fourth_ Experiment, _Of the Deepning and Diluting of several
Tinctures, by the Affusions of Liquors, and by Conical Glasses that
contain'd them, Exemplify'd in the Tinctures of_ Cochineel, Brasil,
Verdigrease, Glass, Litmus, _of which last on this occasion several
pleasant_ Phænomena _are related_ (from 328 to 335.) _To which are adjoyn'd
certain Cautional Corollaries_ (335, 336.) _The Waterdrinker and some of
his Legerdemain tricks related._(337.)
_The forty fifth_ Experiment, _Of the turning Rhenish and White Wine into a
lovely Green, with a preparation of Steel _(338, 339.) _Some further Trial
made about these Tinctures, and a Similar_ Experiment _of_ Olaus Wormius
(340.)
_The forty sixth_ Experiment, _Of the Internal Colour of Metalls exhibited
by Calcination_ (341, 342, 343.) Annotation _the first, That several
degrees of Fire may disclose a differing Colour_ (343.) Annotation _the
second, That the Glasses of Metalls may exhibit also other Kinds of
Colours_ (344.) Annotation _the third, That Minerals by several degrees of
Fire may disclose several Colours_(345).
Experiment _the forty seventh, Of the Internal Colours of Metalls disclos'd
by their Dissolutions in several_ Menstruums (from 345 to 350.)
Annotation _the first, The Authors Apology for Recording some already
known_ Experiments, _without mentioning their Authors_ (from 350 to 352.)
Annotation _the second, That some Minerals also by Dissolutions in_
Menstruums _may exhibit divers Colours_. Annotation _the third, That
Metalls disclose other Colours by Precipitations, instanc'd in_ Mercury
(from 353 to 355.)
_The forty eighth_ Experiment, _Of Tinging Glass Blew with Leaf Silver, and
with Calcin'd Copper, and White with Putty_ (from 355 to 358.) Annotation
_the first, That this white Glass is the Basis of Ammels_ (358.) Annotion
_the second, That Colour'd Glasses may be Compounded like Colour'd Liquors
in Dying Fats_ (359.) Annotation _the third, Of Tinging Glass with Minerel
Substances, and of trying what Metalls they contain by this means_ (from
360 to 362.) Annotation _the fourth, That Metalls may be Ting'd by
Mineralls_ (362, 363.) Annotation _the fifth, Of making several Kinds of
Amauses or Counterfeit Stones_ (from 363 to 365.) Annotation _the sixth, Of
the Scarlet Dye, of the Stains of dissolv'd Gold and Silver_ (366, 367) _Of
the Greenness of Salt Beef, and Redness of Neats Tongues from Salts; of
Gilding Silver with Bathe Water_ (368, 369.) _And Tinging the Nails and
Skin with_ Alcanna (369)
_The forty ninth_ Experiment, _Of making Lakes_ (369.) _A particular
example in Turmerick_ (370, 371.) Annotation _the first, That in
Precipitations wherein Allum is a Coefficient, a great part of them may
consist of the Stony particles of that Compound Body_ (from 372 to 375.)
Annotation _the second, That Lakes may be made of other Substances, as
Madder, Rue,_ &c. _but that Alcalizate Salts do not Always Extract the same
Colour of which the Vegetable appears_ (from 376 to 378.) Annotation _the
third, That the_ Experiments _related may Hint divers others_ (378)
Annotation _the fourth, That Alum is usefull for the preparing other than
Vegetable Pigments_ (379.)
_The fiftieth_ Experiment, _Of the Similar effects of_ Saccarum Saturni
_and_ Alkalies, _of Precipitating with Oyl of_ Vitriol _out of_
Aqua-fortis, _and Spirit of_ Vinegar; _and of divers Varyings of the
Colours, with these Compounded_ (from 380 to 384.) _Another very pretty_
Experiment, _with a Solution of_ Minium (384, 385.) _That these_
Experiments _Skilfully digested may hint divers matters about Colours_
(386.) _The Authors Apologetick conclusion, in which is Cursorily hinted
the Bow or Scarlet Dye_ (387.) _The Authors Letter to Sir_ Robert Moray,
_concerning his Observations on the Shining Diamond_ (391. &c.) _And the
Observations themselves_.
* * * * *
Errata.
Pag. 142. l. 20. These words, _And to manifest_, with the rest of what is
by a mistake further printed in this fourth Experiment, belongeth, and is
to be referred to the end of the second Eperiment, p.137. pag. 145. l. 1.
leg. _matter_. 146. l. 4. leg. _Bolts-head_. pag 161. in the marginal note
l. 2. dele _de_ ib. l. 3. lege lib 1. p 163. l. ult. insert _where_ between
the words _places_ and _the_. p. 164 l. 1. dele _that_. ibid, l. 8. leg
_Epidermis_. ibid. l. 19 leg. 300. for 200. p. 169. l. 22. leg. _into it_.
p. 170. l. 23. & 24. leg. _Some Solutions hereafter to be mentioned_, for
_the Solutions of Potashes_, and other _Lixiviate Salts_. p. 171. l. 6.
insert _part of_ between the words _most_ and _dissolved_ p. 176. l. ult.
insert the participle _it_ between the words _Judged_ and _not_ p. 234. l.
4. leg. _Woud-wax_ or _Wood-wax_. p. 320 l. 29. leg. _urine_ for _urne_.
* * * * *
_THE_
_EXPERIMENTAL HISTORY_
_OF COLOURS BEGUN._
THE FIRST PART.
CHAP. I.
1 I have seen you so passionately addicted, _Pyrophilus_ to the delightful
Art of Limning and Painting, that I cannot but think my self obliged to
acquaint you with some of those things that have occurred to mee concerning
the changes of Colours. And I may expect that I shall as well serve the
_Virtuosi_ in general, as gratifie you in particular, by furnishing a
person, who, I hope, will both improve my Communications, and communicate
his Improvements, with such Experiments and Observations as may both invite
you to enquire seriously into the Nature of Colours, and assist you in the
Investigation of it. This being the principal scope of the following Tract,
I should do that which might prevent my own design, if I should here
attempt to deliver you an accurate and particular Theory of Colours; for
that were to present you with what I desire to receive from you; and, as
farr as in mee lay, to make that study needless, to which I would engage
you.
2 Wherefore my present work shall be but to divert and recreate, as well as
excite you by the delivery of matters of fact, such as you may for the most
part try with much _ease_, and possibly not without some _delight_: And
lest you should expect any thing of Elaborate or Methodical in what you
will meet with here, I must confess to you before-hand, that the seasons I
was wont to chuse to devise and try Experiments about Colours, were those
daies, wherein having taken Physick, and finding my self as unfit to
speculate, as unwilling to be altogether idle, I chose this diversion, as a
kind of Mean betwixt the one and the other. And I have the less scrupled to
set down the following Experiments, as some of them came to my mind, and as
the Notes wherein I had set down the rest, occurr'd to my hands, that by
declining a Methodical way of delivering them, I might leave you and my
self the greater liberty and convenience to add to them, and transpose them
as shall appear expedient.
3 Yea, that you may not think mee too reserv'd, or look upon an Enquiry
made up of meer Narratives, as somewhat jejune, am content to _premise_ a
few considerations, that now offer themselves to my thoughts, which relate
in a more general way, either to the Nature of Colours, or to the study of
it. And I shall _insert_ an _Essay_, as well Speculative as Historical, of
the Nature of Whiteness and Blackness, that you may have a _Specimen_ of
the History of Colours, I have sometimes had thoughts of; and if you
dislike not the Method I have made use of, I hope, you, and some of the
_Virtuosi_, your friends, may be thereby invited to go thorow with _Red,
Blew, Yellow_, and the rest of the particular Colours, as I have done with
_White_ and _Black_, but with farr more sagacity and success. And if I can
invite Ingenious men to undertake such Tasks, I doubt not but the Curious
will quickly obtain a better Account of Colours, than as yet we have, since
in our Method the Theorical part of the Enquiry being attended, and as it
were interwoven with the Historical, whatever becomes of the disputable
Conjectures, the Philosophy of Colours will be promoted by the indisputable
Experiments.
* * * * *
CHAP. II.
1 To come then in the first place to our more general Considerations, I
shall begin with saying something as to the Importance of examining the
Colours of Bodies. For there are some, especially _Chymists_, who think,
that a considerable diversity of Colours does constantly argue an equal
diversity of Nature, in the Bodies wherein it is conspicuous; but I confess
I am not altogether of their mind; for not to mention changeable Taffaties,
the blew and golden necks of Pidgeons, and divers Water-fowl, Rainbows
Natural and Artificial, and other Bodies, whose Colours the Philosophers
have been pleased to call not Real, but Apparent and Phantastical; not to
insist on these, I say, (for fear of needlesly engaging in a Controversie)
we see in Parrots, Goldfinches, and divers other Birds, not only that the
contiguous feathers which are probably as near in properties as place, are
some of them Red, and others White, some of them Blew, & others Yellow,
_&c._ but that in the several parts of the self-same feather there may
often be seen the greatest disparity of Colours; and so in the leaves of
Tulips, July-flowers, and some other Vegetables the several leaves, and
even the several parts of the same leaf, although no difference have been
observed in their other properties, are frequently found painted with very
different Colours. And such a variety we have much more admired in that
lovely plant which is commonly, and not unjustly call'd the _Marvayl of
Peru_; for of divers scores of fine Flowers, which in its season that gaudy
Plant does almost daily produce, I have scarce taken notice of any two that
were dyed perfectly alike. But though _Pyro_: such things as these, among
others, keep mee from daring to affirm, that the Diversity and change of
Colours does _alwaies_ argue any great difference or alteration, betwixt,
or in, the Bodies, wherein it is to be discerned, yet that _oftentimes_ the
Alteration of Colours does signifie considerable Alterations in the
disposition of parts of Bodies, may appear in the Extraction of Tinctures,
and divers other Chymical Operations, wherein the change of Colours is the
chief, and sometimes the only thing, by which the Artist regulates his
proceeding, and is taught to know when 'tis seasonable for him to leave
off. Instances of this sort are more obvious in divers sorts of fruits, as
Cherries, Plums, &c. wherein, according as the Vegetable sap is sweetned,
or otherwise ripened, by passing from one degree to another of Maturation,
the external part of the fruit passes likewise from one to another Colour.
But one of the noblest Instances I have met with of this kind, is not so
obvious; and that is the way of tempering Steel to make Gravers, Drills,
Springs, and other Mechanical Instruments, which we have divers times both
made Artificers practise in our presence, and tryed our selves, after the
following manner, First, the slender Steel to be tempered is to be hardened
by heating as much of it as is requisite among glowing Coals, till it be
glowing hot, but it must not be quenched assoon as it is taken from the
fire (for that would make it too brittle, and spoil it) but must be held
over a bason of water, till it descend from a White heat to a Red one,
which assoon as ever you perceive, you must immediately quench as much as
you desire to harden in the cold water. The Steel thus hardened, will, if
it be good, look somewhat White and must be made bright at the end, that
its change of Colours may be there conspicuous; and then holding it so in
the flame of a Candle, that the bright end may be, for about half an inch,
or more, out of the flame, that the smoak do not stain or sully the
brightness of it, you shall after a while see that clean end, which is
almost contiguous to the flame, pass very nimbly from one Colour to
another, as from a brighter Yellow, to a deeper and reddish Yellow, which
Artificers call a _sanguine_, and from that to a fainter first, and then a
a deeper Blew. And to bring home this Experiment to our present purpose, it
is found by daily Experience, that each of these succeeding Colours argue
such a change made in the texture of the Steel, that if it be taken from
the flame, and immediately quenched in the tallow (whereby it is setled in
whatever temper it had before) when it is Yellow, it is of such a hardness
as makes it fit for Gravers Drills, and such like tools; but if it be kept
a few minutes longer in the flame till it grow Blew, it becomes much
softer, and unfit to make Gravers for Metalls, but fit to make Springs for
Watches, and such like Instruments, which are therefore commonly of that
Colour; and if the Steel be kept in the flame, after that this deep Blew
hath disclosed it self, it will grow so soft, as to need to be new hardened
again, before it can be brought to a temper, fit for Drills or Penknives.
And I confess _Pyro._ I have taken much pleasure to see the Colours run
along from the parts of the Steel contiguous to the flame, to the end of
the Instrument, and succeed one another so fast, that if a man be not
vigilant, to thrust the Steel into the tallow at the very nick of time, at
which it has attain'd its due Colour, he shall miss of giving his tool the
right temper. But because the flame of a Candle is offensive to my weak
eyes, and because it is apt to either black or sully the contiguous part of
the Steel which is held in it, and thereby hinder the change of Colours
from being so long and clearly discern'd, I have sometimes made this
Experiment by laying the Steel to be tempered upon a heated bar of Iron,
which we finde also to be employ'd by some Artificers in the tempering of
such great Instruments, as are too big to be soon heated sufficiently by
the flame of a Candle. And you may easily satisfie your self _Pyro_: of the
differing hardness and toughness, which is ascribed to Steel temper'd at
different Colours, if you break but some slender wires of Steel so
temper'd, and observe how they differ in brittleness, and if with a file
you also make tryal of their various degrees of hardness.
2 But _Pyrophilus_, I must not at present any further prosecute the
Consideration of the importance of Experiments about Colours, not only
because you will in the following papers finde some instances, that would
here be presented you out of their due place, of the use that may be made
of such Experiments, in discovering in divers bodies, what kind the salt
is, that is predominant in them; but also because a speculative Naturalist
might justly enough allege, that as Light is so pleasing an object, as to
be well worth our looking on, though it discover'd to us nothing but its
self; so modifi'd Light called Colour, were worth our contemplation, though
by understanding its Nature we should be taught nothing else. And however,
I need not make either you or my self excuses for entertaining you on the
subject I am now about to treat of, since the pleasure _Pyro_: takes in
mixing and laying on of Colours, will I presume keep him, and will (I am
sure) keep mee from thinking it troublesome to set down, especially after
the tedious processes (about other matters) wherewith I fear I may have
tyr'd him, some easie, and not unpleasant Experiments relating to that
subject.
3 But, before we descend to the more particular considerations, we are to
present you concerning Colours, I presume it will be seasonable to propose
at the very entrance a Distinction; the ignorance or neglect of which,
seems to mee to have frequently enough occasioned either mistakes or
confusion in the Writings of divers Modern Philosophers; for Colour may be
considered, either as it is a quality residing in the body that is said to
be coloured, or to modifie the light after such or such a manner; or else
as the Light it self, which so modifi'd, strikes upon the organ of sight,
and so causes that Sensation which we call Colour; and that this latter may
be look'd upon as the more proper, though not the usual acception of the
word Colour, will be made probable by divers passages in the insuing part
of our discourse; and indeed it is the Light it self, which after a certain
manner, either mingled with shades, or some other waies troubled, strikes
our eyes, that does more immediately produce that motion in the organ, upon
whose account men say they see such or such a Colour in the object; yet,
because there is in the body that is said to be coloured, a certain
disposition of the superficial particles, whereby it sends the Light
reflected, or refracted, to our eyes thus and thus alter'd, and not
otherwise, it may also in some sense be said, that Colour depends upon the
visible body; and therefore we shall not be against that way of speaking of
Colours that is most used among the Modern Naturalists, provided we be
allowed to have recourse when occasion shall require to the premis'd
distinction, and to take the more immediate cause of Colour to be the
modifi'd Light it self, as it affects the Sensory; though the disposition
also of the colour'd body, as that modifies the Light, may be call'd by
that name Metonimically (to borrow a School term) or Efficiently, that is
in regard of its turning the Light, that rebounds from it, or passes thorow
it, into this or that particular Colour.
4 I know not whether I may not on this occasion add, that Colour is so far
from being an Inherent quality of the object in the sense that is wont to
be declar'd by the Schools, or even in the sense of some Modern Atomists,
that, if we consider the matter more attentively, we shall see cause to
suspect, if not to conclude, that though Light do more immediately affect
the organ of sight, than do the bodies that send it thither, yet Light it
self produces the sensation of a Colour, but as it produces such a
determinate kind of local motion in some part of the brain; which, though
it happen most commonly from the motion whereinto the slender strings of
the _Retina_ are put, by the appulse of Light, yet if the like motion
happen to be produc'd by any other cause, wherein the Light concurrs not at
all, a man shall think he sees the same Colour. For proof of this, I might
put you in mind, that 'tis usual for dreaming men to think they see the
Images that appear to them in their sleep, adorn'd some with this, and some
with that lively Colour, whilst yet, both the curtains of their bed, and
those of their eyes are close drawn. And I might add the confidence with
which distracted persons do oftentimes, when they are awake, think, they
see black fiends in places, where there is no black object in sight without
them. But I will rather observe, that not only when a man receives a great
stroak upon his eye, or a very great one upon some other part of his head,
he is wont to see, as it were, flashes of lightning, and little vivid, but
vanishing flames, though perhaps his eyes be shut: But the like apparitions
may happen, when the motion proceeds not from something without, but from
something within the body, provided the unwonted fumes that wander up and
down in the head, or the propagated concussion of any internal part in the
body, do cause about the inward extremities of the Optick Nerve, such a
motion as is wont to be there produc'd, when the stroak of the Light upon
the _Retina_ makes us conclude, that we see either Light, or such and such
a Colour: This the most ingenious _Des Cartes_ hath very well observ'd, but
because he seems not to have exemplifi'd it by any unobvious or peculiar
observation, I shall indeavour to illustrate this doctrine by a few
Instances.
5 And first, I remember, that having, through Gods goodness, been free for
several years, from troublesome Coughs, being afterwards, by an accident,
suddenly cast into a violent one, I did often, when I was awaked in the
night by my distempers, observe, that upon coughing strongly, it would seem
to mee, that I saw very vivid, but immediately disappearing flames, which I
took particular notice of, because of the conjecture I am now mentioning.
6 An excellent and very discreet person, very near ally'd both to you and
mee, was relating to mee, that some time since, whilst she was talking with
some other Ladies, upon a sudden, all the objects, she looked upon,
appeared to her dyed with unusual Colours, some of one kind, and some of
another, but all so bright and vivid, that she should have been as much
delighted, as surpriz'd with them, but that finding the apparition to
continue, she fear'd it portended some very great alteration as to her
health: As indeed the day after she was assaulted with such violence by
Hysterical and Hypocondrical Distempers, as both made her rave for some
daies, and gave her, during that time, a Bastard Palsey.
7 Being a while since in a Town, where the Plague had made great havock,
and inquiring of an ingenious man, that was so bold, as without much
scruple to visit those that were sick of it, about the odd symptomes of a
Disease that had swept away so many there; he told mee, among other things,
that he was able to tell divers Patients, to whom he was called, before
they took their beds, or had any evident symptomes of the Plague, that they
were indeed infected upon peculiar observations, that being asked, they
would tell him that the neighbouring objects, and particularly his cloths,
appear'd to them beautifi'd with most glorious Colours, like those of the
Rainbow, oftentimes succeeding one another; and this he affirm'd to be one
of the most usual, as well as the most early symptomes, by which this odd
Pestilence disclos'd it self: And when I asked how long the Patients were
wont to be thus affected, he answered, that it was most commonly for about
a day; and when I further inquired whether or no Vomits, which in that
Pestilence were usually given, did not remove this symptome (For some used
the taking of a Vomit, when they came ashore, to cure themselves of the
obstinate and troublesome giddiness caus'd by the motion of the ship)
reply'd, that generally, upon the evacuation made by the Vomit, that
strange apparition of Colours ceased, though the other symptomes were not
so soon abated, yet he added (to take notice of that upon the by, because
the observation may perchance do good) that an excellent Physician, in
whose company he was wont to visit the sick, did give to almost all those
to whom he was called, in the beginning before Nature was much weakened, a
pretty odd Vomit consisting of eight or ten dramms of Infusion of _Crocus
Metallorum_, and about half a dramm, or much more, of White Vitriol, with
such success, that scarce one of ten to whom it was seasonably administred,
miscarried.
8 But to return to the consideration of Colours: As an apparition of them
may be produced by motions from within, without the assistance of an
outward object, so I have observed, that 'tis sometimes possible that the
Colour that would otherwise be produced by an outward object, may be
chang'd by some motion, or new texture already produced in the Sensory, as
long as that unusual motion, or new disposition lasts; for I have divers
times try'd, that after I have through a Telescope look'd upon the Sun,
though thorow a thick, red, or blew glass, to make its splendor supportable
to the eye, the impression upon the _Retina_, would be not only so vivid,
but so permanent, that if afterwards I turned my eye towards a flame, it
would appear to mee of a Colour very differing from its usual one. And if I
did divers times successively shut and open the same eye, I should see the
adventitious Colour, (if I may so call it) changed or impair'd by degrees,
till at length (for this unusual motion of the eye would not presently
cease) the flame would appear to mee, of the same hew that it did to other
beholders; a not unlike effect I found by looking upon the Moon, when she
was near full, thorow an excellent Telescope, without colour'd Glass to
screen my eye with; But that which I desire may be taken notice of, because
we may elsewhere have occasion to reflect upon it, and because it seems not
agreeable to what Anatomists and Optical Writers deliver, touching the
relation of the two eyes to each other, is this circumstance, that though
my Right eye, with which I looked thorow the Telescope, were thus affected
by the over-strong impression of the light, yet when the flame of a Candle,
or some other bright object appear'd to me of a very unusual Colour, whilst
look'd upon with the Discompos'd Eye, or (though not so notably) with both
eyes at once; yet if I shut that Eye, and looked upon the same object with
the other, it would appear with no other than its usual Colour, though if I
again opened, and made use of the Dazled eye, the vivid adventitious Colour
would again appear. And on this occasion I must not pretermit an
Observation which may perswade us, that an over-vehement stroak upon the
Sensory, especially if it be naturally of a weak constitution, may make a
more lasting impression than one would imagine, which impression may in
some cases, as it were, mingle with, and vitiate the action of vivid
objects for a long time after.
For I know a Lady of unquestionable Veracity, who having lately, by a
desperate fall, receiv'd several hurts, and particularly a considerable one
upon a part of her face near her Eye, had her sight so troubl'd and
disorder'd, that, as she hath more than once related to me, not only when
the next morning one of her servants came to her bed side, to ask how she
did, his cloaths appear'd adorn'd with such variety of dazling Colours,
that she was fain presently to command him to withdraw, but the Images in
her Hangings, did, for many daies after, appear to her, if the Room were
not extraordinarily darken'd, embellish'd with several offensively vivid
Colours, which no body else could see in them; And when I enquir'd whether
or no White Objects did not appear to her adorn'd with more luminous
Colours than others, and whether she saw not some which she could not now
well describe to any, whose eyes had never been distemper'd, she answer'd
mee, that sometimes she thought she saw Colours so new and glorious, that
they were of a peculiar kind, and such as she could not describe by their
likeness to any she had beheld either before or since, and that White
Objects did so much disorder her sight, that if several daies after her
fall, she look'd upon the inside of a Book, she fanci'd she saw there
Colours like those of the Rain-bow, and even when she thought her self
pretty well recover'd, and made bold to leave her Chamber, the coming into
a place where the Walls and Ceeling were whited over, made those Objects
appear to her cloath'd with such glorious and dazling Colours, as much
offended her sight, and made her repent her venturousness, and she added,
that this Distemper of her Eyes lasted no less than five or six weeks,
though, since that, she hath been able to read and write much without
finding the least Inconvenience in doing so. I would gladly have known,
whether if she had shut the Injur'd Eye, the _Phænomena_ would have been
the same, when she employ'd only the other, but I heard not of this
accident early enough to satisfie that Enquiry.
9 Wherefore, I shall now add, that some years before, a person exceedingly
eminent for his profound Skil in almost all kinds of Philological Learning,
coming to advise with mee about a Distemper in his Eyes, told me, among
other Circumstances of it, that, having upon a time looked too fixedly upon
the Sun, thorow a Telescope, without any coloured Glass, to take off from
the dazling splendour of the Object, the excess of Light did so strongly
affect his Eye, that ever since, when he turns it towards a Window, or any
White Object, he fancies, he seeth a Globe of Light, of about the bigness
the Sun then appeared of to him, to pass before his Eyes: And having
Inquir'd of him, how long he had been troubled with this Indisposition, he
reply'd, that it was already nine or ten years, since the Accident, that
occasioned it, first befel him.
I could here subjoyn, _Pyrophilus_, some memorable Relations that I have
met with in the Account given us by the experienc'd _Epiphanius
Ferdinandus_, of the Symptomes he observ'd to be incident to those that are
bitten with the Tarantula, by which (Relations) I could probably shew, that
without any change in the Object, a change in the Instruments of Vision may
for a great while make some Colours appear Charming, and make others
Provoking, and both to a high degree, though neither of them produc'd any
such Effects before. These things, I say, I could here subjoyn in
confirmation of what I have been saying, to shew, that the Disposition of
the Organ is of great Importance in the Dijudications we make of Colours,
were it not that these strange Stories belonging more properly to another
Discourse, I had rather, (contenting my self to have given you an
Intimation of them here) that you should meet with them fully deliver'd
there.
* * * * *
CHAP. III.
But, _Pyrophilus_, I would not by all that I have hitherto discours'd, be
thought to have forgotten the Distinction (of Colour) that I mentioned to
you about the beginning of the third Section of the former Chapter; and
therefore, after all I have said of Colour, as it is modifi'd Light, and
immediately affects the Sensory, I shall now re-mind you, that I did not
deny, but that Colour might in some sense be consider'd as a Quality
residing in the body that is said to be Colour'd, and indeed the greatest
part of the following Experiments referr to Colour principally under that
Notion, for there is in the bodyes we call Colour'd, and chiefly in their
Superficial parts, a certain disposition, whereby they do so trouble the
Light that comes from them to our Eye, as that it there makes that distinct
Impression, upon whose Account we say, that the Seen body is either White
or Black, or Red or Yellow, or of any one determinate Colour. But because
we shall (God permiting) by the Experiments that are to follow some Pages
hence, more fully and particularly shew, that the Changes, and consequently
in divers places the Production and the appearance of Colours depends upon
the continuing or alter'd Texture of the Object, we shall in this place
intimate (and that too but as by the way) two or three things about this
Matter.
2. And first it is not without some Reason, that I ascribe Colour (in the
sense formerly explan'd) _chiefly_ to the Superficial parts of Bodies, for
not to question how much Opacous Corpuscles may abound even in those Bodies
we call Diaphanous, it seems plain that of Opacous bodies we do indeed see
little else than the Superficies, for if we found the beams of Light that
rebound from the Object to the Eye, to peirce deep into the Colour'd body,
we should not judge it Opacous, but either Translucid, or at least
Semi-diaphanous, and though the Schools seem to teach us that Colour is a
Penetrative Quality, that reaches to the Innermost parts of the Object, as
if a piece of Sealing-wax be broken into never so many pieces, the Internal
fragments will be as Red as the External surface did appear, yet that is
but a Particular Example that will not overthrow the Reason lately offer'd,
especially since I can alleage other Examples of a contrary Import, and two
or three Negative Instances are sufficient to overthrow the Generality of a
Positive Rule, especially if that be built but upon One or a Few Examples.
Not (then) to mention Cherries, Plums, and I know not how many other
Bodies, wherein the skin is of one Colour, and what it hides of another, I
shall name a couple of Instances drawn from the Colours of Durable bodies
that are thought far more Homogeneous, and have not parts that are either
Organical, or of a Nature approaching thereunto.
3 To give you the first Instance, I shall need but to remind you of what I
told you a little after the beginning of this Essay, touching the Blew and
Red and Yellow, that may be produc'd upon a piece of temper'd Steel, for
these Colours though they be very Vivid, yet if you break the Steel they
adorn, they will appear to be but Superficial; not only the innermost parts
of the Metall, but those that are within a hairs breadth of the
Superficies, having not any of these Colours, but retaining that of the
Steel it self. Besides that, we may as well confirm this Observation, as
some other particulars we elsewhere deliver concerning Colours, by the
following Experiment which we purposely made.
4 We took a good quantity of clean Lead, and melted it with a strong Fire,
and then immediately pouring it out into a clean Vessel of a convenient
shape and matter, (we us'd one of Iron, that the great and sudden Heat
might not injure it) and then carefully and nimbly taking off the Scum that
floated on the top, we perceiv'd, as we expected, the smooth and glossie
Surface of the melted matter, to be adorn'd with a very glorious Colour,
which being as Transitory as Delightfull, did almost immediately give place
to another vivid Colour, and that was as quickly succeeded by a third, and
this as it were chas'd away by a fourth, and so these wonderfully vivid
Colours successively appear'd and vanish'd, (yet the same now and then
appearing the second time) till the Metall ceasing to be hot enough to
afford any longer this pleasing Spectacle, the Colours that chanc'd to
adorn the Surface, when the Lead thus began to cool, remain'd upon it; but
were so Superficial, that how little soever we scrap'd off the Surface of
the Lead, we did in such places scrape off all the Colour, and discover
only that which is natural to the Metall it self, which receiving its
adventitious Colours, only when the heat was very Intense, and in that part
which was expos'd to the comparatively very cold Air, (which by other
Experiments seems to abound with subtil Saline parts, perhaps not uncapable
of working upon Lead so dispos'd:) These things I say, together with my
observing that whatever parts of the so strongly melted Lead were expos'd a
while to the Air, turn'd into a kind of Scum or Litharge, how bright and
clean soever they appear'd before, suggested to me some Thoughts or
Ravings, which I have not now time to acquaint You with. One that did not
know me, _Pyrophilus_, would perchance think I endeavour'd to impose upon
You by relating this Experiment, which I have several times try'd, but the
Reason why the _Phænomena_ mention'd have not been taken notice of, may be,
that unless Lead be brought to a much higher degree of Fusion or Fluidity
than is usual, or than is indeed requisite to make it melt, the _Phænomena_
I mention'd will scarce at all disclose themselves; And we have also
observ'd that this successive appearing and vanishing of vivid Colours, was
wont to be impair'd or determin'd whilst the Metal expos'd to the Air
remain'd yet hotter than one would readily suspect. And one thing I must
further Note, of which I leave You to search after the Reason, namely, that
the same Colours did not always and regularly succeed one another, as is
usually in Steel, but in the diversify'd Order mention'd in this following
Note, which I was scarce able to write down, the succession of the Colours
was so very quick, whether that proceeded from the differing degrees of
Heat in the Lead expos'd to the cool Air, or from some other Reason, I
leave you to examine.
[_Blew, Yellow, Purple, Blew; Green, Purple, Blew, Yellow, Red; Purple,
Blew, Yellow and Blew, Yellow, Blew, Purple, Green mixt, Yellow, Red,
Blew, Green, Yellow, Red, Purple, Green_.]
5. The _Atomists_ of Old, and some Learned men of late, have attempted to
explicate the variety of Colours in Opacous bodies from the various Figures
of their Superficial parts; the attempt is Ingenious, and the Doctrine
seems partly True, but I confess I think there are divers other things that
must be taken in as concurrent to produce those differing forms of
Asperity, whereon the Colours of Opacous bodies seem to depend. To declare
this a little, we must assume, that the Surfaces of all such Bodies how
Smooth or polite soever they may appear to our Dull Sight and Touch, are
exactly smooth only in a popular, or at most in a Physical sense, but not
in a strict and rigid sense.
6. This, excellent _Microscopes_ shew us in many Bodies, that seem Smooth
to our naked Eyes; and this not only as to the little Hillocks or
Protuberancies that swell above that which may be conceiv'd to be the Plain
or Level of the consider'd Surface, for it is obvious enough to those that
are any thing conversant with such Glasses, but as to numerous Depressions
beneath that Level, of which sort of Cavities by the help of a
_Microscope_, which the greatest Artificer that makes them, judges to be
the greatest Magnifying Glass in _Europe_, except one that equals it, we
have on the Surface of a thin piece of Cork that appear'd smooth to the
Eye, observ'd about sixty in a Row, within the length of less then an 31
and 32 part of an Inch, (for the Glass takes in no longer a space at one
view) and these Cavities (which made that little piece of Cork look almost
like an empty Honey-comb) were not only very distinct, and figur'd like one
another, but of a considerable bigness, and a scarce credible depth;
insomuch that their distinct shadows as well as sides were plainly
discern'd and easiy to be reckon'd, and might have been well distinguish'd,
though they had been ten times lesser than they were; which I thought it
not amiss to mention to you _Pyrophilus_ upon the by, that you may thence
make some Estimate, what a strange Inequality, and what a multitude of
little Shades, there may really be, in a scarce sensible part of the
Physical superficies, though the naked Eye sees no such matter. And as
Excellent _Microscopes_ shew us this Ruggedness in many Bodies that pass
for Smooth, so there are divers Experiments, though we must not now stay to
urge them, which seem to perswade us of the same thing as to the rest of
such Bodies as we are now treating off; So, that there is no sensible part
of an Opacous body, that may not be conceiv'd to be made up of a multitude
of singly insensible Corpuscles, but in the giving these surfaces that
disposition, which makes them alter the Light that reflects thence to the
Eye after the manner requisite to make the Object appear Green, Blew, &c.
the Figures of these Particles have _a great_, but not _the only_ stroak.
'Tis true indeed that the protuberant Particles may be of very great
variety of Figures, Sphærical, Elliptical, Conical, Cylindrical,
Polyedrical, and some very irregular, and that according to the Nature of
these, and the situation of the Lucid body, the Light must be variously
affected, after one manner from Surfaces (I now speak of Physical Surfaces)
consisting of Sphaerical, and in another from those that are made up of
Conical or Cylindrical Corpuscles; some being fitted to reflect more of the
incident Beams of Light, others less, and some towards one part, others
towards another. But besides this difference of Shape, there may be divers
other things that may eminently concurr to vary the forms of Asperity that
Colours so much depend on. For, willingly allowing the Figure of the
Particles in the first place, I consider secondly, that the superficial
Corpuscles, if I may so call them, may be bigger in one Body, and less in
another, and consequently fitted to allay the Light falling on them with
greater shades. Next, the protuberant Particles may be set more or less
close together, that is, there may be a greater or a smaller number of them
within the compass of one, than within the compass of another small part of
the Surface of the same Extent, and how much these Qualities may serve to
produce Colour may be somewhat guess'd at, by that which happens in the
Agitation of Water; for if the Bubbles that are thereby made be Great, and
but Few, the Water will scarce acquire a sensible Colour, but if it be
reduc'd to a Froth, consisting of Bubbles, which being very Minute and
Contiguous to each other, are a multitude of them crowded into a narrow
Room, the Water (turned to Froth) does then exhibit a very manifest White
Colour,[3] (to which these last nam'd Conditions of the Bubbles do as well
as their Convex figure contribute) and that for Reasons to be mention'd
anon. Besides, it is not necessary that the Superficial particles that
exhibit one Colour, should be all of them Round, or all Conical, or all of
any one Shape, but Corpuscles of differing Figures may be mingled on the
Surface of the Opacous Body, as when the Corpuscles that make a Blew
colour, and those that make a Yellow, come to be Accurately and Skilfully
mix'd, they make up a Green, which though it seem one simple Colour, yet in
this case appears to be made by Corpuscles of very differing Kinds, duely
commix'd. Moreover the Figure and Bigness of the little Depressions,
Cavities, Furrows or Pores intercepted betwixt these protuberant
Corpuscles, are as well to be consider'd as the Sizes and Shapes of the
Corpuscles themselves: For we may conceive the Physical superficies of a
Body, where (as we said) its Colour does as it were reside, to be cut
Transversly by a Mathematical plain, which you know is conceiv'd to be
without any Depth or Thickness at all, and then as some parts of the
Physical Superficies will be Protuberant; or swell above this last plain,
so others may be depress'd beneath it; as (to explane my self by a gross
Comparison) in divers places of the Surface of the Earth, there are not
only Neighbouring Hills, Trees, &c. that are rais'd above the Horizontal
Level of the Valley, but Rivers, Wells, Pits and other Cavities that are
depress'd beneath it, and that such Protuberant and Concave parts of a
Surface may remit the Light so differingly, as much to vary a Colour, some
examples and other things, that we shall hereafter have occasion to take
notice off in this Tract, will sufficiently declare, till when, it may
suffice to put you in mind, that of two Flat-sides of the same piece of,
for example, red Marble, the one being diligently Polished, and the other
left to its former Roughness, the differing degrees or sorts of Asperity,
for the side that is smooth to the Touch wants not its Roughness, will so
diversifie the Light reflected from the several Plains to the Eye, that a
Painter would employ two differing Colours to represent them.
[3] _See the Discourse of the Nature of Whiteness and Blackness._
7. And I hope, _Pyrophilus_, you will not think it strange or impertinent,
that I employ in divers passages of these Papers, examples drawn from
Bodies and Shadows far more Gross, than those minute Protuberances and
shady Pores on which in most cases the Colour of a Body as 'tis an Inherent
Quality or Disposition of its Surface, seems to depend. For sometimes I
employ such Examples, rather to declare my Meaning, than prove my
Conjecture; things, whom their Smallness makes Insensible, being better
represented to the Imagination by such familiar Objects, as being like them
enough in other respects, are of a Visible bulk. And next, though the Beams
of Light are such subtil Bodies, that in respect of them, even Surfaces
that are sensibly Smooth, are not exactly so, but have their own degree of
Roughness, consisting of little Protuberances and Depressions; and though
consequently such Inequalities may suffice to give Bodies differing
Colours, as we see in Marble that appears White or Black, or Red or Blew,
even when the most carefully Polish'd, yet 'tis plain by the late Instance
of Red Marble, and many others, that even bigger Protuberances and greater
Shades may likewise so Diversifie the Roughness of a Bodies Superficies, as
manifestly to concurr to the varying of its Colour, whereby such Examples
appear to be proper enough to be employ'd in such a Subject as we have now
in hand. And having hinted thus much on this Occasion, I now proceed.
8. The Situation also of the Superficial particles is considerable, which I
distinguish into the Posture of the single Corpuscles, in respect of the
Light, and of the Eye, and the Order of them in reference also to one
another; for a Body may otherwise reflect the Light, when its Superficial
particles are more erected upon the Plain that may be conceiv'd to pass
along their Basis, and when the Points or Extremes of such Particles are
Obverted to the Eye, than when those Particles are so Inclin'd, that their
Sides are in great part Discernable, as the Colour of Plush or Velvet will
appear Vary'd to you, if you carefully stroak part of it one way, and part
of it another, the posture of the particular Thrids, in reference to the
Light, or the Eye, becoming thereby different. And you may observe in a
Field of ripe Corn blown upon by the Wind, that there will appear as it
were Waves of a Colour (at least Gradually) differing from that of the rest
of the Field, the Wind by Depressing some of the Ears, and not at the same
time others, making the one Reflect more from the Lateral and Strawy parts,
than do the rest. And so, when Doggs are so angry, as to Erect the Hairs
upon their Necks, and upon some other parts of their Bodies, those Parts
seem to acquire a Colour vary'd from that which the same Hairs made, when
in their usual Posture they did farr more stoop. And that the Order wherein
the Superficial Corpuscles are Rang'd is not to be neglected, we may guess
by turning of Water into Froth, the beating of Glass, and the scraping of
Horns, in which cases the Corpuscles that were before so marshall'd as to
be Perspicuous, do by the troubling of that Order become Dispos'd to
terminate and reflect more Light, and thereby to appear Whitish. And there
are other ways in which the Order of the Protuberant parts, in reference to
the Eye, may much contribute to the appearing of a particular Colour, for I
have often observ'd, that when Pease are Planted, or Set in Parallel Lines,
and are Shot up about half a Foot above the Surface of the Ground, by
looking on the Field or Plot of Ground from that part towards which the
Parallel Lines tended, the greater part of the Ground by farr would appear
of its own dirty Colour, but if I look'd upon it Transversly, the Plot
would appear very Green, the upper parts of the Pease hindering the
intercepted parts of the Ground, which as I said retain'd their wonted
Colour, from being discover'd by the Eye. And I know not, _Pyrophilus_,
whether I might not add, that even the Motion of the Small Parts of a
Visible Object may in some cases contribute, though it be not so easie to
say how, to the Producing or the Varying of a Colour; for I have several
times made a Liquor, which when it has well settled in a close Vial, is
Transparent and Colourless, but as soon as the Glass is unstopp'd, begins
to fly away very plentifully in a White and Opacous fume; and there are
other Bodies, whose Fumes, when they fill a Receiver, would make one
suspect it contains Milk, and yet when these Fumes settle into a Liquor,
that Liquor is not White, but Transparent; And such White Fumes I have seen
afforded by unstopping a Liquor I know, which yet is it self Diaphanous and
Red; Nor are these the only Instances of this Kind, that our Tryals can
supply us with. And if the Superficial Corpuscles be of the Grosser sort,
and be so Framed, that their differing Sides or Faces may exhibit differing
Colours, then the Motion or Rest of those Corpuscles may be considerable,
as to the Colour of the Superficies they compose, upon this account, that
sometimes more, sometimes fewer of the Sides dispos'd to exhibit such a
Colour may by this means become or continue more Obverted to the Eye than
the rest, and compose a Physical Surface, that will be more or less
sensibly interrupted; As, to explane my meaning, by proposing a gross
Example, I remember, that in some sorts of Leavy Plants thick set by one
another, the two sides of whose Leaves were of somewhat differing Colours,
there would be a notable Disparity as to Colour, if you look'd upon them
both when the Leaves being at Rest had their upper and commonly expos'd
sides Obverted to the Eye, and when a breath of Wind passing thorow them,
made great Numbers of the usually Hidden sides of the Leaves become
conspicuous. And though the Little Bodies, we were lately speaking of, may
Singly and Apart seem almost Colourless, yet when Many of them are plac'd
by one another, so near, that the Eye does not easily discern an
Interruption, within a sensible space, they may exhibit a Colour; as we
see, that though a Slenderest Thrid of Dy'd Silk do's, whilst look'd on
Single, seem almost quite Devoyd of Redness, (for instance) yet when
numbers of these Thrids are brought together into one Skein, their Colour
becomes notorious.
9. But the same Occasion that invited me to say what I have mention'd
concerning the Leaves of Trees, invites me also to give you some account of
what happens in Changeable Taffities, where we see differing Colours, as it
were, Emerge and Vanish upon the Ruffling of the same piece of Silk: As I
have divers times with Pleasure observ'd, by the help of such a
_Microscope_, as, though it do not very much Magnifie the Object, has in
recompence this great Conveniency, that you may easily, as fast as you
please, remove it from one part to another of a Large Object, of which the
Glass taking a great part at once, you may thereby presently Survey the
Whole. Now by the help of such a _Microscope_ I could easily (as I began to
say) discern, that in a piece of Changeable Taffity, (that appear'd, for
Instance, sometimes Red, and sometimes Green) the Stuff was compos'd of Red
thrids and Green, passing under and over each other, and crossing one
another in almost innumerable points; and if I look'd through the Glass
upon any considerable portion of the Stuff, that (for example sake) to the
naked Eye appear'd to be Red, I could plainly see, that in that Position,
the Red thrids were Conspicuous, and reflected a vivid Light; and though I
could also perceive, that there were Green ones, yet by reason of their
disadvantagious Position in the _Physical Surface_ of the Taffity, they
were in part hid by the more Protuberant Thrids of the other Colour; and
for the same cause, the Reflection from as much of the Green as was
discover'd, was comparatively but Dim and Faint. And if, on the contrary, I
look'd through the _Microscope_ upon any part that appear'd Green, I could
plainly see that the Red thrids were less fully expos'd to the Eye, and
obscur'd by the Green ones, which therefore made up the Predominant Colour.
And by observing the Texture of the Silken Stuff, I could easisy so expose
the Thrids either of the one Colour or of the other to my Eye, as at
pleasure to exhibit an apparition of Red or Green, or make those Colours
succeed one another: So that, when I observ'd their Succession by the help
of the Glass, I could mark how the Predominant Colour did as it were start
out, when the Thrids that exhibited it came to be advanagiously plac'd; And
by making little Folds in the Stuff after a certain manner, the Sides that
met and terminated in those Folds, would appear to the naked Eye, one of
them Red, and the other Green. When Thrids of more than two differing
Colours chance to be Interwoven, the resulting changeableness of the
Taffity may be also somewhat different. But I choose to give an Instance in
the Stuff I have been speaking off, because the mixture being more Simple,
the way whereby the Changeableness is produc'd, may be the more easily
apprehended: and though Reason alone might readily enough lead a
considering Man to guess at the Explication, in case he knew how Changeable
Taffities are made: yet I thought it not impertinent to mention it, because
both Scholars and Gentlemen are wont to look upon the Inquiry into
Manufactures, as a _Mechanick_ imployment, and consequently below Them; and
because also with such a _Microscope_ as I have been mentioning, the
discovery is as well Pleasant as Satisfactory, and may afford Hints of the
Solution of other _Phænomena_ of Colours. And it were not amiss, that some
diligent Inquiry were made, whether the _Microscope_ would give us an
account of the Variableness of Colour, that is so Conspicuous and so
Delightfull in Mother of Pearl, in Opalls, and some other resembling
Bodies: For though I remember I did formerly attempt something of that Kind
(fruitlesly enough) upon Mother of Pearl, yet not having then the advantage
of my best _Microscope_, nor some Conveniences that might have been wish'd,
I leave it to you, who have better Eyes, to try what you can do further;
since 'twill be _Some_ discovery to find, that, in this case, the best Eyes
and _Microscopes_ themselves can make _None_.
10. I confess, _Pyrophilus_, that a great part of what I have deliver'd,
(or propos'd rather) concerning the differing forms of Asperity in Bodies,
by which Differences the incident Light either comes to be Reflected with
more or less of Shade, and with that Shade more or less Interrupted, or
else happens to be also otherwise Modify'd or Troubl'd, is but Conjectural.
But I am not sure, that if it were not for the Dullness of our Senses,
either these or some other Notions of Kin to them, might be better
Countenanc'd; for I am apt to suspect, that if we were Sharp sighted
enough, or had such perfect _Microscopes_, as I fear are more to be wish'd
than hop'd for, our promoted Sense might discern in the Physical Surfaces
of Bodies, both a great many latent Ruggidnesses, and the particular Sizes,
Shapes, and Situations of the extremely little Bodies that cause them, and
perhaps might perceive among other Varieties that we now can but imagine,
how those little Protuberances and Cavities do Interrupt and Dilate the
Light, by mingling with it a multitude of little and singly undiscernable
Shades, though some of them more, and some of them less Minute, some less,
and some more Numerous; according to the Nature and Degree of the
particular Colour we attribute to the Visible Object; as we see, that in
the Moon we can with Excellent _Telescopes_ discern many Hills and Vallies,
and as it were Pits and other Parts, whereof some are more, and some less
Vividly illustrated, and others have a fainter, others a deeper Shade,
though the naked Eye can discern no such matter in that Planet. And with an
Excellent _Microscope_, where the _Naked_ Eye did see but a Green powder,
the _Assisted_ Eye as we noted above, could discern particular Granules,
some of them of a Blew, and some of them of a Yellow colour, which
Corpuscles we had beforehand caus'd to be exquisitly mix'd to compound the
Green.
11. And, _Pyrophilus_, that you may not think me altogether extravagant in
what I have said of the Possibility, (for I speak of no more) of discerning
the differing forms of Asperity in the Surfaces of Bodies of several
Colours, I'l here set down a Memorable particular that chanc'd to come to
my Knowledge, since I writ a good part of this _Essay_; and it is this.
Meeting casually the other Day with the deservedly Famous[4] Dr. _J.
Finch_, Extraordinary _Anatomist_ to that Great Patron of the _Virtuosi_,
the now Great Duke of _Toscany_, and enquiring of this Ingenious Person,
what might be the chief Rarity he had seen in his late return out of
_Italy_ into _England_, he told me, it was a Man at _Maestricht_ in the
Low-Countrys, who at certain times can discern and _distinguish Colours by
the Touch_ with his Fingers. You'l easily Conclude, that this is farr more
strange, than what I propos'd but as _not Impossible_; since the Sense of
the _Retina_ seeming to be much more Tender and quick than that of those
Grosser Filaments, Nerves or Membranes of our Fingers, wherewith we use to
handle Gross and Hard Bodies, it seems scarce credible, that any
Accustomance, or Diet, or peculiarity of Constitution, should enable a Man
to distinguish with such Gross and Unsuitable Organs, such Nice and Subtile
Differences as those of the forms of Asperity, that belong to differing
Colours, to receive whose Languid and Delicate Impressions by the
Intervention of Light, Nature seems to have appointed and contexed into the
_Retina_ the tender and delicate Pith of the Optick Nerve. Wherefore I
confess, I propos'd divers Scruples, and particularly whether the Doctor
had taken care to bind a Napkin or Hankerchief over his Eyes so carefully,
as to be sure he could make no use of his Sight, though he had but
Counterfeited the want of it, to which I added divers other Questions, to
satisfie my Self, whether there were any Likelihood of Collusion or other
Tricks. But I found that the Judicious Doctor having gone farr out of his
way, purposely to satisfie Himself and his Learned Prince about this
Wonder, had been very Watchfull and Circumspect to keep _Himself_ from
being Impos'd upon. And that he might not through any mistake in point of
Memory mis-inform _Me_, he did me the Favour at my Request, to look out the
Notes he had Written for his Own and his Princes Information, the summ of
which Memorials, as far as we shall mention them here, was this, That the
Doctor having been inform'd at _Utrecht_, that there Lived one at some
Miles distance from _Maestricht_, who could distinguish Colours by the
Touch, when he came to the last nam'd Town, he sent a Messenger for him,
and having Examin'd him, was told upon Enquiry these Particulars:
[4] Since for his eminent Qualities and Loyalty Grac'd, by his Majesty,
with the Honour of Knighthood.
That the Man's name was _John Vermaasen_, at that time about 33 Years of
Age; that when he was but two years Old, he had the Small Pox, which
rendred him absolutely Blind: That at this present he is an _Organist_, and
serves that Office in a publick Quire.
That the Doctor discoursing with him over Night, the Blind man affirm'd,
that he could distinguish Colours by the Touch, but that he could not do
it, unless he were Fasting; Any quantity of Drink taking from him that
Exquisitness of Touch, which is requisite to so Nice a Sensation.
That hereupon the Doctor provided against the next Morning seven pieces of
Ribbon, of these seven Colours, Black, White, Red, Blew, Green, Yellow, and
Gray, but as for _mingled_ Colours, this _Vermaasen_ would not undertake to
discern them, though if offer'd, he would tell that they were _Mix'd_.
That to discern the Colour of the Ribbon, he places it betwixt the Thumb
and the Fore-finger, but his most exquisite perception was in his Thumb,
and much better in the right Thumb than in the left.
That after the Blind man had four or five times told the Doctor the several
Colours, (though Blinded with a Napkin for fear he might have some Sight)
the Doctor found he was twice mistaken, for he call'd the White Black, and
the Red Blew, but still, he, before his Errour, would lay them by in Pairs,
saying, that though he could easily distinguish them from all others, yet
those two Pairs were not easily distinguish'd amongst themselves, whereupon
the Doctor desir'd to be told by him what kind of Discrimination he had of
Colours by his Touch, to which he gave a reply, for whose sake chiefly I
insert all this Narrative in this place, namely, That all the difference
was more or less Asperity, for says he, (I give you the Doctor's own words)
Black feels as if you were feeling Needles points, or some harsh Sand, and
Red feels very Smooth.
That the Doctor having desir'd him to tell in Order the difference of
Colours to his Touch, he did as follows;
Black and White are the most asperous or unequal of all Colours, and so
like, that 'tis very hard to distinguish them, but Black is the most Rough
of the two, Green is next in Asperity, Gray next to Green in Asperity,
Yellow is the fifth in degree of Asperity, Red and Blew are so like, that
they are as hard to distinguish as Black and White, but Red is somewhat
more Asperous than Blew, so that Red has the sixth place, and Blew the
seventh in Asperity.
12. To these Informations the Obliging Doctor was pleas'd to add the
welcome present of three of those very pieces of Ribbon, whose Colours in
his presence the Blind man had distinguished, pronouncing the one Gray, the
other Red, and the third Green, which I keep by me as Rarities, and the
rather, because he fear'd the rest were miscarry'd.
13. Before I saw the Notes that afforded me the precedent Narrative, I
confess I suspected this man might have thus discriminated Colours, rather
by the Smell than by the Touch; for some of the Ingredients imployed by
Dyers to Colour things, have Sents, that are not so Languid, nor so near of
Kin, but that I thought it not impossible that a very Critical Nose might
distinguish them, and this I the rather suspected, because he requir'd,
that the Ribbons, whose Colours he was to Name, should be offer'd him
Fasting in the morning; for I have observ'd in Setting Doggs, that the
feeding of them (especially with some sorts of Aliments) does very much
impair the exquisite sent of their Noses. And though some of the foregoing
particulars would have prevented that Conjecture, yet I confess to you
(_Pyrophilus_) that I would gladly have had the Opportunity of Examining
this Man my self, and of Questioning him about divers particulars which I
do not find to have been yet thought upon. And though it be not incredible
to me, that since the Liquors that Dyers imploy to tinge, are qualifi'd to
do so by multitudes of little Corpuscles of the Pigment or Dying stuff,
which are dissolved and extracted by the Liquor, and swim to and fro in it,
those Corpuscles of Colour (as the _Atomists_ call them) insinuating
themselves into, and filling all the Pores of the Body to be Dyed, may
Asperate its Superficies more or less according to the Bigness and Texture
of the Corpuscles of the Pigment; yet I can scarce believe, that our Blind
man could distinguish all the Colours he did, meerly by the Ribbons having
more or less of Asperity, so that I cannot but think, notwithstanding this
History, that the Blind man distinguish'd Colours not only by the _Degrees_
of Asperity in the Bodies offer'd to him, but by _Forms_ of it, though this
(latter) would perhaps have been very difficult for him to make an
Intelligible mention of, because those Minute disparities having not been
taken notice of by men for want of touch as Exquisite as our Blind Mans,
are things he could not have Intelligibly express'd, which will easily seem
Probable, if you consider, that under the name of Sharp, and Sweet, and
Sour, there are abundance of, as it were, immediate peculiar Relishes or
Tasts in differing sorts of Wine, which though Critical and Experienc'd
Palats can easily discern themselves cannot make them be understood by
others, such Minute differences not having hitherto any Distinct names
assign'd them. And it seems that there was somthing in the Forms of
Asperity that was requisite to the Distinction of Colours, besides the
Degree of it, since he found it so difficult to distingush Black and White
from one another, though not from other Colours. For I might urge, that he
seems not consonant to himself about the _Red_, which as you have seen in
one place, he represents as somewhat more Asperous than the _Blew_; and in
another, very Smooth: But because he speaks of this Smoothness in that
place, where he mentions the Roughness of _Black_, we may favourably
presume that he might mean but a _comparative Smoothness_; and therefore I
shall not Insist on this, but rather Countenance my Conjecture by this,
that he found it so Difficult, not only, to Discriminate Red and Blew,
(though the first of our promiscuous Experiments will inform you, that the
Red reflects by great Odds more Light than the other) but also to
distinguish Black and White from one another, though not from other
Colours. And indeed, though in the Ribbonds that were offer'd him, they
might be almost equally Rough, yet in such slender Corpuscles as those of
Colour, there may easily enough be Conceiv'd, not only a greater Closeness
of Parts, or else Paucity of Protuberant Corpuscles, and the little extant
Particles may be otherwise Figur'd, and Rang'd in the White than in the
Black, but the Cavities may be much Deeper in the one than the other.
14. And perhaps, (_Pyrophilus_) it may prove some _Illustration of what I
mean_, and help you to conceive how _this may_ be, if I Represent, that
where the Particles are so exceeding Slender, we may allow the Parts
expos'd to the Sight and Touch to be a little Convex in comparison of the
Erected Particle of Black Bodies, as if there were Wyres I know not how
many times Slenderer than a Hair: whether you suppose them to be Figur'd
like Needles, or Cylindrically, like the Hairs of a Brush, with
Hemisphærical (or at least Convex) Tops, they will be so very Slender, and
consequently the Points both of the one sort and the other so very Sharp,
that even an exquisite Touch will be able to distinguish no greater
Difference between them, than that which our Blind man allow'd, when
comparing Black and White Bodies, he said, that the latter was the less
Rough of the two. Nor is every Kind of Roughness, though Sensible enough,
Inconsistent with Whiteness, there being Cases, wherein the Physical
Superficies of a Body is made by the same Operation both _Rough_ and
_white_, as when the Level Surface of clear Water being by agitation
Asperated with a multitude of Unequal Bubbles, do's thereby acquire a
Whiteness; and as a Smooth piece of Glass, by being Scratch'd with a
Diamond, do's in the Asperated part of its Surface disclose the same
Colour. But more (perchance) of this elsewhere.
15. And therefore, we shall here pass by the Question, whether any thing
might be consider'd about the Opacity of the Corpuscles of Black Pigments,
and the _Comparative_ Diaphaneity of those of many White Bodies, apply'd to
our present Case; and proceed, to represent, That the newly mention'd
Exiguity and Shape of the extant Particles being suppos'd, it will then be
considerable what we lately but Hinted, (and therefore must now somewhat
Explane) That the Depth of the little Cavities, intercepted between the
extant Particles, without being so much greater in Black Bodies than in
White ones, as to be perceptibly so to the Gross Organs of Touch, may be
very much greater in reference to their Disposition of Reflecting the
imaginary subtile Beams of Light. For in Black Bodies, those Little
intercepted Cavities, and other Depressions, may be so Figur'd, so Narrow
and so Deep, that the incident Beams of Light, which the more extant Parts
of the Physical Superficies are dispos'd to Reflect inwards, may be
Detain'd there, and prove unable to Emerge; whilst in a White Body, the
Slender Particles may not only by their Figure be fitted to Reflect the
Light copiously outwards, but the intercepted Cavities being not Deep, nor
perhaps very Narrow, the Bottoms of them may be so Constituted, as to be
fit to Reflect outwards much of the Light that falls even upon Them; as you
may possibly better apprehend, when we shall come to treat of Whiteness and
Blackness. In the mean time it may suffice, that you take Notice with me,
that the Blind mans Relations import no necessity of Concluding, that,
though, because, according to the Judgment of his Touch, Black was the
Roughest, as it is the Darkest of Colours, therefore White, which
(according to us) is the Lightest, should be also the Smoothest: since I
observe, that he makes Yellow to be two Degrees more Asperous than Blew,
and as much less Asperous than Green; whereas indeed, Yellow do's not only
appear to the Eye a Lighter Colour than Blew, but (by our first Experiment
hereafter to be mention'd) it will appear, that Yellow reflected much more
Light than Blew, and manifestly more than Green, (which we need not much
wonder at, since in this Colour and the two others (Blew and Yellow) 'tis
not _only_ the _Reflected Light_ that is to be considered, since to produce
both these, _Refraction_ seems to Intervene, which by its Varieties may
much alter the Case:) which both seems to strengthen the Conjecture I was
formerly proposing, that there was something else in the _Kinds_ of
Asperity, as well as in the _Degrees_ of it, which enabled our Blind man to
Discriminate Colours, and do's at least show, that we cannot in all Cases
from the bare Difference in the Degrees of Asperity betwixt Colours, safely
conclude, that the Rougher of any two always Reflects the least Light.
16. But this notwithstanding, (_Pyrophilus_) and what ever Curiosity I may
have had to move some Questions to our Sagacious Blind man, yet thus much I
think you will admit us to have gain'd by his Testimony, that since many
Colours may be felt with the Circumstances above related, the Surfaces of
such Coloured Bodies must certainly have differing _Degrees_, and in all
probability have differing _Forms_ or Kinds of Asperity belonging to them,
which is all the Use that my present attempt obliges me to make of the
History above deliver'd, that being sufficient to prove, _that_ Colour do's
much depend upon the Disposition of the Superficial parts of Bodies, and to
shew in general, _wherein_ 'tis probable that such a Disposition do's
(principally at least) consist.
17. But to return to what I was saying before I began to make mention of
our Blind _Organist_, what we have deliver'd touching the causes of the
several Forms or Asperity that may Diversifie the Surfaces of Colour'd
Bodies, may perchance somewhat assist us to make some Conjectures in the
general, at several of the ways whereby 'tis possible for the Experiments
hereafter to be mention'd, to produce the suddain changes of Colours that
are wont to be Consequent upon them; for most of these _Phænomena_ being
produc'd by the Intervention of Liquors, and these for the most part
abounding with very Minute, Active, and Variously Figur'd Saline
Corpuscles, Liquors so Qualify'd may well enough very Nimbly after the
Texture of the Body they are imploy'd to Work upon, and so may change the
form of Asperity, and thereby make them Remit to the Eye the Light that
falls on them, after another manner than they did before, and by that means
Vary the Colour, so farr forth as it depends upon the Texture or
Disposition of the Seen Parts of the Object, which I say, _Pyrophilus_,
that you may not think I would absolutely exclude all other ways of
Modifying the Beams of Light between their Parting from the Lucid Body, and
their Reception into the common Sensory.
18. Now there seem to me divers ways, by which we may conceive that Liquors
may Nimbly alter the Colour of one another, and of other Bodies, upon which
they Act, but my present haste will allow me to mention but some of them,
without Insisting so much as upon those I shall name.
19. And first, the Minute Corpuscles that compose a Liquor may early
insinuate themselves into those Pores of Bodies, whereto their Size and
Figure makes them Congruous, and these Pores they may either exactly Fill,
or but Inadequately, and in this latter Case they will for the most part
alter the Number and Figure, and always the Bigness of the former Pores.
And in what capacity soever these Corpuscles of a Liquor come to be Lodg'd
or Harbour'd in the Pores that admit them, the Surface of the Body will for
the most part have its Asperity alter'd, and the Incident Light that meets
with a Grosser Liquor in the little Cavities that before contain'd nothing
but Air, or some yet Subtiler Fluid, will have its Beams either Refracted,
or Imbib'd, or else Reflected more or less Interruptedly, than they would
be, if the Body had been Unmoistned, as we see, that even fair Water
falling on white Paper, or Linnen, and divers other Bodies apt to soak it
in, will for some such Reasons as those newly mention'd, immediately alter
the Colour of them, and for the most part make it Sadder than that of the
Unwetted Parts of the same Bodies. And so you may see, that when in the
Summer the High-ways are Dry and Dusty, if there falls store of Rain, they
will quickly appear of a much Darker Colour than they did before, and if a
Drop of Oyl be let fall upon a Sheet of White Paper, that part of it, which
by the Imbibition of the Liquor acquires a greater Continuity, and some
Transparency, will appear much Darker than the rest, many of the Incident
Beams of Light being now Transmitted, that otherwise would be Reflected
towards the Beholders Eyes.
20. Secondly, A Liquor may alter the Colour of a Body by freeing it from
those things that hindred it from appearing in its Genuine Colour; and
though this may be said to be rather a Restauration of a Body to its own
Colour, or a Retection of its native Colour, than a Change, yet still there
Intervenes in it a change of the Colour which the Body appear'd to be of
before this Operation. And such a change a Liquor may work, either by
Dissolving, or Corroding, or by some such way of carrying off that Matter,
which either Veil'd or Disguis'd the Colour that afterwards appears. Thus
we restore Old pieces of Dirty Gold to a clean and nitid Yellow, by putting
them into the Fire, and into _Aqua-fortis_, which take off the adventitious
Filth that made that pure Metall look of a Dirty Colour. And there is also
an easie way to restore Silver Coyns to their due Lustre, by fetching off
that which Discolour'd them. And I know a _Chymical_ Liquor, which I
employ'd to restore pieces of Cloath spotted with Grease to their proper
Colour, by Imbibing the Spotted part with this Liquor, which Incorporating
with the Grease, and yet being of a very Volatile Nature, does easily carry
it away with it Self. And I have sometimes try'd, that by Rubbing upon a
good Touch-stone a certain _Metalline_ mixture so Compounded, that the
Impression it left upon the Stone appear'd of a very differing Colour from
that of Gold, yet a little of _Aqua-fortis_ would in a Trice make the
Golden Colour disclose it self, by Dissolving the other _Metalline_
Corpuscles that conceal'd those of the Gold, which you know that
_Menstruum_ will leave Untouch'd.
21. Thirdly, A Liquor may alter the Colour of a Body by making a
Comminution of its Parts, and that principally two ways, the first by
Disjoyning and Dissipating those Clusters of Particles, if I may so call
them, which stuck more Loosely together, being fastned only by some more
easily Dissoluble Ciment, which seems to be the Case of some of the
following Experiments, where you'l find the Colour of many Corpuscles
brought to cohere by having been Precipitated together, Destroy'd by the
Affusion of very peircing and incisive Liquors. The other of the two ways I
was speaking of, is, by Dividing the Grosser and more Solid Particles into
Minute ones, which will be always Lesser, and for the most part otherwise
Shap'd than the Entire Corpuscle so Divided, as it will happen in a piece
of Wood reduc'd into Splinters or Chips, or as when a piece of Chrystal
heated red Hot and quench'd in Cold water is crack'd into a multitude of
little Fragments, which though they fall not asunder, alter the Disposition
of the Body of the Chrystal, as to its manner of Reflecting the Light, as
we shall have Occasion to shew hereafter.
22. There is a fourth way contrary to the third, whereby a Liquor may
change the Colour of another Body, especially of another Fluid, and that
is, by procuring the Coalition of several Particles that before lay too
Scatter'd and Dispers'd to exhibit the Colour that afterwards appears. Thus
sometimes when I have had a Solution of Gold so Dilated, that I doubted
whether the Liquor had really Imbib'd any true Gold or no, by pouring in a
little _Mercury_, I have been quickly able to satisfie my Self, that the
Liquor contain'd Gold, that Mettall after a little while Cloathing the
Surface of the _Quick-silver_, with a Thin Film of its own Livery. And
chiefly, though not only by this way of bringing the Minute parts of Bodies
together in such Numbers as to make them become Notorious to the Eye, many
of these Colours seem to be Generated which are produc'd by Precipitations,
especially by such as are wont to be made with fair Water, as when Resinous
Gumms dissolv'd in Spirit of Wine, are let fall again, if the Spirit be
Copiously diluted with that weakning Liquor. And so out of the Rectify'd
and Transparent Butter of _Antimony_, by the bare Mixture of fair Water,
there will be plentifully Precipitated that Milk-white Substance, which by
having its Looser Salts well wash'd off, is turn'd into that Medicine,
which Vulgar _Chymists_ are pleas'd to call _Mercurius Vitæ._
23. A fifth way, by which a Liquor may change the Colour of a Body, is, by
Dislocating the Parts, and putting them out of their former Order into
another, and perhaps also altering the Posture of the single Corpuscles as
well as their Order or Situation in respect of one another. What certain
Kinds of Commotion or Dislocation of the Parts of a Body may do towards the
Changing its Colour, is not only evident in the Mutations of Colour
observable in _Quick-silver_, and some other Concretes long kept by
_Chymists_ in a Convenient Heat, though in close Vessels, but in the
Obvious Degenerations of Colour, which every Body may take notice of in
Bruis'd Cherries, and other Fruit, by comparing after a while the Colour of
the Injur'd with that of the Sound part of the same Fruit. And that also
such Liquors, as we have been speaking of, may greatly Discompose the
Textures of many Bodies, and thereby alter the Disposition of their
Superficial parts, the great Commotion made in Metalls, and several other
Bodies by _Aqua-fortis_, Oyl of _Vitriol_, and other Saline _Menstruums_,
may easily perswade us, and what such Vary'd Situations of Parts may do
towards the Diversifying of the manner of their Reflecting the Light, may
be Guess'd in some Measure by the Beating of Transparent Glass into a White
Powder, but farr better by the Experiments lately Pointed at, and hereafter
Deliver'd, as the Producing and Destroying Colours by the means of subtil
Saline Liquors, by whose Affusion the Parts of other Liquors are manifestly
both Agitated, and likewise Dispos'd after another manner than they were
before such Affusion. And in some _Chymical_ Oyls, as particularly that of
Lemmon Pills, by barely Shaking the Glass, that holds it, into Bubbles,
that Transposition of the Parts which is consequent to the Shaking, will
shew you on the Surfaces of the Bubbles exceeding Orient and Lively
Colours, which when the Bubbles relapse into the rest of the Oyl, do
immediately Vanish.
24. I know not, _Pyrophilus_, whether I should mention as a Distinct way,
because it is of a somewhat more General Nature, that Power, whereby a
Liquor may alter the Colour of another Body, by putting the Parts of it
into Motion; For though possibly the Motion so produc'd, does, as such,
seldome suddenly change the Colour of the Body whose Parts are Agitated,
yet this seems to be one of the most General, however not Immediate causes
of the Quick change of Colours in Bodies. For the Parts being put into
Motion by the adventitious Liquor, divers of them that were before United,
may become thereby Disjoyn'd, and when that Motion ceases or decays others
of them may stick together, and that in a new Order, by which means the
Motion may sometimes produce Permanent changes of Colours, as in the
Experiment you will meet with hereafter, of presently turning a Snowy White
Body into a Yellow, by the bare Affusion of fair Water, which probably so
Dissolves the Saline Corpuscles that remain'd in the _Calx_, and sets them
at Liberty to Act upon one another, and the Metall, far more Powerfully
than the Water without the Assistance of such Saline Corpuscles could do.
And though you rubb Blew _Vitriol_, how Venereal and Unsophisticated soever
it be, upon the Whetted Blade of a Knife, it will not impart to the Iron
its Latent Colour, but if you moisten the _Vitriol_ with your Spittle, or
common Water, the Particles of the Liquor disjoyning those of the
_Vitriol_, and thereby giving them the Various Agitation requisite to Fluid
Bodies, the Metalline Corpuscles of the thus Dissolv'd _Vitriol_ will Lodge
themselves in Throngs in the Small and Congruous Pores of the Iron they are
Rubb'd on, and so give the Surface of it the Genuine Colour of the Copper.
25. There remains yet a way, _Pyrophilus_ to be mention'd, by which a
Liquor may alter the Colour of another Body, and this seems the most
Important of all, because though it be nam'd but as One, yet it may indeed
comprehend Many, and that is, by Associating the Saline Corpuscles, or any
other Sort of the more Rigid ones of the Liquor, with the Particles of the
Body that it is employ'd to Work upon. For these Adventitious Corpuscles
Associating themselves with the Protuberant Particles of the Surface of a
Colour'd Body, must necessarily alter their Bigness, and will most commonly
alter their Shape. And how much the Colours of Bodies depend upon the Bulk
and Figure of their Superficial Particles, you may Guess by this, that
eminent antient _Philosophers_ and divers _Moderns_, have thought that all
Colours might in a general way be made out by these two; whose being
Diversify'd, will in our Case be attended with these two Circumstances, the
One, that the Protuberant Particles being Increas'd in Bulk, they will
oftentimes be Vary'd as to the Closness or Laxity of their Order, fewer of
them being contain'd within the same Sensible (though Minute) space than
before; or else by approaching to one another, they must Straighten the
Pores, and it may be too, they will by their manner of Associating
themselves with the Protuberant Particles, intercept new Pores. And this
invites me to consider farther, that the Adventitious Corpuscles, I have
been speaking of, may likewise produce a great Change as well in the Little
Cavities or Pores as in the Protuberances of a Colour'd Body; for besides
what we have just now taken notice of, they may by Lodging themselves in
those little Cavities, fill them up, and it may well happen, that they may
not only fill the Pores they Insinuate themselves into, but likewise have
their Upper Parts extant above them; and partly by these new Protuberances,
partly by Increasing the Bulk of the former, these Extraneous Corpuscles
may much alter the Number and Bigness of the Surfaces Pores, changing the
Old and Intercepting new ones. And then 'tis Odds, but the Order of the
Little Extancies, and consequently that of the Little Depressions in point
of Situation will be alter'd likewise: as if you dissolve _Quick-silver_ in
some kind of _Aqua-fortis_, the Saline Particles of the _Menstruum_
Associating themselves with the Mercurial Corpuscles, will make a Green
Solution, which afterwards easily enough Degenerates. And Red Lead or
_Minium_ being Dissolv'd in Spirit of Vinegar, yields not a Red, but a
Clear Solution, the Redness of the Lead being by the Liquor Destroy'd. But
a better Instance may be taken from Copper, for I have try'd, that if upon
a Copper-plate you let some Drops of weak _Aqua-fortis_ rest for a while,
the Corpuscles of the _Menstruum_, joyning with those of the Metall, will
produce a very sensible Asperity upon the Surface of the Plate, and will
Concoagulate that way into very minute Grains of a Pale Blew _Vitriol_;
whereas if upon another part of the same Plate you suffer a little strong
Spirit of Urine to rest a competent time, you shall find the Asperated
Surface adorn'd with a Deeper and Richer Blew. And the same _Aqua-fortis_,
that will quickly change the Redness of Red Lead into a Darker Colour,
will, being put upon Crude Lead, produce a Whitish Substance, as with
Copper it did a Blewish. And as with Iron it will produce a Reddish, and on
White Quills a Yellowish, so much may the Coalition of the Parts of the
same Liquor, with the differingly Figur'd Particles of Stable Bodies,
divers ways Asperate the differingly Dispos'd Surfaces, and to Diversifie
the Colour of those Bodies. And you'l easily believe, that in many changes
of Colour, that happen upon the Dissolutions of Metalls, and Precipitations
made with Oyl of _Tartar_, and the like Fix'd Salts, there may Intervene a
Coalition of Saline Corpuscles with the Particles of the Body Dissolv'd or
Precipitated, if you examine how much the _Vitriol_ of a Metall may be
Heavier than the Metalline part of it alone, upon the Score of the Saline
parts Concoagulated therewith, and, that in Several Precipitations the
weight of the _Calx_ does for the same Reason much exceed that of the
Metall, when it was first put in to be Dissolv'd.
26. But, _Pyrophilus_, to consider these Matters more particularly would be
to forget that I declar'd against Adventuring, at least for this time, at
particular Theories of Colours, and that accordingly you may justly expect
from me rather Experiments than Speculations, and therefore I shall Dismiss
this Subject of the Forms of Superficial Asperity in Colour'd Bodies, as
soon as I shall but have nam'd to you by way of Supplement to what we have
hitherto Discours'd in this Section, a Couple of Particulars, (which you'l
easily grant me) The one, That there are divers other ways for the speedy
Production even of True and Permanent Colours in Bodies, besides those
Practicable by the help of Liquors; for proof of which Advertisement,
though several Examples might be alleged, yet I shall need but Re-mind you
of what I mention'd to you above, touching the change of Colours suddenly
made on Temper'd Steel, and on Lead, by the Operation of Heat, without the
Intervention of a Liquor. But the other particular I am to observe to you
is of more Importance to our present Subject and it is, That though Nature
and Art may in some cases so change the Asperity of the Superficial parts
of a Body, as to change its Colour by either of the ways I have propos'd
Single or Unassisted, yet for the most part 'tis by two or three, or
perhaps by more of the fore-mention'd ways Associated together, that the
Effect is produc'd, and if you consider how Variously those several ways
and some others Ally'd unto them, which I have left unmention'd, may be
Compounded and Apply'd, you will not much wonder that such fruitfull,
whether Principles (or Manners of Diversification) should be fitted to
Change or Generate no small store of Differing Colours.
27. Hitherto, _Pyrophilus_, we have in discoursing of the Asperity of
Bodies consider'd the little Protuberances of other Superficial particles
which make up that Roughness, as if we took it for granted, that they must
be perfectly Opacous and Impenetrable by the Beams of Light, and so, must
contribute to the Variety of Colours as they terminate more or less Light,
and reflect it to the Eye mix'd with more or less of thus or thus mingl'd
Shades. But to deal Ingenuously with you, _Pyrophilus_, before I proceed
any further, I must not conceal from you, that I have often thought it
worth a Serious Enquiry, whether or no Particles of Matter, each of them
sing'y Insensible, and therefore small enough to be capable of being such
Minute Particles as the _Atomists_ both of old and of late have (not
absurdly) called _Corpuscula Coloris_, may not yet consist each of them of
divers yet Minuter Particles, betwixt which we may conceive little
Commissures where they Adhere to one another, and, however, may not be
Porous enough to be, at least in some degree, Pervious to the unimaginably
subtile Corpuscles that make up the Beams of Light, and consequently to be
in such a degree Diaphanous. For, _Pyrophilus_, that the proposed Enquiry
may be of moment to him that searches after the Nature of Colour, you'l
easily grant, if you consider, that whereas Perfectly Opacous bodies can
but reflect the incident Beams of Light, those that are Diaphanous are
qualified to refract them too, and that Refraction has such a stroak in the
Production of Colours, as you cannot but have taken notice of, and perhaps
admir'd in the Colours generated by the Trajection of Light through Drops
of Water that exhibit a Rain-bow, through Prismatical glasses, and through
divers other Transparent bodies. But 'tis like, _Pyrophilus_, you'l more
easily allow that about this matter 'tis rather Important to have a
Certainty, than that 'tis Rational to entertain a Doubt; wherefore I must
mention to you some of the Reasons that make me think it may need a further
Enquiry, for I find that in a Darkned Room, where the Light is permitted to
enter but at One hole, the little wandering Particles of Dust, that are
commonly called Motes, and, unless in the Sunbeams, are not taken notice of
by the unassisted Sight, I have, I say, often observ'd, that these roving
Corpuscles being look'd on by an Eye plac'd on one side of the Beams that
enter'd the Little hole, and by the Darkness having its Pupill much
Enlarg'd, I could discern that these Motes as soon as they came within the
compass of the Luminous, whether Cylinder or Inverted Cone, if I may so
call it, that was made up by the Unclouded Beams of the Sun, did in certain
positions appear adorn'd with very vivid Colours, like those of the
Rain-bow, or rather like those of very Minute, but Sparkling fragments of
Diamonds; and as soon as the Continuance of their Motion had brought them
to an Inconvenient position in reference to the Light and the Eye, they
were only visible without Darting any lively Colours as before, which seems
to argue that these little Motes, or minute Fragments, of several sorts of
bodies reputed Opacous, and only crumbled as to their Exteriour and Looser
parts into Dust, did not barely Reflect the Beams that fell upon them, but
remit them to the Eye Refracted too. We may also observe, that several
Bodies, (as well some of a Vegetable, as others of an Animal nature) which
are wont to pass for Opacous, appear in great part Transparent, when they
are reduc'd into Thin parts, and held against a powerful Light. This I have
not only taken notice of in pieces of Ivory reduc'd but into Thick leaves,
as also in divers considerable Thick shells of Fishes, and in shaving of
Wood, but I have also found that a piece of Deal, far thicker than one
would easily imagine, being purposly interposed betwixt my Eye plac'd in a
Room, and the clear Daylight, was not only somewhat Transparent, but
(perhaps by reason of its Gummous nature) appear'd quite through of a
lovely Red. And in the Darkned Room above mention'd, Bodies held against
the hole at which the Light enter'd, appear'd far less Opacous then they
would elsewhere have done, insomuch that I could easily and plainly see
through the whole Thickness of my Hand, the Motions of a Body plac'd (at a
very near distance indeed, but yet) beyond it. And even in Minerals, the
Opacity is not always so great as many think, if the Body be made Thin, for
White Marble though of a pretty Thickness, being within a Due distance
plac'd betwixt the Eye and a Convenient Light, will Suffer the Motions of
ones Finger to be well discern'd through it, and so will pieces, Thick
enough, of many common Flints. But above all, that Instance is remarkable,
that is afforded us by _Muscovie_ glass, (which some call _Selenites_,
others _Lapis Specularis_) for though plates of this Mineral, though but of
a moderate Thickness, do often appear Opacous, yet if one of these be
Dextrously split into the thinnest Leaves 'tis made up of, it will yield
such a number of them, as scarce any thing but Experience could have
perswaded me, and these Leaves will afford the most Transparent sort of
consistent Bodies, that, for ought I have observ'd, are yet known; and a
single Leaf or Plate will be so far from being Opacous, that 'twill scarce
be so much as Visible. And multitudes of Bodies there are, whose Fragments
seem Opacous to the naked Eye, which yet, when I have included them in good
_Microscopes_, appear'd Transparent; but, _Pyrophilus_, on the other side I
am not yet sure that there are no Bodies, whose Minute Particles even in
such a _Microscope_ as that of mine, which I was lately mentioning, will
not appear Diaphanous. For having consider'd _Mercury_ Precipitated _per
se_, the little Granules that made up the powder, look'd like little
fragments of Coral beheld by the naked Eye at a Distance (for very Near at
hand Coral will sometimes, especially if it be Good, shew some
Transparency.) Filings likewise of Steel and Copper, though in an excellent
_Microscope_, and a fair Day, they show'd like pretty Big Fragments of
those Metalls, and had considerable Brightness on some of their Surfaces,
yet I was not satisfi'd, that I perceiv'd any Reflection from the Inner
parts of any of the Filings. Nay, having look'd in my best _Microscope_
upon the Red _Calx_ of Lead, (commonly call'd _Minium_) neither I, nor any
I shew'd it to, could discern it to be other than Opacous, though the Day
were Clear, and the Object strongly Enlightned. And the deeply Red Colour
of _Vitriol_ appear'd in the same _Microscope_ (notwithstanding the great
Comminution effected by the Fire) but like Grossy beaten Brick. So that,
_Pyrophilus_, I shall willingly resign you the care of making some further
Enquiries into the Subject we have now been considering; for I confess, as
I told you before, that I think that the Matter may need a further
Scrutiny, nor would I be forward to Determine how far or in what cases the
Transparency or Semi-diaphaniety of the Superficial Corpuscles of Bigger
Bodies, may have an Interest in the Production of their Colours, especially
because that even in divers White bodies, as Beaten Glass, Snow and Froth,
where it seems manifest that the Superficial parts are singly Diaphanous,
(being either Water, or Air, or Glass) we see not that such Variety of
Colours are produc'd as usually are by the Refraction of Light, even in
those Bodies, when by their Bigness, Shape, &c. they are conveniently
qualify'd to exhibit such Various and Lively Colours as those of the
Rain-bow, and of Prismatical Glasses.
28. By what has been hitherto discours'd, _Pyrophilus_, we may be assisted
to judge of that famous Controversie which was of Old disputed betwixt the
_Epicureans_ and other _Atomists_ on the one side, and most other
_Philosophers_ on the other side. The former Denying Bodies to be Colour'd
in the Dark, and the Latter making Colour to be an Inherent quality, as
well as Figure, Hardness; Weight, or the like. For though this Controversie
be Reviv'd, and hotly Agitated among the _Moderns_, yet I doubt whether it
be not in great part a Nominal dispute, and therefore let us, according to
the Doctrine formerly deliver'd, Distinguish the Acceptions of the word
Colour, and say, that if it be taken in the Stricter Sense, the
_Epicureans_ seem to be in the Right, for if Colour be indeed, though not
according to them, but Light Modify'd, how can we conceive that it can
Subsist in the Dark, that is, where it must be suppos'd there is no Light;
but on the other side, if Colour be consider'd as a certain Constant
Disposition of the Superficial parts of the Object to Trouble the Light
they Reflect after such and such a Determinate manner, this Constant, and,
if I may so speak, Modifying disposition persevering in the Object, whether
it be Shin'd upon or no, there seems no just reason to deny, but that in
this Sense, Bodies retain their Colour as well in the Night as Day; or, to
Speak a little otherwise, it may be said, that Bodies are Potentially
Colour'd in the Dark, and Actually in the Light. But of this Matter
discoursing more fully elsewhere, as 'tis a difficulty that concerns
Qualities in general, I shall forbear to insist on it here.
* * * * *
CHAP. IV
1. Of greater Moment in the Investigation of the Nature of Colours is the
Controversie, Whether those of the Rain-bow, and those that are often seen
in Clouds, before the Rising, or after the Setting of the Sun; and in a
word, Whether those other Colours, that are wont to be call'd Emphatical,
ought or ought not to be accounted True Colours. I need not tell you that
the Negative is the Common Opinion, especially in the Schools, as may
appear by that Vulgar distinction of Colours, whereby these under
Consideration are term'd Apparent, by way of Opposition to those that in
the other Member of the Distinction are call'd True or Genuine. This
question I say seems to me of Importance, upon this Account, that it being
commonly Granted, (or however, easie enough to be Prov'd) that Emphatical
Colours are Light it self Modify'd by Refractions chiefly, with a
concurrence sometimes of Reflections, and perhaps some other Accidents
depending on these two; if these Emphatical Colours be resolv'd to be
Genuine, it will seem consequent, that Colours, or at least divers of them,
are but Diversify'd Light, and not such Real and Inherent qualities as they
are commonly thought to be.
2. Now since we are wont to esteem the Echoes and other Sounds of Bodies,
to be True Sounds, all their Odours to be True Odours, and (to be short)
since we judge other Sensible Qualities to be True ones, because they are
the proper Objects of some or other of our Senses, I see not why Emphatical
Colours, being the proper and peculiar Objects of the Organ of Sight, and
capable to Affect it as Truly and as Powerfully as other Colours, should be
reputed but Imaginary ones.
And if we have (which perchance you'l allow) formerly evinc'd Colour, (when
the word is taken in its more Proper sense) to be but Modify'd Light, there
will be small Reason to deny these to be true Colours, which more
manifestly than others disclose themselves to be produc'd by
Diversifications of the Light.
3. There is indeed taken notice of a Difference betwixt these Apparent
colours, and those that are wont to be esteem'd Genuine, as to the
Duration, which has induc'd some Learned Men to call the former rather
Evanid than Fantastical. But as the Ingenious _Gassendus_ does somewhere
Judiciously observe, if this way of Arguing were Good, the Greeness of a
Leaf ought to pass for Apparent, because, soon Fading into a Yellow, it
Scarce lasts at all, in comparison of the Greeness of an Emerauld. I shall
add, that if the Sun-beams be in a convenient manner trajected through a
Glass-prism, and thrown upon some well-shaded Object within a Room, the
Rain-bow thereby Painted on the Surface of the Body that Terminates the
Beams, may oftentimes last longer than Some Colours I have produc'd in
certain Bodies, which would justly, and without scruple be accounted
Genuine Colours, and yet suddenly Degenerate, and lose their Nature.
4. A greater Disparity betwixt Emphatical Colours, and others, may perhaps
be taken from this, that Genuine Colours seem to be produc'd in Opacous
Bodies by Reflection, but Apparent ones in Diaphanous Bodies, and
principally by Refraction, I say Principally rather than Solely, because in
some cases Reflection also may concurr, but still this seems not to
conclude these Latter Colours not to be True ones. Nor must what has been
newly said of the Differences of True and Apparent Colours, be interpreted
in too Unlimited a Sense, and therefore it may perhaps somewhat Assist you,
both to Reflect upon the two fore-going Objections, and to judge of some
other Passages which you'l meet with in this Tract, if I take this Occasion
to observe to you, that if Water be Agitated into Froth, it exhibits you
know a White colour, which soon after it Loses upon the Resolution of the
Bubbles into Air and Water, now in this case either the Whiteness of the
Froth is a True Colour or not, if it be, then True Colours, supposing the
Water pure and free from Mixtures of any thing Tenacious, may be as
Short-liv'd as those of the Rain-bow; also the Matter, wherein the
Whiteness did Reside, may in a few moments perfectly Lose all foot-steps or
remains of it. And besides, even Diaphanous Bodies may be capable of
exhibiting True Colours by Reflection, for that Whiteness is so produc'd,
we shall anon make it probable. But if on the other side it be said, that
the Whiteness of Froth is an Emphatical Colour, then it must no longer be
said, that Fantastical Colours require a certain Position of the Luminary
and the Eye, and must be Vary'd or Destroy'd by the Change thereof, since
Froth appears White, whether the Sun be Rising or Setting, or in the
Meridian, or any where between it and the Horizon, and from what
(Neighbouring) place soever the Beholders Eye looks upon it. And since by
making a Liquor Tenacious enough, yet without Destroying its Transparency,
or Staining it with any Colour, you may give the Little Films, whereof the
Bubbles consist, such a Texture, as may make the Froth last very many
Hours, if not some Days, or even Weeks, it will render it somewhat Improper
to assign Duration for the Distinguishing Character to Discriminate Genuine
from Fantastical Colours. For such Froth may much outlast the Undoubtedly
true Colours of some of Nature's Productions, as in that Gaudy Plant not
undeservedly call'd the Mervail of _Peru_, the Flowers do often Fade, the
same Day they are Blown; And I have often seen a _Virginian_ Flower, which
usually Withers within the compass of a Day; and I am credibly Inform'd,
that not far from hence a curious Herborist has a Plant, whose Flowers
perish in about an Hour. But if the Whiteness of Water turn'd into Froth
must therefore be reputed Emphatical, because it appears not that the
Nature of the Body is Alter'd, but only that the Disposition of its Parts
in reference to the Incident Light is Chang'd, why may not the Whiteness be
accounted Emphatical too, which I shall shew anon to be Producible, barely
by such another change in Black Horn? and yet this so easily acquir'd
Whiteness seems to be as truly its Colour as the Blackness was before, and
at least is more Permanent than the Greenness of Leaves, the Redness of
Roses, and, in short, than the Genuine Colours of the most part of Nature's
Productions. It may indeed be further Objected, that according as the Sun
or other Luminous Body changes place, these Emphatical Colours alter or
vanish. But not to repeat what I have just now said, I shall add, that if a
piece of Cloath in a Drapers Shop (in such the Light being seldome Primary)
be variously Folded, it will appear of differing Colours, as the Parts
happen to be more Illuminated or more Shaded, and if you stretch it Flat,
it will commonly exhibit some one Uniform Colour, and yet these are not
wont to be reputed Emphatical, so that the Difference seems to be chiefly
this, that in the Case of the Rain-bow, and the like, the Position of the
Luminary Varies the Colour, and in the Cloath I have been mentioning, the
Position of the Object does it. Nor am I forward to allow that in all Cases
the Apparition of Emphatical Colours requires a Determinate position of the
Eye, for if Men will have the Whiteness of Froth Emphatical, you know what
we have already Inferr'd from thence. Besides, the Sun-beams trajected
through a Triangular Glass, after the manner lately mention'd, will, upon
the Body that Terminates them, Paint a Rain-bow, that may be seen whether
the Eye be plac'd on the Right Hand of it or the Left, or Above or Beneath
it, or Before or Behind it; and though there may appear some Little
Variation in the Colours of the Rain-bow, beheld from Differing parts of
the Room, yet such a Diversity may be also observ'd by an Attentive Eye in
Real Colours, look'd upon under the like Circumstances, Nor will it follow,
that because there remains no Footsteps of the Colour upon the Object, when
the Prism is Remov'd, that therefore the Colour was not Real, since the
Light was truly Modify'd by the Refraction and Reflection it Suffer'd in
its Trajection through the Prism; and the Object in our case serv'd for a
Specular Body, to Reflect that Colour to the Eye. And that you may not be
Startled, _Pyrophilus_, that I should Venture to say, that a Rough and
Coiour'd Object may serve for a _Speculum_ to Reflect the Artificial
Rain-bow I have been mentioning, consider what usually happens in Darkned
Rooms, where a Wall, or other Body conveniently Situated within, may so
Reflect the Colours of Bodies, without the Room, that they may very clearly
be Discern'd and Distinguish'd, and yet 'tis taken for granted, that the
Colours seen in a Darkned Room, though they leave no Traces of themselves
upon the Wall or Body that Receives them, are the True Colours of the
External Objects, together with which the Colours of the Images are Mov'd
or do Rest. And the Errour is not in the Eye, whose Office is only to
perceive the Appearances of things, and which does Truly so, but in the
Judging or Estimative faculty, which Mistakingly concludes that Colour to
belong to the Wall, which does indeed belong to the Object, because the
Wall is that from whence the Beams of Light that carry the Visible
_Species_, do come in Straight Lines directly to the Eye, as for the same
Reason we are wont at a certain Distance from Concave Sphærical Glasses, to
perswade our Selves that we see the Image come forth to Meet us, and Hang
in the Air betwixt the Glass and Us, because the Reflected Beams that
Compose the image cross in that place, where the Image seems to be, and
thence, and not from the Glass, do in Direct Lines take their Course to the
Eye, and upon the like Cause it is, that divers Deceptions in Sounds and
other Sensible Objects do depend, as we elsewhere declare.
5. I know not, whether I need add, that I have purposely Try'd, (as you'l
find some Pages hence, and will perhaps think somewhat strange) that
Colours that are call'd Emphatical, because not Inherent in, the Bodies in
which they Appear, may be Compounded with one another, as those that are
confessedly Genuine may. But when all this is said, _Pyrophilus_, I must
Advertise you, that it is but Problematically Spoken, and that though I
think the Opinion I have endeavour'd to fortifie Probable, yet a great part
of our Discourse concerning Colours may be True, whether that Opinion be so
or not.
* * * * *
CHAP. V.
1. There are you know, _Pyrophilus_, besides those Obsolete Opinions about
Colours which have been long since Rejected, very Various Theories that
have each of them, even at this day, Eminent Men for its Abetters; for the
Peripatetick Schools, though they dispute amongst themselves divers
particulars concerning Colours, yet in this they seem Unanimously enough to
Agree, that Colours are Inherent and Real Qualities, which the Light doth
but Disclose, and not concurr to Produce. Besides there are _Moderns_, who
with a slight Variation adopt the Opinion of _Plato_, and as he would have
Colour to be nothing but a Kind of Flame consisting of Minute Corpuscles as
it were Darted by the Object against the Eye, to whose Pores their
Littleness and Figure made them congruous, so these would have Colour to be
an Internal Light of the more Lucid parts of the Object, Darkned and
consequently Alter'd by the Various Mixtures of the less Luminous parts.
There are also others, who in imitation of some of the Ancient _Atomists_,
make Colour not to be Lucid steam, but yet a Corporeal _Effluvium_ issuing
out of the Colour'd Body, but the Knowingst of these have of late Reform'd
their Hypothesis, by acknowledging and adding that some External Light is
necessary to Excite, and as _they_ speak, Sollicit these Corpuscles of
Colour as _they_ call them, and Bring them to the Eye. Another and more
principal Opinion of the _Modern_ Philosophers, to which this last nam'd
may by a Favourable explication be reconcil'd, is that which derives
Colours from the Mixture of Light and Darkness, or rather Light and
Shadows. And as for the _Chymists_ 'tis known, that the generality of them
ascribes the Origine of Colours to the Sulphureous Principle in Bodies,
though I find, as I elsewhere largely shew, that some of the Chiefest of
them derive Colours rather from Salt than Sulphur, and others, from the
third Hypostatical Principle, _Mercury_. And as for the _Cartesians_ I need
not tell you, that they, supposing the Sensation of Light to bee produc'd
by the Impulse made upon the Organs of Sight, by certain extremely Minute
and Solid Globules, to which the Pores of the Air and other Diaphanous
bodies are pervious, endeavour to derive the Varieties of Colours from the
Various Proportion of the Direct Progress or Motion of these Globules to
their Circumvolution or Motion about their own Centre, by which Varying
Proportion they are by this Hypothesis suppos'd qualify'd to strike the
Optick Nerve after several Distinct manners, so to produce the perception
of Differing Colours.
2. Besides these six principal Hypotheses, _Pyrophilus_, there may be some
others, which though Less known, may perhaps as well as thesc deserve to be
taken into consideration by you; but that I should copiously debate any of
them at present, I presume you will not expect, if you consider the Scope
of these Papers, and the Brevity I have design'd in them, and therefore I
shall at this time only take notice to you in the general of two or three
things that do more peculiarly concern the Treatise you have now in your
hands.
3. And first, though the Embracers of the Several Hypotheses I have been
naming to you, by undertaking each Sect of them to explicate Colours
indefinitely, by the particular Hypotheses they maintain, seem to hold it
forth as the only Needful Theory about that Subject, yet for my part I
doubt whether any one of all these Hypotheses have a right to be admitted
Exclusively to all others, for I think it Probable, that Whiteness and
Blackness may be explicated by Reflection alone without Refraction, as
you'l find endeavour'd in the Discourse you'l meet with e're long Of the
Origine of Whiteness and Blackness, and on the other side, since I have not
found that by any Mixture of White and True Black, (for there is a Blewish
Black which many mistake for a Genuine) there can be a Blew, a Yellow, or a
Red, to name no other Colours, produced, and since we do find that these
Colours may be produc'd in the Glass-prism and other Transparent bodies, by
the help of Refractions, it seems that Refraction is to be taken in into
the Explication of some Colours, to whose Generation they seem to concurr,
either by making a further or other Commixture of Shades with the Refracted
Light, or by some other way not now to be discours'd. And as it seems not
improbable, that in case the Pores of the Air, and other Diaphanous bodies
be every where almost fill'd with such _Globuli_ as the _Cartesians_
suppose, the Various kind of Motion of these _Globuli_, may in many cases
have no small stroak in Varying our Perception of Colour, so without the
Supposition of these _Globuli_, which 'tis not so easie to evince, I think
we may probably enough conceive in general, that the Eye may be Variously
affected, not only by the Entire Beams of Light that fall upon it as they
are such, but by the Order, and by the Degree of Swiftness, and in a word
by the Manner according to which the Particles that compose each Particular
Beam arrive at the Sensory, so that whatever be the Figure of the Little
Corpuscles, of which the Beams of Light consist, not only the Celerity or
Slowness of their Revolution or Rotation in reference to their Progressive
Motion, but their more Absolute Celerity, their Direct or Undulating
Motion, and other Accidents, which may attend their Appulse to the Eye, may
fit them to make Differing Impressions on it.
4. Secondly, For these and the like Considerations, _Pyrophilus_, I must
desire that you would look upon this little Treatise, not as a Discourse
written Principally to maintain any of the fore-mention'd Theories,
Exclusively to all others, or substitute a New one of my Own, but as the
beginning of a History of Colours, upon which, when you and your Ingenious
friends shall have Enrich'd it, a Solid Theory may be safely built. But yet
because this History is not meant barely for a Register of the things
recorded in it, but for an _Apparatus_ to a sound and comprehensitive
Hypothesis, I thought fit, so to temper the whole Discourse, as to make it
as conducible, as conveniently I can to that End, and therefore I have not
scrupled to let you see that I was willing, as to save you the labour of
Cultivating some Theories that I thought would never enable you to reach
the Ends you aim at, so to contract your Enquiries into a Narrow compass,
for both which purposes I thought it requisite to do these two things, the
_One_, to set down some Experiments which by the help of the Reflections
and Insinuations that attend them, may assist you to discover the
Infirmness and Insufficiency both of the common Peripatetick Doctrine, and
of the now more applauded Theory of the _Chymists_ about Colour, because
those two Doctrines having Possess'd themselves, the one of the most part
of the Schools, and the other of the Esteem of the Generality ef Physicians
and other Learned Men, whose Professions and Ways of Study do not exact
that they should Scrupulously examine the very First and Simplest
Principles of Nature, I fear'd it would be to little purpose, without doing
something to discover the Insufficiency of these Hypotheses, that I should,
(which was the _Other_ thing I thought requisite for me to do) set down
among my other Experiments those in the greatest Number, that may let you
see, that, till I shall be Better Inform'd, I encline to take Colour to be
a Modification of Light, and would invite you chiefly to Cultivate that
Hypothesis, and Improve it to the making out of the Generation of
Particular Colours, as I have Endeavour'd to apply it to the Explication of
Whiteness and Blackness.
5. Thirdly. But, _Pyrophilus_, though this be at present the Hypothesis I
preferr, yet I propose it but in a General Sense, teaching only that the
Beams of Light, Modify'd by the Bodies whence they are sent (Reflected or
Refracted) to the Eye, produce there that Kind of Sensation, Men commonly
call Colour; But whether I think this Modification of the Light to be
perform'd by Mixing it with Shades, or by Varying the Proportion of the
Progress and Rotation of the _Cartesian Globuli Cælestes_, or by some other
way which I am not now to mention, I pretend not here to Declare. Much less
do I pretend to Determine, or scarce so much as to Hope to know all that
were requisite to be Known, to give You, or even my Self, a perfect account
of the Theory of Vision and Colours, for in Order to such an undertaking I
would first Know what Light is, and if it be a Body (as a Body or the
Motion of a Body it seems to be) what Kind of Corpuscles for Size and Shape
it consists of, with what Swiftness they move Forwards, and Whirl about
their own Centres. Then I would Know the Nature of Refraction, which I take
to be one of the Abstrusest things (not to explicate Plausibly, but to
explicate Satisfactorily) that I have met with in Physicks; I would further
Know what Kind and what Degree of Commixture of Darkness or Shades is made
by Refractions or Reflections, or both, in the Superficial particles of
those Bodies, that being Shin'd upon, constantly exhibit the one, for
Instance, a Blew, the other a Yellow, the third a Red Colour; I would
further Know why this Contemperation of Light and Shade, that is made, for
Example, by the Skin of a Ripe Cherry, should exhibit a Red, and not a
Green, and the Leaf of the same Tree should exhibit a Green rather than a
Red; and indeed, Lastly, why since the Light that is Modify'd into these
Colours consists but of Corpuscles moved against the _Retina_ or Pith of
the Optick Nerve, it should there not barely give a Stroak, but produce a
Colour, whereas a Needle wounding likewise the Eye, would not produce
Colour but Pain. These, and perhaps other things I should think requisite
to be Known, before I should judge my Self to have fully Comprehended the
True and Whole Nature of Colours; and therefore, though by making the
Experiments and Reflections deliver'd in this Paper, I have endeavour'd
somewhat to Lessen my Ignorance in this Matter, and think it far more
Desireable to discover a Little, than to discover Nothing, yet I pretend
but to make it Probable by the Experiments I mention, that some Colours may
be Plausibly enough Explicated in the General by the Doctrine here
propos'd; For whensoever I would Descend to the Minute and Accurate
Explication of Particulars, I find my Self very Sensible of the great
Obscurity of things, without excepting those which we never see but when
they are Enlightned, and confess with _Scaliger_[5], _Latet natura hæc_,
(says he, Speaking of that of Colour) _& sicut aliarum rerum species in
profundissima caligine inscitiæ humanæ._
[5] Exercitat. 325 Parag. 4
* * * * *
_THE_
_EXPERIMENTAL HISTORY_
_OF COLOURS._
* * * * *
PART. II.
_Of the Nature of Whiteness and_
_Blackness._
CHAP. I.
1. Though after what I have acknowledged, _Pyrophilus_, of the Abstruse
Nature of Colours in _particular_, you will easily believe, that I pretend
not to give you a Satisfactory account of Whiteness and Blackness; Yet not
wholly to frustrate your Expectation of my offering something by way of
Specimen towards the Explication of some Colours in particular, I shall
make choice of These as the most Simple Ones, (and by reason of their
mutual Opposition the Least hardly explicable) about which to present you
my Thoughts, upon condition you will take them at most to be my
Conjectures, not my Opinions.
2. When I apply'd my Self to consider, how the cause of Whiteness might be
explan'd by Intelligible and Mechanical Principles, I remembred not to have
met with any thing among the Antient _Corpuscularian_ Philosophers,
touching the Quality we call Whiteness, save that _Democritus_ is by
_Aristotle_ said to have ascrib'd the Whiteness of Bodies to their
Smoothness, and on the contrary their Blackness to their Asperity.[6] But
though about the Latter of those Qualities his Opinion be allowable, as we
shall see anon, yet that he heeds a Favourable Interpretation in what is
Deliver'd concerning the First, (at least if his Doctrine be not
Mis-represented in this point, as it has been in many others) we shall
quickly have Occasion to manifest. But amongst the _Moderns_, the most
Learned _Gassendus_ in his Ingenious Epistle publish'd in the Year 1642.
_De apparente Magnitudine solis humilis & sublimis_, reviving the
_Atomical_ Philosophy, has, though but Incidentally, deliver'd something
towards the Explication of Whiteness upon Mechanical Principles: And
because no Man that I know of, has done so before him, I shall, to be sure
to do him Right, give you his Sense in his own Words:[7] _Cogites velim_
(says he) _lucem quidem in Diaphano nullius coloris videri, sed in Opaco
tamen terminante Candicare, ac tantò magis, quantò densior seu collectior
fuerit. Deinde aquam non esse quidem coloris ex se candidi & radium tamen
ex eâ reflexum versus oculum candicare. Rursus cum plana aquæ Superficies
non nisi ex una parte eam reflexionem faciat: si contigerit tamen illam in
aliquot bullas intumescere, bullam unamquamque reflectionem facere, &
candoris speciem creare certa Superficiei parte. Ad hæc Spumam ex aqua pura
non alia ratione videri candescere & albescerere quam quod sit congeries
confertissima minutissimarum bullarum, quarum unaquæque suum radium
reflectit, unde continens candor alborve apparet. Denique Nivem nihil aliud
videri quam speciem purissimæ spumæ ex bullulis quam minutissimis &
confertissimis cohærentis. Sed ridiculam me exhibeam, si tales meas nugas
uberius proponem._
[6] _Album quippe & agrum, hoc quidem asperum esse dicit, hoc vero læve.
de Sensu & Sensib. 3. 3._
[7] Epist. 2. pag. 45.
3. But though in this passage, that very Ingenous Person has Anticipated
part of what I should say; Yet I presume you will for all that expect, that
I should give you a fuller Account of that Notion of Whiteness, which I
have the least Exceptions to, and of the Particulars whence I deduce it,
which to do, I must mention to you the following Experiments and
Observations.
Whiteness then consider'd as a Quality in the Object, seems chiefly to
depend upon this, That the Superficies of the Body that is call'd White, is
Asperated by almost innumerable Small Surfaces, which being of an almost
Specular Nature, are also so Plac'd, that some Looking this way, and some
that way, they yet Reflect the Rays of Light that fall on them, not towards
one another, but outwards towards the Spectators Eye. In this Rude and
General account of Whiteness, it seems that besides those Qualities, which
are common to Bodies of other Colours, as for instance the Minuteness and
Number of the Superficial parts, the two chief things attributed to Bodies
as White are made to be, First, that its Little Protuberances and
Superficial parts be of somewhat a Specular Nature, that they may as little
Looking-glasses each of them Reflect the Beams it receives, (or the little
Picture of the Sun made on it) without otherwise considerably Altering
them; whereas in most other Colours, they are wont to be much Chang'd, by
being also Refracted, or by being Return'd to the Eye, mixt with Shades or
otherwise. And next, that its Superficial parts be so Situated, that they
Retain not the Incident Rays of Light by Reflecting them Inwards, but Send
them almost all Back, so that the Outermost Corpuscles of a White Body,
having their Various Little Surfaces of a Specular Nature, a Man can from
no place Behold the Body, but that there will be among those Innumerable
_Superficieculæ_, that Look some one way, and some another, enough of them
Obverted to his Eye, to afford like a broken Looking-glass, a confused
Idæa, or Representation of Light, and make such an Impression on the Organ,
as that for which Men are wont to call a Body White. But this Notion will
perhaps be best Explan'd by the same Experiments and Observations, on which
it is Built, And therefore I shall now advance to _Them_.
4. And in the first place I consider, that the Sun and other Powerfully
Lucid Bodies, are not only wont to Offend, which we call to Dazle our Eyes,
but that if any Colour be to be Ascrib'd to them as they are Lucid, it
seems it should be Whiteness: For the Sun at Noon-day, and in Clear
weather, and when his Face is less Troubled, and as it were Stained by the
Steams of Sublunary Bodies, and when his Beams have much less of the
Atmosphere to Traject in their Passage to our Eyes, appears of a Colour
more approaching to White, than when nearer the Horizon, the Interposition
of certain Sorts of Fumes and Vapours make him oftentimes appear either
Red, or at least more Yellow. And when the Sun Shines upon that Natural
Looking-glass, a Smooth water, that part of it, which appears to this or
that particular Beholder, the most Shin'd on, does to his Eye seem far
Whiter than the rest. And here I shall add, that I have sometimes had the
Opportunity to observe a thing, that may make to my present purpose,
namely, that when the Sun was Veil'd over as it were, with a Thin White
Cloud, and yet was too Bright to be Look'd upon Directly without Dazling,
by casting my Eyes upon a Smooth water, as we sometimes do to observe
Eclipses without prejudice to our Eyes, the Sun then not far from the
Meridian, appear'd to me not Red, but so White, that 'twas not without some
Wonder, that I made the Observation. Besides, though we in _English_ are
wont to say, a thing is Red hot, as an Expression of its being
Superlatively _Ignitum_, (if I may so Speak for want of a proper _English_
word) yet in the Forges of Smiths, and the Furnaces of other Artificers, by
that which they call a White heat, they mean a further Degree of
_Ignition_, than by that which both they and we call a Red heat.
5. Secondly, I consider, that common Experience informs us, that as much
Light Over-powers the Eye, so when the Ground is covered with Snow, (a Body
extremely White) those that have Weak Eyes are wont to complain of too much
Light: And even those that have not, are generally Sensible of an
Extraordinary measure of Light in the Air; and if they are fain to Look
very long upon the Snow, find their Sight Offended by it. On which occasion
we may call to mind what _Xenophon_ relates, that his _Cyrus_ marching his
Army for divers days through Mountains covered with Snow, the Dazling
splendor of its Whiteness prejudic'd the Sight of very many of his
Souldiers, and Blinded some of them; and other Stories of that Nature be
met with in Writers of good Note. And the like has been affirm'd to me by
credible Persons of my own Acquaintance, and especially by one who though
Skill'd in Physick and not Ancient confess'd to me when I purposely ask'd
him, that not only during his stay in _Muscovy_, he found his Eyes much
Impair'd, by being reduc'd frequently to Travel in the Snow, but that the
Weakness of his Eyes did not Leave him when he left that Country, but has
follow'd him into these Parts, and yet continues to Trouble him. And to
this doth agree what I as well as others have observ'd, namely, that when I
Travell'd by Night, when the Ground was all cover'd with Snow, though the
Night otherwise would not have been Lightsome, yet I could very well see to
Choose my way. But much more Remarkable to my present purpose is that,
which I have met with in _Olaus Magnus_,[8] concerning the way of
Travelling in Winter in the _Northern_ Regions, where the Days of that
Season are so very Short; for after other things not needfull to be here
Transcribed: _Iter_, says he, _Diurnum duo scilicet montana milliaria (quæ
12 Italica sunt) consiciunt. Nocte verò sub splendissima luna, duplatum
iter consumunt aut triplatum. Neque id incommodè fit, cum nivium
reverberatione lunaris splendoris sublimes & declives campos illustret, ac
etiam montium præcipitia ac noxias feras à lorgè prospiciant evitandas_.
Which Testimony I the less Scruple to allege, because that it agrees very
well with what has been Affirm'd to me by a Physician of _Mosco_, whom the
Notion I have been Treating of concerning Whiteness invited me to ask
whether he could not See much farther when he Travell'd by Night in
_Russia_ than he could do in _England_, or elsewhere, when there was no
Snow upon the Ground; For this Ingenious Person inform'd me, that he could
See Things at a farr greater Distance, and with more Clearness, when he
Travell'd by Night on the _Russian_ Snow, though without the Assistance of
Moon-shine, than we in these Parts would easily be perswaded. Though it
seems not unlikely to me, that the Intenseness of the Cold may contribute
something to the considerableness of the Effect, by much Clearing the Air
of Darkish Steams, which in these more Temperate Climates are wont to
Thicken it in Snowy weather: For having purposely inquir'd of this Doctor,
and consulted that Ingenious Navigator Captain _James_'s Voyage hereafter
to be further mention'd, I find both their Relations agree in this, that in
Dark Frosty Nights they could Discover more Stars, and See the rest Clearer
than we in _England_ are wont to do.
[8] Gent. Septen. Histor. lib. 4 cap. 13.
6. I know indeed that divers Learned Men think, that Snow so strongly
Affects our Eye, not by a Borrow'd, but a Native Light; But I venture to
give it as a Proof, that White Bodies reflect more Light than Others,
because having once purposely plac'd a parcel of Snow in a Room carefully
Darkned, that no Celestial Light might come to fall upon it; neither I, nor
an ingenous Person, (Skill'd in Opticks) whom I desir'd for a Witness,
could find, that it had any other Light than what it receiv'd. And however,
'tis usual among those that Travel in Dark Nights, that the Guides wear
something of White to be Discern'd by, there being scarce any Night so
Dark, but that in the Free Air there remains some Light, though Broken and
Debilitated perhaps by a thousand Reflections from the Opacous Corpuscles
that Swim in the Air, and lend it to one another before it comes to arrive
at the Eye.
7. Thirdly, And the better to shew that White Bodies reflect store of
Light, in comparson of those that are otherwise Colour'd, I did in the
Darkn'd Room, formerly mention'd, hold not far from the Hole, at which the
Light was admitted, a Sheet only of White Paper, from whence casting the
Sun-beams upon a White Wall, whereunto it was Obverted, it manifestly
appear'd both to Me, and to the Person I took for a Witness of the
Experiment, that it Reflected a far greater Light, than any of the other
Colours formerly mention'd, the Light so thrown upon one Wall notably
Enlightning it, and by it a good part of the Room. And yet further to show
you, that White Bodies Reflect the Beams From them, and not Towards
themselves, Let me add, that Ordinary Burning-glasses, such as are wont to
be employ'd to light Tobacco, will not in a great while Burn, or so much as
Discolour a Sheet of White Paper. Insomuch that even when I was a Boy, and
Lov'd to make Tryals with Burning-glasses, I could not but wonder at this
Odd _Phænomenon_, which set me very Early upon Guessing at the Nature of
Whiteness, especially because I took notice, that the Image of the Sun upon
a White Paper was not so well Defin'd (the Light seeming too Diffus'd) as
upon Black, and because I try'd, that Blacking over the Paper with Ink, not
only the Ink would be quickly Dry'd up, but the Paper that I could not Burn
before, would be quickly set on Fire. I have also try'd, that by exposing
my Hand with a Thin Black Glove over it to the Warm Sun, it was thereby
very quickly and considerably more Heated, than if I took off the Glove,
and held my Hand Naked, or put on it another Glove of Thin but White
Leather. And having thus shewn you, _Pyrophilus_, that White Bodies reflect
the most Light of any, let us now proceed, to consider what is further to
be taken notice of in them, in order to our present Enquiry.
8. And Fourthly, whereas among the Dispositions we attributed to White
Bodies, we also intimated this, That such Bodies are apt, like _Speculums_,
though but Imperfect ones, to Reflect the Light that falls on them
Untroubled or Unstain'd, we shall besides other particulars to be met with
in these Papers, offer you this in favour of the Conjecture; That in the
Darkned Room several times mention'd in this Treatse, we try'd that the
Sun-beams being cast from a Coloured Body upon a neighbouring White Wall,
the Determinate Colour of the Body was from the Wall reflected to the Eye;
whereas we could in divers cases manifestly Alter the Colour arriving at
the Eye, by Substituting at a convenient Distance, a (conveniently)
Colour'd (and Glossy) Body instead of the White Wall. As by throwing the
Beams from a Yellow Body upon a Blew, there would be Exhibited a kind of
Green, as in the Experiments about Colours is more fully Declar'd.
9. I know not whether I should on this Occasion take notice, that when, as
when looking upon the Calm and Smooth Surface of a River betwixt my Eye and
the Sun, it appear'd to be a natural _Speculum_, wherein that Part which
Reflected to my Eye the Entire and defin'd Image of the Sun, and the Beams
less remote from those which exhibited That Image, appear'd indeed of a
great and Whitish Brightness, but the rest Comparatively Dark enough: if
afterwards the Superficies chanc'd to be a little, but not much troubled,
by a gentle Breath of Wind, and thereby reduc'd into a Multitude of Small
and Smooth _Speculums_, the Surface of the River would suitably to the
Doctrine lately deliver'd, at a Distance appear very much of Kin to White,
though it would lose that Brightness or Whiteness upon the Return of the
Surface to Calmness and an Uniform Level. And I have sometimes for Tryals
sake brought in by a Lenticular Glass, the Image of a River, Shin'd upon by
the Sun, into an Upper Room Darkn'd, and Distant about a Quarter of a Mile
from the River, by which means the Numerous Declining Surfaces of the Water
appear'd so Contracted, that upon the Body that receiv'd the Images, the
whole River appear'd a very White Object at two or three paces distance.
But if we drew Near it, this Whiteness appear'd to proceed from an
Innumerable company of Lucid Reflections, from the several Gently wav'd
Superficies of the Water, which look'd Near at hand like a Multitude of
very Little, but Shining Scales of Fish, of which many did every moment
Disappear, and as many were by the Sun, Wind and River generated anew. But
though this Observation seem'd Sufficiently to discover, how the Appearing
Whiteness in that case was Produc'd, yet in some other cases Water may have
the Same, though not so Vivid a Colour upon other Accounts; for oftentimes
it happens that the Smooth Surface of the Water does appear Bright or
Whitish, by reason of the Reflection not immediatly of the Images of the
Sun, but of the Brightness of the Sky; and in such cases a Convenient Wind
may where it passes along make the Surface look Black, by causing many such
Furrows and Cavities, as may make the Inflected Superficies of the Water
reflect the Brightness of the Sky rather Inward than Outward. And again if
the Wind increase into a Storm, the Water may appear White, especially near
the Shore and the Ship, namely because the Rude Agitation Breaks it into
Fome or Froth. So much do Whiteness and Blackness depend upon the
Disposition of the Superficial parts of a Body to Reflect the Beams of
Light Inward or Outward. But that as White Bodies reflect the most Light of
any, so there Superficial Particles are, in the Sense newly Deliver'd, of a
Specular Nature, I shall now further endeavour to shew both by the making
of Specular bodies White, and the making of a White body Specular.
10. In the Fifth place then, I will inform You, that (not to repeat what
_Gassendus_ observes concerning Water) I have for Curiosity sake Distill'd
Quicksilver in a Cucurbit, fitted with a Capacious Glass-head, and observ'd
that when the Operation was perform'd by the Degrees of Fire requisite for
my purpose, there would stick to the Inside of the Alembick a multitude of
Little round drops of _Mercury_. And as you know that _Mercury_ is a
Specular Body, so each of these Little drops was a small round
Looking-glass, and a Multitude of them lying Thick and Near one another,
they did both in my Judgment, and that of those I Invited to see it, make
the Glass they were fastened to, appear manifestly a White Body. And yet as
I said, this Whiteness depended upon the Minuteness and Nearness of the
Little Mercurial _Globuli_, the Convexity of whose Surfaces fitted them to
represent in a Narrow compass a Multitude of Little Lucid Images to
differingly situated Beholders. And here let me observe a thing that seems
much to countenance the Notion I have been recommending: namely, that
whereas divers parts of the Sky, and especially the Milky-way, do to the
naked Eye appear White, (as the name it self imports) yet the Galaxie
look'd upon through the Telescope, does not shew White, but appears to be
made up of a Vast multitude of Little Starrs; so that a Multitude of Lucid
Bodies, if they be so Small that they cannot Singly or apart be discern'd
by the Eye, and if they be sufficiently Thick set by one another, may by
their confus'd beams appear to the Eye One White Body. And why it is not
possible, that the like may be done, when a Multitude of Bright and Little
Corpuscles being crowded together, are made to send together Vivid beams to
the Eye, though they Shine but as the Planets by a Borrow'd Light?
11. But to return to our Experiments. We may take notice, That the White of
an Egg, though in part Transparent, yet by its power of Reflecting some
Incident Rays of Light, is in some measure a Natural _Speculum_, being long
agitated with a Whisk or Spoon, loses its Transparency, and becomes very
White, by being turn'd into Froth, that is into an Aggregate of Numerous
small Bubbles, whose Convex Superficies fits them to Reflect the Light
every way Outwards. And 'tis worth Noting, that when Water, for instance,
is Agitated into Froth, if the Bubbles be Great and Few, the Whiteness will
be but Faint, because the number of _Specula_ within a Narrow compass is
but Small, and they are not Thick set enough to Reflect so Many Little
Images or Beams of the Lucid Body, as are requisite to produce a Vigorous
sensation of Whiteness: And partly least it should be said, that the
Whiteness of such Globulous Particles proceeds from the Air Included in the
Froth; (which to make good, it should be prov'd that the Air it self is
White) and partly to illustrate the better the Notion we have propos'd of
Whiteness, I shall add, that I purposely made this Experiment, I took a
quantity Fair water, & put to it in a clear Glass phial, a convenient
quantity of Oyl or Spirit of Turpentine, because that Liquor will not
incorporate with Water, and yet is almost as Clear and Colourless as it;
these being Gently Shaken together, the Agitation breaks the Oyl (which as
I said, is Indispos'd to Mix like Wine or Milk _per minima_ with the Water)
into a Multitude of Little Globes, which each of them Reflecting Outwards a
Lucid Image, make the Imperfect Mixture of the two Liquors appear Whitish;
but if by Vehemently Shaking the Glass for a competent time you make a
further Comminution of the Oyl into far more Numerous and Smaller
_Globuli_, and thereby confound it also better with the Water, the Mixture
will appear of a Much greater Whiteness, and almost like Milk; whereas if
the Glass be a while let alone, the Colour will by degrees Impair, as the
Oyly globes grow Fewer and Bigger, and at length will quite Vanish, leaving
both the Liquors Distinct and Diaphanous as before. And such a Tryal hath
not ill succeeded, when insteed of the Colourless Oyl of Turpentine I took
a Yellow Mixture made of a good Proportion of Crude Turpentine dissolv'd in
that Liquor; and (if I mis-remember not) it also Succeeded better than one
would expect, when I employ'd an Oyl brought by Filings of Copper infused
in it, to a deep Green. And this (by the way) may be the Reason, why often
times when the Oyls of some Spices and of Anniseeds &c. are Distilled in a
Limbec with Water, the Water (as I have several times observ'd) comes over
Whitish, and will perhaps continue so for a good while, because if the Fire
be made too Strong, the subtile Chymical Oyl is thereby much Agitated and
Broken, and Blended with the Water in such Numerous and Minute Globules, as
cannot easily in a short time Emerge to the Top of the Water, and whilst
they Remain in it, make it, for the Reason newly intimated, look Whitish;
and perhaps upon the same Ground a cause may be rendred, why Hot water is
observ'd to be usually more Opacous and Whitish, than the same Water Cold,
the Agitation turning the more Spirituous or otherwise Conveniently
Dispos'd Particles of the Water into Vapours, thereby Producing in the Body
of the Liquor a Multitude of Small Bubbles, which interrupt the Free
passage, that the Beams of Light would else have Every way, and from the
Innermost parts of the Water Reflect many of them Outwards. These and the
like Examples, _Pyrophilus_, have induc'd me to Suspect, that the
Superficial Particles of White bodies, may for the Most part be as well
Convex as Smooth; I content my self to say _Suspect_ and _for the most
part_, because it seems not Easie to prove, that when Diaphanous bodies, as
we shall see by and by, are reduc'd into White Powders, each Corpuscle must
needs be of a Convex Superficies, since perhaps it may Suffice that
Specular Surfaces look severally ways. For (as we have seen) when a
Diaphanous Body comes to be reduc'd to very Minute parts, it thereby
requires a Multitude of Little Surfaces within a Narrow compass. And though
each of these should not be of a Figure Convenient to Reflect a Round Image
of the Sun, yet even from such an Inconveniently Figur'd body, there may be
Reflected some (either Streight or Crooked) Physical Line of Light, which
Line I call Physical, because it has some Breadth in it, and in which Line
in many cases some Refraction of the Light falling upon the Body it depends
on, may contribute to the Brightness, as if a Slender Wire, or Solid
Cylinder of Glass be expos'd to the Light, you shall see in some part of it
a vivid Line of Light, and if we were able to draw out and lay together a
Multitude of these Little Wires or Thrids of Glass, so Slender, that the
Eye could not discern a Distance betwixt the Luminous Lines, there is
little doubt (as far as I can guess by a Tryal purposely made with very
Slender, but far less Slender Thrids of Glass, whose Aggregate was Look'd
upon one way White) but the whole Physical Superficies compos'd of them,
would to the Eye appear White, and if so, it will not be always necessary
that the Figure of those Corpuscles, that make a Body appear White, should
be _Globulous_. And as for Snow it self, though the Learned _Gassendus_ (as
we have seen above) makes it to seem nothing else but a pure Frozen Froth,
consisting of exceedingly Minute and Thickset Bubbles; yet I see no
necessity of Admitting that, since not only by the Variously and Curiously
Figur'd Snow, that I have divers times had the Opportunity with Pleasure to
observe, but also by the Common Snow, it rather doth appear both to the
Naked Eye, and in a _Microscope_, often, if not most commonly, to consist
principally of Little Slender Icicles of several Shapes, which afford such
Numerous Lines of Light, as we have been newly Speaking of.
12. Sixthly, If you take a Diaphanous Body, as for instance a Piece of
Glass, and reduce it to Powder, the same Body, which when it was Entire,
freely Transmitted the Beams of Light, acquiring by Contusion a multitude
of Minute Surfaces, each of which is as it were a Little, but Imperfect
_Speculum_, is qualify'd to Reflect in a Confus'd manner, so many either
Beams, or Little and Singly Unobservable Images of the Lucid Body, that
from a Diaphanous it Degenerates into a White Body. And I remember, I have
for Trials sake taken Lumps of Rock Crystal, and Heating them Red hot in a
Crucible, I found according to my Expectation, that being Quench'd in Fair
water, even those that remain'd in seemingly entire Lumps exchang'd their
Translucency for Whiteness, the Ignition and Extinction having as it were
Crack'd each Lump into a multitude of Minute Bodies, and thereby given it a
great multitude of new Surfaces. And ev'n with Diaphanous Bodies, that are
Colour'd, there may be this way a Greater Degree of Whiteness produced,
than one would lightly think; as I remember, I have by Contusion obtain'd
Whitish Powders of _Granates_, Glass of _Antimony_, and _Emeralds_ finely
Beaten, and you may more easily make the Experiment, by taking Good
Venereal _Vitriol_ of a Deep Blew, and comparing with some of the Entire
Crystalls purposely reserv'd, some of the Subtile Powder of the same Salt,
which will Comparatively exhibit a very considerable degree of Whitishness.
13. Seventhly, And as by a Change of Position in the Parts, a Body that is
not White, may be made White, so by a Slight change of the Texture of its
Surface, a White Body may be Depriv'd of its Whiteness. For if, (as I have
try'd in Gold-smiths Shops) you take a piece of Silver that has been
freshly Boyl'd, as the Artificers call it, (which is done by, first
Brushing, and then Decocting it with Salt and Tartar, and perhaps some
other Ingredients) you shall find it to be of a Lovely White. But if you
take a piece of Smooth Steel, and therewith Burnish a part of it, which may
be presently done, you shall find that Part will Lose its Whiteness, and
turn a _Speculum_, looking almost every where Dark, as other
Looking-glasses do, which may not a little confirm our Doctrine. For by
this we may guess, what it is chiefly that made the Body White before, by
considering that all that was done to deprive it of that Whiteness, was
only to Depress the Little Protuberances that were before on the Surface of
the Silver into one Continu'd Superficies, and thereby effect this, that
now the Image of the Lucid Body, and consequently a Kind of Whiteness shall
appear to your Eye, but in some place of the greater Silver Looking-glass
(whence the Beams reflected at an Angle Equal to that wherewith they fall
on it, may reach your Eye) whilst the Asperity remain'd Undestroy'd, the
Light falling on innumerable Little _Specula_ Obverted some one way, and
some another, did from all Sensibly Distinguishable parts of the
Superficies reflect confus'd Beams or Representations of Light to the
Beholders Eye, from whence soever he chance to Look upon it. And among the
Experiments annex'd to this Discourse, you will find One, wherein by the
Change of Texture in Bodies, Whiteness is in a Trice both Generated and
Destroy'd.
* * * * *
CHAP. II.
1. What we have Discours'd of Whiteness, may somewhat Assist us to form a
Notion of Blackness, those two Qualities being Contrary enough to
Illustrate each other. Yet among the Antient _Philosophers_ I find less
Assistance to form a Notion of Blackness than of Whiteness, only
_Democritus_ in the passage above Recited out of _Aristotle_ has given a
General Hint of the Cause of this Colour, by referring the Blackness of
Bodies to their Asperity. But this I call but a General Hint, because those
Bodies that are Green, and Purple, and Blew, seem to be so as well as Black
ones, upon the Account of their Superficial Asperity. But among the
_Moderns_, the formerly mention'd _Gassendus_, perhaps invited by this Hint
of _Democritus_, has Incidentally in another Epistle given us, though a
very Short, yet a somewhat Clearer account of the Nature of Blackness in
these words: _Existimare par est corpora suâpte Naturâ nigra constare ex
particulis, quarum Superficieculæ scabræ sint, nec facilè lucem extrorsum
reflectant._ I wish this Ingenious Man had enlarg'd himself upon this
Subject; For indeed it seems, that as that which makes a Body White, is
chiefly such a Disposition of its Parts, that it Reflects (I mean without
much Interruption) more of the Light that falls on it, than Bodies of any
other Colour do, so that which makes a Body Black is principally a Peculiar
kind of Texture, chiefly of its Superficial Particle, whereby it does as it
were Dead the Light that falls on it, so that very little is Reflected
Outwards to the Eye.
2. And this Texture may be Explicated two, and perhaps more than two
several ways, whereof the first is by Supposing in the Superficies of the
Black Body a Particular kind of Asperity, whereby the Superficial Particles
reflect but Few of the Incident Beams Outwards, and the rest Inwards
towards the Body it self. As if for Instance, we should conceive the
Surface of a Black Body to be Asperated by an almost Numberless throng of
Little Cylinders, Pyramids, Cones, and other such Corpuscles, which by
their being Thick Set and _Erected_, reflect the Beams of Light from one to
another Inwards, and send them too and fro so often, that at length they
are Lost before they can come to Rebound out again to the Eye. And this is
the first of the two mention'd ways of Explicating Blackness. The other way
is by Supposing the Texture of Black Bodies to be such, that either by
their Yielding to the Beams of Light, or upon some other Account, they do
as it were Dead the Beams of Light, and keep them from being Reflected in
any Plenty, or with any Considerable Vigour of Motion, Outwards. According
to this Notion it may be said, that the Corpuscles that make up the Beams
of Light, whether they be Solary _Effluviums_, or Minute Particles of some
Ætherial Substance, Thrusting on one another from the Lucid Body, do,
falling on Black Bodies, meet with such a Texture, that such Bodies receive
Into themselves, and Retain almost all the Motion communicated to them by
the Corpuscles that make up the Beams of Light, and consequently Reflect
but Few of them, or those but Languidly, towards the Eye, it happening here
almost in like manner as to a ball, which thrown against a Stone or Floor,
would Rebound a great way Upwards, but Rebounds very Little or not at all,
when it is thrown against Water, or Mud, or a Loose Net, because the Parts
yield, and receive into themselves the Motion, on whose Account the Ball
should be Reflected Outwards. But this Last way of Explicating Blackness, I
shall content my Self to have Propos'd, without either Adopting it, or
absolutely Rejecting it. For the Hardness of Touchstones, Black Marble and
other Bodies, that being Black are Solid, seem to make it somewhat
Improbable, that such Bodies should be of so Yielding a Texture, unless we
should say, that some Bodies may be more Dispos'd to Yield to the Impulses
of the Corpuscles of Light by reason of a Peculiar Texture, than other
Bodies, that in other Tryals appear to be Softer than they. But though the
Former of these two Explications of Blackness be that, by which we shall
Endeavour to give an Account of it, yet as we said, we shall not Absolutely
Reject this Latter, partly because they both Agree in this, that Black
Bodies Reflect but Little of the Light that falls on them, and partly
because it is not Impossible, that in some Cases both the Disposition of
the Superficial particles, as to Figure and Position, and the Yielding of
the Body, or some of its Parts, may joyntly, though not in an Equal measure
concurr to the rendring of a Body Black. The Considerations that induc'd me
to propose this Notion of Blackness, as I Explan'd it, are principally
these:
3. First, That as I lately said, Whiteness and Blackness being generally
reputed to be Contrary Qualities, Whiteness depending as I said upon the
Disposition of the Parts of a Body to Reflect much Light, it seems likely,
that Blackness may depend upon a Contrary Disposition of the Black Bodies
Surface; But upon this I shall not Insist.
4. Next then we see, that if a Body of One and the same Colour be plac'd,
part in the Sun-beams, and part in the Shade, that part which is not Shin'd
on will appear more of Kin to Blackness than the other, from which more
Light Rebounds to the Eye; And Dark Colours seem the Blacker, the less
Light they are Look'd upon in, and we think all Things Black in the Dark,
when they send no Beams to make Impressions on our Organs of Sight, so that
Shadows and Darkness are near of Kin, and Shaddow we know is but a
Privation of Light; and accordingly Blackness seems to proceed from the
Paucity of Beams Reflected from the Black Body to the Eye, I say the
Paucity of Beams, because those Bodies that we call Black, as Marble, Jeat,
&c. are Short of being perfectly so, else we should not See them at all.
But though the Beams that fall on the Sides of those Erected Particles that
we have been mentioning, do Few of them return Outwards, yet those that
fall upon the Points of those Cylinders, Cones, or Pyramids, may thence
Rebound to the Eye, though they make there but a Faint Impression, because
they Arrive not there, but Mingl'd with a great Proportion of Little
Shades. This may be Confirm'd by my having procur'd a Large piece of Black
Marble well Polish'd, and brought to the Form of a Large Sphærical and
Concave _Speculum_; For on the Inside this Marble being well Polish'd, was
a kind of Dark Looking-glass, wherein I could plainly see a Little Image of
the Sun, when that Shin'd upon it. But this Image was very far from
Offending and Dazling my Eyes, as it would have done from another
_Speculum_; Nor, though the _Speculum_ were Large, could I in a Long time,
or in a Hot Sun set a piece of Wood on Fire, though a far less _Speculum_
of the same Form, and of a more Reflecting Matter, would have made it Flame
in a Trice.
5. And on this Occasion we may as well in Reference to something formerly
deliver'd concerning Whiteness, as in Reference to what has been newly
said, Subjoyn what we further observ'd touching the Differing Reflections
of Light from White and Black Marble, namely, that having taking a pretty
Large Mortar of White Marble, New and Polish'd in the Inside, and Expos'd
it to the Sun, we found that it Reflected a great deal of Glaring Light,
but so Dispers'd, that we could not make the Reflected Beams concurr in any
such Conspicuous _Focus_, as that newly taken notice of in the Black
Marble, though perhaps there may enough of them be made to meet near the
Bottom, to make some Kind of _Focus_, especially since by holding in the
Night-time a Candle at a convenient Distance, we were able to procure a
Concourse of some, though not many of the Reflected Beams, at about two
Inches distant from the Bottom of the Mortar: But we found the Heat even of
the Sunbeams so Dispersedly Reflected to be very Languid, even in
Comparison of the Black Marbles _Focus_. And the Little Picture of the Sun,
that appear'd upon the White Marble as a _Speculum_, was but very Faint and
exceeding ill Defin'd. Secondly, That taking two pieces of Plain and
Polish'd Surfaces, and casting on them Successively the Beams of the Same
Candle, In such manner, as that the Neighbouring Superficies being Shaded
by an Opacous and Perforated Body, the Incident Beams were permitted to
pass but through a Round Hole of about Half an Inch Diameter, the Circle of
Light that appear'd on the White Marble was in Comparison very Bright, but
very ill Defin'd; whereas that on the Black Marble was far less Luminous,
but much more precisely Defin'd.
6. Thirdly, When you Look upon a piece of Linnen that has Small Holes in
it, those Holes appear very Black, and Men are often deceiv'd in taking
Holes for Spots of Ink; And Painters to represent Holes, make use of Black,
the Reason of which seems to be, that the Beams that fall on those Holes,
fall into them So Deep, that none of them is Reflected back to the Eye. And
in narrow Wells part of the Mouth seems Black, because the Incident Beams
are Reflected Downwards from one side to another, till they can no more
Rebound to the Eye.
We may consider too, that if Differing parts of the same piece of Black
Velvet be stroak'd Opposite ways, the piece of Velvet will appear of two
Distinct kinds of Blackness, the one far Darker than the other, of which
Disparity the Reason Seems to be, that in the Less obscure part of the
Velvet, the Little Silken Piles whereof 'tis made up, being Inclin'd, there
is a Greater part of each of them Obverted to the Eye, whereas in the other
part the Piles of Silk being more Erected, there are far Fewer Beams
Reflected Outwards from the Lateral parts of each Pile, So that most of
those that Rebound to the Eye, come from the Tops of the Piles, which make
but a small part of the whole Superficies, that may be cover'd by the piece
of Velvet. Which Explication I propose, not that I think the Blackness of
the Velvet proceeds from the Cause assign'd, since each Single Pile of Silk
is Black by reason of its Texture, in what Position soever you Look upon
it; But that the Greater Blackness of one of these Tuffts seems to proceed
from the Greater Paucity of Beams Reflected from it, and that from the
Fewness of those Parts of a Surface that Reflect Beams, and the Multitude
of those Shaded Parts that Reflect none. And I remember, that I have
oftentimes observ'd, that the Position of Particular Bodies far greater
than Piles of Silk in reference to the Eye, may notwithstanding their
having each of them a Colour of its own, make one part of their Aggregate
appear far Darker than the other; For I have near Great Towns often taken
notice, that a Cart-load of Carrots pack'd up, appear'd of a much Darker
Colour when Look'd upon, where the Points of the Carrots were Obverted to
the Eye, than where the Sides of them were so.
7. Fourthly, In a Darkned Room, I purposely observ'd, that if the
Sun-beams, which came in at the Hole were receiv'd upon White or any other
Colour, and directed to a Convenient place of the Room, they would
Manifestly, though not all Equally, Encrease the Light of that Part;
whereas if we Substituted, either a piece of Black Cloth or Black Velvet,
it would so Dead the Incident Beams, that the place (newly mention'd)
whereto I Obverted the Black Body, would be Less Enlightned than it was
before, when it received its Light but from the Weak and Oblique
Reflections of the Floor and Walls of a pretty Large Room, through which
the Beams that came in at the Hole were Confusedly and Brokenly Dispers'd.
8. Fifthly, And to shew that the Beams that fall on Black Bodies, as they
do not Rebound Outwards to the Eye, so they are Reflected towards the Body
it self, as the Nature of those Erected Particles to which we have imputed
Blackness, requires, we will add an Experiment that will also confirm our
Doctrine touching Whiteness; Namely, that we took a Broad and Large Tile,
and having Whitened over one half of the Superficies of it, and Black'd the
other, we expos'd it to the Summer Sun; And having let it lye there a
convenient time (for the Difference is more Apparent, if it have not lain
there too long) we found, as we expected, that whilst the Whited part of
the Tile remained Cool enough, the Black'd part of the same Tile was grown
not only Sensible, but very Hot, (sometimes to a strong Degree.) And to
satisfie some of our Friends the more, we have sometimes left upon the
Surface of the Tile, besides the White and Black parts thereof, a part that
Retain'd the native Red of the Tile it self, and Exposing them to the Sun,
we observ'd this Last mention'd to have Contracted a Heat in comparison of
the White, but a Heat Inferiour to that of the Black, of which the Reason
seems to be, that the Superficial Particles of Black Bodies, being, as we
said, more Erected, than those of White or Red ones, the Corpuscles of
Light falling on their sides, being for the most part Reflected Inwards
from one Particle to another, and thereby engag'd as it were and kept from
Rebounding Upwards, they communicate their brisk Motion, wherewith they
were impell'd against the Black Body, (upon whose account had they fallen
upon a White Body, they would have been Reflected Outwards) to the Small
parts of the Black Body, and thereby Produce in those Small parts such an
Agitation, as (when we feel it) we are wont to call Heat. I have been
lately inform'd, that an Observation near of Kin to Ours, has been made by
some Learned Men in _France_ and _Italy_, by long Exposing to a very Hot
Sun, two pieces of Marble, the one White, the other Black; But though the
Observation be worthy of them, and may confirm the same Truth with Our
Experiment, yet besides that our Tryal needs not the Summer, nor any Great
Heat to succeed, It seems to have this Advantage above the other, that
whereas Bodies more Solid, and of a Closer Texture, though they use to be
more Slowly Heated, are wont to receive a Greater Degree of Heat from the
Sun or Fire, than (_Cæteris paribus_) Bodies of a Slightest Texture; I have
found by the Information of Stone-cutters, and by other ways of Enquiry,
that Black Marble is much Solider and Harder than White, so that possibly
the Difference betwixt the Degrees of Heat they receive from the Sunbeams
will by many be ascrib'd to the Difference of their Texture, rather than to
that of their Colour, though I think our Experiment will make it Probable
enough that the greater part of that Difference may well be ascrib'd to
that Disposition of Parts, which makes the one Reflect the Sunbeams Inward;
and the other Outwards. And with this Doctrine accords very well, that
Rooms hung with Black, are not only Darker than else they would be, but are
wont to be Warmer too; Insomuch that I have known a great Lady, whose
Constitution was somewhat Tender, complain that she was wont to catch Cold,
when she went out into the Air, after having made any long Visits to
Persons, whose Rooms were hung with Black. And this is not the only Lady I
have heard complain of the Warmth of such Rooms, which though perhaps it
may be partly imputed to the _Effluvia_ of those Materials wherewith the
hangings were Dy'd, yet probably the Warmth of such Rooms depends chiefly
upon the same Cause that the Darkness does; As (not to repeat what I
formerly Noted touching my Gloves,) to satisfie some Curious Persons of
that Sex, I have convinc'd them, by Tryall, that of two Pieces of Silken
Stuff given me by themselves, and expos'd in their Presence, to the same
Window, Shin'd on by that Sun, the White was _considerably_ Heated, when
the Black was not so much as _Sensibly_ so.
9. Sixthly, I remember, that Acquainting one Day a _Virtuoso_ of
Unsuspected Credit, that had Visited Hot Countries, with part of what I
have here Deliver'd concerning Blackness, he Related to me by way of
Confirmation of it, a very notable Experiment, which he had both others
make, and Made himself in a Warm Climate, namely, that having carefully
Black'd over Eggs, and Expos'd them to the Hot Sun, they were thereby in no
very Long time well Roasted, to which Effect I conceive the Heat of the
Climate must have Concurr'd with the Disposition of the Black Surface to
Reflect the Sunbeams Inward, for I remember, that having made that among
other Tryals in _England_, though in Summer-time, the Eggs I Expos'd,
acquir'd indeed a considerable Degree of Heat, but yet not so Intense a
One, as prov'd Sufficient to Roast them.
10. Seventhly, and Lastly, Our Conjectures at the Nature of Blackness may
be somewhat Confirm'd by the (formerly mention'd) Observation of the Blind
_Dutch-man_, that Discerns Colours with his Fingers; for he Says, that he
Feels a greater Roughness upon the Surfaces of Black Bodies, than upon
those of Red, or Yellow, or Green. And I remember, that the Diligent
_Bartholinus_ says,[9] that a Blind Earl of _Mansfield_ could Distinguish
White from Black only by the Touch, which would Sufficiently Argue a great
Disparity in the Asperities, or other Superficial Textures of Bodies of
those two Colours, if the Learn'd Relator had Affirm'd the Matter upon his
own Knowledge.
[9] Hist. Anatom. Cent. 3. Hist. 44.
II. These, _Pyrophilus_, are the chief things that Occurr to me at present,
about the Nature of Whiteness and Blackness, which it they have Rendred it
so much as Probable, that in _Most_; or at least _Many_ Cases, the Causes
of these Qualities may be such as I have Adventur'd to Deliver, it is as
much as I Pretend to; for till I have Opportunity to Examine the Matter by
some further Tryals, I am not sure, but that in some White and Black
Bodies, there may Concurr to the Colour some peculiar Texture or
Disposition of the Body, whereby the Motion of the Small Corpuscles that
make up the Incident Beams of Light, may be Differingly Modify'd, before
they reach the Eye, especially in this, that White Bodies do not only
Copiously Reflect those Incident Corpuscles Outwards, but Reflect them
Briskly, and do not otherwise Alter them in the manner of their Motion. Nor
shall I now stay to Enquire, whether some of those other ways, (as a
Disposition to Alter the Velocity, the Rotation, or the Order and Manner of
Appulse so the Eye of the Reflected Corpuscles that Compos'd the Incident
Beams of Light) which we mention'd when we consider'd the Production of
Colours in General, may not in some Cases be Applicable to those of White
and Black Bodies: For I am yet so much a _Seeker_ in this Matter, and so
little Wedded to the Opinions I have propos'd, that what I am to add shall
be but the Beginning of a Collection of Experiments and Observation towards
the History of Whiteness and Blackness, without at present interposing my
Explications of them, that so, I may assist your Enquires without much
Fore-stalling or Biassing your Judgment.
* * * * *
EXPERIMENT
IN
CONSORT,
Touching
Whiteness & Blackness.
* * * * *
EXPERIMENT I.
Having promis'd in the 114, and 115. Pages of the foregoing Discourse of
Whiteness and Blackness, to shew, that those two Colours may by a change of
Texture in bodies, each of them apart Diaphanous and Colourless, be at
pleasure and in a trice as well Generated as Destroy'd, We shall begin with
Experiments that may acquit us of that promise.
Take then what Quantity you please of Fair Water, and having Heated it, put
into it as much good Common Sublimate, as it is able to Dissolve, and (to
be sure of having it well glutted:) continue putting in the Sublimate, till
some of it lye Untouch'd in the bottom of the Liquor, Filter this Solution
through Cap-paper, to have it cleer and limpid, and into a spoonfull or two
thereof, (put into a clean glass vessel,) shake about four or five drops
(according as you took more or less of this Solution) of good limpid
Spirits of Urine, and immediately the whole mixture will appear White like
Milk, to which mixture if you presently add a convenient proportion of
Rectifi'd _Aqua Fortis_ (for the number of drops is hard to determine,
because of the Differing Strength of the liquor, but easily found by tryal)
the Whiteness will presently disappear, and the whole mixture become
Transparent, which you may, if you please, again reduce to a good degree of
Whiteness (though inferiour to the first) onely by a more copious affusion
of fresh Spirit of Urine. _N_. First, That it is not so necessary to employ
either _Aqua Fortis_ or Spirit of Urine about this Experiment, but that we
have made it with other liquors instead of these, of which perhaps more
elsewhere. Secondly, That this Experiment, though not made with the same
_Menstruums_, nor producing the same Colour is yet much of Kin to that
other to be mentioned in this Tract among our other Experiments of Colours,
about turning a Solution of Præcipitate into an Orange-colour, and the
Chymical Reason being much alike in both, the annexing it to one of them
may suffice FOR both.
_EXPERIMENT II._
Make a strong Infusion of broken Galls in Fair Water, and having Filtred it
into a clean Vial, add more of the same liquor to it, till you have made it
somewhat Transparent, and sufficiently diluted the Colour, for the credit
of the Experiment, lest otherwise the Darkness of the liquor might make it
be objected, that 'twas already almost Ink; Into this Infusion shake a
convenient quantity of a Cleer, but very strong Solution of Vitriol, and
you shall immediately see the mixture turn Black almost like Ink, and such
a way of producing Blackness is vulgar enough; but if presently after you
doe upon this mixture drop a small quantity of good oyl of Vitriol, and, by
shaking the Vial disperse it nimbly through the two other liquors, you
shall (if you perform your part well, and have employ'd oyl of Vitriol
Cleer and Strong enough) see the Darkness of the liquor presently begin to
be discuss'd, and grow pretty Cleer and Transparent, losing its Inky
Blackness, which you may again restore to it by the affusion of a small
quantity of a very strong Solution of Salt of Tartar. And though neither of
these Atramentous liquors will seem other than very Pale Ink, if you write
with a clean Pen dipt in them, yet that is common to them with some sorts
of Ink that prove very good when Dry, as I have also found, that when I
made these carefully, what I wrote with either of them, especially with the
Former, would when throughly Dry grow Black enough not to appear bad Ink.
This Experiment of taking away and restoring Blackness from and to the
liquors, we have likewise tryed in Common Ink; but there it succeeds not so
well, and but very slowly, by reason that the Gum wont to be employed in
the making it, does by its Tenacity oppose the operations of the above
mention'd Saline liquors. But to consider Gum no more, what some kind of
Præcipitation may have to do in the producing and destroying of Inks
without it, I have elsewhere given you some occasion and assistance to
enquire; But I must not now stay to do so my self, only I shall take notice
to you, that though it be taken for granted that bodies will not be
Præcipitated by Alcalizat Salts, that have not first been dissolved in some
Acid _Menstruums_, yet I have found upon tryals, which my conjectures lead
me to make on purpose, That divers Vegetables _barely infus'd_, or, _but
slightly decocted in common water_, would, upon the affusion of a Strong
and Cleer _Lixivium_ of Potashes, and much more of some other Præcipitating
liquors that I sometimes employ, afford good store of a Crudled matter,
such as I have had in the Præcipitations of Vegetable substances, by the
intervention of Acid things, and that this matter was easily separable from
the rest of the liquor, being left behind by it in the Filtre; and in
making the first Ink mention'd in this Experiment, I found that I could by
Filtration separate pretty store of a very Black pulverable substance, that
remain'd in the Filtre, and when the Ink was made Cleer again by the Oyl of
Vitriol, the affusion of dissolv'd _Sal Tartari_ seem'd but to Præcipitate,
and thereby to Unite and render Conspicuous the particles of the Black
mixture that had before been dispers'd into very Minute and singly
Invisible particles by the Incisive and resolving power of the highly
Corrosive Oyl of Vitriol.
And to manifest, _Pyrophilus_, that Galls are not so requisite as many
suppose to the making Atramentous Liquors, we have sometimes made the
following Experiment, We took dryed Rose leaves and Decocted them for a
while in Fair Water, into two or three spoonfulls of this Decoction we
shook a few drops of a strong and well filtrated Solution of Vitriol (which
perhaps had it been Green would have done as well) and immediately the
mixture did turn Black, and when into this mixture presently after it was
made, we shook a just Proportion of _Aqua Fortis_, we turn'd it from a
Black Ink to a deep Red one, which by the affusion of a little Spirit of
Urine may be reduc'd immediately to an Opacous and Blackish Colour. And in
regard, _Pyrophilus_, that in the former Experiments, both the Infusion of
Galls, and the Decoction of Roses, and the Solution of Copperis employ'd
about them, are endow'd each of them with its own Colour, there may be a
more noble Experiment of the sudden production of Blackness made by the
way mention'd in the Second Section of the Second Part of our Essays, for
though upon the Confusion of the two Liquors there mention'd, there do
immediately emerge a very Black mixture, yet both the Infusion of
_Orpiment_ and the Solution of _Minium_ were before their being joyn'd
together, Limpid and Colourless.
_EXPERIMENT III._
If pieces of White Harts-horn be with a competent degree of Fire distill'd
in a Glass-retort, they will, after the avolation of the Flegm, Spirit,
Volatile Salt, and the looser and lighter parts of the Oleagenous
substance, remain behind of a Cole-black colour. And even Ivory it self
being skilfully Burnt (how I am wont to do it, I have elsewhere set down)
affords Painters one of the best and deepest Blacks they have, and yet in
the Instance of distill'd Harts-horn, the operation being made in
Glass-vessels carefully clos'd, it appears there is no Extraneous Black
substance that Insinuates it self into White Harts-horn, and thereby makes
it turn Black; but that the Whiteness is destroy'd, and the Blackness
generated, only by a Change of Texture, made in the burnt Body, by the
Recess of some parts and the Transposition of others. And though I remember
not that in many Distillations of Harts-horn I ever sound the _Cap. Mort_.
to pass from Black to a true Whiteness, whilst it continu'd in Clos'd
vessels, yet having taken out the Cole-black fragments, and Calcin'd them
in Open vessels, I could in few hours quite destroy that Blackness, &
without sensibly changing their Bulk or Figure, reduce them to great
Whiteness. So much do these two Colours depend upon the Disposition of the
little parts, that the Bodies wherein they are to be met with do consist
of. And we find, that if Whitewine Tartar, or even the white Crystalls of
such Tartar be burnt without being truly Calcin'd, the _Cap. Mortuum_ (as
the Chymists call the more Fixt part) will be Black. But if you further
continue the Calcination till you have perfectly Incinerated the Tartar, &
kept it long enough in a Strong fire, the remaining _Calx_ will be White.
And so we see that not only other Vegetable substances, but even White
woods, as the Hazel, will yield a Black Charcoal, and afterwards Whitish
ashes; And so Animal substances naturally White, as Bones and Eggshels,
will grow Black upon the being Burnt, and White again when they are
perfectly Calcin'd.
_EXPERIMENT IV._
But yet I much Question whether that Rule delivered by divers, as well
Philosophers as Chymists, _adusta nigra, sed perusta alba_, will hold as
Universally as is presum'd, since I have several Examples to allege against
it: For I have found that by burning Alablaster, so as both to make it
appear to boyl almost like Milk, and to reduce it to a very fine Powder, it
would not at all grow Black, but retain its Pure and Native Whiteness, and
though by keeping it longer than is usual in the fire, I produced but a
faint Yellow, even in that part of the Powder that lay nearest the top of
the Crucible, yet having purposely enquired of an Experienced Stone-cutter,
who is Curious enough in tryng Conclusions in his own Trade, he told me he
had found that if Alabaster or Plaster of Paris be very long kept in a
Strong fire, the whole heap of burnt Powder would exchange its Whiteness
for a much deeper Colour than the Yellow I observ'd. Lead being Calcin'd
with a Strong fire turns (after having purhaps run thorough divers other
Colour) into _Minium_, whose Colour we know is a deep red; and if you urge
this _Minium_, as I have purposely done with a Strong fire, you may much
easier find a Glassie and Brittle Body darker than _Minium_, than any white
_Calx_ or Glass. 'Tis known among Chymists, that the white _Calx_ of
Antimony, by the further and more vehement operation of the fire, may be
melted into Glass, which we have obtain'd of a Red Colour, which is far
deeper than that of the _Calx_ of Burnt Antimony, and though common Glafs
of Antimony being usually Adulterated with _Borax_, have its Colour thereby
diluted, oftentimes to a very pale Yellow; yet not onely ours made more
sincerily, was, as we said, of a Colour less remote from Black, than was
the _Calx_; but we observ'd, that by Melting it once or twice more, and so
exposing it to the further operation of the Fire, we had, as we expected,
the Colour heightned. To which we shall add but this one Instance, (which
is worth the taking notice of in Reference to Colours:) That, if you take
Blew, but Unsophisticated, Vitriol, and burn it very slowly, and with a
Gentle degree of Heat, you may observe, that when it has Burnt but a
Little, and yet so far as that you may rub it to Powder betwixt your
fingers, it will be of a White or Whitish Colour; But if you Prosecute the
Calcination, this Body which by a light Adustion was made White, will pass
through other Colours, as Gray, Yellowish, and Red; and if you further burn
it with a Long and Vehement fire, by that time it comes to be _Perustum_,
it will be of a dark purple, nearer to Black, not only than the first
_Calx_, but than the Vitriol before it at all felt the fire. I might add
that _Crocus_ _Martis_ (_per se_ as they call it) made by the Lasting
violence of the Reverberated flames is not so near a Kin to White, as the
Iron or Steel that afforded it was before its Calcinations; but that I
suppose, these Instances may Suffice to satisfie you, that Minerals are to
be excepted out of the forementioned Rule, which perhaps, though it seldome
fail in substances belonging to the Vegetable or Animal Kingdome, may yet
be Question'd even in some of these, if that be true, which the Judicious
Traveller _Bellonius_ affirms, that Charcoales made out of the Wood of
_Oxycæder_ are White; And I could not find that though in Retorts Hartshorn
and other White Bodies will be Denigrated by Heat, yet Camphire would not
at all lose its Whiteness, though I have purposely kept it in such a heat,
as made it melt and boyl.
_EXPERIMENT V._
And now I speak of Camphire, it puts me in mind of adding this Experiment,
That, though as I said in Clos'd Glasses, I could not Denigrate it by Heat,
but it would Sublime to the sides and top of the Glass, as it was before,
yet not only it will, being set on fire in the Free Air, send forth a
Copious smoak, but having purposely upon some of it that was Flaming, clapt
a Large Glass, almost in the form of a Hive, (but more Slender only) with a
Hole at the top, (which I caus'd to be made to trye Experiments of Fire and
Flame in) it continued so long burning that it Lin'd all the Inside of the
Glass with a Soot as Black as Ink, and so Copious, that the Closeness of
the Vessel consider'd, almost all that part of the White Camphire that did
take Fire, seem'd to have been chang'd into that deep Black Substance.
_EXPERIMENT VI_
And this also brings into my mind another Experiment that I made about the
production of Blackness, whereof, for Reasons too long to be here deduced,
I expected and found a good Success, an it was this: I took Rectifi'd Oyl
of Vitriol (that I might have the Liquor Clean as well as Strong) and by
degrees mixt with it a convenient proportion of the Essential Oyl, as
Chymists call it, of Wormwood, drawn over with store of Water in a Limbec,
and warily Distilling the mixture in a Retort, there remain'd a scarce
credible quantity of dry Matter, Black as a Coal. And because the Oyl of
Wormwood, though a Chymical Oyl drawn by a _Virtuoso_, seem'd to have
somewhat in it of the Colour of the Plant, I Substituted in its Room, the
Pure and Subtile Essential Oyl of Winter-Savory, and mixing little by
little this Liquor, with (if I mis-remember not) an Equal weight of the
formerly mention'd Rectifi'd Oyl of Vitriol, and Distilling them as before
in a Retort, besides what there pass'd over into the Receiver, even these
two clear Liquors left me a Considerable Proportion, (though not so great
as the two former) of a Substance Black as Pitch, which I yet Keep by me
as a Rarity.
_EXPERIMENT VII._
A way of Whiting Wax Cheaply and in Great Quantity may be a thing of good
Oeconomical Use, and we have elsewhere set down the Practice of Trades-men
that Blanch it; But here Treating of Whiteness only in Order to the
Philosophy of Colours, I shall not Examine which of the Slow wayes may be
best Employ'd, to free Wax from the Yellow Melleous parts, but shall rather
set down a Quick way of making it White, though but in very Small
Quantities. Take then a little Yellow Wax, scraped or thinly sliced, and
putting it into a Bolts-head or some other Convenient Glass, pour to it a
pretty deal of Spirit of Wine, and placing the Vessel in Warm Sand,
Encrease the Heat by degrees, till the Spirit of Wine begin to Simper or to
Boyl a little; and continuing that degree of Fire, if you have put Liquor
enough, you will quickly have the Wax dissolv'd, then taking it off the
fire, you may either suffer it to Cool as hastily as with Safety to the
Glass you can, or Pour it whilst 'tis yet Hot into a Filtre of Paper, and
either in the Glass where it Cools, or in the Filtre, you will soon find
the Wax and _Menstruum_ together reduc'd into a White Substance, almost
like Butter, which by letting the Spirit Exhale will shrink into a much
Lesser Bulk, but still retaining its Whiteness. And that which is pretty in
the working of this Magistery of Wax, is, that the Yellowness vanishes,
neither appearing in the Spirit of Wine that passes Limpid through the
Filtre, nor in the Butter of Wax, if I may so call it, that, as I said, is
White.
_EXPERIMENT VIII._
There is an Experiment, _Pyrophilus_, which though I do not so exactly
remember, and though it be somewhat Nice to make, yet I am willing to
Acquaint You with, because the thing Produc'd, though it be but a
Curiosity, is wont not a little to please the Beholders, and it is a way of
turning by the help of a Dry Substance, an almost Golden-Colour'd Concrete,
into a White one, the Several Tryals are not at present so fresh in my
Memory to enable me to tell you Certainly, whether an Equal onely or a
Double weight of Common Sublimate must be taken in reference to the
Tinglass, but if I mistake not, there was in the Experiment that succeeded
best, Two parts of the Former taken to One of the Latter. These Ingredients
being finely Powdred and Exactly mix'd, we Sublim'd together by degrees of
fire (the due Gradation of which is in this Experiment a thing of main
Importance) there ascended a matter of a very peculiar Texture, for it was
for the most part made up of very Thin, Smooth, Soft and Slippery Plates,
almost like the finest sort of the Scales of Fishes, but of so Lovely a
White Inclining to Pearl-Colour, and of so Curious and Shining a Gloss,
that they appear'd in some respect little Inferiour to Orient Pearls, and
in other Regards, they seem'd to Surpass them, and were Applauded for a
sort of the Prettiest Trifles that we had ever prepar'd to Amuse the Eye. I
will not undertake that though you'l hardly miss changing the Colour of
your shining Tinglass, yet you will the first or perhaps the second time
hit Right upon the way of making the Glistring Sublimate I have been
mentioning.
_EXPERIMENT IX._
When we Dissolve in _Aqua Fortis_ a mixture of Gold and Silver melted into
one Lump, it usually happens that the Powder of Gold that falls to the
bottom, as not being Dissoluble by that _Menstruum_, will not have its own
Yellow, but appear of a Black Colour, though neither the Gold, nor the
Silver, nor the _Aqua Fortis_ did before manifest any Blackness. And divers
Alchymists, when they make Solutions of Minerals they would Examine, are
very Glad, if they see a Black Powder Præcipitated to the Bottom, taking it
for a Hopefull Sign, that those Particles are of a Golden Nature, which
appear in a Colour so ordinary to Gold parted from other Metalls by _Aqua
Fortis_, that it is a trouble to the Refiner to Reduce the Præcipitated
_Calx_ to its Native Colour. For though, (as we have try'd,) that may be
Quickly enough done by Fire, which will make this Gold look very Gloriously
(as indeed 'tis at least one of the Best wayes that is Practis'd for the
Refining of Gold,) yet it requires both Watchfulness and Skill, to give it
such a Degree of Fire as will serve to Restore it to its Lustre, without
giving it such a One, as may bring it to Fusion, to which the Minuteness of
the _Corpuseles_ it consists of makes the Powder very apt. And this brings
into my Mind, that having taken a Flat and Bright piece of Gold, that was
Refin'd by a Curious and Skilfull Person on purpose to Trye to what height
of Purity Gold could be brought by Art, I found that this very piece, as
Glorious as it look'd, being rubb'd a little upon a piece of fine clean
Linnen, did sully it with a kind of Black; and the like I have observ'd in
Refin'd Silver, which I therefore mention, because I formerly suspected
that the Impurity of the Metall might have been the only Cause of what I
have divers times obferv'd in wearing Silver-hilted Swords, Namely, that
where they rubb'd upon my Clothes, if they were of a Light-Colour'd Cloath,
the Affriction would quickly Black them; and Congruously hereunto I have
found Pens Blackt almost all over, when I had a while carri'd them about me
in a Silver Ink-case. To which I shall only add, that whereas in these
several Instances of Denigration, the Metalls are worn off, or otherwise
Reduc'd into very Minute Parts, that Circumstance may prove not Unworthy
your Notice.
_EXPERIMENT X._
That a Solution of Silver does Dye Hair of a Black Colour, is a Known
Experiment, which some persons more Curious than Dextrous, have so
Unluckily made upon themselves as to make their Friends very Merry. And I
remember that the other day, I made my self some Sport by an Improvement of
this Observation, for having dissolv'd some Pure Silver in _Aqua Fortis_,
and Evaporated the _Menstruum ad siccitatem_, as they speak, I caus'd a
Quantity of fair Water to be pour'd upon the _Calx_ two or three several
times, and to be at each Evaporated, till the _Calx_ was very Drye, and all
the Greenish Blewness that is wont to appear in Common Crystals of Silver,
was quite carry'd away. Then I made those I meant to Deceive, Moisten some
part of their Skin with their own Spittle, and slightly Rub the moistned
parts with a little of this Prepar'd Silver, Whereupon they Admir'd to see,
that a Snow-white Body laid upon the White Skin should presently produce a
deep Blackness, as if the stains had been made with Ink, especially
considering that this Blackness could not, like that produc'd by ordinary
Ink, be readily Wash'd off, but requir'd many Hours, and part of it some
dayes to its Obliteration. And with the same White _Calx_ and a little Fair
Water we likewise Stain'd the White Hafts of Knives, with a lasting Black
in those parts where the _Calx_ was Plentifully enough laid on, for where
it was laid on but very Thinly, the Stain was not quite of so Deep a
Colour.
_EXPERIMENT XI_
The Cause of the Blackness of those many Nations, which by one common Name
we are wont to call _Negroes_, has been long since Disputed of by Learned
Men, who possibly had not done amiss, if they had also taken into
Consideration, why some whole races of other Animals besides Men, as Foxes
and Hares, are Distinguish'd by a Blackness not familiar to the Generality
of Animals of the same Species; The General Opinion (to be mention'd a
little lower) has been rejected even by some of the Antient Geographers,
and among our Moderns _Ortelius_ and divers other Learned Men have
Question'd it. But this is no place to mention what thoughts I have had to
and fro about these Matters: Only as I shall freely Acknowledge, that to me
the inquiry seems more Abstruse than it does to many others, and that
because consulting with Authors, and with Books of Voyages, and with
Travellers, to satisfie my self in matters of Fact, I have met with some
things among them, which seem not to agree very well with the Notions of
the most Classick Authors concerning these things; for it being my Present
Work to deliver rather matters Historical than Theorys, I shall Annex Some
few of my Collections, instead of a Solemn Disputation. It is commonly
presum'd that the Heat of the Climate wherein they live, is the reason, why
so many Inhabitants of the Scorching Regions of _Africa_ are Black; and
there is this familiar Observation to Countenance this Conjecture, That we
plainly see that Mowers, Reapers, and other Countrey-people, who spend the
most part of the Hot Summer dayes expos'd to the Sun, have the skin of
their Hands and Faces, which are the parts immediately Expos'd to the Sun
and Air, made of a Darker Colour than before, and consequently tending to
Blackness; And Contrarywise we observe that the _Danes_ and some other
people that Inhabit Cold Climates, and even the _English_ who feel not so
Rigorous a Cold, have usually Whiter faces than the _Spaniards_,
_Portugalls_ and other European Inhabitants of Hotter Climates. But this
Argument I take to be far more Specious than Convincing; for though the
Heat of the Sun may Darken the Colour of the Skin, by that Operation, which
we in _English_ call Sun-burning, yet Experience doth not Evince, that I
remember, That that Heat alone can produce a Discolouring that shall amount
to a true Blackness, like that of _Negroes_, and we shall see by and by
that even the Children of some _Negroes_ not yet 10. dayes Old (perhaps not
so much by three quarters of that time) will notwithstanding their Infancy
be of the same Hue with their Parents. Besides, there is this strong
Argument to be alleg'd against the Vulgar Opinion, that in divers places in
_Asia_ under the same Parallel, or even of the same Degree of Latitude with
the _African_ Regions Inhabited by Blacks, the People are at most but
Tawny;[10] And in _Africa_ it self divers Nations in the Empire of
_Ethiopia_ are not _Negroes_, though Situated in the Torrid Zone, and as
neer the Æquinoctial, as other Nations that are so (as the Black
Inhabitants of _Zeylan_ and _Malabar_ are not in our Globes plac'd so near
the Line as _Amara_ the Famousest place in _Ethiopia_.) Moreover, (that
which is of no small Moment in our present Disquisition) I find not by the
best Navigators and Travellers to the _West-Indies_, whose Books or
themselves I have consulted on this Subject, that excepting perhaps one
place or two of small extent, there are any Blacks Originally Natives of
any part of _America_ (for the Blacks now there have been by the
_Europeans_ long Transplanted thither) though the New World contain in it
so great a Variety of Climates, and particularly reach quite Cross the
Torri'd Zone from one Tropick to another. And enough it be true that the
_Danes_ be a Whiter People than the _Spaniards_, yet that may proceed
rather from other causes (not here to be enquired into) than from the
Coldness of the Climate, since not onely the _Swedes_ and other Inhabitants
of those Cold Countreys, are not usually so White as the _Danes_, nor
Whiter than other Nations in proportion to their Vicinity to the Pole. [And
since the Writing of the former part of this Essay, having an opportunity
on a Solemn occasion to take Notice of the Numerous Train of Some
Extraordinary Embassadours sent from the _Russian_ Emperour to a great
Monarch, observ'd, that (though it were then Winter) the Colour of their
Hair and Skin was far less Whitish than the _Danes_ who Inhabit a milder
Region is wont to be, but rather for the most part of a Darkish Brown; And
the Physician to the Embassadour with whom those _Russes_ came, being ask'd
by me whether in _Muscovy_ it self the Generality of the People were more
inclin'd to have Dark-colour'd Hair than Flaxen, he answer'd Affirmatively;
but seem'd to suspect that the True and Antient _Russians_, a Sept of whom
he told me he had met with in one of the Provinces of that vast Empire,
were rather White like the _Danes_, than any thing near so Brown as the
present _Muscovites_ whom he guesses to be descended of the _Tartars_, and
to have inherited their Colour from them.] But to Prosecute our former
Discourse, I shall add for further Proof of the Conjecture I was
countenancing that good Authors inform us that there are _Negroes_ in
_Africa_ not far from the _Cape of good Hope_, and consequently beyond the
Southern Tropick, and without the Torrid Zone, much about the same Northern
Latitude (or very little more) wherein there are divers _American_ Nations
that are not _Negroes_, and wherein the Inhabitants of _Candia_, some parts
of _Sicily_, and even of _Spain_ are not so much as Tawny-Mores. But (which
is a fresh and strong Argument against the common Opinion,) I find by our
recent Relations of _Greenland_ (our Accounts whereof we owe to the
Curiosity of that Royal _Virtuoso_ the present King of _Denmark_,) that the
Inhabitants are Olive-colour'd, or rather of a Darker Hiew. But if the Case
were the same with Men, and those other kinds of Animals I formerly nam'd,
I should offer something as a considerable proof, That, Cold may do much
towards the making Men White or Black, and however I shall let down the
Observation as I have met with it, as worthy to come into the History of
Whiteness and Blackness, and it is, that in some parts of _Russia_ and of
_Livonia_ it is affirm'd by _Olaus Magnus_ and others, that Hares and Foxes
(some add Partridges) which before were Black, or Red, or Gray, do in the
depth of Winter become White by reason of the great Cold; (for that it
should be, as some conceive, by Looking upon the Snow, seems improbable
upon divers accounts) And I remember that having purposely enquir'd of a
_Virtuoso_ who lately Travell'd through _Livonia_ to _Mosco_ concerning the
Truth of this Tradition, he both told me, he believ'd it, and added, that
he saw divers of those lately nam'd Animals either in _Russia_ or
_Livonia_, (for I do not very well remember whether of the two) which,
though White when he saw them in Winter, they assur'd him had been Black,
or of other Colours before the Winter began, and would be so again when it
was over. But for further satisfaction, I also consulted one that had for
some years been an Eminent Physician in _Russia_, who though he rejected
some other Traditions that are generally enough believ'd concerning that
Countrey, told me nevertheless, that he saw no cause to doubt of this
Tradition of _Olaus Magnus_ as to Foxes and Hares, not onely because 'tis
the common and uncontroul'd Assertion of the Natives, but also because he
himself in the Winter could never that he remember'd see Foxes and Hares of
any other Colour than White; And I my self having seen a small White Fox
brought out of _Russia_ into _England_ towards the latter end of Winter,
foretold those that shew'd him me, that he would change Colour in Summer,
and accordingly coming to look upon him again in _July_, I found that the
Back and Sides, together with the upper part of the Head and Tayl were
already grown of a Dark Colour, the lower part of the Head and Belly
containing as yet a Whiteness. Let me add, that were it not for some
scruple I have, I should think more than what _Olaus_ relates, confirm'd by
the judicious _Olearius_, who was twice employ'd into those parts as a
Publick Minister, who in his Account of _Moscovy_ has this Passage: _The
Hares there are Gray; but in some Provinces they grow white in the Winter_.
And within some few Lines after: _It is not very Difficult to find the
Cause of this Change, which certainly proceeds only from the Outward Cold,
since I know that even in Summer, Hares will change Colour, if they be kept
a competent time in a Cellar_; I say, were it not for Some Scruple, because
I take notice, that in the same Page the Author Affirms, that the like
change of Colour that happens to Hares in some Provinces of _Muscovy_,
happens to them also in _Livonia_, and yet immediately subjoyns, that in
_Curland_ the Hares vary not their Colour in Winter, though these two last
named Countries be contiguous, (that is) sever'd only by the River of
_Dugna_; For it is scarce conceivable how Cold alone should have, in
Countries so near, so strangely differing an operation, though no less
strange a thing is confess'd by many, that ascribe the Complexion of
_Negroes_ to the Heat of the Sun, when they would have the River of
_Cenega_ so to bound the _Moors_, that though on the North-side they are
but Tawny, on the other side they are Black.
[10] Olearius Voyage de Mosco. et de Perse _liv_. 3.
There is another Opinion concerning the Complexion of _Negroes_, that is
not only embrac'd by many of the more Vulgar Writers, but likewise by that
ingenious Traveller Mr. _Sandys_, and by a late most learned Critick,
besides other men of Note, and these would have the Blackness of _Negroes_
an effect of _Noah's_ Curse ratify'd by God's, upon _Cham_; But though I
think that even a Naturalist may without disparagement believe all the
Miracles attested by the Holy Scriptures, yet in this case to flye to a
Supernatural Cause, will, I fear, look like Shifting off the Difficulty,
instead of Resolving it; for we enquire not the First and Universal, but
the Proper, Immediate, and Physical Cause of the Jetty Colour of _Negroes_;
And not only we do not find expressed in the Scripture, that the Curse
meant by _Noah_ to _Cham_, was the Blackness of his Posterity, but we do
find plainly enough there that the Curse was quite another thing, namely
that he should be a Servant of Servants, that is by an Ebraism, a very
Abject Servant to his Brethren, which accordingly did in part come to pass,
when the _Israelites_ of the posterity of _Sem_, subdued the _Canaanites_,
that descended from _Cham_, and kept them in great Subjection. Nor is it
evident that Blackness is a Curse, for Navigators tell us of Black Nations,
who think so much otherwise of their own condition, that they paint the
Devil White. Nor is Blackness inconsistent with Beauty, which even to our
European Eyes consists not so much in Colour, as an Advantageous Stature, a
Comely Symmetry of the parts of the Body, and Good Features in the Face. So
that I see not why Blackness should be thought such a Curse to the
_Negroes_, unless perhaps it be, that being wont to go Naked in those Hot
Climates, the Colour of their Skin does probably, according to the Doctrine
above deliver'd, make the Sun-beams more Scorching to them, than they would
prove to a people of a White Complexion.
Greater probability there is, That the Principal Cause (for I would not
exclude all concurrent ones) of the Blackness of _Negroes_ is some Peculiar
and Seminal Impression, for not onely we see that _Blackmore_ boyes brought
over into these Colder Climates lose not their Colour; But good Authors
inform us, That the Off-spring of _Negroes_ Transplanted out of _Africa_,
above a hundred years ago, retain still the Complexion of their
Progenitors, though possibly in Tract of time it will decay; As on the
other side, the White people removing into very Hot Climates, have their
Skins by the Heat of the Sun scorch'd into Dark Colours; yet neither they,
nor their Children have been observ'd, even in the Countreys of _Negroes_,
to descend to a Colour amounting to that of the Natives; whereas I remember
I have Read in _Pisos_[11] excellent account of _Brasile_, that betwixt the
_Americans_ and _Negroes_ are generated a distinct sort of Men, which they
call _Cabocles_, and betwixt _Portugalls_ and _Æthiopian_ women, He tells
us, he has sometimes seen Twins, whereof one had a White skin, the other a
Black; not to mention here some other instances, he gives, that the
productions of the mixtures of differing people, that is (indeed,) the
effects of Seminal Impressions which they consequently argue to have been
their Causes; and we shall not much scruple at this, if we consider, that
even Organical parts may receive great Differences from such peculiar
Impressions, upon what account soever they came to be setled in the first
Individual persons, from whom they are Propogated to Posterity, as we see
in the Blobber-Lips and Flat-Noses of most Nations of _Negroes_. And if we
may Credit what Learned men deliver concerning the Little Feet of the
_Chinesses_, the _Macrocephali_ taken notice of by _Hippocrates_, will not
be the only Instance we might apply to our present purpose. And on this
occasion it will not perchance be Impertinent to add something of what I
have observ'd in other Animals, as that there is a sort of Hens that want
Rumps; And that (not to mention that in several places there is a sort of
Crows or Daws that are not Cole-black as ours, but partly of a Whitish
Colour) in spight of _Porphyries_ examples of Inseparable Accidents, I have
seen a perfectly White Raven, as to Bill as well as Feathers, which I
attentively considered, for fear of being impos'd upon. And this recalls
into my Memory, what a very Ingenious Physician has divers times related to
me of a young Lady, to whom being call'd, he found that though she much
complain'd of want of Health, yet there appear'd so little cause either in
her Body, or her Condition to Guess that She did any more than fancy her
self Sick, that scrupling to give her Physick, he perswaded her Friends
rather to divert her Mind by little Journeys of Pleasure, in one of which
going to Visit St. _Winifrids_ Well, this Lady, who was a _Catholick_, and
devout in her Religion, and a pretty while in the Water to perform some
Devotions, and had occasion to fix her Eyes very attentively upon the Red
pipple-stones, which in a scatter'd order made up a good part of those that
appear'd through the water, and a while after growing Bigg, she was
deliver'd of a Child, whose White Skin was Copiously speckl'd with spots of
the Colour and Bignesss of those Stones, and though now this Child have
already liv'd several years, yet she still retains them. I have but two
things to add concerning the Blackness of _Negroes_, the one is, that the
Seat of that Colour seems to be but the thin _Epidermes_, or outward Skin,
for I knew a young _Negroe_, who having been lightly Sick of the Small Pox
or Measles, (for it was doubted which of the two was his Disease) I found
by enquiry of a person that was concern'd for him, that in those places
where the little Tumors had broke their passage through the Skin, when they
were gone, they left Within specks behind them; And the lately commended
_Piso_ assures us, that having the opportunity in _Brasil_ to Dissect many
_Negroes_, he cleerly found that their Blackness went no deeper than the
very outward Skin, which _Cuticula_ or _Epidermis_ being remov'd, the
undermost Skin or _Cutis_ appear'd just as White as that of _Europæan_
Bodyes. And the like has been affirmed to me by a Physician of our own,
whom, hearing he had Dissectcd a _Negroe_ here in _England_, I consulted
about this particular. The other thing to be here taken notice of
concerning _Negroes_ is, That having enquir'd of an Intelligent
acquaintance of mine (who keeps in the _Indies_ about 300. of them as well
Women as Men to work in his Plantations,) whether their Children come Black
into the world; he answer'd, That they did not, but were brought forth of
almost the like Reddish Colour with our _European_ Children; and having
further enquir'd, how long it was before these Infants appear'd Black, be
reply'd, that 'twas not wont to be many daies. And agreeable to this
account I find that, given us in a freshly publish'd French Book written by
a _Jesuit_, that had good opportunity of Knowing the Truth of what he
Delivers, for being one of the Missionaries of his Order into the Southern
_America_ upon the Laudable Design of Converting Infidels to Christianity,
he Baptiz'd several Infants, which when newly Born, were much of the same
Colour with _European_ Babes, but within about a Week began to appear of
the Hue of their Parents. But more Pregnant is the Testimony of our
Countrey-man _Andrew Battel_, who being sent Prisoner by the _Portugalls_
to _Angola_, liv'd there, and in the adjoyning Regions, partly as a
Prisoner, partly as a Pilot, and partly as a Souldier, near 18. years, and
he mentioning the _African_ Kingdom of _Longo_, peopl'd with Blacks, has
this passage:[12] _The Children in this Countrey are Born White, and change
their Colour in two dayes to a Perfect Black_. As for Example, _The_
Portugalls _which dwell in the Kingdome of_ Longo _have sometimes Children
by the_ Negroe_-women, and many times the Fathers are deceived, thinking,
when the Child is Born, that it is theirs, and within two dayes it proves
the Son or Daughter of a_ Negroe,_ which the_ Portugalls _greatly grieve
at_; And the same person has elsewhere a Relation, which, if he have made
no use at all of the liberty of a Traveller, is very well worth our Notice,
since this, together with that we have formerly mention'd of Seminal
Impressions, shews a possibility, that a Race of _Negroes_ might be begun,
though none of the Sons of _Adam_, for many Precedent Generations were of
that Complexion. For I see not why it should not be at least as possible,
that White Parents may sometimes have Black Children, as that _African
Negroes_ should sometimes have lastingly White ones, especially since
concurrent causes may easily more befriend the Productions of the Former
kind, than under the scorching Heat of _Africa_ those of the Latter. And I
remember on the occasion of what he delivers, that of the White Raven
formerly mention'd, the Possessor affirm'd to me, that in the Nest out of
which he was taken White, they found with him but one other Young one, and
that he was of as Jetty a Black as any common Raven. But let us hear our
Author himself[13]; _Here are_ (sayes he, speaking of the formerly
mention'd Regions) _Born in this Countrey White Children, which is very
rare among them, for their Parents are_ Negroes; _And when any of them are
Born, they are presented to the King, and are call'd_ Dondos; _these are as
White as any White Men. These are the Kings Witches, and are brought up in
Witchcraft, and alwayes wait on the King: There is no man that dare meddle
with these_ Dondos, _if they go to the Market they may take what they lift,
for all Men stand in awe of them. The King of_ Longo _hath four of them_.
And yet this Countrey in our Globes is plac'd almost in the midst of the
Torrid Zone (four or five Degrees Southward of the Line.) And our Author
elsewhere tells us of the Inhabitants, that they are so fond of their
Blackness, that they will not suffer any that is not of that Colour (as the
_Portugalls_ that come to Trade thither) to be so much as Buri'd in their
Land, of which he annexes a particular example,[14] that may be seen in his
Voyage preserv'd by our Industrious Countreyman Mr. _Purchas_. But it is
high time for me to dismiss Observations, and go on with Experiments.
[11] _Piso_ Nat. & Med. Hist. _Brasil. lib_ 1. in fine.
[12] _Purchas_ Pilgrim. Second part, Seventh Book 3. Chap. Sect 5.
[13] _Purchas_. Ibid.
[14] _Purchas_ Ibid. in fin
_EXPERIMENT XII._
The way, _Pyrophilus,_ of producing Whiteness by Chymical Præcipitations is
very well worth our observing, for thereby Bodyes of very Differing Colours
as well as Natures, though dissolv'd in Several Liquors, are all brought
into _Calces_ or Powders that are White. Thus we find that not only
Crabs-eyes, that are of themselves White, and Pearls that are almost so,
but _Coral_ and _Minium_ that are Red, being dissolv'd in Spirit of
Vinegar, may be uniformly Præcipitated by Oyl of _Tartar_ into White
Powders. Thus Silver and Tin separately dissolv'd in _Aqua Fortis_, will
the one Præcipitate it self, and the other be Præcipitated by common
Salt-water into a White _Calx_, and so will Crude Lead and Quicksilver
first dissolv'd likewise in _Aqua Fortis_. The like _Calx_ will be afforded
as I have try'd by a Solution of that shining Mineral Tinglass dissolv'd in
_Aqua Fortis_, and Præcipitated out of it; and divers of these _Calces_ may
be made at least as Fair and White, if not better Colour'd, if instead of
Oyl of _Tartar_ they were Præcipitated with Oyl of _Vitriol_, or with
another Liquor I could Name. Nay, that Black Mineral _Antimony_ it self,
being reduc'd by and with the Salts that concurr to the Composition of
common Sublimate, into that Cleer though Unctuous Liquor that Chymists
commonly call Rectifi'd Butter of _Antimony_, will by the bare affusion of
store of Fair Water be struck down into that Snow-white Powder, which when
the adhering Saltness is well wash'd off, Chymists are pleas'd to call
_Mercurius Vitæ_, though the like Powder may be made of _Antimony_, without
the addition of any _Mercury_ at all. And this Lactescence if I may so call
it, does also commonly ensue when Spirit of Wine, being Impregnated with
those parts of Gums or other Vegetable Concretions, that are suppos'd to
abound with Sulphureous Corpuscles, fair Water is suddenly pour'd upon the
Tincture or Solution. And I remember that very lately I did, for Tryal
sake, on a Tincture of _Benjamin_ drawn with Spirit of Wine, and brought to
be as Red as Blood, pour some fair Water, which presently mingling with the
Liquor, immediately turn'd the whole Mixture White. But if such Seeming
Milks be suffer'd to stand unstirr'd for a convenient while, they are wont
to let fall to the bottome a Resinous Substance, which the Spirit of Wine
Diluted and Weakned by the Water pour'd into it was unable to support any
longer. And something of Kin to this change of Colour in Vegetables is
that, which Chymists are wont to observe upon the pouring of Acid Spirits
upon the Red Solution of _Sulphur_, dissolv'd in an Infusion of Pot-ashes,
or in some other sharp _Lixivium_, the Præcipitated _Sulphur_ before it
subsides, immediately turning the Red Liquor into a White one. And other
Examples might be added of this way of producing Whiteness in Bodyes by
Præcipitating them out of the Liquors wherein they have been Dissolv'd; but
I think it may be more usefull to admonish you, _Pyrophilus_, that this
observation admits of Restrictions, and is not so Universal, as by this
time perhaps you have begun to think it; For though most Præcipitated
Bodyes are White, yet I know some that are not; For Gold Dissolv'd in _Aqua
Regis_, whether you Præcipitate it with Oyl of _Tartar_, or with Spirit of
_Sal Armoniack_, will not afford a White but a Yellow _Calx_. _Mercury_
also though reduc'd into Sublimate, and Præcipitated with Liquors abounding
with Volatile Salts, as the Spirits drawn from Urine, Harts-horn, and other
Animal substances, yet will afford, as we Noted in our first Experiment
about Whiteness and Blackness, a White Præcipitate, yet with some Solutions
hereafter to be mentioned, it will let fall an Orange-Tawny Powder. And so
will Crude _Antimony_, if, being dissolv'd in a strong Lye, you pour (as
farr as I remember) any Acid Liquor upon the Solution newly Filtrated,
whilst it is yet Warm. And if upon the Filtrated Solution of _Vitriol_, you
pour a Solution of one of these fix'd Salts, there will subside a Copious
substance, very farr from having any Whiteness, which the Chymists are
pleas'd to call, how properly I have elsewhere examin'd, the _Sulphur of
Vitriol_. So that most part of Dissolv'd Bodyes being by Præcipitation
brought to White Powders, and yet some affording Præcipitates of other
Colours, the reason of both the Phænomena may deserve to be enquir'd into.
_EXPERIMENT XIII._
Some Learned Modern Writers[15] are of Opinion, that the Account upon which
Whiteness and Blackness ought to be call'd, as they commonly are, the two
Extreme Colours, is, That Blackness (by which I presume is meant the Bodyes
endow'd with it) receives no other Colours; but Whiteness very easily
receives them all; whence some of them compare Whiteness to the
_Aristotelian Materia prima_, that being capable of any sort of Forms, as
they suppose White Bodyes to be of every kind of Colour. But not to Dispute
about Names or Expressions, the thing it self that is affirm'd as Matter of
Fact, seems to be True enough in most Cases, not in all, or so, as to hold
Universally. For though it be a common observation among Dyers, That
Clothes, which have once been throughly imbu'd with Black, cannot so well
afterwards be Dy'd into Lighter Colours, the præexistent Dark Colour
infecting the Ingredients, that carry the Lighter Colour to be introduc'd,
and making it degenerate into Some more Sad one; Yet the Experiments lately
mention'd may shew us, that where the change of Colour in Black Bodies is
attempted, not by mingling Bodyes of Lighter Colours with them, but by
Addition of such things as are proper to alter the Texture of those
Corpuscles that contain the Black Colour, 'tis no such difficult matter, as
the lately mention'd Learned Men imagine, to alter the Colour of Black
Bodyes. For we saw that Inks of several Kinds might in a trice be depriv'd
of all their Blackness; and those made with Logwood and Red-Roses might
also be chang'd, the one into a Red, the other into a Reddish Liquor; and
with Oyl of _Vitriol_ I have sometimes turn'd Black pieces of Silk into a
kind of Yellow, and though the Taffaty were thereby made Rotten, yet the
spoyling of that does no way prejudice the Experiment, the change of Black
Silk into Yellow, being never the less True, because the Yellow Silk is the
less good. And as for Whiteness, I think the general affirmation of its
being so easily Destroy'd or Transmuted by any other Colour, ought not to
be receiv'd without some Cautions and Restrictions. For whereas, according
to what I formerly Noted, Lead is by Calcination turned into that Red
Powder we call _Minium_; And Tin by Calcination reduc'd to a White _Calx_,
the common Putty that is sold and us'd so much in Shops, instead of being,
as it is pretended and ought to be, only the _Calx_ of Tin, is, by the
Artificers that make it, to save the charge of Tin, made, (as some, of
themselves have confess'd, and as I long suspected by the Cheap rate it may
be bought for) but of half Tin and half Lead, if not far more Lead than
Tin, and yet the Putty in spight of so much Lead is a very White Powder,
without disclosing any mixture of _Minium_. And so if you take two parts of
Copper, which is a High-colour'd Metall, to but one of Tin, you may by
Fusion bring them into one Mass, wherein the Whiteness of the Tin is much
more Conspicuous and Predominant than the Reddishness of the Copper. And on
this occasion it may not be Impertinent to mention an Experiment, which I
relate upon the Credit of a very Honest man, whom I purposely enquir'd of
about it, being my self not very fond of making Tryals with _Arsenick_, the
Experiment is this, That if you Colliquate _Arsenick_ and Copper in a due
proportion, the _Arsenick_ will Blanch the Copper both within and without,
which is an Experiment well enough Known; but when I enquir'd, whether or
no this White mixture being skilfully kept a while upon the Cupel would not
let go its _Arsenick_, which made Whiteness its prædominant Colour, and
return to the Reddishness of Copper, I was assur'd of the Affirmative; so
that among Mineral Bodyes, some of those that are White, may be far more
capable, than those I am reasoning with seem to have known, of Eclipsing
others, and of making their Colour Prædominant in Mixtures. In further
Confirmation of which may be added, that I remember that I also took a lump
of Silver and Gold melted together, wherein by the Æstimate of a very
Experienced Refiner, there might be about a fourth or third part of Gold,
and yet the Yellow Colour of the Gold was so hid by the White of the
Silver, that the whole Mass appear'd to be but Silver, and when it was
rubb'd upon the Touchstone, an ordinary beholder could scarce have
distinguish'd it from the Touch of common Silver; though if I put a little
_Aqua Fortis_ upon any part of the White Surface it had given the
Touchstone, the Silver in the moistned part being immediately taken up and
conceal'd by the Liquor, the Golden Particles would presently disclose that
native Yellow, and look rather as if Gold, than if the above mention'd
mixture, had been rubb'd upon the Stone.
[15] See _Scaliger_ Exercit. 325. Sect. 9.
_EXPERIMENT XIV._
I took a piece of Black-horn, (polish'd as being part of a Comb) this with
a piece of broken glass I scrap'd into many thin and curdled flakes, some
shorter and some longer, and having laid a pretty Quantity of these
scrapings together, I found, as I look'd for, that the heap they compos'd
was White, and though, if I laid it upon a clean piece of White Paper, its
Colour seem'd somewhat Eclips'd by the greater Whiteness of the Body it was
compar'd with, looking somewhat like Linnen that had been sulli'd by a
little wearing, yet if I laid it upon a very Black Body, as upon a Beaver
Hatt, it then appear'd to be of a good White, which Experiment, that you
may in a trice make when you please, seems very much to Disfavour both
their Doctrine that would have Colours to flow from the Substantial Forms
of Bodyes, and that of the Chymists also, who ascribe them to one or other
of their three Hypostatical Principles; for though in our Case there was so
great a Change made, that the same Body without being substantially either
Increas'd or Lessened, passes immediately from one extreme Colour to
another (and that too from Black to White) yet this so great and sudden
change is effected by a slight Mechanical Transposition of parts, there
being no Salt or _Sulphur_ or _Mercury_ that can be pretended to be Added
or Taken away, nor yet any substantial Form that can reasonably be suppos'd
to be Generated and Destroy'd, the Effect proceeding only from a Local
Motion of the parts which so vary'd their Position as to multiply their
distinct Surfaces, and to Qualifie them to Reflect far more Light to the
Eye, than they could before they were scrap'd off from the entire piece of
Black horn.
_EXPERIMENT XV._
And now, _Pyrophilus_, it will not be improper for us to take some notice
of an Opinion touching the cause of Blackness, which I judged it not so
seasonable to Question, till I I had set down some of the Experiments, that
might justifie my dissent from it. You know that of late divers Learned
Men, having adopted the three Hypostatical Principles, besides other
Notions of the Chymists, are very inclinable to reduce all Qualities of
Bodies to one or other of those three Principles, and Particularly assign
for the cause of Blackness the Sootie steam of _adust_ or _torrifi'd
Sulphur_. But I hope that what we have deliver'd above to countenance the
Opinion we have propos'd about the Cause of Blackness, will so easily
supply you with several Particulars that may be made use of against this
Opinion, that I shall now represent to You but two things concerning it.
And First it seems that the favourers of the Chymicall Theories might have
pitcht upon some more proper term, to express the Efficient of Blackness
than _Sulphur adust_; for we know that _common Sulphur_, not only when
Melted, but even when Sublim'd, does not grow Black by suffering the Action
of the fire, but continues and ascends Yellow, and rather more than less
White, than it was before its being expos'd to the fire. And if it be set
on fire, as when we make that acid Liquor, that Chymists call _Oleum
Sulphuris per campanam_, it affords very little Soot, and indeed the flame
yeelds so little, that it will scarce in any degree Black a sheet of White
Paper, held a pretty while over the flame and smoak of it, which is
observed rather to Whiten than Infect linnen, and which does plainly make
Red Roses grow very Pale, but not at all Black, as far as the Smoak is
permitted to reach the leaves. And I can shew you of a sort of fixt Sulphur
made by an Industrious Laborant of your acquaintance, who assur'd me that
he was wont to keep it for divers weeks together night and day in a naked
and Violent fire, almost like that of the Glass-house, and when, to
satisfie my Curiosity, I made him take out a lump of it, though it were
glowing hot (and yet not melted,) it did not, when I had suffered it to
cool, appear Black, the true Colour of it being a true Red. I know it may
be said, that _Chymists_ in the Opinion above recited mean the _Principle
of Sulphur_, and not _common Sulphur_ which receives its name, not from its
being _all_ perfectly of a Sulphureous Nature, but for that _plenty_ and
_Predominancy_ of the Sulphureous Principle in it. But allowing this, 'tis
easie to reply, that still according to this very Reason, torrifi'd Sulphur
should afford more Blackness, than most other concretes, wherein that
Principle is confess'd to be far less copious. Also when I have expos'd
Camphire to the fire in Close Vessels, as Inflamable, and consequenly
(according to the Chymists) as Sulphureous a Body as it is, I could not by
such a degree of Heat, as brought it to Fusion, and made it Boyl in the
glass, impress any thing of Blackness, or of any other Colour, than its own
pure White, upon this Vegetable concrete. But what shall we say to Spirit
of Wine, which being made by a Chymical Analysis of the Liquor that affords
it, and being totally Inflamable, seems to have a full right to the title
they give it of _Sulphur Vegetabile_, & yet this fluid Sulphur not only
contracts not any degree of Blackness by being often so heated, as to be
made to Boyl, but when it burns away with an Actual flame, I have not found
that it would discolour a piece of White Paper held over it, with any
discernable soot. Tin also, that wants not, according to the Chymists, a
_Sulphur Joviale_, when throughly burned by the fire into a _Calx_, is not
Black, but eminently White. And I lately noted to you out of _Bellonius_,
that the Charcoals of Oxy-cedar are not of the former of these two Colours,
but of the latter. And the Smoak of our Tinby coals here in _England_, has
been usually observ'd, rather to Blanch linnen then to Black it. To all
which, other Particulars of the like nature might be added, but I rather
choose to put you in mind of the third Experiment, about making Black
Liquors, or Inks, of Bodies that were non of them Black before. For how can
it be said, that when those Liquors are put together actually Cold, and
continue so after their mixture, there intervenes any new _Adustion of
Sulphur_ to produce the emergent Blackness? (and the same question will be
appliable to the Blackness produc'd upon the blade of a Knife, that has cut
Lemmons and some kind of Sowr apples, if the juyce (though both Actually
and Potentially Cold) be not quickly wip'd of) And when by the instilling
either of a few drops of Oyl of Vitriol as in the second Experiment, or of
a little of the Liquor mention'd in the Passage pointed at in the fourth
Experiment, (where I teach at once to Destroy one black Ink, and make
another) the Blackness produc'd by those Experiments is presently
destroy'd; if the Colour proceeded only from the Plenty of Sulphurous
parts, torrify'd in the Black Bodies, I demand, what becomes of them, when
the Colour so suddenly dissappears? For it cannot Reasonably be said, that
all those that suffic'd to make so great a quantity of Black Matter, should
resort to so very small a proportion of the Clarifying Liquor, (if I may so
call it) as to be deluted by it, with out at all Denigrating it. And if it
be said that the Instill'd Liquor dispers'd those Black Corpuscles, I
demand, how that Dispersion comes to destroy their Blackness, but by making
such a Local Motion of their parts, as destroys their former Texture? which
may be a Matter of such moment in cases like ours, that I remember that I
have in few houres, without addition, from Soot it self, attain'd pretty
store of Crystalline Salt, and good store of Transparent Liquor, and (which
I have on another occasion noted as remarkable) this so Black Substance had
its Colour so alter'd, by the change of Texture it receiv'd from the fire,
wherewith it was distill'd, that it did for a great while afford such
plenty of very white Exhalations, that the Receiver, though large, seem'd
to be almost fill'd with Milk.
Secondly, But were it granted, as it is in some cases not Improbable, that
divers Bodies may receive a Blackness from a Sootie Exhalation, occasion'd
by the Adustion of their Sulphur, which (for the Reasons lately mention'd I
should rather call their Oyly parts;) yet still this account is applicable
but to some Particular Bodies, and will afford us no General Theory of
Blackness. For if, for example, White Harts-horn, being, in Vessels well
luted to each other, expos'd to the fire, be said to turn Black by the
Infection of its own Smoak, I think I may justly demand, what it is that
makes the Smoak or Soot it self Black, since no Such Colour, but its
contrary, appear'd before in the Harts-horn? And with the same Reason, when
we are told, that torrify'd Sulphur makes bodies Black, I desire to be told
also, why Torrefaction makes Sulphur it self Black? nor will there be any
Satisfactory Reason assign'd of these Quæries, without taking in those
Fertile as well as intelligible Mechanical Principles of the Position and
Texture of the Minute parts of the body in reference to the Light and the
Eye; and these applicable Principles may Serve the turn in many cases,
where the Adustion of Sulphur cannot be pretended; as in the appearing
Blackness of an Open window, lookt upon at a somewhat remote distance from
the house, as also in the Blackness Men think they see in the Holes that
happen to be in White linnen, or Paper of the like Colour; and in the
Increasing Blackness immediatly Produc'd barely by so rubbing Velvet, whose
Piles were Inclin'd before, as to reduce them to a more Erected posture, in
which and in many other cases formerly alleg'd, there appears nothing
requisite to the Production of _the_ Blackness, but the hindering of the
incident Beams of Light from rebounding plentifully enough to the Eye. To
be short, those I reason with, do concerning Blackness, what the Chymists
are wont also to do concerning other Qualities, namely to content
themselves to tell us, in what Ingredient of a Mixt Body, the Quality
enquir'd after, does reside, instead of explicating the Nature of it, which
(to borrow a comparison from their own Laboratories) is much as if in an
enquiry after the cause of Salivation, they should think it enough to tell
us, that the several Kinds of Præcipitates of Gold and _Mercury_) as
likewise of Quick-silver and Silver (for I know that make and use of such
Precipitates also) do Salivate upon the account of the _Mercury_, which
though Disguis'd abounds in them, whereas the Difficulty is as much to know
upon what account _Mercury_ it self, rather than other Bodies, has that
power of working by Salivation. Which I say not, as though it were not
_something_ (and too often the most we can arrive at) to discover in which
of the Ingredients of a Compounded Body, the Quality, whose Nature is
sought, resides, but because, though this Discovery it self may pass for
_something_, and is oftentimes more than what is taught us about the same
subjects in the Schools, yet we ought not to think it _enough_, when more
Clear and Particular accounts are to be had.
* * * * *
THE
Experimental History
OF
COLOURS
Begun.
* * * * *
The Third PART.
* * * * *
Containing
Promiscuous Experiments
About
COLOURS.
* * * * *
EXPERIMENT I.
Because that, according to the Conjectures I have above propos'd, one of
the most General Causes of the Diversity of Colours in Opacous Bodyes, is,
that some reflect the Light mingl'd with more, others with less of Shade
(either as to Quantity, or as to Interruption) I hold it not unfit to
mention in the first place, the Experiments that I thought upon to examine
this Conjecture. And though coming to transcribe them out of some
Physiological _Adversaria_ I had written in loose Papers, I cannot find one
of the chief Records I had of my Tryals of this Nature, yet the Papers that
scap'd miscarrying, will, I presume, suffice to manifest the main thing for
which I now allege them; I find then Among my _Adversaria_, the following
Narrative.
_October_ the 11. About ten in the Morning in Sun-shiny Weather, (but not
without fleeting Clouds) we took several sorts of Paper Stain'd, some of
one Colour, and some of another; and in a Darken'd Room whose Window look'd
Southward, we cast the Beams that came in at a hole about three Inches and
a half in Diameter, upon a White wall that was plac'd on one side, about
five foot distance from them.
The White gave much the Brightest Reflection.
The Green, Red, and Blew being Compar'd together, the Red gave much the
strongest Reflection, and manifestly enough also threw its _Colour_ upon
the Wall; The Green and Blew were scarce Discernable by their Colours, and
seem'd to reflect an almost Equal Light.
The Yellow Compar'd with the two last nam'd, Reflected somewhat more Light.
The Red and Purple being Compar'd together, the former manifestly Reflected
a good deal more Light.
The Blew and Purple Compar'd together, the former seem'd to Reflect a
little more Light, though the Purple Colour were more manifestly seen.
A Sheet of very well fleck'd Marbl'd Paper being Apply'd as the others, did
not cast any or its Distinct Colours upon the Wall; nor throw its Light
upon it with an Equal Diffusion, but threw the Beams Unstain'd and Bright
to this and that part of the Wall, as if it's Polish had given it the
Nature of a specular Body. But comparing it with a sheet of White Paper, we
found the Reflection of the latter to be much Stronger, it diffusing almost
as much Light to a _good Extent_ as the Marble Paper did to _one part_ of
the Wall.
The Green and Purple left us somewhat in suspence which Reflected the most
Light; only the Purple seem'd to have some little Advantage over the Green,
which was Dark in its kind.
Thus much I find in our above mention'd _Collections_, among which there
are also some Notes concerning the Production of _Compounded Colours_, _by
Reflection_ from Bodyes differingly Colour'd. And these Notes we intended
should supply us with what we should mention as our second Experiment: but
having lost the Paper that contain'd the Particulars, and remembring onely
in General, that if the Objects which Reflected the Light were not Strongly
Colour'd and somewhat Glossy, the Reflected Beams would not manifestly make
a Compounded Colour upon the Wall, and even then but very Faintly, we shall
now say no more of that Matter, only reserving our selves to mention
hereafter the Composition of a Green, which we still retain in Memory.
_EXPERIMENT II._
We may add, _Pyrophilus_, on this Occasion, that though a Darken'd Room be
Generally thought requisite to make the Colour of a Body appear by
Reflection from another Body, that is not one of those that are commonly
agreed upon to be Specular (as Polish'd Metall, Quick silver, Glass, Water,
&c.) Yet I have often observ'd that when I wore Doublets Lin'd with some
silken Stuff that was very Glossy and Vividly Colour'd, especially Red, I
could in an Inlightned Room plainly enough Discern the Colour, upon the
Pure White Linnen that came out at my Sleeve and reach'd to my Cufs; as if
that Fine White Body were more Specular, than Colour'd and Unpolish'd
Bodyes are thought Capable of being.
_EXPERIMENT III._
Whilst we were making the newly mention'd Experiments, we thought fit to
try also what Composition of Colours might be made by Altering the Light in
its Passage to the Eye by the Interposition not of Perfectly Diaphanous
Bodies, (that having been already try'd by others as well as by us (as we
shall soon have occasion to take notice) but of Semi-opacous Bodyes, and
those such as look'd upon in an ordinary Light, and not held betwixt it and
the Eye, are not wont to be Discriminated from the rest of Opacous Bodyes;
of this Tryal, our mention'd _Adversaria_ present us the following Account.
Holding these Sheets, sometimes one sometimes the other of them, before the
Hole betwixt the Sun and the Eye, with the Colour'd sides obverted to the
Sun; we found them _single_ to be somewhat Transparent, and appear of the
same Colour as before, onely a little alter'd by the great Light they were
plac'd in; but laying _two_ of them one over another and applying them so
to the Hole, the Colours were compounded as follows.
The Blew and Yellow scarce exhibited any thing but a Darker Yellow, which
we ascrib'd to the Coarseness of the Blew Papers, and its Darkness in its
Kind. For applying the Blew parts of the Marbl'd Paper with the Yellow
Paper after the same manner, they exhibited a good Green.
The Yellow and Red look'd upon together gave us but a Dark Red, somewhat
(and but a little,) inclining to an Orange Colour.
The Purple and Red look'd on together appear'd more Scarlet.
The Purple and Yellow made an Orange.
The Green and Red made a Dark Orange Tawny.
The Green and Purple made the Purple appear more Dirty.
The Blew and Purple made the Purple more Lovely, and far more Deep.
The Red parts of the Marbl'd Paper look'd upon with the Yellow appear'd of
a Red far more like Scarlet than without it.
[Page 191]
But the Fineness or Coarseness of the Papers, their being carefully or
slightly Colour'd, and divers other Circumstances, may so vary the Events
of such Experiments as these, that if, _Pyrophilus_, you would Build much
on them, you must carefully Repeat them.
_EXPERIMENT IV._
The Triangular Prismatical Glass being the Instrument upon whose Effects we
may the most Commodiously speculate the Nature of Emphatical Colours, (and
perhaps that of Others too;) we thought it might be usefull to observe the
several Reflections and Refractions which the Incident Beams of Light
suffer in Rebounding from it, and Passing through it. And this we thought
might be Best done, not (as is usual,) in an ordinary Inlightn'd Room,
where (by reason of the Difficulty of doing otherwise) ev'n the Curious
have left Particulars Unheeded, which may in a convenient place be easily
taken notice of; but in a Darken'd Room, where by placing the Glass in a
convenient Posture, the Various Reflections and Refractions may be
Distinctly observ'd; and where it may appear _what_ Beams are Unting'd; and
_which_ they are, that upon the Bodyes that terminate them, do Paint either
the Primary or Secondary Iris. In pursuance of this we did in the above
mention'd Darken'd Room, make observation of no less than four Reflections,
and three Refractions that were afforded us by the same Prism, and thought
that notwithstanding what was taught us by the Rules of Catoptricks and
Dioptricks, it would not be amiss to find also, by hiding sometimes one
part of the Prism, and sometimes another, and observing where the Light or
Colour Vanish'd thereupon, by which Reflection and by which Refraction each
of the several places whereon the Light rebounding from, or passing
through, the Prism appear'd either Sincere or Tincted, was produc'd. But
because it would be Tedious and not so Intelligible to deliver this in
Words, I have thought fit to Referr You to the Annexed Scheme where the
Newly mention'd particulars may be at one View taken Notice of.
_EXPERIMENT V._
[Illustration: _The Explication of the Scheme._]
_PPP_. An Aequilaterotriangular Crystalline Prism, one of whose edges _P_.
is placed directly towards the Sun.
_A B_ & [alpha] [beta] Two rays from the Sun falling on the Prism at _B_
[beta]. and thence partly reflected towards _C_ & [gamma]. and partly
refracted towards _D_ & [delta].
_B C_ & [beta] [gamma]. Those reflected Rays.
_B D_ & [beta] [delta]. Those refracted Rays which are partly refracted
towards _E_ & [epsilon]. and there paint an Iris 1 2 3 4 5. denoting the
five consecutions of colours Red, Yellow, Green, Blew, and Purple; and are
partly reflected towards _F_ & [zeta].
_D F_ & [delta] [zeta]. Those Reflected Rays which are partly refracted
towards _G_ & [eta]. colourless, and partly reflected, towards _H_ &
[theta].
_F H_ & [zeta] [theta]. Those reflected Rays which are refracted towards
_I_ & [iota]. and there paint an other fainter Iris, the colours of which
are contrary to the former 5 4 3 2 1. signifying Purple, Blew, Green,
Yellow, Red, so that the Prism in this posture exhibits four Rainbows.
I know not whether you will think it Inconsiderable to annex to this
Experiment, That we observ'd in a Room not Darken'd, that the Prismatical
Iris (if I may so call it) might be Reflected without losing any of its
several _Colours_ (for we now consider not their _Order_) not onely from a
plain Looking-glass and from the calm Surface of Fair Water, but also from
a Concave Looking-glass; and that Refraction did as little Destroy those
Colours as Reflection. For by the help of a large (double Convex)
Burning-glass through which we Refracted the Suns Beams, we found that one
part of the Iris might be made to appear either beyond, or on this side of
the other Parts of the same Iris; but yet the same Vivid Colours would
appear in the Displac'd part (if I may so term it) as in the other. To
which I shall add, that having, by hiding the side of the Prism, obverted
to the Sun with an Opacous Body, wherein only one small hole was left for
the Light to pass through, reduc'd the Prismatical Iris (cast upon White
Paper) into a very narrow compass, and look'd upon it througn a Microscope;
the Colours appear'd the same as to kind that they did to the naked Eye.
_EXPERIMENT VI._
It may afford matter of Speculation to the Inquisitive, such as you,
_Prophilus_, that as the Colours of outward Objects brought into a Darken'd
Room, do so much depend for their Visibility upon the Dimness of the Light
they are there beheld by; that the ordinary Light of the day being freely
let in upon them, they immediately disappear: so our Tryals have inform'd
us, that as to the Prismatical Iris painted on the Floor by the beams of
the Sun Trajected through a Triangular-glass; though the Colours of it
appear very Vivid ev'n at Noon-day, and in Sun shiny Weather, yet by a more
Powerfull Light they may be made to disappear. For having sometimes, (in
prosecution of some Conjectures of mine not now to be Insisted on,) taken a
large Metalline Concave _Speculum_, and with it cast the converging Beams
of the Sun upon a Prismatical Iris which I had caus'd to be projected upon
the Floor, I found that the over-powerfull Light made the Colours of the
Iris disappear. And if I so Reflected the Light as that it cross'd but the
middle of the Iris, in that part only the Colours vanish'd or were made
Invisible; those parts of the Iris that were on the right and left hand of
the Reflected Light (which seem'd to divide them, and cut the Iris asunder)
continuing to exhibit the same Colours as before. But upon this we must not
now stay to Speculate.
_EXPERIMENT VII._
I have sometimes thought it worth while to take notice, whether or no the
Colours of Opacous Bodies might not appear to the Eye somewhat Diversify'd,
not only by the Disposition of the Superficial parts of the Bodyes
themselves and by the Position of the Eye in Reference to the Object and
the Light, (for these things are Notorious enough;) but according also to
the Nature of the Lucid Body that shines upon them. And I remember that in
Prosecution of this Curiosity, I observ'd a manifest Difference in some
Kinds of Colour'd Bodyes look'd on by Day-light, and afterwards by the
light of the Moon; either directly falling on them or Reflected upon them
from a Concave Looking-glass. But not finding at present in my Collections
about Colours any thing set down of this Kind, I shall, till I have
opportunity to repeat them, content my self to add what I find Register'd
concerning Colours look'd on by Candle-light, in regard that not only the
Experiment is more easie to be repeated, but the Objects being the Same
Sorts of Colour'd Paper lastly mention'd, the Collation of the two
Experiments may help to make the Conjectures they will suggest somewhat the
less uncertain.
Within a few dayes of the time above mention'd, divers Sheets of Colour'd
Paper that had been look'd upon before in the Sunshine were look'd upon at
night by the light of a pretty big Candle, (snuff'd) and the Changes that
were observ'd were these.
The Yellow seem'd much fainter than in the Day, and inclinable to a pale
Straw Colour.
The Red seem'd little Chang'd; but seem'd to Reflect Light more strongly
than any other Colour (for White was none of them.)
A fair Deep Green look'd upon by it self seem'd to be a Dark Blew: But
being look'd upon together with a Dark Blew, appear'd Greenish; and beheld
together with a Yellow appear'd more Blew than at first.
The Blew look'd more like a Deep Purple or Murray than it had done in the
Daylight.
The Purple seem'd very little alter'd.
The Red look'd upon with the Yellow made the Yellow look almost like Brown
Cap-paper.
_N_. The Caution Subjoyned to the third Experiments is also Applicable to
this.
_EXPERIMENT VIII._
But here I must not omit to subjoyn, that to satisfie our Selves, whether
or no the Light of a Candle were not made unsincere, and as it were Ting'd
with a Yellow Colour by the Admixtion of the Corpuscles it assumes from its
Fuel; we did not content our selves with what appears to the Naked Eye, but
taking a pretty thick Rod or Cylinder (for thin Peeces would not serve the
turn) of deep Blew Glass, and looking upon the Candles flame at a
Convenient distance througn it, we perceiv'd as we expected, the Flame to
look Green; which as we often note, is the Colour wont to emerge from the
Composition of Opacous Bodies, which were apart one of them Blew, and the
other Yellow. And this perchance may be the main Reason of that which some
observe, that a sheet of very White Paper being look'd upon by Candle
light, 'tis not easie at first to discern it from a light Yellow or Lemon
Colour; White Bodyes (as we have elsewhere observ'd) having more than those
that are otherwise Colour'd, of a Specular Nature; in regard that though
they exhibit not, (unless they be Polish'd,) the shape of the Luminary that
shines on them, yet they Reflect its Light more Sincere and Untroubl'd, by
either Shades or Refractions, than Bodyes of other Colours (as Blew, or
Green, or Yellow or the like.)
_EXPERIMENT IX._
We took a Leaf of Such Foliated Gold as Apothecaries are wont to Gild their
Pills with; and with the Edge of a Knife, (lightly moysten'd by drawing it
over the Surface of the Tongue, and afterwards) laid upon the edge of the
Gold Leaf; we so fasten'd it to the Knife, that being held against the
light, it conctinu'd extended like a little Flagg. This Leaf being held
very near the Eye, and obverted to the Light, appear'd so full of Pores,
that it seem'd to have such a kind of Transparency as that of a Sive, or a
piece of Cyprus, or a Love-Hood; but the Light that pass'd by these Pores
was in its Passages So Temper'd with Shadow, and Modify'd, that the Eye
discern'd no more a Golden Colour, but a Greenish Blew. And for other's
satisfaction, we did in the Night look upon a Candle through such a Leaf of
Gold; and by trying the Effect of Several Proportions of Distance betwixt
the Leaf, the Eye and the Light, we quickly hit upon such a Position for
the Leaf of Gold, as that the flame, look'd on through it, appear'd of a
Greenish Blew, as we have seen in the Day time. The like Experiment try'd
with a Leaf of Silver succeeded not well.
* * * * *
_EXPERIMENT X._
We have sometimes found in the Shops of our Druggists, a certain Wood,
which is there called _Lignum Nephriticum_, because the Inhabitants of the
Country where it grows, are wont to use the Infusion of it made in fair
Water against the Stone of the Kidneys, and indeed an Eminent Physician of
our Acquaintance, who has very Particularly enquir'd into that Disease,
assures me, that he has found such an Infusion one of the most effectual
Remedyes, which he has ever tried against that formidable Disease. The
ancientest Account I have met with of this Simple, is given us by the
Experienc'd _Monardes_ in these Words. _Nobis,_ says he,[16] _Nova Hispania
mittit quoddam ligni genus crassum & enode, cujus usus jam diu receptus
fuit in his Regionibus ad Renum vitia & urinæ difficultates ac arenulas
pellendas. Fit autem hac ratione, Lignum assulatim & minutim concisum in
limpidissima aqua fontana maceratur, inque ea relinquitur, donec aqua à
bibentibus absumpta sit, dimidia hora post injectum lignum aqua cæruleum
colorem contrabit, qui sensim intenditur pro temporis diuturnitate, tametsi
lignum candidum fit_. This Wood, _Pyrophilus_, may afford us an Experiment,
which besides the singularity of it, may give no small assistance to an
attentive Considerer towards the detection of the Nature of Colours. The
Experiment as we made it is this. Take _Lignum Nephriticum_, and with a
Knife cut it into thin Slices, put about a handfull of these Slices into
two three or four pound of the purest Spring-water, let them infuse there a
night, but if you be in hast, a much shorter time may suffice; _decant_
this Impregnated Water into a clear Glass Vial, and if you hold it directly
between the Light and your Eye, you shall see it wholly Tincted (excepting
the very top of the Liquor, wherein you will some times discern a
Sky-colour'd Circle) with an almost Golden Colour, unless your Infusion
have been made too Strong of the Wood, for in that case it will against the
Light appear somewhat Dark and Reddish, and requires to be diluted by the
addition of a convenient quantity of fair Water. But if you hold this Vial
from the Light, so that your Eye be plac'd betwixt the Window and the Vial,
the Liquor will appear of a deep and lovely Cæruleous Colour, of which
also the drops, if any be lying on the outside of the Glass, will seem to
be very perfectly; And thus far we have try'd the Experiment, and found it
to Succeed even by the Light of Candles of the larger size. If you so hold
the Vial over against your Eyes, that it may have a Window on one side of
it, and a Dark part of the Room both before it and on the other side, you
shall see the Liquor partly of a Blewish and partly of a Golden Colour. If
turning your back to the Window, you powr out some of the Liquor towards
the Light and towards your Eyes, it will seem at the comming out of the
Glass to be perfectly Cæruleous, but when it is fallen down a little way,
the drops may seem Particolour'd, according as the Beams of Light do more
or less fully Penetrate and Illustrate them. If you take a Bason about half
full of Water, and having plac'd it so in the Sun-beams Shining into a
Room, that one part of the Water may be freely illustrated by the Beams of
Light, and the other part of it Darkned by the shadow of the Brim of the
Bason, if then I say you drop of our Tincture, made somewhat strong, both
into the Shaded and Illuminated parts of the Water, you may by looking upon
it from several places, and by a little Agitation of the water, observe
divers pleasing Phænomena which were tedious to particularize. If you powr
a little of this Tincture upon a sheet of White Paper, so as the Liquor may
remain of some depth upon it, you may perceive the Neighbouring drops to be
partly of one Colour, and partly of the other, according to the position of
your Eye in reference to the Light when it looks upon them, but if you powr
off all the Liquor, the Paper will seem Dy'd of an almost Yellow Colour.
And if a sheet of Paper with some of this Liquor in it be plac'd in a
window where the Sunbeams may shine freely on it, then if you turn your
back to the Sun and take a Pen or some such slender Body, and hold it
over-thwart betwixt the Sun and the Liquor, you may perceive that the
Shadow projected by the Pen upon the Liquor, will not all of it be a vulgar
and Dark, but in part a curiously Colour'd shadow, that edge of it, which
is next the Body that makes it, being almost of a lively Golden Colour, and
the remoter verge of a Cæruleous one.
[16] _Nicolaus Monardes_ lib _simplic. ex India allatis_, cap. 27.
These and other Phænomena, which I have observ'd in this delightfull
Experiment, divers of my friends have look'd upon not without some wonder,
and I remember an excellent Oculist finding by accident in a friends
Chamber a fine Vial full of this Liquor, which I had given that friend, and
having never heard any thing of the Experiment, nor having any Body near
him that could tell him what this strange Liquor might be, was a great
while apprehensive, as he presently after told me, that some strange new
distemper was invading his Eyes. And I confess that the unusualness of the
Phænomena made me very sollicitous to find out the Cause of this
Experiment, and though I am far from pretending to have found it, yet my
enquiries have, I suppose, enabled me to give such hints, as may lead your
greater sagacity to the discovery of the Cause of this wonder. And first
finding that this Tincture, if it were too copious in the water, Kept the
Colours from being so lively, and their Change from being so discernable,
and finding also that the Impregnating Virtue of this Wood did by its being
frequently Infus'd in New Water by degrees Decay, I Conjectur'd that the
Tincture afforded by the Wood must proceed from some Subtiler parts of it
drawn forth by the Water, which swimming too and fro in it did so Modifie
the Light, as to exhibit such and such Colours; and because these Subtile
parts were so easily Soluble even in Cold water, I concluded that they must
abound with Salts, and perhaps contain much of the Essential Salt, as the
_Chymists_ call it, of the Wood. And to try whether these Subtile parts
were Volatile enough to be Distill'd, without the Dissolution of their
Texture, I carefully Distill'd some of the Tincted Liquor in very low
Vessels, and the gentle heat of a Lamp Furnace; but found all that came
over to be as Limpid and Colourless as Rock-water, and the Liquor remaining
in the Vessel to be so deeply Cæruleous, that it requir'd to be oppos'd to
a very strong Light to appear of any other Colour. I took likewise a Vial
with Spirit of Wine, and a little Salt of Harts-horn, and found that there
was a certain proportion to be met with betwixt the Liquor and the Salt,
which made the Mixture fit to exhibit some little Variety of Colours not
Observable in ordinary Liquors, as it was variously directed in reference
to the Light and the Eye, but this Change of Colour was very far short from
that which we had admir'd in our Tincture. But however, I suspected that
the Tinging Particles did abound with such Salts, whose Texture, and the
Colour springing from it, would probably be alter'd by peircing Acid Salts,
which would in likelihood either make some Dissipation of their Parts, or
Associate themselves to the like Bodies, and either way alter the Colour
exhibited by them; whereupon Pouring into a small Vial full of Impregnated
Water, a very little Spirit of Vinegar, I found that according to my
Expectation, the Cæruleous Colour immediately vanish'd, but was deceiv'd
in the Expectation I had, that the Golden Colour would do so too; for,
which way soever I turned the Vial, either to or from the Light, I found
the Liquor to appear always of a Yellowish Colour and no other: Upon this I
imagin'd that the Acid Salts of the Vinegar having been able to deprive the
Liquor of its Cæruleous Colour, a Sulphureous Salt being of a contrary
Nature, would be able to Mortifie the Saline Particles of Vinegar, and
Destroy their Effects; And accordingly having plac'd my Self betwixt the
Window, and the Vial, and into the Same Liquor dropt a few drops of Oyl of
Tartar _per Deliquium_, (as _Chymists_ call it) I observ'd with pleasure,
that immediately upon the Diffusion of this Liquor, the Impregnated Water
was restor'd to its former Cæruleous Colour; And this Liquor of _Tartar_
being very Ponderous, and falling at first to the Bottom of the Vial, it
was easie to observe that for a little while the Lower part of the Liquor
appear'd deeply Cæruleous; whilst all the Upper part retain'd its former
Yellowness, which it immediately lost as soon as either Agitation or Time
had made a competent Diffusion of the Liquor of _Tartar_ through the Body
of the former Tincture; and this restored Liquor did, as it was Look'd upon
against or from the Light, exhibit the Same _Phænomena_ as the Tincted
Water did, before either of the Adventitious Liquors was pour'd into it.
Having made, _Pyrophilus_, divers Tryals upon this Nephritick Wood, we
found mention made of it by the Industrious Jesuit _Kircherus_, who having
received a Cup Turned of it from the _Mexican_ Procurator of his Society,
has probably receiv'd also from him the Information he gives us concerning
that _Exotick_ Plant, and therefore partly for that Reason, and partly
because what he Writes concerning it, does not perfectly agree with what we
have deliver'd, we shall not Scruple to acquaint you in his own Words, with
as much of what he writes concerning our Wood, as is requisite to our
present purpose. _Hoc loco_ (says he)[17] _neutiquam omittendum duximus
quoddam ligni candidi Mexicani genus, quod Indigenæ Coalle & Tlapazatli
vocant, quod etsi experientia hucusque non nisi Cæruleo aquam colore
tingere docuerit, nos tamen continua experientia invenimus id aquam in omne
Colorum genus transformare, quod merito cuipiam Paradoxum videri posset;
Ligni frutex grandis, ut aiunt, non rarò in molem arboris excrescit,
truncus illius eft crassus, enodis, instar piri arboris, folia ciceris
foliis, aut rutæ haud absimilia, flores exigui, oblongi, lutei & spicatim
digesti; est frigida & humida planta, licet parum recedat à medio
temperamento. Hujus itaque descriptæ arboris lignum in poculum efformatum,
aquam eidem infusam primo in aquam intense Cæruleam, colore floris
Buglossæ; tingit, & quo diutius in eo steterit, tanto intensiorem colorem
acquirit. Hanc igitur aquam si Vitreæ Sphæræ infuderis, lucique exposueris,
ne ullum quidem Cærulei coloris vestigium apparebit, sed instar aquæ puræ
putæ fontanæ limpidam claramque aspicientibus se præbebit. Porro si hanc
phialam vitream versus locum magis umbrosum direxeris, totus humor
gratissimum virorem referet; si adhuc umbrosioribus locis, subrubrum, & sic
pro rerum objectarum conditione, mirum dictu, colorem mutabit; in tenebris
verò vel in vase opaco posita, Cæruleum colorem suum resumet._
[17] Kircher. Art. Mag. lucis & umbræ, _lib. 1. part. 3._
In this passage we may take notice of the following Particulars. And first,
he calls it a White _Mexican_ Wood, whereas (not to mention that
_Mornardes_ informs us that it is brought out of _Nova Hispania_) the Wood
that we have met with in several places, and employ'd as _Lignum
Nephriticum_, was not White, but for the most part of a much Darker Colour,
not unlike that of the Sadder Colour'd Wood of Juniper. 'Tis true, that
_Monardes_ himself also says, that the Wood is White; and it is affirm'd,
that the Wood which is of a Sadder Colour is Adulterated by being Imbu'd
with the Tincture of a Vegetable, in whose Decoction it is steep'd. But
having purposely enquir'd of the Eminentest of our _English_ Druggists, he
peremptorily deny'd it. And indeed, having consider'd some of the fairest
Round pieces of this Wood that I could meet with in these Parts, I had
Opportunity to take notice that in one or two of them it was the External
part of the Wood that was White, and the more Inward part that was of the
other Colour, the contrary of which would probably have appear'd, if the
Wood had been Adulterated after the afore-mention'd manner. And I have at
present by me a piece of such Wood, which for about an Inch next the Bark
is White, and then as it were abruptly passes to the above-mention'd
Colour, and yet this Wood by the Tincture, it afforded us in Water, appears
to have its Colour'd part Genuine enough; for as for the White part, it
appears upon tryal of both at once, much less enrich'd with the tingent
Property.
Next, whereas our Author tells us, that the Infusion of this Wood expos'd
in a Vial to the Light, looks like Spring-water, in which he afterwards
adds, that there is no Tincture to be seen in it, our Observation and his
agree not, for the Liquor, which opposed to the Darker part of a Room
exhibits a Sky-colour, did constantly, when held against the Light, appear
Yellowish or Reddish, according as its Tincture was more Dilute or Deep;
and then, whereas it has been already said, that the Cæruleous Colour was
by Acid Salts abolished, this Yellowish one surviv'd without any
considerable Alteration, so that unless our Author's Words be taken in a
very Limited Sense, we must conclude, that either his Memory mis-inform'd
him, or that his White _Nephritick_ Wood, and the Sadder Colour'd one which
we employ'd, were not altogether of the same Nature: What he mentions of
the Cup made of _Lignum Nephriticum_, we have not had Opportunity to try,
not having been able to procure pieces of that Wood great enough, and
otherwise fit to be turned into Cups; but as for what he says in the Title
of his Experiment, that this Wood tinges the Water with all Sorts of
Colours, that is much more than any of those pieces of Nephritick Wood that
we have hitherto employ'd, was able to make good; The change of Colours
discernable in a Vial full of Water, Impregnated by any of them, as it is
directed towards a place more Lightsome or Obscure, being far from
affording a Variety answerable to so promising a Title. And as for what he
tells us, that in the Dark the Infusion of our Wood will resume a
Cæruleous Colour, I wish he had Inform'd us how he Try'd it.
But this brings into my mind, that having sometimes for Curiosity sake,
brought a round Vial with a long Neck fill'd with the Tincture of _Lignum
Nephriticum_ into the Darken'd Room already often mention'd, and holding it
sometimes in, sometimes near the Sun-beams that enter'd at the hole, and
sometimes partly in them, and partly out of them, the Glass being held in
several postures, and look'd upon from several Neighbouring parts of the
Room, disclos'd a much greater Variety of Colours than in ordinary
inlightn'd Rooms it is wont to do; exhibiting, besides the usual Colours, a
Red in some parts, and a Green in others, besides Intermediate Colours
produc'd by the differing Degrees, and odd mixtures of Light and Shade.
By all this You may see, _Pyrophilus_, the reasonableness of what we
elsewhere had occasion to mention, when we have divers times told you, that
it is usefull to have New Experiments try'd over again, though they were,
at first, made by Knowing and Candid Men, such Reiterations of Experiments
commonly exhibiting some New Phænomena, detecting some Mistake or hinting
some Truth, in reference to them, that was not formerly taken notice of.
And some of our friends have been pleas'd to think, that we have made no
unusefull addition to this Experiment, by shewing a way, how in a moment
our Liquor may be depriv'd of its Blewness, and restor'd to it again by the
affusion of a very few drops of Liquors, which have neither of them any
Colour at all of their own. And that which deserves some particular wonder,
is, that the Cæruleous Tincture of our Wood is subject by the former
Method to be Destroy'd or Restor'd, the Yellowish or Reddish Tincture
continuing what it was. And that you may see, that Salts are of a
considerable use in the striking of Colours, let me add to the many
Experiments which may be afforded us to this purpose by the Dyers Trade,
this Observation; That as far as we have hitherto try'd, those Liquors in
general that are strong of Acid Salts have the Power of Destroying the
Blewness of the Infusion of our Wood, and those Liquors indiscriminatly
that abound with Sulphureous Salts, (under which I comprehend the Urinous
and Volatile Salts of Animal Substances, and the Alcalisate or fixed Salts
that are made by Incineration) have the vertue of Restoring it.
_A Corollary of the Tenth Experiment._
That this Experiment, _Pyrophilus_, may be as well Usefull as Delightfull
to You, I must mind You, _Pyrophilus_, that in the newly mention'd
Observation, I have hinted to You a New and Easie way of Discovering in
many Liquors (for I dare not say in all) whether it be an Acid or
Sulphureous Salt, that is Predominant; and that such a Discovery is
oftentimes of great Difficulty, and may frequently be of great Use, he that
is not a Stranger to the various Properties and Effects of Salts, and of
how great moment it is to be able to distinguish their Tribes, may readily
conceive. But to proceed to the way of trying other Liquors by an Infusion
of our Wood, take it briefly thus. Suppose I have a mind to try whether I
conjecture aright, when I imagine that Allom, though it be plainly a Mixt
Body, does abound rather with Acid than Sulphureous Salt. To satisfie my
self herein, I turn my back to the Light, and holding a small Vial full of
the Tincture of _Lignum Nephriticum_, which look'd upon in that Position,
appears Cæruleous, I drop into it a little of a strong Solution of Allom
made in Fair Water, and finding upon the Affusion and shaking of this New
liquor, that the Blewness formerly conspicuous in our Tincture does
presently vanish, I am thereby incited to suppose, that the Salt
Prædominant in Allom belongs to the Family of Sour Salts; but if on the
other side I have a mind to examine whether or no I rightly conceive that
Salt of Urine, or of Harts-horn is rather of a Saline Sulphureous (if I may
so speak) than of an Acid Nature, I drop a little of the Saline Spirit of
either into the Nephritick Tincture, and finding that the Cæruleous Colour
is rather thereby Deepned than Destroy'd, I collect that the Salts, which
constitute these Spirits, are rather Sulphureous than Acid. And to satisfie
my self yet farther in this particular, I take a small Vial of fresh
Tincture, and placing both it and my self in reference to the Light as
formerly, I drop into the Infusion just as much Distill'd Vinegar, or other
Acid liquor as will serve to Deprive it of its Blewness (which a few drops,
if the Sour Liquor be strong, and the Vial small will suffice to do) then
without changing my Posture, I drop and shake into the same Vial a small
proportion of Spirit of Hartshorn or Urine, and finding that upon this
affusion, the Tincture immediately recovers its Cæruleous Colour, I am
thereby confirm'd firm'd in my former Opinion, of the Sulphureous Nature of
these Salts. And so, whereas it is much doubted by Some Modern Chymists to
what sort of Salt, that which is Prædominant in Quick-lime belongs, we have
been perswaded to referr it rather to Lixiviate than Acid Salts, by having
observ'd, that though an Evaporated Infusion of it will scarce yield such a
Salt, as Ashes and other Alcalizate Bodyes are wont to do, yet if we
deprive our Nephritick Tincture of its Blewness by just so much Distill'd
Vinegar as is requisite to make that Colour Vanish, the _Lixivium_ of
Quick-lime will immediately upon its Affusion recall the Banished Colour;
but not so Powerfully as either of the Sulphureous Liquors formerly
mention'd. And therefore I allow my self to guess at the _Strength_ of the
Liquors examin'd by this Experiment, by the _Quantity_ of them which is
sufficient to Destroy or Restore the Cæruleous Colour of our Tincture. But
whether concerning Liquors, wherein neither Acid nor Alcalisate Salts are
Eminently Prædominant, our Tincture will enable us to conjecture any thing
more than that such Salts are not Prædominant in them, I take not upon me
to determine here, but leave to further Tryal; For I find not that Spirit
of Wine, Spirit of Tartar freed from Acidity, or Chymical Oyl of
Turpentine, (although Liquors which must be conceiv'd very Saline, if
Chymists have, which is here no place to Dispute, rightly ascrib'd tasts to
the Saline Principle of Bodyes,) have any Remarkable Power either to
deprive our Tincture of its Cæruleous Colour, or restore it, when upon the
Affusion of Spirit of Vinegar it has disappear'd.
_EXPERIMENT XI._
And here I must not omit, _Pyrophilus_, to inform You, that we can shew You
even in a Mineral Body something that may seem very near of Kin to the
Changeable Quality of the Tincture of _Lignum Nephriticum_, for we have
several flat pieces of Glass, of the thickness of ordinary Panes for
Windows one of which being interposed betwixt the Eye and a clear Light,
appears of a Golden Colour, not much unlike that of the moderate Tincture
of our Wood, but being so look'd upon as that the Beams of light are not so
much Trajected thorough it as Reflected from it to the Eye, that Yellow
seems to degenerate into a pale Blew, somewhat like that of a Turquoise.
And what which may also appear strange, is this, that if in a certain
posture you hold one of these Plates Perpendicular to the Horizon, so that
the Sun-beams shine upon half of it, the other half being Shaded, You may
see that the part Shin'd upon will be of a much Diluter Yellow than the
Shaded part which will appear much more Richly Colour'd; and if You alter
the Posture of the Glass, so that it be not held Perpendicular, but
Parallel in reference to the Horizon, You may see, (which perhaps you will
admire) the Shaded part look of a Golden Colour, but the other that the Sun
shines freely on, will appear considerably Blew, and as you remove any part
of the Glass thus held Horizontally into the Sun-beams or Shade, it will in
the twinkling of an Eye seem to pass from one of the above mention'd
Colours to the other, the Sun-beams Trajected through it upon a sheet of
White Paper held near it, do colour it with a Yellow, somewhat bordering
upon a Red, but yet the Glass may be so oppos'd to the Sun, that it may
upon Paper project a mix'd Colour here and there more inclin'd to Yellow,
and here and there more to Blew. The other Phænomena of this odd Glass, I
fear it would be scarce worth while to Record, and therefore I shall rather
advertise You, _First_ that in the trying of these Experiments with it, you
must take notice that one of the sides has either alone, or at least
principally its Superficial parts dispos'd to the Reflection of the Blew
Colour above nam'd, and that therefore you must have a care to keep that
side nearest to the Eye. And next, that we have our selves made Glasses not
unfit to exhibit an Experiment not unlike that I have been speaking of, by
laying upon pieces of Glass some very finely foliated Silver, and giving it
by degrees a much stronger Fire than is requisite or usual for the Tinging
of Glasses of other Colours. And this Experiment, not to mention that it
was made without a Furnace in which Artificers that Paint Glass are wont to
be very Curious, is the more considerable, because, that though a Skilfull
Painter could not deny to me that 'twas with Silver he Colour'd his Glasses
Yellow; yet he told me, that when to Burn them (as they speak) he layes on
the plates of Glass nothing but a _Calx_ of Silver Calcin'd without
Corrosive Liquors, and Temper'd with Fair Water, the Plates are Ting'd of a
fine Yellow that looks of a Golden Colour, which part soever of it you turn
to or from the Light; whereas (whether it be what an Artificer would call
Over-doing, or Burning, or else the imploying the Silver Crude that makes
the Difference,) we have found more than once, that some Pieces of Glass
prepar'd as we have related, though held against the Light they appear'd of
a Transparent Yellow, yet look'd on with ones back turn'd to the Light they
exhibited an Untransparent Blew.
_EXPERIMENT XII._
If you will allow me, _Pyrophilus_, for the avoiding of Ambiguity, to
imploy the Word Pigments, to signifie such prepared materials (as
Cochinele, Vermilion, Orpiment,) as Painters, Dyers and other Artificers
make use of to impart or imitate particular Colours, I shall be the better
understood in divers passages of the following papers, and particularly
when I tell you, That the mixing of Pigments being no inconsiderable part
of the Painters Art, it may seem an Incroachment in me to meddle with it.
But I think I may easily be excus'd (though I do not altogether pass it by)
if I restrain my self to the making of a Transient mention of some few of
their Practices about this matter; and that only so far forth, as may
warrant me to observe to you, that there are but few Simple and Primary
Colours (if I may so call them) from whose Various Compositions all the
rest do as it were Result. For though Painters can imitate the Hues (though
not always the Splendor) of those almost Numberless differing Colours that
are to be met with in the Works of Nature, and of Art, I have not yet
found, that to exhibit this strange Variety they need imploy any more than
_White_, and _Black_, and _Red_, and _Blew_, and _Yellow_; these _five_,
Variously _Compounded_, and (if I may so speak) _Decompounded_, being
sufficient to exhibit a Variety and Number of Colours, such, as those that
are altogether Strangers to the Painters Pallets, can hardly imagine.
Thus (for Instance) Black and White differingly mix'd, make a Vast company
of Lighter and Darker Grays.
Blew and Yellow make a huge Variety of Greens.
Red and Yellow make Orange Tawny.
Red with a little White makes a Carnation.
Red with an Eye of Blew, makes a Purple; and by these simple Compositions
again Compounded among themselves, the Skilfull Painter can produce what
kind of Colour he pleases, and a great many more than we have yet Names
for. But, as I intimated above, 'tis not my Design to prosecute this
Subject, though I thought it not unfit to take some Notice of it, because
we may hereafter have occasion to make use of what has been now deliver'd,
to illustrate the Generation of Intermediate Colours; concerning which we
must yet subjoyn this Caution, that to make the Rules about the Emergency
of Colours, fit to be Relied upon, the Corpuscles whereof the Pigments
consist must be such as do not Destroy one anothers Texture, for in case
they do, the produced Colour may be very Different from that which would
Result from the Mixture of other harmless Pigments of the same Colours, as
I shall have Occasion to shew ere long.
_EXPERIMENT XIII._
It may also give much light to an Enquirer into the Nature of Colours, to
know that not only in Green, but in many (if not all) other Colours, the
Light of the Sun passing through Diaphanous Bodies of differing Hues may be
tinged of the same Compound Colour, as if it came from some Painters
Colours of the same Denomination, though this later be exhibited by
Reflection, and be (as the former Experiment declares) manifestly
Compounded of material Pigments. Wherefore to try the Composition of
Colours by Trajection, we provided several Plates of Tinged Glass, which
being laid two at a time one on the top of another, the Object look'd upon
through them both, appear'd of a Compounded Colour, which agrees well with
what we have observ'd in the second Experiment, of Looking against the
Light through differingly Colour'd Papers. But we thought the Experiment
would be more Satisfactory, if we procur'd the Sun-beams to be so Ting'd in
their passage through Plates of Glass, as to exhibit the Compounded Colour
upon a Sheet of White Paper. And though by reason of the Thickness of the
Glasses, the Effect was but Faint, even when the Sun was High and Shin'd
forth clear, yet, we easily remedied that by Contracting the Beams we cast
on them by means of a Convex Burning-glass, which where it made the Beams
much converge Increas'd the Light enough to make the Compounded Colour very
manifest upon the Paper. By this means we observ'd, that the Beams
trajected through Blew and Yellow compos'd a Green, that an intense and
moderate Red did with Yellow make differing degrees of Saffron, and Orange
Tawny Colours, that Green and Blew made a Colour partaking of both, such as
that which some Latin Writers call _Pavonaceus_, that Red and Blew made a
Purple, to which we might add other Colours, that we produc'd by the
Combinations of Glasses differingly Ting'd, but that I want proper Words to
express them in our Language, and had not when we made the Tryals, the
Opportunity of consulting with a Painter, who perchance might have Suppli'd
me with some of the terms I wanted.
I know not whether it will be requisite to subjoyn on this Occasion, what I
tried concerning Reflections from Colour'd Glasses, and other Transparent
Bodies, namely, that having expos'd four or five sorts of them to the Sun,
and cast the Reflected Beams upon White Paper held near at hand, the Light
appear'd not manifestly Ting'd, but as if it had been Reflected from the
Impervious parts of a Colourless Glass, only that Reflected from the Yellow
was here and there stain'd with the same Colour, as if those Beams were not
all Reflected from the Superficial, but some from the Internal parts of the
Glass; upon which Occasion you may take notice, that a Skilfull Tradesman,
who makes such Colour'd Glass told me, that where as the Red Pigment was
but Superficial, the Yellow penetrated to the very midst of the Plate. But
for further Satisfaction, not having the Opportunity to Foliate those
Plates, and so turn them into Looking-glasses, we Foliated a Plate of
_Muscovy_ Glass, and then laying on it a little Transparent Varnish of a
Gold Colour, we expos'd it to the Sun-beams, so as to cast them upon a Body
fit to receive them, on which the Reflected Light, appearing, as we
expected, Yellow, manifested that Rebounding from the Specular part of the
_Selenitis_, it was Ting'd in its return with the Colour of the Transparent
Varnish through which it pass'd.
_EXPERIMENT XIV._
After what we have said of the Composition of Colours, it will now be
seasonable to annex some Experiments that we made in favour of those
Colours, that are taught in the Schools not to be Real, but only Apparent
and Phantastical; For we found by Tryals, that these Colours might be
Compounded, both with True and Stable Colours, and with one another, as
well as unquestionably Genuine and Lasting Colours, and that the Colours
resulting from such Compositions, would respectively deserve the same
Denominations.
For first, having by the Trajection of the Sun-beams through a Glass-prism
thrown an Iris on the Floor, I found that by placing a Blew Glass at a
convenient distance betwixt the Prism and the Iris, that part of the Iris
that was before Yellow, might be made to appear Green, though not of a
Grass Green, but of one more Dilute and Yellowish. And it seems not
improbable, that the narrow Greenish List (if I may so call it) that is
wont to be seen between the Yellow and Blew parts of the Iris, is made by
the Confusion of those two Bordering Colours.
Next, I found, that though the want of a sufficient Liveliness in either of
the Compounding Colours, or a light Error in the manner of making the
following Tryals, was enough to render some of them Unsuccessfull, yet when
all necessary Circumstances were duely observ'd, the Event was answerable
to our Expectation and Desire.
And (as I formerly Noted) that Red and Blew compound a Purple, so I could
produce this last nam'd Colour, by casting at some Distance from the Glass
the Blew part of the Prismatical Iris (as I think it may be call'd for
Distinction sake) upon a Lively Red, (for else the Experiment succeeds not
so well.) And I remember, that sometimes when I try'd this upon a piece of
Red Cloath, _that_ part of the Iris which would have been Blew, (as I try'd
by covering that part of the Cloath with a piece of White Paper) and
Compounded with the Red, wherewith the Cloath was Imbued before, appear'd
of a fair Purple, did, when I came to View it near at hand, look very Odly,
as if there were some strange Reflection or Refraction or both made in the
Hairs of which that Cloath was composed.
Calling likewise the Prismatical Iris upon a very Vivid Blew, I found that
part of it, which would else have been the Yellow, appear Green. (Another
somewhat differing Tryal, and yet fit to confirm this, you will find in the
fifteenth Experiment.)
But it may seem somewhat more strange, that though the Prismatical Iris
being made by the Refraction of Light through a Body that has no Colour at
all, must according to the Doctrine of the Schools consist of as purely
Emphatical Colours, as may be, yet even these may be Compounded with one
another, as well as Real Colours in the Grossest Pigments. For I took at
once two Triangular Glasses, and one of them being kept fixt in the same
Posture, that the Iris it projected on the Floor might not Waver, I cast on
the same Floor another Iris with the other Prism, and Moving it too and fro
to bring what part of the second Iris I pleas'd, to fall upon what part of
the first I thought fit, we did sometimes (for a small Errour suffices to
hinder the Success) obtain by this means a Green Colour in that part of the
more Stable Iris, that before was Yellow, or Blew, and frequently by
casting those Beams that in one of the Iris's made the Blew upon the Red
parts of the other Iris, we were able to produce a lovely Purple, which we
can Destroy or Recompose at pleasure, by Severing and Reapproaching the
Edges of the two Iris's.
_EXPERIMENT XV._
On this occasion, _Pyrophilus_, I shall add, that finding the Glass-prism
to be the usefullest Instrument Men have yet imploy'd about the
Contemplation of Colours, and considering that Prisms hitherto in use are
made of Glass, Transparent and Colourless, I thought it would not be amiss
to try, what change the Superinduction of a Colour, without the Destruction
of the Diaphaneity, would produce in the Colours exhibited by the Prism.
But being unable to procure one to be made of Colour'd Glass, and fearing
also that if it were not carefully made, the Thickness of it would render
it too Opacous, I endeavoured to substitute one made of Clarify'd Rosin, or
of Turpentine brought (as I elsewhere teach) to the consistence of a
Transparent Gum. But though these Endeavours were not wholly lost, yet we
found it so difficult to give these Materials their true Shape, that we
chose rather to Varnish over an ordinary Prism with some of these few
Pigments that are to be had Transparent; as accordingly we did first with
Yellow, and then with Red, or rather Crimson, made with Lake temper'd with
a convenient Oyl, and the Event was, That for want of good Transparent
Colours, (of which you know there are but very few) both the Yellow and the
Red made the Glass so Opacous, (though the Pigment were laid on but upon
two Sides of the Glass, no more being absolutely necessary) that unless I
look'd upon an Inlightned Window, or the Flame of a Candle, or some other
Luminous or very Vivid object, I could scarce discern any Colours at all,
especially when the Glass was cover'd with Red. But when I did look on such
Objects, it appear'd (as I expected) that the Colour of the Pigment had
Vitiated or Drown'd some of those which the Prism would according to its
wont have exhibited, and mingling with others, Alter'd them: as I remember,
that both to my Eyes, and others to whom I show'd it, when the Prism was
cover'd with Yellow, it made those Parts of bright Objects, where the Blew
would else have been Conspicuous, appear of a light Green. But,
_Pyrophilus_, both the Nature of the Colours, and the Degree of
Transparency, or of Darkness in the Pigment, besides divers other
Circumstances, did so vary the _Phænomena_ of these Tryals, that till I can
procure small Colour'd Prisms, or Hollow ones that may be filled with
Tincted Liquor, or obtain Some better Pigments than those I was reduc'd to
imploy, I shall forbear to Build any thing upon what has been delivered,
and shall make no other use of it, than to invite you to prosecute the
Inquiry further.
_EXPERIMENT XVI._
And here, _Pyrophilus_, since we are treating of Emphatical Colours, we
shall add what we think not unworthy your Observation, and not unfit to
afford some Exercise to the Speculative. For there are some Liquors, which
though Colourless themselves, when they come to be Elevated, and Dispers'd
into Exhalations, exhibit a conspicuous Colour, which they lose again, when
they come to be Reconjoyn'd into a Liquor, as good Spirit of _Nitre_; or
upon its account strong _Aqua-fortis_, though devoid of all appearance of
Redness whilst they continue in the form of a Liquor, if a little Heat
chance to turn the Minute parts of them into Vapour, the Steam will appear
of a Reddish or deep Yellow Colour, which will Vanish when those
Exhalations come to resume the form of Liquor.
And not only if you look upon a Glass half full of _Aqua-fortis_, or Spirit
of _Nitre_, and half full of _Nitrous_ steams proceeding from it, you will
see the Upper part of the Glass of the Colour freshly mention'd, if through
it you look upon the Light. But which is much more considerable, I have
tried, that putting _Aqua-fortis_ in a long clear Glass, and adding a
little Copper or some such open Metall to it, to excite Heat and Fumes, the
Light trajected through those Fumes, and cast upon a sheet of White Paper,
did upon that appear of the Colour that the Fumes did, when directly Look'd
upon, as if the Light were as well Ting'd in its passage through these
Fumes, as it would have been by passing through some Glass or Liquor in
which the same Colour was Inherent.
To which I shall further add, that having sometimes had the Curiosity to
observe whether the Beams of the Sun near the Horizon trajected through a
very Red Sky, would not (though such rednesses are taken to be but
Emphatical Colours) exhibit the like Colour, I found that the Beams falling
within a Room upon a very White Object, plac'd directly opposite to the
Sun, disclos'd a manifest Redness, as if they had pass'd through a Colour'd
_Medium_.
_EXPERIMENT XVII._
The emergency, _Pyrophilus_, of Colours upon the Coalition of the Particles
of such Bodies as were neither of them of the Colour of that Mixture
whereof they are the Ingredients, is very well worth our attentive
Observation, as being of good use both Speculative and Practical; For much
of the Mechanical use of Colours among Painters and Dyers, doth depend upon
the Knowledge of what Colours may be produc'd by the Mixtures of Pigments
so and so Colour'd. And (as we lately intimated) 'tis of advantage to the
contemplative Naturalist, to know how many and which Colours are Primitive
(if I may so call them) and Simple, because it both eases his Labour by
confining his most sollicitous Enquiry to a small Number of Colours upon
which the rest depend, and assists him to judge of the nature of particular
compounded Colours, by shewing him from the Mixture of what more Simple
ones, and of what Proportions of them to one another, the particular Colour
to be consider'd does result. But because to insist on the Proportions, the
Manner and the Effects of such Mixtures would oblige me to consider a
greater part of the Painters Art and Dyers Trade, than I am well acquainted
with, I confin'd my self to make Trial of _several ways to produce Green_,
by the composition of Blew and Yellow. And shall in this place both
Recapitulate most of the things I have Dispersedly deliver'd already
concerning that Subject, and Recruit them.
And first, whereas Painters (as I noted above) are wont to make Green by
tempering Blew and Yellow, both of them made into a soft Consistence, with
either Water or Oyl, or some Liquor of Kin to one of those two, according
as the Picture is to be Drawn with those they call _water Colours_, or
those they term _Oyl Colours_, I found that by choosing fit Ingredients,
and mixing them in the form of Dry Powders, I could do, what I could not if
the Ingredients were temper'd up with a Liquor; But the Blew and Yellow
Powders must not only be finely Ground, but such as that the Corpuscles of
the one may not be too unequal to those of the other, lest by their
Disproportionate Minuteness the Smaller cover and hide the Greater. We us'd
with good success a slight Mixture of the fine Powder of Bise, with that of
Orpiment, or that of good Yellow Oker, I say a _slight_ Mixture, because we
found that an _exquisite_ Mixture did not do so well, but by lightly
mingling the two Pigments in several little Parcels, those of them in which
the Proportion and Manner of Mixture was more Lucky, afforded us a good
Green.
2. We also learn'd in the Dye-houses, that Cloth being Dy'd Blew with Woad,
is afterwards by the Yellow Decoction of _Luteola_ or Woud-wax or Wood-wax
Dy'd into a Green Colour.
3. You may also remember what we above Related, where we intimated, that
having in a Darkn'd Room taken two Bodies, a Blew and a Yellow, and cast
the Light Reflected from the one upon the other, we likewise obtain'd a
Green.
4. And you may remember, that we observ'd a Green to be produc'd, when in
the same Darkn'd Room we look'd at the Hole at which alone the Light
enter'd, through the Green and Yellow parts of a sheet of Marbl'd Paper
laid over one another.
5. We found too, that the Beams of the Sun being trajected through two
pieces of Glass, the one Blew and the other Yellow, laid over one another,
did upon a sheet of White paper on which they were made to fall, exhibit a
lovely Green.
6. I hope also, that you have not already forgot, what was so lately
deliver'd, concerning the composition of a Green, with a Blew and Yellow;
of which most Authors would call the one a _Real_, and the other an
_Emphatical_.
7. And I presume, you may have yet fresh in your memory, what the
fourteenth Experiment informs you, concerning the exhibiting of a Green, by
the help of a Blew and Yellow, that were both of them Emphatical.
8. Wherefore we will proceed to take notice, that we also devis'd a way of
trying whether or no Metalline Solutions though one of them at least had
its Colour Adventitious, by the mixture of the _Menstruum_ employ'd to
dissolve it, might not be made to compound a Green after the manner of
other Bodies. And though this seem'd not easie to be perform'd by reason of
the Difficulty of finding Metalline Solutions of the Colour requisite, that
would mix without Præcipitating each other; yet after a while having
consider'd the matter, the first Tryal afforded me the following
Experiment. I took a High Yellow Solution of good Gold in _Aqua-Regis_,
(made of _Aqua-fortis_, and as I remember half its weight of Spirit of
Salt) To this I put a due Proportion of a deep and lovely Blew Solution of
Crude Copper, (which I have elsewhere taught to be readily Dissoluble in
strong Spirit of Urine) and these two Liquors though at first they seem'd a
little to Curdle one another, yet being throughly mingl'd by Shaking, they
presently, as had been Conjectur'd, united into a Transparent Green Liquor,
which continu'd so for divers days that I kept it in a small Glass wherein
'twas made, only letting fall a little Blackish Powder to the Bottom. The
other _Phænomena_ of this Experiment belong not to this place, where it may
suffice to take notice of the Production of a Green, and that the
Experiment was more than once repeated with Success.
9. And lastly, to try whether this way of compounding Colours would hold
ev'n in Ingredients actually melted by the Violence of the Fire, provided
their Texture were capable of safely induring Fusion, we caus'd some Blew
and Yellow Ammel to be long and well wrought together in the Flame of a
Lamp, which being Strongly and Incessantly blown on them kept them in some
degree of Fusion, and at length (for the Experiment requires some Patience
as well as Skil) we obtain'd the expected Ammel of a Green Colour.
I know not, _Pyrophilus_, whether it be worth while to acquaint you with
the ways that came into my Thoughts, whereby in some measure to explicate
the first of the mention'd ways of making a Green; for I have sometimes
Conjectur'd, that the mixture of the Bise and the Orpiment produc'd a Green
by so altering the Superficial Asperity, which each of those Ingredients
had apart, that the Light Incident on the mixture was Reflected with
differing Shades, as to Quantity, or Order, or both, from those of either
of the Ingredients, and such as the Light is wont to be Modify'd with, when
it Reflects from Grass, or Leaves, or some of those other Bodies that we
are wont to call Green. And sometimes too I have doubted, whether the
produced Green might not be partly at least deriv'd from this, That the
Beams that Rebound from the Corpuscles of the Orpiment, giving one kind of
stroak upon the _Retina_, whose Perception we call Yellow, and the Beams
Reflected from the Corpuscles of the Bise, giving another stroak upon the
same _Retina_, like to Objects that are Blew, the Contiguity and Minuteness
of these Corpuscles may make the Appulse of the Reflected Light fall upon
the _Retina_ within so narrow a Compass, that the part they Beat upon being
but as it were a Physical point, they may give a Compounded stroak, which
may consequently exhibit a Compounded and new Kind of Sensation, as we see
that two Strings of a Musical Instrument being struck together, making two
Noises that arrive at the Ear at the same time as to Sense, yield a Sound
differing from either of them, and as it were Compounded of both; Insomuch
that if they be Discordantly ton'd, though each of them struck apart would
yield a Pleasing Sound, yet being struck together they make but a Harsh and
troublesome Noise. But this not being so fit a place to prosecute
Speculations, I shall not insist, neither upon these Conjectures nor any
others, which the Experiment we have been mentioning may have suggested to
me. And I shall leave it to you, _Pyrophilus_, to derive what Instruction
you can from comparing together the Various ways whereby a Yellow and a
Blew can be made to Compound a Green. That which I now pretend to, being
only to shew that the first of those mention'd ways, (not to take at
present notice of the rest) does far better agree with our Conjectures
about Colours, than either with the Doctrine of the Schools, or with that
of the _Chymists_, both which seem to be very much Disfavour'd by it.
For first, since in the Mixture of the two mention'd Powders I could by the
help of a very excellent _Microscope_ (for ordinary ones will scarce serve
the turn) discover that which seem'd to the naked Eye a Green Body, to be
but a heap of Distinct, though very small Grains of Yellow Orpiment and
Blew Bise confusedly enough Blended together, it appears that the Colour'd
Corpuscles of either kind did each retain its own Nature and Colour; By
which it may be guess'd, what meer Transposition and Juxtaposition of
Minute and Singly unchang'd Particles of Matter can do to produce a new
Colour; For that this Local Motion and new Disposition of the small parts
of the Orpiment did Intervene is much more manifest than it is easie to
Explicate how they should produce this new Green otherwise than by the new
Manner of their being put together, and consequently by their new
Disposition to Modifie the Incident Light by Reflecting it otherwise than
they did before they were Mingl'd together.
Secondly, The Green thus made being (if I may so speak) Mechanically
produc'd, there is no pretence to derive it from I know not what
incomprehensible Substantial Form, from which yet many would have us
believe that Colours must flow; Nor does this Green, though a Real and
Permanent, not a Phantastical and Vanid Colour, seem to be such an Inherent
Quality as they would have it, since not only each part of the Mixture
remains unalter'd in Colour, and consequently of a differing Colour from
the Heap they Compose, but if the Eye be assisted by a _Microscope_ to
discern things better and more distinctly than before it could, it sees not
a Green Body, but a Heap of Blew and Yellow Corpuscles.
And in the third place, I demand what either Sulphur, or Salt, or Mercury
has to do in the Production of this Green; For neither the Bise nor the
Orpiment were indu'd with that Colour before, and the bare Juxtaposition of
the Corpuscles of the two Powders that work not upon each other, but might
if we had convenient Instruments be separated, unalter'd, cannot with any
probability be imagin'd either to Increase or Diminish any of the three
Hypostatical Principles, (to which of them soever the _Chymists_ are
pleas'd to ascribe Colours) nor does there here Intervene so much as Heat
to afford them any colour to pretend, that at least there is made an
Extraversion (as the _Helmontians_ speak) of the Sulphur or of any of the
two other supposed Principles; But upon this Experiment we have already
Reflected enough, if not more than enough for once.
_EXPERIMENT XVIII._
But here, _Pyrophilus_, I must advertise you, that 'tis not every Yellow
and every Blew that being mingl'd will afford a Green; For in case one of
the Ingredients do not Act only as endow'd with such a Colour, but as
having a power to alter the Texture of the Corpuscles of the other, so as
to Indispose them to Reflect the Light, as Corpuscles that exhibit a Blew
or a Yellow are wont to Reflect it, the emergent Colour may be not Green,
but such as the change of Texture in the Corpuscles of one or both of the
Ingredients qualifies them to shew forth; as for instance, if you let fall
a few Drops of Syrrup of Violets upon a piece of White Paper, though the
Syrrup being spread will appear Blew, yet mingling with it two or three
Drops of the lately mention'd Solution of Gold, I obtain'd not a Green but
a Reddish mixture, which I expected from the remaining Power of the Acid
Salts abounding in the Solution, such Salts or Saline Spirits being wont,
as we shall see anon, though weakn'd, so to work upon that Syrrup as to
change it into a Red or Reddish Colour. And to confirm that for which I
allege the former Experiment, I shall add this other, that having made a
very strong and high-colour'd Solution of Filings of Copper with Spirit of
Urine, though the _Menstruum_ seem'd Glutted with the Metall, because I put
in so much Filings that many of them remain'd for divers days Undissolv'd
at the Bottom, yet having put three or four Drops of Syrrup of Violets upon
White Paper, I found that the deep Blew Solution proportionably mingl'd
with this other Blew Liquor did not make a Blew mixture, but, as I
expected, a fair Green, upon the account of the Urinous Salt that was in
the _Menstruum_.
_EXPERIMENT XIX._
To shew the _Chymists_, that Colours may be made to Appear or Vanish, where
there intervenes no Accession or Change either of the Sulphureous, or the
Saline, or the Mercurial principle (as they speak) of Bodies: I shall not
make use of the Iris afforded by the Glass-prism, nor of the Colours to be
seen in a fair Morning in those drops of Dew that do in a convenient manner
Reflect and Refract the Beams of Light to the Eye; But I will rather mind
them of what they may observe in their own Laboratories, namely, that
divers, if not all, Chymical Essential Oyls, as also good Spirit of Wine,
being shaken till they have good store of Bubbles, those Bubbles will (if
attentively consider'd) appear adorn'd with various and lovely Colours,
which all immediately Vanish, upon the relapsing of the Liquor that affords
those Bubbles their Skins, into the rest of the Oyl, or Spirit of Wine, so
that a Colourless Liquor may be made in a trice to exhibit variety of
Colours, and may lose them in a moment without the Accession or Diminution
of any of its Hypostatical Principles. And, by the way, 'tis not unworthy
our notice, that some Bodies, as well Colourless, as Colour'd, by being
brought to a great Thinness of parts, acquire Colours though they had none
before, or Colours differing from them they were before endued with: For,
not to insist on the Variety of Colours, that Water, made somewhat
Glutinous by Sope, acquires, when 'tis blown into such Sphærical Bubbles as
Boys are wont to make and play with; Turpentine (though it have a Colour
deep enough of its own) may (by being blown into after a certain manner) be
brought to afford Bubbles adorn'd with variety of Orient Colours, which
though they Vanish after some while upon the breaking of the Bubbles, yet
they would in likelihood always exhibit Colours upon their _Superfices_,
(though not always the same in the same Parts of them, but Vary'd according
to the Incidence of the Sight, and the Position of the Eye) if their
Texture were durable enough: For I have seen one that was Skill'd at
fashioning Glasses by the help of a Lamp, blowing some of them so strongly
as to burst them, whereupon it was found, that the Tenacity of the Metall
was such, that before it broke it suffer'd it self to be reduc'd into Films
so extremely thin, that being kept clean they constantly shew'd on their
Surfaces (but after the manner newly mention'd) the varying Colours of the
Rain-bow, which were exceedingly Vivid, as I had often opportunity to
observe in some, that I caus'd purposely to be made, to keep by me.
But lest it should be objected, that the above mentioned Instances are
drawn from Transparent Liquors, it may possibly appear, not impertinent to
add, what I have sometimes thought upon, and several times tried, when I
was considering the Opinions of the _Chymists_ about Colours, I took then a
Feather of a convenient Bigness and Shape, and holding it at a fit distance
betwixt my Eye and the Sun when he was near the Horizon, me thought there
appear'd to me a Variety of little Rain-bows, with differing and very vivid
Colours, of which none was constantly to be seen in the Feather; the like
_Phænomenon_ I have at other times (though not with altogether so good
success) produc'd, by interposing at a due distance a piece of Black
Ribband betwixt the almost setting Sun and my Eye, not to mention the
Trials I have made to the same purpose, with other Bodies.
_EXPERIMENT XX._
Take good Syrrup of Violets, Imprægnated with the Tincture of the flowers,
drop a little of it upon a White Paper (for by that means the Change of
Colour will be more conspicuous, and the Experiment may be practis'd in
smaller Quantities) and on this Liquor let fall two or three drops of
Spirit either of Salt or Vinegar, or almost any other eminently Acid
Liquor, and upon the Mixture of these you shall find the Syrrup immediatly
turn'd Red, and the way of Effecting such a Change has not been unknown to
divers Persons who have produc'd the like, by Spirit of Vitriol, or juice
of Limmons, but have Groundlessly ascrib'd the Effect to some Peculiar
Quality of those two Liquors, whereas, (as we have already intimated)
almost any Acid Salt will turn Syrrup of Violets Red. But to improve the
Experiment, let me add what has not (that I know of) been hitherto
observ'd, and has, when we first shew'd it them, appear'd something
strange, even to those that have been inquisitive into the Nature of
Colours; namely, that if instead of Spirit of Salt, or that of Vinegar, you
drop upon the Syrrup of Violets a little Oyl of Tartar _per Deliquium_, or
the like quantity of Solution of Potashes, and rubb them together with your
finger, you shall find the Blew Colour of the Syrrup turn'd in a moment
into a perfect Green, and the like may be perform'd by divers other
Liquors, as we may have occasion elsewhere to Inform you.
_Annotation upon the twentieth Experiment_.
The use of what we lately deliver'd concerning the way of turning Syrrup of
Violets, Red or Green, may be this; That, though it be a far more common
and procurable Liquor than the Infusion of _Lignum Nephriticum_, it may yet
be easily substituted in its Room, when we have a mind to examine, whether
or no the Salt predominant in a Liquor or other Body, wherein 'tis Loose
and Abundant, belong to the Tribe of _Acid_ Salts or not. For if such a
Body turn the Syrrup of a Red or Reddish Purple Colour, it does for the
most part argue the Body (especially if it be a distill'd Liquor) to abound
with Acid Salt. But if the Syrrup be made Green, that argues the
Predominant Salt to be of a Nature repugnant to that of the Tribe of Acids.
For, as I find that either Spirit of Salt, or Oyl of Vitriol, or
_Aqua-fortis_, or Spirit of Vinegar, or Juice of Lemmons, or any of the
Acid Liquors I have yet had occasion to try, will turn Syrrup of Violets,
of a _Red_, (or at least, of a _Reddish_ Colour, so I have found, that not
only the Volatile Salts of all Animal Substances I have us'd, as Spirit of
Harts-horn, of Urine, of Sal-Armoniack, of Blood, &c. but also all the
Alcalizate Salts I have imploy'd, as the Solution of Salt of Tartar, of
Pot-ashes, of common Wood-ashes, Lime-water, &c. will immediately change
the Blew Syrrup, into a perfect Green. And by the same way (to hint that
upon the by) I elsewhere show you, both the changes that Nature and Time
produce, in the more Saline parts of some Bodies, may be discover'd, and
also how ev'n such Chymically prepar'd Bodies, as belong not either to the
Animal Kingdome, or to the Tribe of _Alcali's_, may have their new and
superinduc'd Nature successfully Examin'd. In this place I shall only add,
that not alone the Changing the Colour of the Syrrup, requires, that the
Changing Body be more strong, of the Acid, or other sort of Salt that is
Predominant in it, than is requisite for the working upon the Tincture of
_Lignum Nephriticum_; but that in this is also, the Operation of the
formerly mention'd Salts upon our Syrrup, differs from their Operation upon
our Tinctures, that in this Liquor, if the Cæruleous Colour be _Destroy'd_
by an Acid Salt, it may be _Restor'd_ by one that is either Volatile, or
Lixiviate; whereas in Syrrup of Violets, though one of these contrary Salts
will _destroy_ the Action of the other, yet neither of them will _restore_
the Syrrup to its native Blew; but each of them will Change it into the
Colour which it self doth (if I may so speak) affect, as we shall have
Occasion to show in the Notes on the twenty fifth Experiment.
_EXPERIMENT XXI._
There is a Weed, more known to Plowmen than belov'd by them, whose Flowers
from their Colour are commonly call'd _Blew-bottles_, and _Corn-weed_ from
their Growing among Corn[18]. These Flowers some Ladies do, upon the
account of their Lovely Colour, think worth the being Candied, which when
they are, they will long retain so fair a Colour, as makes them a very fine
Sallad in the Winter. But I have try'd, that when they are freshly
gather'd, they will afford a Juice, which when newly express'd, (for in
some cases 'twill soon enough degenerate) affords a very deep and pleasant
Blew. Now, (to draw this to our present Scope) by dropping on this fresh
Juice, a little Spirit of Salt, (that being the Acid Spirit I had then at
hand) it immediately turn'd (as I predicted) into a Red. And if instead of
the Sowr Spirit I mingled with it a little strong Solution of an Alcalizate
Salt, it did presently disclose a lovely Green; the same Changes being by
those differing sorts of Saline Liquors, producible in this _Natural
juice_, that we lately mention'd to have happen'd to that _factitious
Mixture_, the Syrrup of Violets. And I remember, that finding this Blew
Liquor, when freshly made, to be capable of serving in a Pen for an Ink of
that Colour, I attempted by moistning one part of a piece of White Paper
with the Spirit of Salt I have been mentioning, and another with some
Alcalizate or Volatile Liquor, to draw a Line on the leisurely dry'd Paper,
that should, e'vn before the Ink was dry, appear partly Blew, partly Red,
and partly Green: But though the latter part of the Experiment succeeded
not well, (whether because Volatile Salts are too Fugitive to be retain'd
in the Paper, and Alcalizate ones are too Unctuous, or so apt to draw
Moisture from the Air, that they keep the Paper from drying well) yet the
former Part succeeded well enough; the Blew and Red being Conspicuous
enough to afford a surprizing Spectacle to those, I acquaint not with (what
I willingly allow you to call) the _Trick_.
[18] _Herbarists_ are wont to call this Plant _Cyanus vulgaris minor_.
_Annotation upon the one and twentieth Experiment._
But lest you should be tempted to think (_Pyrophilus_) that Volatile or
Alcalizate Salts change Blews into Green, rather upon the score of the
easie Transition of the former Colour into the latter, than upon the
account of the Texture, wherein most Vegetables, that afford a Blew, seem,
though otherwise differing, to be Allied, I will add, that when I purposely
dissolv'd Blew Vitriol in fair Water, and thereby imbu'd sufficiently that
Liquor with that Colour, a Lixiviate Liquor, and a Urinous Salt being
Copiously pour'd upon distinct Parcels of it, did each of them, though
perhaps with some Difference, turn the Liquor not Green, but of a deep
Yellowish Colour, almost like that of Yellow Oker, which Colour the
Precipitated Corpuscles retain'd, when they had Leisurely subsided to the
Bottom. What this Precipitated Substance is, it is not needfull now to
Enquire in this place, and in another, I have shown you, that
notwithstanding its Colour, and its being Obtainable from an Acid
_Menstruum_ by the help of Salt of Tartar, it is yet far enough from being
the true Sulphur of Vitriol.
_EXPERIMENT XXII._
Our next Experiment (_Pyrophilus_) will perhaps seem to be of a contrary
Nature to the two former, made upon Syrrup of Violets, and Juice of
Blew-bottles. For as in them by the Affusion of Oyl of Tartar, a Blewish
Liquor is made Green, so in this, by the sole Mixture of the same Oyl, a
Greenish Liquor becomes Blew. The hint of this Experiment was given us by
the practice of some _Italian_ Painters, who being wont to Counterfeit
_Ultra-marine Azure_ (as they call it) by Grinding Verdigrease with
Sal-Armoniack, and some other Saline Ingredients, and letting them Rot (as
they imagine) for a good while together in a Dunghill, we suppos'd, that
the change of Colour wrought in the Verdigrease by this way of Preparation,
must proceed from the Action of certain Volatile and Alcalizate Salts,
abounding in some of the mingled Concretes, and brought to make a further
Dissolution of the Copper abounding in the Verdigrease, and therefore we
Conjectur'd, that if both the Verdigrease, and such Salts were dissolv'd in
fair Water, the small Parts of both being therein more subdivided, and set
at liberty, would have better access to each other, and thereby Incorporate
much the more suddenly; And accordingly we found, that if upon a strong
Solution of good French Verdigrease (for 'tis that we are wont to imploy,
as the best) you pour a just quantity of Oyl of Tartar, and shake them well
together, you shall immediately see a notable Change of Colour, and the
Mixture will grow thick, and not transparent, but if you stay a while, till
the Grosser part be Precipitated to, and setled in the Bottom, you may
obtain a clear Liquor of a very lovely Colour, and exceeding delightfull to
the Eye. But, you must have a care to drop in a competent Quantity of Oyl
of Tartar, for else the Colour will not be so Deep, and Rich; and if
instead of this Oyl you imploy a clear _Lixivium_ of Pot-ashes, you may
have an Azure somewhat Lighter or Paler than, and therefore differing from,
the former. And if instead of either of these Liquors, you make use of
Spirit of Urine, or of Harts-horn, you may according to the Quantity and
Quality of the Spirit you pour in, obtain some further Variety (though
scarce considerable) of Cæruleous Liquors. And yet lately by the help of
this Urinous Spirit we made a Blew Liquor, which not a few Ingenious
Persons, and among them, some, whose Profession makes them very Conversant
with Colours, have looked upon with some wonder. But these Azure Colour'd
Liquors should be freed from the Subsiding matter, which the Salts of
Tartar or Urine precipitate out of them, rather by being Decanted, than by
Filtration. For by the latter of these ways we have sometimes found, the
Colour of them very much Impair'd, and little Superiour to that of the
grosser Substance, that it left in the Filtre.
_EXPERIMENT XXIII._
That Roses held over the Fume of Sulphur, may quickly by it be depriv'd of
their Colour, and have as much of their Leaves, as the Fume works upon,
burn'd pale, is an Experiment, that divers others have tried, as well as I.
But (_Pyrophilus_) it may seem somewhat strange to one that has never
consider'd the Compounded nature of Brimstone, That, whereas the Fume of
Sulphur will, as we have said, Whiten the Leaves of Roses; That Liquor,
which is commonly call'd Oyl of Sulphur _per Campanam_, because it is
suppos'd to be made by the Condensation of these Fumes in Glasses shap't
like Bells, into a Liquor, does powerfully heighten the Tincture of Red
Roses, and make it more Red and Vivid, as we have easily tried by putting
some Red-Rose Leaves, that had been long dried, (and so had lost much of
their Colour) into a Vial of fair Water. For a while after the Affusion of
a convenient Quantity of the Liquor we are speaking of, both the Leaves
themselves, and the Water they were Steep'd in, discover'd a very fresh and
lovely Colour.
_EXPERIMENT XXIV._
It may (_Pyrophilus_) somewhat serve to Illustrate, not only the Doctrine
of _Pigments_, and of _Colours_, but divers other Parts of the _Corpuscular
Philosophy_; as that explicates Odours, and many other things, not as the
Schools by Aery Qualities, but by Real, though extremely Minute Bodies; to
examine, how much of a Colourless Liquor, a very small Parcel of a Pigment
may Imbue with a _discernable_ Colour. And though there be scarce any thing
of Preciseness to be expected from such Trials, yet I presum'd, that (at
least) I should be able to show a much further Subdivision of the Parts of
Matter into _Visible_ Particles, than I have hitherto found taken notice
of, and than most men would imagine; no Body, that I know of, having yet
attempted to reduce this Matter to any Measure.
The Bodies, the most promising for such a purpose, might seem to be the
Metalls, especially Gold, because of the Multitude, and Minuteness of its
Parts, which might be argu'd from the incomparable Closeness of its
Texture: But though we tried a Solution of Gold made in _Aqua Regia_ first,
and then in fair Water; yet in regard we were to determine the Pigment we
imploy'd, not by _Bulk_ but _Weight_, and because also, that the Yellow
Colour of Gold is but a faint one in Comparison of the deep Colour of
_Cochineel_, we rather chose this to make our Trials with. But among divers
of these it will suffice to set down one, which was carefully made in
Vessels conveniently Shap'd; (and that in the presence of a Witness, and an
Assistant) the Sum whereof I find among my _Adversaria_, Registred in the
following Words. To which I shall only premise, (to lessen the wonder of so
strange a diffusion of the Pigment) That _Cochineel_ will be better
Dissolv'd, and have its Colour far more heightn'd by Spirit of Urine, than
(I say not by common Water, but) by Rectify'd Spirit of Wine it self.
The Note I spoke off is this. [One Grain of _Cochineel_ dissolv'd in a
pretty Quantity of Spirit of Urine, and then dissolv'd further by degrees
in fair Water, imparted a discernable, though but a very faint Colour, to
about six Glass-fulls of Water, each of them containing about forty three
Ounces and an half, which amounts to above a hundred twenty five thousand
times its own Weight.]
_EXPERIMENT XXV._
It may afford a considerable Hint (_Pyrophilus_) to him, that would improve
the Art of Dying, to know what change of Colours may be produc'd by the
three several sorts of Salts already often mention'd, (some or other of
which may be procur'd in Quantity at reasonable Rates) in the Juices,
Decoctions, Infusions, and (in a word) the more soluble parts of
Vegetables. And, though the design of this Discourse be the Improvement of
Knowledge, not of Trades: yet thus much I shall not scruple to intimate
here, That the Blew Liquors, mention'd in the twentieth and one and
twentieth Experiments, are far from being the only Vegetable Substances,
upon which Acid, Urinous, and Alcalizate Salts have the like Operations to
those recited in those two Experiments. For Ripe _Privet Berries_ (for
instance) being crush'd upon White Paper, though they stain it with a
Purplish Colour, yet if we let fall on some part of it two or three drops
of Spirit of Salt, and on the other part a little more of the Strong
Solution of Pot-ashes, the former Liquor immediately turn'd that part of
the Thick juice or Pulp, on which it fell, into a lovely Red, and the
latter turn'd the other part of it into a delightfull Green. Though I will
not undertake, that those Colours in that Substance shall not be much more
Orient, than Lasting; and though (_Pyrophilus_) this Experiment may seem to
be almost the same with those already deliver'd concerning Syrrup of
Violets, and the Juice of Blew-bottles, yet I think it not amiss to take
this Occasion to inform you, that this Experiment reaches much farther,
than perhaps you yet imagine, and may be of good Use to those, whom it
concerns to know, how Dying Stuffs may be wrought upon by Saline Liquors.
For, I have found this Experiment to succeed in so many Various Berries,
Flowers, Blossoms, and other finer Parts of Vegetables, that neither my
Memory, nor my Leisure serves me to enumerate them. And it is somewhat
surprizing to see, by how Differingly-colour'd Flowers, or Blossoms, (for
example) the Paper being stain'd, will by an Acid Spirit be immediately
turn'd Red, and by any _Alcaly_ or any Urinous Spirit turn'd Green;
insomuch that ev'n the crush'd Blossoms of _Meserion_, (which I gather'd in
Winter and frosty Weather) and those of Pease, crush'd upon White Paper,
how remote soever their Colours be from Green, would in a moment pass into
a deep Degree of that Colour, upon the Touch of an Alcalizate Liquor. To
which let us add, That either of those new Pigments (if I may so call them)
may by the Affusion of enough of a contrary Liquor, be presently chang'd
from Red into Green, and from Green into Red, which Observation will hold
also in Syrrup of Violets, Juices of Blew-bottles, &c.
_Annotation._
After what I have formerly deliver'd to evince, That there are many
Instances, wherein new Colours are produc'd or acquir'd by Bodies, which
_Chymists_ are wont to think destitute of Salt, or to whose change of
Colours no new Accession of Saline Particles does appear to contribute, I
think we may safely enough acknowledge, that we have taken notice of so
many Changes made by the Intervention of Salts in the Colours of Mix'd
Bodies, that it has lessen'd our Wonder, That though _many Chymists_ are
wont to ascribe the Colours of Such Bodies to their Sulphureous, and _the
rest_ to their Mercurial Principle; yet _Paracelsus_ himself directs us in
the Indagation of Colours, to have an Eye principally upon Salts, as we
find in that passage of his, wherein he takes upon him to Oblige his
Readers much by Instructing them, of what things they are to expect the
Knowledge from each of the three distinct Principles of Bodies. _Alias_
(says he) _Colorum similis ratio est: De quibus brevem institutionem hanc
attendite, quod scilicet colores omnes ex Sale prodeant. Sal enim dat
colorem, dat Balsamum._[19] And a little beneath. _Iam natura Ipsa colores
protrathit ex sale, cuique speciei dans illum, qui ipsi competit_, &c.
After which he concludes; _Itaque qui rerum omnium corpora cognoscere vult,
huic opus est, ut ante omnia cognoscat Sulphur, Ab hoc, qui desiderat
novisse Colores is scientiam istorum petat à Sale, Qui scire vult Virtutes,
is scrutetur arcana Mercurii. Sic nimirum fundamentum hauserit Mysteriorum,
in quolibet crescenti indagandorum, prout natura cuilibet speciei ea
ingessit_. But though _Paracelsus_ ascribes to each of his belov'd
Hypostatical Principles, much more than I fear will be found to belong to
it; yet if we please to consider Colours, not as _Philosophers_, but as
_Dyers_, the concurrence of Salts to the striking and change of Colours,
and their Efficacy, will, I suppose, appear so considerable, that we shall
not need to quarrel much with _Paracelsus_, for ascribing in this place
(for I dare not affirm that he uses to be still of one Mind) the Colours of
Bodies to their Salts, if by Salts he here understood, not only Elementary
Salts, but such also as are commonly taken for Salts, as Allom, Crystals of
Tartar, Vitriol, &c. because the Saline principle does chiefly abound in
them, though indeed they be, as we elsewhere declare, mix'd Bodies, and
have most of them, besides what is Saline, both Sulphureous, Aqueous, and
Gross or Earthy parts.
[19] Paracelsus de Mineral. tract. 1. pag. m. 243
But though (_Pyrophilus_) I have observ'd a Red and Green to be produc'd,
the former, by Acid Salts, the later by Salts not Acid, in the express
Juices of so many differing Vegetable Substances, that the Observation, if
persued, may prove (as I said) of good Use: yet to show you how much e'vn
these Effects depend upon the particular Texture of Bodies, I must subjoyn
some cases wherein I (who am somewhat backwards to admit Observations for
Universal) had the Curiosity to discover, that the Experiments would not
Uniformly succeed, and of these Exceptions, the chief that I now remember,
are reducible to the following three.
_EXPERIMENT XXVI._
And, (first) I thought fit to try the Operation of Acid Salts upon
Vegetable Substances, that are already and by their own Nature Red. And
accordingly I made Trial upon Syrrup of Clove-july-flowers, the clear
express'd Juice of the succulent Berries of _Spina Cervina_, or Buckthorn
(which I had long kept by me for the sake of its deep Colour) upon Red
Roses, Infusion of Brazil, and divers other Vegetable Substances, on some
of which crush'd (as is often mention'd) upon White Paper, (which is also
to be understood in most of these Experiments, if no Circumstance of them
argue otherwise) Spirit of Salt either made no considerable Change, or
alter'd the Colour but from a Darker to a Lighter Red. How it will succeed
in many other Vegetable Juices, and Infusions of the same Colour, I have at
present so few at hand, that I must leave you to find it out your self. But
as for the Operation of the other sorts of Salts upon these Red Substances,
I found it not very Uniform, some Red, or Reddish Infusions, as of Roses,
being turn'd thereby into a dirty Colour, but yet inclining to Green. Nor
was the Syrrup of Clove-july-flowers turn'd by the solution of Pot-ashes to
a much better, though somewhat a Greener, Colour. Another sort of Red
Infusions was by an _Alcaly_ not turn'd into a Green, but advanc'd into a
Crimson, as I shall have occasion to note ere long. But there were other
sorts, as particularly the lovely Colour'd juice of Buckthorn Berries, that
readily pass'd into a lovely Green.
_EXPERIMENT XXVII._
Among other Vegetables, which we thought likely to afford Exceptions to the
General Observation about the differing Changes of Colours produc'd by Acid
and Sulphureous Salts, we thought fit to make Trial upon the Flowers of
_Jasmin_, they being both White as to Colour, and esteem'd to be of a more
Oyly nature than other Flowers. Whereupon having taken the White parts only
of the Flowers, and rubb'd them somewhat hard with my Finger upon a piece
of clean Paper, it appear'd very little Discolour'd. Nor had Spirit of
Salt, wherewith I moisten'd one part of it, any considerable Operation upon
it. But Spirit of Urine, and somewhat more effectually a strong Alcalizate
Solution, did immediately turn the almost Colourless Paper moisten'd by the
Juice of the _Jasmin_, not as those Liquors are wont to do, when put upon
the Juices of other Flowers, of a good Green, but of a Deep, though
somewhat Greenish Yellow, which Experiment I did afterwards at several
times repeat with the like success. But it seems not that a great degree of
Unctuousness is necessary to the Production of the like Effects, for when
we try'd the Experiment with the Leaves of those purely White Flowers that
appear about the end of Winter, and are commonly call'd _Snow drops_, the
event, was not much unlike that, which, we have been newly mentioning.
_EXPERIMENT XXVIII._
Another sort of Instances to show, how much changes of Colour effected by
Salts, depend upon the particular Texture of the Colour'd Bodies, has been
afforded me by several _Yellow_ Flowers, and other Vegetables, as Mary-gold
Leaves, early Prim-roses, fresh Madder, &c. For being rubb'd upon White
Paper, till they imbued it with their Colour, I found not, that by the
addition of Alcalizate Liquors, nor yet by that of an Urinous Spirit, they
would be turn'd either Green or Red: nor did so Acid a Spirit, as that of
Salt, considerably alter their Colour, save that it seem'd a little to
Dilute it. Only in some early Prim-roses it destroy'd the greatest part of
the Colour, and made the Paper almost White agen. And Madder also afforded
some thing peculiar, and very differing from what we have newly mention'd:
For having gather'd Some Roots of it, and, (whilst they were recent)
express'd upon White Paper the Yellow Juice, an Alcalizate Solution drop'd
upon it did not turn it either Green or White, but Red. And the bruis'd
Madder it self being drench'd with the like Alcalizate Solution, exchang'd
also its Yellowishness for a Redness.
_An admonition touching the four preceding Experiments._
Having thus (_Pyrophilus_) given you divers Instances, to countenance the
General observation deliver'd in the twenty fifth Experiment, and divers
Exceptions whereby it ought to be Limited; I must leave the further Inquiry
into these Matters to your own Industry. For not remembring at present many
of those other Trials, long since made to satisfie my self about
Particulars, and not having now the Opportunity to repeat them, I must
content my Self to have given you the Hint, and the ways of prosecuting the
search your Self; and only declare to you in general, that, As I have made
many Trials, unmention'd in this Treatise, whose Events were agreeable to
those mention'd in the twenty fifth Experiment, so (to name now no other
Instances) what I have try'd with Acid and Sulphureous Salts upon the Pulp
of Juniper Berries, rubb'd upon White Paper, inclines me to think, That
among that vast Multitude, and strange Variety of Plants that adorn the
face of the Earth, perhaps many other Vegetables may be found, on which
such _Menstruums_ may not have such Operations, as upon the Juice of
Violets, Pease-blossoms, &c. no nor upon any of those three other sorts of
Vegetables, that I have taken notice of in the three fore-going
Experiments. It sufficiently appearing ev'n by these, that the effects of a
Salt upon the Juices of particular Vegetables do very much depend upon
their particular Textures.
_EXPERIMENT XXIX._
It may be of some Use towards the discovery of the nature of these Changes,
which the Alimental Juice receives in some Vegetables, according to the
differing degrees of their Maturity, and according to the differing kinds
of Plants of the same Denomination, to observe what Operation Acid,
Urinous, and Alcalizate Salts will have upon the Juices of the several
sorts of the Vegetable substances I have been mentioning.
To declare my meaning by an Example, I took from the same Cluster, one
Blackberry full Ripe, and another that had not yet gone beyond a Redness,
and rubbing apiece of white Paper, with the former, I observ'd, that the
Juice adhering to it was of adark Reddish Colour, full of little Black
Specks; and that this Juice by a drop of a strong _Lixivium_, was
immediately turn'd into a Greenish Colour deep enough, by as much Urinous
Spirit into a Colour much of Kin to the former, though somewhat differing,
and fainter; and by a drop of Spirit of Salt into a fine and lightsome Red:
where as the Red Berry being in like manner rubb'd upon Paper, left on it a
Red Colour, which was very little alter'd by the Acid Spirit newly nam'd,
and by the Urinous and Lixiviate Salts receiv'd changes of Colour differing
from those that had been just before produc'd in the dark Juice of the Ripe
Blackberry.
I remember also, that though the Infusion of Damask-Roses would as well,
though not so much, as that of Red, be heightned by Acid Spirits to an
intense degree of Redness, and by Lixiviate Salts be brought to a Darkish
Green; yet having for Trials sake taken a Rose, whose Leaves, which were
large and numerous, like those of a Province Rose, were perfectly Yellow,
though in a Solution of Salt of Tartar, they afforded a Green Blewish
Tincture, yet I did not by an Acid Liquor obtain a Red one; all that the
Saline Spirit I imploy'd, perform'd, being (if I much misremember not) to
Dilute Somewhat the Yellowness of the Leaves. I would also have tried the
Tincture of Yellow Violets, but could procure none. And if I were in those
Islands of _Banda_, which are made Famous as well as Rich, by being the
almost only places, where Cloves will prosper, I should think it worth my
Curiosity to try, what Operation the three differing Kinds of Salts, I have
so often mention'd, would have upon the Juice of this Spice, (express'd at
the several Seasons of it) as it grows upon the Tree. Since good Authors
inform us, (of what is remarkable) that these whether Fruits, or Rudiments
of Fruits, are at first _White_, afterward _Green_, and then _Reddish_,
before they be beaten off the Tree, after which being Dry'd before they are
put up, they grow _Blackish_ as we see them. And one of the recentest
_Herbarists_ informs us, that the Flower grows upon the top of the Clove it
self, consisting of four small Leaves, like a Cherry Blossom, but of an
excellent _Blew_. But (_Pyrophilus_) to return to our own Observations, I
shall add, that I the rather choose, to mention to you an Example drawn
from Roses, because that though I am apt to think, as I elsewhere
advertise, that something may be guess'd at about some of the Qualities of
the Juices of Vegetables, by the Resemblance or Disparity that we meet with
in the Changes made of their Colours, by the Operation of the same kinds of
Salts; yet that those Conjectures should be very warily made, may appear
among other things, by the Instance I have chosen to give in Roses. For
though, (as I formerly told you) the Dry'd Leaves, both of the Damask, and
of Red ones, give a Red Tincture to Water sharpen'd with Acid Salts, yet
the one sort of Leaves is known to have a Purgative faculty,[20] and the
other are often, and divers ways, imploy'd for Binding.
[20] See _Parkinson_ Th. Boran. Trib. 9. cap. 26.
And I also choose (_Pyrophilus_) to subjoyn this twenty ninth Experiment to
those that precede it, about the change of the Colours of Vegetables by
Salts, for these two reasons: The first, that you may not easily entertain
Suspitions, if in the Trials of an Experiment of some of the Kinds formerly
mention'd, you should meet with an Event somewhat differing from what my
Relations may have made you expect. And the second, That you may hereby be
invited to discern, that it may not be amiss to take notice of the
particular Seasons wherein you gather the Vegetables which in Nicer
Experiments you make use of. For, it I were not hindred both by haste and
some justifiable Considerations, I could perhaps add considerable
Instances, to those lately deliver'd, for the making out of this
Observation; but for certain reasons I shall at present substitute a
remarkable passage to be met with in that Laborious Herbarist Mr.
_Parkinson_, where treating of the Virtues of the (already divers times
mention'd) Buckthorn Berries, he subjoyns the following account of several
Pigments that are made of them, not only according to the several ways of
Handling them, but according to the differing Seasons of Maturity, at which
they are Gather'd; _Of these Berries_, (says he) _are made three several
sorts of Colours as they shall be gather'd, that is, being gather'd while
they are Green, and kept Dry, are call'd Sapberries, which being steep'd
into some Allom-water, or fresh bruis'd into Allom-water, they give a
reasonable fair Yellow Colour which Painters use for their Work, and
Book-binders to Colour the edges of Books, and Leather-dressers to Colour
Leather, as they use also to make a Green Colour, call'd Sap-green, taken
from the Berries when they are Black, being bruis'd and put into a Brass or
Copper Kettle or Pan, and there suffer'd to abide three or four_ _Days, or
a little heated upon the Fire, and some beaten Allom put unto them, and
afterwards press'd forth, the Juice or Liquor is usually put in great
Bladders tied with strong thred at the Head and hung up untill it be Dry,
which is dissolv'd in Water or Wine, but Sack_ (he affirms) _is the best to
preserve the Colour from Starving, (as they call it) that is, from
Decaying, and make it hold fresh the longer. The third Colour (where of
none_ (says he) _that I can find have made mention but only_ Tragus_) is a
Purplish Colour, which is made of the Berries suffer'd to grow upon the
Bushes untill the middle or end of_ November, _that they are ready to drop
from the Trees._
And, I remember (_Pyrophilus_) that I try'd, with a success that pleas'd me
well enough, to make such a kind of Pigment, as Painters call Sap-green, by
a way not unlike that, deliver'd here by our Author, but I cannot now find
any thing relating to that matter among my loose Papers. And my Trials were
made so many years ago, that I dare not trust my Memory for Circumstances,
but will rather tell you, that in a noted Colour-shop, I brought them by
Questions to confess to me, that they made their Sap-green much after the
ways by our _Botanist_ here mention'd. And on this occasion I shall add an
Observation, which though it does not strictly belong to this place, may
well enough be mention'd here, namely, that I find by an account given us
by the Learned _Clusius_, of _Alaternus_, that ev'n the Grosser Parts of
the same Plant, are some of them one Colour, and some another; For speaking
of that Plant, he tells us, that the _Portugalls_ use the Bark to Dye their
Nets into a Red Colour, and with the Chips of the Wood, which are Whitish,
they Dye a Blackish Blew.
_EXPERIMENT XXX._
Among the Experiments that tend to shew that the change of Colours in
Bodies may proceed from the Vary'd Texture of their Parts, and the
consequent change of their Disposition to Reflect or Refract the Light,
that sort of Experiments must not be left unmention'd, which is afforded us
by Chymical Digestions. For, if _Chymists_ will believe several famous
Writers about what they call the Philosophers Stone, they must acknowledge
that the same Matter, seald up Hermetically in a Philosophical Egg, will by
the continuance of Digestion, or if they will have it so (for it is not
Material in our case which of the two it be) of Decoction, run through a
great Variety of differing Colours, before it come to that of the Noblest
_Elixir_; whether that be Scarlet, or Purple, or what ever other Kind of
Red. But without building any thing on so Obtruse and Questionable an
Operation, (which yet may be pertinently represented to those that believe
the thing) we may observe, that divers Bodies digested in carefully-clos'd
Vessels, will in tract of time, change their Colour: As I have elsewhere
mention'd my having observ'd ev'n in Rectify'd Spirit of Harts-horn, and as
is evident in the Precipitations of Amalgams of Gold, and Mercury, without
Addition, where by the continuance of a due Heat the Silver-Colour'd
Amalgam is reduc'd into a shining Red Powder. Further Instances of this
Kind you may find here and there in divers places of my other Essays. And
indeed it has been a thing, that has much contributed to deceive many
_Chymists_, that there are more Bodies than one, which by Digestion will be
brought to exhibit that Variety and Succession of Colours, which they
imagine to be Peculiar to what they call the _True matter of the
Philosophers_. But concerning this, I shall referr you to what you may
elsewhere find in the Discourse written touching the passive Deceptions of
_Chymists_, and more about the Production of Colours by Digestion you will
meet with presently. Wherefore I shall now make only this Observation from
what has been deliver'd, That in these Operations there appears not any
cause to attribute the new Colours emergent to the Action of a new
Substantial form, nor to any Increase or Decrement of either the Salt,
Sulphur, or Mercury of the Matter that acquires new Colours: For the
Vessels are clos'd, and these Principles according to the _Chymists_ are
Ingenerable and Incorruptible; so that the Effect seems to proceed from
hence, that the Heat agitating and shuffling the Corpuscles of the Body
expos'd to it, does in process of time so change its Texture, as that the
Transposed parts do Modifie the incident Light otherwise, than they did
when the Matter appear'd of another Colour.
_EXPERIMENT XXXI._
Among the several changes of Colour, which Bodies acquire or disclose by
Digestion, it it very remarkable, that _Chymists_ find a Redness rather
than any other Colour in most of the Tinctures they Draw, and ev'n in the
more Gross Solutions they make of almost all Concretes, that abound either
with Mineral or Vegetable Sulphur, though the _Menstruum_ imploy'd about
these Solutions or Tinctures be never so Limpid or Colourless.
This we have observ'd in I know not how many Tinctures drawn with Spirit of
Wine from _Jalap_, _Guaicum_, and several other Vegetables; and not only in
the Solutions of _Amber_, _Benzoin_, and divers other Concretes made with
the same _Menstruum_, but also in divers Mineral Tinctures. And, not to
urge that familiar Instance of the Ruby of Sulphur, as _Chymists_ upon the
score of its Colour, call the Solution of Flowers of Brimstone, made with
the Spirit of Turpentine, nor to take notice of other more known Examples
of the aptness of Chymical Oyls, to produce a Red Colour with the Sulphur
they extract, or dissolve; not to insist (I say) upon Instances of this
nature, I shall further represent to you, as a thing remarkable, that, both
Acid and Alcalizate Salts, though in most other cases of such contrary
Operations, in reference to Colours, will with many Bodies that abound with
Sulphureous, or with Oyly parts, produce a Red; as is manifest partly in
the more Vulgar Instances of the Tinctures, or Solutions of Sulphur made
with _Lixiviums_, either of Calcin'd Tartar or Pot-ashes, and other Obvious
examples, partly by this, that the true Glass of Antimony extracted with
some Acid Spirits, with or without Wine, will yield a Red Tincture, and
that I know an Acid Liquor, which in a moment will turn Oyl of Turpentine
into a deep Red. But among the many Instances I could give you of the easie
Production of Redness by the Operation of Saline Spirit, as well as of
Spirit of Wine; I remember two or three of those I have tried, which seem
remarkable enough to deserve to be mention'd to you apart.
_EXPERIMENT XXXII._
But before we set them down, it will not perhaps appear impertinent to
premise;
That there seems to be a manifest Disparity betwixt Red Liquors, so that
some of them may be said to have a Genuine Redness in comparison of others,
that have a Yellowish Redness: For if you take (for example) a good
Tincture of _Chochineel_, dilute it never so much with fair Water, you will
not (as far as I can judge by what I have tried) be able to make it a
Yellow Liquor. Insomuch that a Single drop of a rich Solution of
_Cochineel_ in Spirit of Urine, being Diluted with above an Ounce of fair
Water, exhibited no Yellowishness at all, but a fair (though somewhat
faint) Pinck or Carnation; and even when _Cochineel_ was by degrees Diluted
much beyond the newly mention'd Colour, by the way formerly related to you
in the twenty fourth Experiment, I remember not, that there appear'd in the
whole Trial any Yellow. But if you take Balsom of Sulphur (for Instance)
though it may appear in a Glass, where it has a good Thickness, to be of a
deep Red, yet if you shake the Glass, or pour a few drops on a sheet of
White Paper, spreading them on it with your Finger, the Balsom that falls
back along the sides of the Glass, and that which stains the Paper, will
appear Yellow, not Red. And there are divers Tinctures, such as that of
Amber made with Spirit of Wine, (to name now no more) that will appear
either Yellow or Red, according as the Vessels that they fill, are Slender
or Broad.
_EXPERIMENT XXXIII._
But to proceed to the Experiments I was about to deliver; _First_; Oyl or
Spirit of Turpentine, though clear as fair Water, being Digested upon the
purely White Sugar of Lead, has, in a short time, afforded us a high Red
Tincture, that some Artists are pleas'd to call the Balsom of _Saturn_,
which they very much (and probably not altogether without cause) extoll as
an excellent Medicine in divers Outward affections.
_EXPERIMENT XXXIV._
_Next_, take of common Brimstone finely powdred five Ounces, of
Sal-Armoniack likewise pulveriz'd an equal weight, of beaten Quick-lime six
Ounces, mix these Powders exquisitely, and Distill them through a Retort
plac'd in Sand by degrees of Fire, giving at length as intense a Heat as
you well can in Sand, there will come over (if you have wrought well) a
Volatile Tincture of Sulphur, which may probably prove an excellent
Medicine, and should have been mention'd among the other Preparations of
Sulphur, which we have elsewhere imparted to you, but that it is very
pertinent to our present Subject, The change of Colours. For though none of
the Ingredients be Red, the Distill'd Liquor will be so: and this Liquor if
it be well Drawn, will upon a little Agitation of the Vial first unstop'd
(especially if it be held in a Warmer hand) lend forth a copious Fume, not
Red, like that of Nitre, but White; And sometimes this Liquor may be so
Drawn, that I remember, not long since, I took pleasure to observe in a
parcel of it, that Ingredients not Red, did not only yield by Distillation
a Volatile Spirit that was Red, but though that Liquor did upon the bare
opening of the Bottle it was kept in, drive us away with the plenty and
sulphureous sent of a White steam which it sent forth, yet the Liquor it
self being touch'd by our Fingers, did immediately Dye them Black.
_EXPERIMENT XXXV._
The third and _last_ Experiment I shall now mention to shew, how prone
Bodies abounding in Sulphureous parts are to afford a Red Colour, is one,
wherein by the Operation of a Saline Spirit upon a White or Whitish Body,
which according to the _Chymists_ should be altogether Sulphureous, a
Redness may be produc'd, not (as in the former Experiments) slowly, but in
the twinkling of an Eye. We took then of the Essential Oyl of Anniseeds,
which has this Peculiarity, that in Cold weather it loses its Fluidity and
the greatest part of its Transparency, and looks like a White or Whitish
Oyntment, and near at hand seems to consist of a Multitude of little soft
Scales: Of this Coagulated Stuff we spread a little with a Knife upon a
piece of White Paper, and letting fall on it, and mixing with it a drop or
two of Oyl of Vitriol, immediately (as we fore-saw) there emerg'd together
with some Heat and Smoak, a Blood-Red Colour, which therefore was in a
trice produc'd by two Bodies, whereof the one had but a Whitish Colour, and
the other (if carefully rectify'd) had no Colour at all.
_EXPERIMENT XXXVI._
But on this Occasion (_Pyrophilus_) we must add once for all, that in many
of the above-recited Experiments, though the changes of Colour happen'd as
we have mention'd them: yet the emergent or produc'd Colour is oft times
very subject to Degenerate, both quickly and much. Notwithstanding which,
since the Changes, we have set down, do happen presently upon the Operation
of the Bodies upon each other, or at the times by us specify'd; _that_ is
sufficient both to justifie our Veracity, and to shew what we Intend; it
not being Essential to the Genuineness of a Colour to be Durable. For a
fading Leaf, that is ready to Rot, and moulder into Dust, may have as true
a Yellow, as a Wedge of Gold, which so obstinately resists both Time and
Fire. And the reason, why I take occasion from the former Experiment to
subjoyn this general Advertisement, is, that I have several times observ'd,
that the Mixture resulting from the Oyls of Vitriol, and of Anniseeds,
though it acquire a thicker consistence than either of the Ingredients had,
has quickly lost its Colour, turning in a very short time into a dirty
Gray, at least in the Superficial parts, where 'tis expos'd to the Air;
which last Circumstance I therefore mention, because that, though it seem
probable, that this Degeneration of Colours may oft times and in divers
cases proceed from the further Action of the Saline Corpuscles, and the
other Ingredients upon one another, yet in many cases much of the Quick
change of Colours seems ascribeable to the Air, as may be made probable by
several reasons: The first whereof may be fetcht from the newly recited
Example of the two Oyls; The next may be, that we have sometimes observ'd
long Window-Curtains of light Colours, to have that part of them, which was
expos'd to the Air, when the Window was open, of one Colour, and the lower
part, that was sheltred from the Air by the Wall, of another Colour: And
the third Argument may be fetch'd from divers Observations, both of others,
and our own; For of that Pigment so well known in Painters Shops, by the
name of _Turnsol_, our Industrious _Parkinson_, in the particular account
he gives of the Plant that bears it, tells us also, That _the Berries when
they are at their full Maturity, have within them between the outer Skin
and the inward Kirnel or Seed, a certain Juice or Moisture, which being
rubb'd upon Paper or Cloath, at the first appears of a fresh and lovely
Green Colour, but presently changeth into a kind of Blewish Purple, upon
the Cloath or Paper, and the same Cloath afterwards wet in Water, and wrung
forth, will Colour the Water into a Claret Wine Colour, and these_
(concludes he) _are those Raggs of Cloath, which are usually call'd_
Turnsol _in the Druggists or Grocers Shops_[21]. And to this Observation of
our _Botanist_ we will add an Experiment of our own, (made before we met
with That) which, though in many Circumstances, very differing, serves to
prove the same thing; for having taken of the deeply Red Juice of
_Buckthorn_ Berries, which I bought of the Man that uses to sell it to the
Apothecaries, to make their Syrrup _de Spina Cervina_, I let some of it
drop upon a piece of White Paper, and having left it there for many hours,
till the Paper was grown dry again, I found what I was inclin'd to suspect,
namely, That this Juice was degenerated from a deep Red to a dirty kind of
Greyish Colour, which, in a great part of the stain'd Paper seem'd not to
have so much as an Eye of Red: Though a little Spirit of Salt or dissolv'd
_Alcaly_ would turn this unpleasant Colour (as formerly I told you it would
change the not yet alter'd Juice) into a Red or Green. And to satisfie my
self, that this Degeneration of Colour did not proceed from the Paper, I
drop'd some of the deep Red or Crimson Juice upon a White glaz'd Tile, and
suffering it to dry on there, I found that ev'n in that Body, on which it
could not Soak, and by which it could not be Wrought, it nevertheless lost
its Colour. And these Instances (_Pyrophilus_) I am the more carefull to
mention to you, that you may not be much Surpris'd or Discourag'd, if you
should sometimes miss of performing punctually what I affirm my self to
have done in point of changing Colours; since in these Experiments the
over-sight or neglect of such little Circumstances, as in many others would
not be perhaps considerable, may occasion the mis-carrying of a Trial. And
I was willing also to take this occasion of Advertising you in the
repeating of the Experiments mention'd in this Treatise, to make use of the
Juices of Vegetables, and other things prepar'd for your Trials, as soon as
ever they are ready, lest one or other of them grow less fit, if not quite
unfit by delay; and to estimate the Event of the Trials by the Change, that
is produc'd presently upon the due and sufficient Application of Actives to
Passives, (as they speak) because in many cases the effects of such
Mixtures may not be lasting, and the newly produc'd Colour may in a little
time degenerate. But, (_Pyrophilus_) I forgot to add to the two former
Observations lately made about Vegetables, a third of the same Import, made
in Mineral substances, by telling you, That the better to satisfie a Friend
or two in this particular, I sometimes made, according to some Conjectures
of mine, this Experiment; That having dissolv'd good Silver in
_Aqua-fortis_, and Precipitated it with Spirit of Salt, upon the first
Decanting of the Liquor, the remaining Matter would be purely White; but
after it had lain a while uncover'd, that part of it, that was Contiguous
to the Air, would not only lose its Whiteness, but appear of a very Dark
and almost Blackish Colour, I say that part that was Contiguous to the Air,
because if that were gently taken off, the Subjacent part of the same Mass
would appear very White, till that also, having continu'd a while expos'd
to the Air, would likewise Degenerate. Now whether the Air perform these
things by the means of a Subtile Salt, which we elsewhere show it not to be
destitute of, or by a peircing Moisture, that is apt easily to insinuate it
self into the Pores of some Bodies, and thereby change their Texture, and
so their Colour; Or by solliciting the Avolation of certain parts of the
Bodies, to which 'tis Contiguous; or by some other way, (which possibly I
may elsewhere propose and consider) I have not now the leisure to
discourse. And for the same reason, though I could add many other
Instances, of what I formerly noted touching the emergency of Redness upon
the Digestion of many Bodies, insomuch that I have often seen upon the
Borders of _France_ (and probably we may have the like in _England_) a sort
of Pears, which digested for some time with a little Wine, in a Vessel
exactly clos'd, will in not many hours appear throughout of a deep Red
Colour, (as also that of the Juice, wherein they are Stew'd, becomes) but
ev'n on pure and white Salt of Tartar, pure Spirit of Wine, as clear as
Rock-water, will (as we elsewhere declare) by long Digestion acquire a
Redness; Though I say such Instances might be Multiply'd, and though there
be some other Obvious changes of Colours, which happen so frequently, that
they cannot but be as well Considerable as Notorious; such as is the
Blackness of almost all Bodies burn'd in the open Air: yet our haste
invites us to resign you the Exercise of enquiring into the Causes of these
Changes. And certainly, the reason both _why_ the Soots of such differing
Bodies are almost all of them all Black, _why_ so much the greater part of
Vegetables should be rather Green than of any other Colour, and
particularly (which more directly concerns this place) _why_ gentle Heats
do so frequently in Chymical Operations produce rather a Redness than
another Colour in digested _Menstruums_, not only Sulphureous, as Spirit of
Wine, but Saline, as Spirit of Vinegar, may be very well worth a serious
Inquiry; which I shall therefore recommend to _Pyrophilus_ and his
Ingenious Friends.
[21] _Parkinson_, Thea. Bot. Trib. 4 cap. 12.
_EXPERIMENT XXXVII._
It may seem somewhat strange, that if you take the Crimson Solution of
_Cochineel_, or the Juice of Black Cherries, and of some other Vegetables
that afford the like Colour, (which because many take but for a deep Red,
we do with them sometimes call it so) and let some of it fall upon a piece
of Paper, a drop or two of an Acid Spirit, such as Spirit of Salt, or
_Aqua-fortis_, will immediately turn it into a fair Red. Whereas if you
make an Infusion of Brazil in fair Water, and drop a little Spirit of Salt
or _Aqua-fortis_ into it, that will destroy its Redness, and leave the
Liquor of a Yellow, (sometimes Pale) I might perhaps plausibly enough say
on this occasion, that if we consider the case a little more attentively,
we may take notice, that the action of the Acid Spirit seems in both cases,
but to weaken the Colour of the Liquor on which it falls. And so though it
destroy Redness in the Tincture of Brazil, as well as produce Red in the
Tincture of _Chochineel_, its Operations may be Uniform enough, since as
Crimson seems to be little else than a very deep Red, with (perhaps) an Eye
of Blew, so some kinds of Red seem (as I have lately noted) to be little
else than heightned Yellow. And consequently in such Bodies, the Yellow
seems to be but a diluted Red. And accordingly Alcalizate Solutions and
Urinous Spirits, which seem dispos'd to Deepen the Colours of the Juices
and Liquors of most Vegetables, will not only restore the Solution of
_Cochineel_ and the Infusion of Brazil to the Crimson, whence the Spirit of
Salt had chang'd them into a truer Red; but will also (as I lately told
you) not only heighthen the Yellow Juice of Madder into Red, but advance
the Red Infusion of Brazil to a Crimson. But I know not whether it will not
be much safer to derive these Changes from vary'd Textures, than certain
kinds of Bodies; and you will perhaps think it worth while, that I should
add on this occasion, That it may deserve some Speculation, why,
notwithstanding what we have been observing, though Blew and Purple seem to
be deeper Colours than Red, and therefore the Juices of Plants of either of
the two former Colours may (congruously enough to what has been just now
noted) be turn'd Red by Spirit of Salt or _Aqua-fortis_, yet Blew Syrrup of
Violets and some Purples should both by Oyl of Tartar and Spirit of Urine
be chang'd into Green, which seems to be not a deeper but a more diluted
Colour than Blew, if not also than Purple.
_EXPERIMENT XXXVIII._
It would much contribute to the History of Colours, if _Chymists_ would in
their Laboratories take a heedfull notice, and give us a faithfull account
of the Colours observ'd in the Steams of Bodies either Sublim'd or
Distill'd, and of the Colours of those Productions of the Fire, that are
made up by the Coalition of those Steams. As (for Instance) we observe in
the Distilling of pure Salt peter, that at a certain season of the
Operation, the Body, though it seem either Crystalline, or White, affords
very Red Fumes: whereas though Vitriol be Green or Blew, the Spirit of it
is observ'd to come over in Whitish Fumes. The like Colour I have taken
notice of in the Fumes of several other Concretes of differing Colours, and
Natures, especially when Distill'd with strong Fires. And we elsewhere
note, that ev'n Soot, as Black as it is, has fill'd our Receivers with such
copious White Fumes, that they seem'd to have had their In-sides wash'd
with Milk. And no less observable may be, the Distill'd Liqours, into which
such Fumes convene, (for though we will not deny, that by skill and care a
Reddish Liqour may be obtain'd from Nitre) yet the common Spirit of it, in
the making ev'n of which store of these Red Fumes are wont to pass over
into the Receiver, appears not to be at all Red. And besides, that neither
the Spirit of Vitriol, nor that of Soot is any thing White; And, besides
also, that as far as I have observ'd, most (for I say not all) of the
Empyreumatical Oyls of Woods, and other Concretes, are either of a deep
Red, or of a Colour between Red and Black; besides this, I say, 'tis very
remarkable that notwithstanding that great Variety of Colours to be met
with in the Herbs, Flowers, and other Bodies wont to be Distill'd in
_Balneo_: yet (as far at least as our common Distillers Experience
reacheth) all the Waters and Spirits that first come over by that way of
Distillation, leave the Colours of their Concretes behind them, though
indeed there be one or two Vegetables not commonly taken notice of, whose
Distill'd Liqours I elsewhere observe to carry over the Tincture of the
Concrete with them. And as in Distillations, so in Sublimations, it were
worth while to take notice of what comes up, in reference to our present
scope, by purposely performing them (as I have in some cafes done) in
conveniently shap'd Glasses, that the Colour of the ascending Fumes may be
discern'd; For it may afford a Naturalist good Information to observe the
Congruities or the Differences betwixt the Colours of the ascending Fumes,
and those of the _Flowers_, they compose by their Convention. For it is
evident, that these _Flowers_, do many of them in point of Colour, much
differ, not only from one another, but oft times from the Concretes that
afforded them. Thus, (not here to repeat what I formerly noted of the Black
Soots of very differingly Colour'd Bodies) though Camphire and Brimstone
afford _Flowers_ much of their own Colour, save that those of Brimstone are
wont to be a little Paler, than the Lumps that yielded them; yet ev'n of
Red _Benzoin_, that sublim'd Substance, which _Chymists_ call its
_Flowers_, is wont to be White or Whitish. And to omit other Instances,
ev'n one and the same Black Mineral, Antimony, may be made to afford
_Flowers_, some of them Red, and some Grey, and, which is more strange,
some of them purely White. And 'tis the Prescription of some Glass-men by
exquisitely mingling a convenient proportion of Brimstone, Sal-Armoniack,
and Quicksilver, and Subliming them, together, to make a Sublimate of an
excellent Blew; and though having caus'd the Experiment to be made, we
found the produc'd Sublimate to be far from being of a lovely Colour, (as
was promis'd) that there and there, it seem'd Blewish, and at least was of
a Colour differing enough from either of the Ingredients, which is
sufficient for our present purpose. But a much finer Colour is promis'd by
some of the Empiricks, that pretend to Secrets, who tell us, that Orpiment,
being Sublim'd, will afford among the Parts of it that fly Upward, some
little Masses, which, though the Mineral it self be of a good Yellow, will
be Red enough to emulate Rubies, both in Colour and Translucency. And this
Experiment may, for ought I know, sometimes succeed; for I remember, that
having in a small Bolt-head purposely sublim'd some powder'd Orpiment, we
could in the Lower part of the Sublimate discern here and there some
Reddish Lines, though much of the Upper part of the Sublimate consisted of
a matter, which was not alone purely Yellow, but transparent almost like a
Powder. And we have also this way obtain'd a Sublimate, the Lower part
whereof though it consisted not of Rubies, yet the small pieces of it,
which were Numerous enough, were of a pleasant Reddish Colour, and
Glitter'd very prettily. But to insist on such kind of Trials and
Observations (where the ascending Fumes of Bodies differ in Colour from the
Bodies themselves) though it might indeed Inrich the History of Colours,
would Robb me of too much of the little time I have to dispatch what I have
further to tell you concerning them.
_EXPERIMENT XXXIX_
Take the dry'd Buds (or Blossoms) of the Pomegranate Tree, (which are
commonly call'd in the Shops _Balaustiums_) pull off the Reddish Leaves,
and by a gentle Ebullition of them in fair Water, or by a competent
Infusion of them in like Water well heated, extract a faint Reddish
Tincture, which if the Liquor be turbid, you may Clarifie it by Filtrating
it Into this, if you pour a little good Spirit of Urine, or some other
Spirit abounding in the like sort of Volatile Salts, the Mixture will
presently turn of a dark Greenish Colour, but if instead of the
fore-mention'd Liquor, you drop into the simple Infusion a little rectify'd
Spirit of Sea-Salt, the Pale and almost Colourless Liquor will immediately
not only grow more Transparent, but acquire a high Redness, like that of
Rich Claret Wine, which so suddenly acquir'd Colour, may as quickly be
Destroy'd and turn'd into a dirty Blewish Green, by the affusion of a
competent quantity of the above-mention'd Spirit of Urine.
_Annotation._
This Experiment may bring some Light to, and receive some from a couple of
other Experiments, that I remember I have met with in the ingenious
_Gassendus_'s Animadversions upon _Epicurus_'s Philosophy, whilst I was
turning over the Leaves of those Learned Commentaries; (my Eyes being too
weak to let me read such Voluminous Books quite thorough) And I the less
scruple (notwithstanding my contrary Custom in this Treatise) to set down
these Experiments of another, because I shall a little improve the latter
of them, and because by comparing there with that which I have last
recited, we may be assisted to Conjecture upon what account it is, that Oyl
of Vitriol heightens the Tincture of Red-rose Leaves, since Spirit of Salt,
which is a highly Acid _Menstruum_, but otherwise differing enough from Oyl
of Vitriol, does the same thing. Our Authors Experiments then, as we made
them, are these; We took about a Glass-full of luke-warm Water, and in it
immerg'd a quantity of the Leaves of _Senna_, and presently upon the
Immersion there did not appear any Redness in the Water, but dropping into
it a little Oyl of Tartar, the Liquor soon discover'd a Redness to the
watchfull Eye, whereas by a little of that Acid Liquor of Vitriol, which is
like the former, undeservedly called Oyl, such a Colour would not be
extracted from the infused _Senna_. On the other side we took some Red-rose
Leaves dry'd, and having shaken them into a Glass of fair Water, they
imparted to it no Redness, but upon the affusion of a little Oyl of Vitriol
the Water was immediately turn'd Red, which it would not have been, if
instead of Oyl of Vitriol, we had imployed Oyl of Tartar to produce that
Colour: That these were _Gassendus_ his Experiments, I partly remember, and
was assur'd by a Friend, who lately Transcribed them out of _Gassendus_ his
Book, which I therefore add, because I have not now that Book at hand. And
the design of _Gassendus_ in these Experiments our Friend affirms to be, to
prove, that of things not Red a Redness may be made only by Mixture, and
the Varied position of parts, wherein the Doctrine of that Subtil
Philosopher doth not a little Authorize, what we have formerly delivered
concerning the Emergency and Change of Colours. But the instances, that we
have out of him set down, seem not to be the most Eminent, that may be
produced of this truth: For our next Experiment will shew the production of
several Colours out of Liquors, which have not any of them any such Colour,
nor indeed any discernable one at all; and whereas though our Author tells
us, that there was no Redness either in the Water, or the Leaves of
_Senna_, or the Oyl of Tartar; And though it be true, that the Predominant
Colour of the Leaves of _Senna_ be another than Red, yet we have try'd,
that by steeping that Plant a Night even in Cold water, it would afford a
very deep Yellow or Reddish Tincture without the help of the Oyl of Tartar,
which seems to do little more than assist the Water to extract more nimbly
a plenty of that Red Tincture, wherewith the Leaves of _Senna_ do of
themselves abound, and having taken off the Tincture of _Senna_, made only
with fair Water, before it grew to be Reddish, and Decanted it from the
Leaves, we could not perceive, that by dropping some Oyl of Tartar into it,
that Colour was considerable, though it were a little heightned into a
Redness; which might have been expected, if the particles of the Oyl did
eminently Co-operate, otherwise than we have expressed, to the production
of this Redness.
And as for the Experiment with Red-rose Leaves, the same thing may be
alleged, for we found that such Leaves by bare Infusion for a Night and Day
in fair Water, did afford us a Tincture bordering at least upon Redness,
and that Colour being conspicuous in the Leaves themselves, would not by
some seem so much to be produc'd as to be extracted by the affusion of Oyl
of Vitriol. And the Experiment try'd with the dry'd Leaves of Damask-roses
succeeded but imperfectly, but that is indeed observable to our Authors
purpose, that Oyl of Tartar will not perform in this Experiment what Oyl of
Vitriol doth; but because this last named Liquor is not so easily to be
had, give me leave to Advertise you, that the Experiment will succeed, if
instead of it you imploy _Aqua-fortis_. And though some Trials of our own
formerly made, and others easily deducible from what we have already
deliver'd, about the different Families and Operations of Salt, might
enable us to present you an Experiment upon Red-rose Leaves, more
accommodated to our Authors purpose, than that which he hath given us; yet
our Reverence to so Candid a Philosopher, invites us rather to improve his
Experiment, than substitute another in its place. Take therefore of the
Tincture of Red-rose Leaves, (for with Damask-rose Leaves the Experiment
succeedeth not well) made as before hath been taught with a little Oyl of
Vitriol, and a good quantity of fair Water, pour off this Liquor into a
clear Vial, half fill'd with Limpid water; till the Water held against the
Light have acquir'd a competent Redness, without losing its Transparency,
into this Tincture drop leisurely a little good Spirit of Urine, and
shaking the Vial, which you must still hold against the Light, you shall
see the Red Liquor immediately turn'd into a fine Greenish Blew, which
Colour was not to be found in any of the Bodies, upon whose Mixture it
emerg'd, and this Change is the more observable, because in many Bodies the
Degenerating of Blew into Red is usual enough, but the turning of Red into
Blew is very unfrequent. If at every drop of Spirit of Urine you shake the
Vial containing the Red Tincture, you may delightfully observe a pretty
variety of Colours in the passage of that Tincture from a Red to a Blew,
and sometimes we have this way hit upon such a Liquor, as being look't upon
against and from the Light, did seem faintly to emulate the above-mention'd
Tincture of _Lignum Nephriticum_. And if you make the Tincture of Red-roses
very high, and without Diluting it with fair Water, pour on the Spirit of
Urine, you may have a Blew so deep, as to make the Liquor Opacous, but
being dropt upon White Paper the Colour will soon disclose it self. Also
having made the Red, and consequently the Blew Tincture very Transparent,
and suffer'd it to rest in a small open Vial for a Day or two, we found
according to our Conjecture, that not only the Blew but the Red Colour also
was Vanish'd; the clear Liquor being of a bright Amber Colour, at the
bottom of which subsided a Light, but Copious feculency of almost the same
Colour, which seems to be nothing but the Tincted parts of the Rose Leaves
drawn out by the Acid Spirits of the Oyl of Vitriol, and Precipitated by
the Volatile Salt of the Spirit of Urine, which makes it the more probable,
that the Redness drawn by the Oyl of Vitriol, was at least as well an
extraction of the Tinging parts of the Roses, as a production of Redness;
and lastly, if you be destitute of Spirit of Urine, you may change the
Colour of the Tincture of Roses with many other Sulphureous Salts, as a
strong Solution of Pot-ashes, Oyl of Tartar, &c. which yet are seldome so
free from Feculency, as the Spirituous parts of Urine becomes by repeated
Distillation.
_Annotation_.
On this, occasion, I call to mind, that I found, a way of producing, though
not the same kind of Blew, as I have been mentioning, yet a Colour near of
Kin to it, namely, a fair Purple, by imploying a Liquor not made Red by
Art, instead of the Tincture of Red-roses, made with an Acid Spirit; And my
way was only to take Log-wood, (a Wood very well known to Dyers) having by
Infusion the Powder of it a while in fair Water made that Liquor Red, I
dropt into it a _Tantillum_ of an Urinous Spirit, as that of Sal-Armoniack,
(and I have done the same thing with an _Alcali_) by which the Colour was
in a moment turn'd into a Rich, and lovely Purple. But care must be had,
that you let not fall into a Spoonfull above two or three Drops, lest the
Colour become so deep, as to make the Liquor too Opacous. And (to answer
the other part of _Gassendus_ his Experiment) if instead of fair Water, I
infus'd the Log-wood in Water made somewhat sowr by the Acid Spirit of
Salt, I should obtain neither a Purple Liquor, nor a Red, but only a Yellow
one.
_EXPERIMENT XL._
The Experiment I am now to mention to you, _Pyrophilus_, is that which both
you, and all the other _Virtuosi_ that have seen it, have been pleas'd to
think very strange; and indeed of all the Experiments of Colours, I have
yet met with, it seems to be the fittest to recommend the Doctrine propos'd
in this Treatise, and to shew that we need not suppose, that all Colours
must necessarily be Inherent Qualities, flowing from the Substantial Forms
of the Bodies they are said to belong to, since by a bare Mechanical change
of Texture in the Minute parts of Bodies; two Colours may in a moment be
Generated quite _De novo,_ and utterly Destroy'd. For there is this
difference betwixt the following Experiment, and most of the others
deliver'd in these Papers, that in this, the Colour that a Body already
had, is not chang'd into another, but betwixt two Bodies, each of them
apart devoid of Colour, there is in a moment generated a very deep Colour,
and which if it were let alone, would be permanent; and yet by a very small
Parcel of a third Body, that has no Colour of its own, (lest some may
pretend I know not what Antipathy betwixt Colours) this otherwise permanent
Colour will be in another trice so quite Destroy'd, that there will remain
no foot-stepts either of it or of any other Colour in the whole Mixture.
The Experiment is very easie, and it is thus perform'd: Take good common
Sublimate, and fully satiate with it what quantity of Water you please,
Filtre the Solution carefully through clean and close Paper, that it may
drop down as Clear and Colourless as Fountain water. Then when you'l shew
the Experiment, put of it about a Spoonfull into a small Wine-glass, or any
other convenient Vessel made of clear Glass, and droping in three or four
drops of good Oyl of Tartar, _per Deliquium_; well Filtred that it may
likewise be without Colour, these two Limpid Liquors will in the twinkling
of an Eye turn into an Opacous mixture of a deep Orange Colour, which by
keeping the Glass continually shaking in your hand, you must preserve from
setling too soon to the Bottom; And when the Spectators have a little
beheld this first Change, then you must presently drop in about four or
five drops of Oyl of Vitriol, and continuing to shake the Glass pretty
strongly, that it may the Nimbler diffuse it self, the whole Colour, if you
have gone Skilfully to work, will immediately disappear, and all the Liquor
in the Glass will be Clear and Colourless as before, without so much as a
Sediment at the Bottom. But for the more gracefull Trial of this
Experiment, 'twill not be amiss to observe, First, That there should not be
taken too much of the Solution of Sublimate, nor too much of the Oyl of
Tartar drop'd in, to avoid the necessity of putting in so much Oyl of
Vitriol as may make an Ebullition, and perhaps run over the Glass.
Secondly, That 'tis convenient to keep the Glass always a little shaking,
both for the better mixing of the Liquors, and to keep the Yellow Substance
from Subsiding, which else it would in a short time do, though when 'tis
subsided it will retain its Colour, and also be capable of being depriv'd
of it by the Oyl newly mention'd. Thirdly, That if any Yellow matter stick
at the sides of the Glass, 'tis but inclining the Glass, till the clarify'd
Liquor can wash alongst it, and the Liquor will presently imbibe it, and
deprive it of its Colour.
Many have somewhat wondred, how I came to light upon this Experiment, but
the Notions or Conjectures I have about the differing Natures of the
Several Tribes of Salts, having led me to devise the Experiment, it will
not be difficult for me to give you the Chymical Reason, if I may so speak,
of the _Phænomenon_. Having then observ'd, that _Mercury_ being dissolv'd
in Some _Menstruums_, would yield a dark Yellow Precipitate, and supposing
that, as to this, common Water, and the Salts that stick to the _Mercury_
would be equivalent to those Acid _Menstruums_, which work upon the
_Quick-silver_, upon the account of their Saline particles, I substituted a
Solution of Sublimate in fair Water, instead of a Solution of _Mercury_ in
_Aqua-fortis_, or Spirit of _Nitre_, that simple Solution being both
clearer and free from that very offensive Smell, which accompanies the
Solutions of _Mercury_ made with those other corrosive Liquors; then I
consider'd, that That, which makes the Yellow Colour, is indeed but a
Precipitate made by the means of the Oyl of Tartar, which we drop in, and
which, as _Chymists_ know, does generally precipitate Metalline Bodies
corroded by Acid Salts; so that the Colour in our case results from the
Coalition of the Mercurial particles with the Saline ones, wherewith they
were formerly associated, and with the Alcalizate particles of the Salt of
Tartar that swim up and down in the Oyl. Wherefore considering also, that
very many of the effects of Lixiviate Liquors, upon the Solutions of other
Bodies, may be destroy'd by Acid _Menstruums_, as I elsewhere more
particularly declare, I concluded, that if I chose a very potently Acid
Liquor, which by its Incisive power might undo the work of the Oyl of
Tartar, and disperse again those Particles, which the other had by
Precipitation associated, into such minute Corpuscles as were before singly
Inconspicuous, they would become Inconspicuous again, and consequently
leave the Liquor as Colourless as before the Precipitation was made.
This, as I said, _Pyrophilus_, seems to be the Chymical reason of this
Experiment, that is such a reason, as, supposing the truth of those
Chymical Notions I have elsewhere I hope evinc'd, may give such an account
of the _Phænomena_ as Chymical Notions can supply us with; but I both here
and elsewhere make use of this way of speaking, to intimate that I am
sufficiently aware of the difference betwixt a Chymical Explication of a
_Phænomenon_, and one that is truly Philosophical or Mechanical; as in our
present case, I tell you something, when I tell you that the Yellowness of
the Mercurial Solution and the Oyl of Tartar is produc'd by the
Precipitation occasion'd by the affusion of the latter of those Liquors,
and that the destruction of the Colour proceeds from the Dissipation of
that Curdl'd matter, whose Texture is destroy'd, and which is dissolv'd
into Minute and Invisible particles by the potently Acid _Menstruum_, which
is the reason, why there remains no Sediment in the Bottom, because the
infused Oyl takes it up, and resolves it into hidden or invisible Parts, as
Water does Salt or Sugar. But when I have told you all this, I am far from
thinking I have told all that such an Inquisitive Person as your self would
know, for I presume you would desire as well as I to learn (at least) why
the Particles of the _Mercury_, of the Tartar, and of the Acid Salts
convening together, should make rather an Orange Colour than a Red, or a
Blew, or a Green, for 'tis not enough to say what I related a little
before, that divers Mercurial Solutions, though otherwise made, would yield
a Yellow precipitate, because the Question will recurr concerning them; and
to give it a satisfactory answer, is, I freely acknowledge, more than I
dare as yet pretend to.
But to confirm my conjecture about the Chymical reason of our Experiment, I
may add, that as I have (_viz._ pag. 34th. of this Treatise) elsewhere (on
another occasion) told you, with Saline Liquors of another kind and nature
than Salt of Tartar, (namely, with Spirit of Urine, and Liquors of kin to
that) I can make the _Mercury_ precipitate out of the first simple Solution
quite of another Colour than that hitherto mention'd; Nay, if instead of
altering the Precipitating liquor, I alter'd the Texture of the Sublimate
in such a way as my Notions about Salt requir'd, I could produce the same
_Phænomenon_. For having purposely Sublim'd together Equal parts (or
thereabout) of Sal-Armoniack and Sublimate, first diligently Mix'd, the
ascending Flowers being diffolv'd in fair Water, and Filtred, gave a
Solution Limpid and Colourless, like that of the other Sublimates, and yet
an _Akaly_ drop'd into this Liquor did not turn it Yellow but White. And
upon the same Grounds we may with _Quick-silver_, without the help of
common Sublimate, prepare another sort of Flowers dissoluble in Water
without Discolouring it, with which I could likewise do what I newly
mention'd; to which I shall add, (what possibly you'l somewhat wonder at)
That so much does the Colour depend upon the Texture resulting from the
Convention of the several sorts of Corpuscles, that though in out
Experiment, Oyl of Vitriol destroys the Yellow Colour, yet with
_Quick-silver_ and fair Water, by the help of Oyl of Vitriol alone, we may
easily make a kind of Precipitate of a fair and permanent Yellow, as you
will e're long (in the forty second Expement of this third Part) be taught.
And I may further add, that I chose Oyl of Vitriol, not so much for any
other or peculiar Quality, as for its being, when 'tis well rectify'd,
(which 'tis somewhat hazardous to bring it to be) not only devoid of Colour
and in Smells, but extremely Strong and Incisive; For though common and
undephlegmated _Aqua-fortis_ will not perform the same thing well, yet that
which is made exceeding Strong by being carefully Dephlegm'd, will do it
pretty well, though not so well as Oyl of Vitriol which is so Strong, that
even without Rectification it may for a need be made use of. I will not
here tell you what I have try'd, that I may be able to deprive at pleasure
the Precipitate that one of the Sulphureous Liquors had made, by the
copious Affusion of the other: Because I found, though this Experiment is
too ticklish to let me give a full account of it in few words, I shall
therefore tell you, that it is not only for once, that the other
above-mention'd Experiment may be made, the same Numerical parcels of
Liquor being still imploy'd in it; for after I have Clarify'd the Orange
Colour'd Liquor, by the addition of as little of the Oyl of Viriol as will
suffice to perform the effect, I can again at pleasure re-produce the
Opacous Colour, by the dropping in of fresh Oyl of Tartar, and destroy it
again by the Re-affusion of more of the Acid _Menstruum_; and yet oftner if
I please, can I with these two contrariant Liquors recall and disperse the
Colour, though by reason of the addition of so much new Liquor, in
reference to the Mercurial particles, the Colour will at length appear more
dilute and faint.
_An improvement of the fortieth Experiment_.
And, _Pyrophilus_, to confirm yet further the Notions that led me to think
on the propos'd Experiment, I shall acquaint you with another, which when I
had conveniency I have sometimes added to it, and which has to the
Spectators appear'd little less Odd than the first; And though because the
Liquor, requisite to make the Trial succeed well, must be on purpose
prepar'd anew a while before, because it will not long retain its fitness
for this work, I do but seldome annex this Experiment to the other, yet I
shall tell you how I devis'd it, and how I make it. If you boyl Crude
Antimony in a strong and clear _Lixivium_, you shall separate a Substance
from it, which some Modern _Chymists_ are pleas'd to call its Sulphur, but
how deservedly I shall not here examine, having elsewhere done it in an
Opportune place; wherefore I shall now but need to take notice, that when
this suppos'd Sulphur (not now to call it rather a kind of _Crocus_) is let
fall by the Liquor upon its Refrigeration, it often settles in Flakes, or
such like parcels of a Yellow Substance, (which being by the precedent
dissolution reduc'd into Minute parts, may peradventure be made to take
Fire much more easily than the Grosser Powder of unprepar'd Antimony would
have done.) Considering therefore, that common Sulphur boyl'd in a
_Lixivium_ may be Precipitated out of it by Rhenish-wine or White-wine,
which are Sowrish Liquors, and have in them, as I elsewhere shew, an Acid
Salt; and having found also by Trial, that with other Acid Liquors I could
Precipitate out of Lixiviate Solvents some other Mineral concretions
abounding with Sulphureous parts, of which sort is crude Antimony, I
concluded it to be easie to Precipitate the Antimony dissolv'd, as was
lately mention'd, with the Acid Oyl of Vitriol; and though common Sulphur
yields a White Precipitate, which the _Chymists_ call _Lac Sulphuris_, yet
I suppos'd the Precipitated Antimony would be of a deep Yellow Colour, as
well, if made with Oyl of Vitriol, as if made only by Refrigeration and
length of Time. From this 'twas easie to deduce this Experiment, that if
you put into one Glass some of the freshly Impregnated and Filtrated
Solution of Antimony, and into another some of the Orange-Colour'd Mixture,
(which I formerly shew'd you how to make with a Mercurial Solution and Oyl
of Tartar) a few drops of Oyl of Vitriol dropp'd into the last mention'd
Glass, would, as I told you before, turn the Deep Yellow mixture into a
Cleer Liquor; whereas a little of the same Oyl dropp'd out of the same Viol
into the other Glass would presently (but not without some ill sent) turn
the moderately cleer Solution into a Deep Yellow Substance, But this, as I
Said, succeeds not well, unless you employ a _Lixivium_ that has but newly
dissolv'd Antimony, and has not yet let it fall. But yet in Summer time, if
your _Lixivium_ have been duly Impregnated and well Filtred after it is
quite cold, it will for some dayes (perhaps much longer than I had occasion
to try) retain Antimony enough to exhibit, upon the Affusion of the
Corrosive Oyl, as much of a good Yellow Substance as is necessary to
satisfie the Beholders of the Possibility of the Experiment.
_Reflections upon the XL. Experiment Compared with the X. and XX._
The Knowledge of the Distinction of Salts which we have propos'd, whereby
they are discriminated into _Acid, Volatile,_ or _Salfuginous_ (if I may
for Distinction sake so call the Fugitive Salts of Animal Substances) and
_fix'd_ or _Alcalizate_, may possibly (by that little part which we have
already deliver'd, of what we could say of its Applicableness) appear of so
much Use in Natural Philosophy (especially in the Practick part of it) that
I doubt not but it will be no Unwelcome Corollary of the Preceding
Experiment, if by the help of it I teach you to distinguish, which of those
Salts is Predominant in Chymical Liquors, as well as whether any of them be
so or not. For though in our Notes upon the X. and XX. Experiments I have
shown you a way by means of the Tincture of _Lignum Nephriticum_, or of
Syrrup of Violets, to discover whether a propounded Salt be Acid or not,
yet you can thereby only find in general that such and such Salts belong
not to the Tribe of Acids, but cannot determine whether they belong to the
Tribe of Urinous Salts (under which for distinction sake I comprehend all
those Volatile Salts of Animal or other Substances that are contrary to
Acids) or to that of Alcalies. For as well the one as the other of these
Salino-Sulphurous Salts will restore the Cæruleous Colour to the Tincture
of _Lignum Nephriticum_, and turn that of Syrrup of Violets into Green.
Wherefore this XL. Experiment does opportunely supply the deficiency of
those. For being sollicitous to find out some ready wayes of discriminating
the Tribes of Chymical Salts, I found that all those I thought fit to make
Tryal of, would, if they were of a Lixiviate Nature, make with Sublimate
dissolv'd in Fair Water an _Orange Tawny_ Precipitate; whereas if they were
of an Urinous Nature the Precipitate would be _White_ and Milky. So that
having alwayes by me some Syrrup of Violets and some Solution of Sublimate,
I can by the help of the first of those Liquors discover in a trice,
whether the propounded Salt or Saline Body be of an Acid Nature or no, if
it be I need (you know) inquire no further; but if it be not, I can very
easily, and as readily distinguish between the other two kinds of Salts, by
the White or Orange-Colour that is immediately produc'd, by letting fall a
few Drops or Grains of the Salt to be examin'd, into a spoonfull of the
cleer Solution of Sublimate. For Example, it has been suppos'd by some
eminently Learned, That when Sal Armoniack being mingled with an Alcaly is
forc'd from it by the Fire in close Vessels, the Volatile Salt that will
thereby be obtain'd (if the Operation be skilfully perform'd,) is but a
more fine and subtile sort of Sal Armoniack, which, 'tis presum'd, this
Operation do's but more exquisitely purifie, than common Solutions,
Filtrations, and Coagulations. But this Opinion may be easily shown to be
Erroneous, as by other Arguments, so particularly by the lately deliver'd
Method of distinguishing the Tribes of Salts. For the Saline Spirit of Sal
Armoniack, as it is in many other manifest Qualities very like the Spirit
of Urine, so like, that it will in a trice make Syrrup of Violets of a
Lovely Green, turn a Solution of good Verdigrease into an Excellent Azure,
and make the Solution of a Sublimate yield a White Precipitate, insomuch
that in most (for I say not all of the Experiments) where I Aim onely at
producing a sudden change of Colour, I scruple not to use Spirit of Sal
Armoniack when it is at hand, instead of Spirit of Urine, as indeed it
seems chiefly to consist (besides the flegm that helps to make it fluid) of
the Volatile Urinous Salt (yet not excluding that of Soot) that abounds in
the Sal Armoniack and is set at liberty from the Sea Salt wherewith it was
formerly associated, and clogg'd, by the Operation of the Alcaly, that
divides the Ingredients of Sal Armoniack, and retains that Sea Salt with it
self. What use may be made of the like way of exploration in that inquiry
which puzzles so many Modern Naturalists, whether the Rich Pigment (which
we have often had occasion to mention) belongs to the Vegetable or Animal
Kingdome, you may find in another place where I give you some account of
what I try'd about Cocheneel. But I think it needless to exemplifie here
our Method by any other Instances, many such being to be met with in divers
parts of this Treatise; but I will rather advertise you, that, by this way
of examining Chymical Liquors, you may not onely in most Cases conclude
_Affirmatively_, but in some Cases _Negatively_. As since Spirit of Wine,
and as far as I have try'd, those Chymical Oyles which Artists call
Essential, did not (when I us'd them as I had us'd the several Families of
Salts upon that Syrrup) turn Syrrup of Violets Red or Green, nor the
Solution of Sublimate White or Yellow, I inferr'd it may thence be probably
argued, that either they are destitute of Salt, or have such as belongs not
to either of the three Grand families already often mention'd. When I went
to examine the Spirit of Oak or of such like Concretes forced over through
a Retort, I found by this means amongst others, that (as I elsewhere show)
these Chymists are much mistaken in it, that account it a simple Liquor,
and one of their Hypostatical Principles: for not to mention what flegm it
may have, I found that with a few drops of one of this sort of Spirits
mix'd with a good proportion of Syrrup of Violets, I could change the
Colour and make it Purplish, by the affinity of which Colour to Redness, I
conjectur'd that this Spirit had some Acid Corpuscles in it, and
accordingly I found that as it would destroy the Blewness of a Tincture of
_Lignum Nephriticum_, so being put upon Corals it would Corrode them, as
common Spirit of Vinegar, and other Acid Liquors are wont to do. And
farther to examine whether there were not a great part of the Liquor that
was not of an Acid nature, having separated the Sour or Vinegar-like part
from the rest, which (if I mistake not) is far the more Copious, we
concluded as we had conjectured, the other or remaining part, though it had
a strong taste as well as smell, to be of a nature differing from that of
either of the three sorts of Salts above mention'd, since it did as little
as Spirit of Wine, and Chymical Oyls, alter the Colour either of Syrrup of
Violets or Solution of Sublimate, whence we also inferr'd that the change
that had been made of that Syrrup into a Purple Colour, was effected by the
Vinegar, that was one of the two Ingredients of the Liquor, which was wont
to pass for a Simple or Uncompounded Spirit. And, upon this account, 'twas
of the Spirit of Oak (and the like Concretes) freed from it's Vinegar that
I elsewhere told you, that I had not then observ'd it, (and I have repeated
the Tryal but very lately) to destroy the Cæruleous Tincture of _Lignum
Nephriticum_. But this onely, _en passant_; for the Chief thing I had to
add was this, That by the same way may be examin'd and discover'd, divers
changes that are produc'd in Bodies either by Nature only, or by Art;
either of them being able by changing the Texture of some Concretes I could
name, to qualifie them to Operate after a New manner upon the above
mention'd Syrrup, or Solution, or both. And by this means, to tell you that
upon the by, I have been able to discover, that there may be made Bodies,
which though they run _per Deliquium_, as readily as Salt of Tartar, belong
in other respects, not to the family of Alcaliz, much less to that of
Salfuginous, or that of Acid Salts. Perhaps too, I may know a way of making
a highly operative Saline Body that shall neither change the Colour of
Syrrup of Violets, nor Precipitate the Solution of Sublimate; And, I can
likewise if I please conceal by what Liquors I perform such changes of
Colour, as I have been mentioning to you, by quite altering the Texture of
some ordinary Chymical productions, the Exploration of which is the main
use of the fortieth Experiment, which I think teaches not a little, if it
teach us to discover the nature of those things (in reference to Salt) that
are obtain'd by the ordinary Chymical Analysis of mix'd Bodyes, though
perhaps there may be other Bodyes prepar'd by Chymistry which may have the
same Effects in the change of Colours; and yet be produc'd not from what
Chymists call the Resolution of Bodies, but from their Composition. But the
discoursing of things of this nature is more proper for another place. I
shall now onely add, what might perhaps have been more seasonably told you
before; That the Reason why the way of Exploration of Salts hitherto
deliver'd, succeeds in the Solution of Sublimate, depends upon the
particular Texture of that Solution, as well as upon the differing Natures
of the Saline Liquors imploy'd to Precipitate it. For Gold dissolv'd in
_Aqua Regia_, whether you Precipitate it with Oyl of Tartar which is an
Alcaly, or with Spirit of Urine, or Sal Armoniack which belongs to the
family of Volatile Salts, will either way afford a Yellow substance: though
with such an Acid Liquor, as, I say not Spirit of Salt, the Body that
yields it, being upon the matter an Ingredient of _Aqua Regis_, but Oyl of
Vitriol it self, I did not find that I could Precipitate the Metall out of
the Solution, or destroy the Colour of it, though the same Oyl of Vitriol
would readily Precipitate Silver dissolv'd in _Aqua-fortis_. And if you
dissolve pure Silver in _Aqua-fortis_, and suffer it to shoot into
Crystals, the cleer Solution of these made in fair Water, will afford a
very White Precipitate, whether it be made with an Alcaly, or an Acid
Spirit, as that of Salt, whereas, which may seem somewhat strange, with
Spirit of Sal Armoniack (that I us'd was made of Quicklime) I could obtain
no such White Precipitate; that Volatile Spirit, nor (as I remember) that
of Urine, scarce doing any more than striking down a very small quantity of
Matter, which was neither White nor Whitish, so that the remaining Liquor
being suffer'd to evaporate till the superfluous Moisture was gone, the
greatest part of the Metalline Corpuscles with the Saline ones that had
imbib'd them, concoagulated into Salt, as is usual in such Solutions,
wherein the Metall has not been Precipitated.
_EXPERIMENT XLI._
Of Kin to the last or fortieth Experiment is another which I remember I
have sometimes shewn to _Virtuosi_ that were pleas'd not to dislike it. I
took Spirit of Urine made by Fermentation, and with a due proportion of
Copper brought into small parts, I obtain'd a very lovely Azure Solution,
and when I saw the Colour was such as was requisite, pouring into a clean
Glass, about a spoonfull of this tincted Liquor, (of which I us'd to keep a
Quantity by me,) I could by shaking into it some drops of Strong Oyl of
Vitriol, deprive it in a trice of its Deep Colour, and make it look like
Common-water.
_Annotation_.
This Experiment brings into my mind this other, which oftentimes succceds
well enough, though not quite so well as the former; Namely, that if into
about a small spoonfull of a Solution of good French Verdigrease made in
fair Water, I drop't and shak'd some strong Spirit of Salt, or rather
deflegm'd _Aqua Fortis_, the Greenness of the Solution would be made in a
trice almost totally to disappear, & the Liquor held against the Light
would scarce seeme other than Cleer or Limpid, to any but an Attentive Eye,
which is therefore remarkable; because we know that _Aqua-fortis_ corroding
Copper, which is it that gives the Colour to Verdigrease, is wont to reduce
it to a Green Blew Solution. But if into the other altogether or almost
Colourless Liquor I was speaking of, you drop a just quantity either of Oyl
of Tartar or Spirit of Urine, you shall find that after the Ebullition is
ceas'd, the mixture will disclose a lively Colour, though somewhat
differing from that which the Solution of Verdigrease had at first.
_EXPERIMENT XLII._
That the Colour (_Pyrophilus_) of a Body may be chang'd by a Liquor which
of it self is of no Colour, provided it be Saline, we have already
manifested by a multitude of instances. Nor doth it seem so strange,
because Saline Particles swimming up and down in Liquors, have been by many
observ'd to be very operative in the Production and change of Colours. But
divers of our Friends that are not acquainted with Chymical Operations have
thought it very strange that a White Body, and a Dry one too, should
immediately acquire a rich new Colour upon the bare affusion of
Spring-Water destitute as well of adventitious Salt as of Tincture. And yet
(_Pyrophilus_) the way of producing such a change of Colours may be easily
enough lighted on by those that are conversant in the Solutions of Mercury.
For we have try'd, that though by Evaporating a Solution of Quick-Silver in
_Aqua-fortis_, and abstracting the Liquor till the remaining matter began
to be well, but not too strongly dryed, fair Water pour'd on the remaining
_Calx_ made it but somewhat Yellowish; yet when we took good Quick-Silver,
and three or four times its weight of Oyl of Vitriol, in case we in a Glass
Retort plac'd in Sand drew off the Saline _Menstruum_ from the Metalline
Liquor, till there remain'd a dry _Calx_ at the bottome, though this
Precipitate were a Snow White Body, yet upon pouring on it a large quantity
of fair Water, we did almost in a moment perceive it to pass from a Milky
Colour to one of the loveliest Light Yellows that ever we had beheld. Nor
is the Turbith Mineral, that Chymists extol for its power to Salivate, and
for other vertues, of a Colour much inferiour to this, though it be often
made with a differing proportion of the Ingredients, a more troublesome
way. For _Beguinus_,[22] who calls it _Mercurius præcipitatus optimus_,
takes to one part of Quick-Silver, but two of Liquor, and that is Rectifi'd
Oyl of Sulphur, which is (in _England_ at least) far more scarce and dear
than Oyl of Vitriol; he also requires a previous Digestion, two or three
Cohobations, and frequent Ablutions with hot Distill'd Water, with other
prescriptions, which though they may conduce to the Goodness of the
Medicine, which is that he aims at, are troublesome, and, our Tryals have
inform'd you unneccessary to the _obtaining the Lemmon Colour_ which he
regards not. But though we have very rarely seen either in Painters Shops,
or elsewhere a finer Yellow than that which we have divers times this way
produc'd (which is the more considerable, because durable and pleasant
Yellows are very hard to be met with, as may appear by the great use which
Painters are for its Colours sake fain to make of that pernicious and heavy
Mineral, Orpiment) yet I fear our Yellow is too costly, to be like to be
imploy'd by Painters, unless about Choice pieces of Work, nor do I know how
well it will agree with every Pigment, especially, wich Oyl'd Colours. And
whether this Experiment, though it have seem'd somewhat strange to most we
have shown it to, be really of another Nature than those wherein Saline
Liquors are imploy'd, may, as we formerly also hinted, be so plausibly
doubted, that whether the Water pour'd on the _Calx_, do barely by imbibing
some of its Saline parts alter its Colour by altering its Texture, or
whether by dissolving the Concoagulated Salts, it does become a Saline
_Menstruum_, and, as such, work upon the Mercury, I freely leave to you
(_Pyrophilus_) to consider. And that I may give you some Assistance in your
Enquiry, I will not only tell you, that I have several times with fair
Water wash'd from this _Calx_, good store of strongly tasted Corpuscles,
which by the abstraction of the _Menstruum_, I could reduce into Salt; but
I will also subjoyn an Experiment, which I devis'd, to shew among other
things, how much a real and permanent Colour may be as it were drawn forth
by a Liquor that has neither Colour, nor so much as Saline or other Active
parts, provided it can but bring the parts of the Body it imbibes to
convene into clusters dispos'd after the manner requisite to the exhibiting
of the emergent Colour. The Experiment was this.
[22] _Beguinus_, Tyr. Chy. Lib. 2º. Cap. 13º.
_EXPERIMENT XLIII._
We took good common Vitriol, and having beaten it to Powder, and put it
into a Crucible, we kept it melted in a gentle heat, till by the
Evaporation of some parts, and the shuffling of the rest, it had quite lost
its former Colour, what remain'd we took out, and found it to be a friable
_Calx_, of a dirty Gray. On this we pour'd fair Water, which it did not
Colour Green or Blew, but only seem'd to make a muddy mixture with it, then
stopping the Vial wherein the Ingredients were put, we let it stand in a
quiet place for some dayes, and after many hours the water having dissolv'd
a good part of the imperfectly calcin'd Body, the Vitriolate Corpuscles
swiming to and fro in the Liquor, had time by their opportune Occursions to
constitute many little Masses of Vitriol, which gave the water they
impregnated a fair Vitriolate Colour; and this Liquor being pour'd off, the
remaining dirty Powder did in process of time communicate the like Colour,
but not so deep, to a second parcel of cleer Water that we pour'd on it.
But this Experiment _Pyrophilus_ is, (to give you that hint by the way) of
too Luciferous a Nature to be fit to be fully prosecuted, now that I am in
haste, and willing to dispatch what remains. And we have already said of
it, as much as is requisite to our present purpose.
_EXPERIMENT XLIV._
It may (_Pyrophilus_) somewhat contribute towards the shewing how much some
Colours depend upon the less or greater mixture, and (as it were,)
Contemperation of the Light with shades, to observe, how that sometimes the
number of Particles, of the same Colour, receiv'd into the Pores of a
Liquor, or swiming up and down in it, do seem much to vary the Colour of
it. I could here present you with particular instances to show, how in many
(if not most) consistent Bodyes, if the Colour be not a Light one, as
White, Yellow, or the like, the closeness of parts in the Pigments makes it
look Blackish, though when it is display'd and laid on thinly, it will
perhaps appear to be either Blew, or Green, or Red. But the Colours of
consistent Pigments, not being those which the Preamble of this Experiment
has lead you to expect Examples in, I shall take the instances I am now to
give you, rather from Liquors than Dry Bodyes. If then you put a little
fair Water into a cleer and slender Vial, (or rather into one of those
pipes of Glass, which we shall by and by mention;) and let fall into it a
few drops of a strong Decoction or Infusion of _Cochineel_, or (for want of
that) of _Brazil_; you may see the tincted drops descend like little Clouds
into the Liquor; through which, if, by shaking the Vial, you diffuse them,
they will turn the water either of a Pinck Colour, or like that which is
wont to be made by the washing of raw flesh in fair Water; by dropping a
little more of the Decoction, you may heighten the Colour into a fine Red,
almost like that which ennobles Rubies; by continuing the affusion, you may
bring the Liquor to a kind of a Crimson, and afterwards to a Dark and
Opacous Redness, somewhat like that of Clotted Blood. And in the passage of
the Liquor from one of these Colours to the other, you may observe, if you
consider it attentively, divers other less noted Colours belonging to Red,
to which it is not easie to give Names; especially considering how much the
proportion of the Decoction to the fair Water, and the strength of that
Decoction, together with that of the trajected Light and other
Circumstances, may vary the Phænomena of this Experiment. For the
convenienter making whereof, we use instead of a Vial, any slender Pipe of
Glass of about a foot or more in length, and about the thickness of a mans
little finger; For, if leaving one end of this Pipe open, you Seal up the
other Hermetically, (or at least stop it exquisitely with a Cork well
fitted to it, and over-laid with hard Sealing Wax melted, and rubb'd upon
it;) you shall have a Glass, wherein may be observ'd the Variations of the
Colours of Liquors much better than in large Vials, and wherein Experiments
of this Nature may be well made with very small quantities of Liquor. And
if you please, you may in this Pipe produce variety of Colours in the
various parts of the Liquor, and keep them swimming upon one another
unmix'd for a good while. And some have marveil'd to see, what variety of
Colours we have sometimes (but I confess rather by chance than skill)
produc'd in those Glasses, by the bare infusion of Brazil, variously
diluted with fair Water, and alter'd by the Infusion of several Chymical
Spirits and other Saline Liquors devoid themselves of Colour, and when the
whole Liquor is reduc'd to an Uniform degree of Colour, I have taken
pleasure to make that very Liquor seem to be of Colours gradually
differing, by filling with it Glasses of a Conical figure, (whether the
Glass have its basis in the ordinary position, or turn'd upwards.) And yet
you need not Glasses of an extraordinary shape to see an instance of what
the vari'd mixture of Light and Shadow can do in the diversifying of the
Colour. For if you take but a large round Vial, with a somewhat long and
slender Neck, and filling it with our Red Infusion of Brazil, hold it
against the Light, you will discern a notable Disparity betwixt the Colour
of that part of the Liquor which is in the Body of the Vial, and that which
is more pervious to the Light in the Neck. Nay, I remember, that I once had
a Glass and a Blew Liquor (consisting chiefly (or only, if my memory
deceive me not,) of a certain Solution of Verdigrease) so fitted for my
purpose, that though in other Glasses the Experiment would not succeed, yet
when that particular Glass was fill'd with that Solution, in the Body of
the Vial it appear'd of a Lovely Blew, and in the neck, (where the Light
did more dilute the Colour,) of a manifest Green; and though I suspected
there might be some latent Yellowness in the substance of the neck of the
Glass, which might with the Blew compose that Green, yet was I not
satisfi'd my self with my Conjecture, but the thing seem'd odd to me, as
well as to divers curious persons to whom it was shown. And I lately had a
Broad piece of Glass, which being look'd on against the Light seem'd clear
enough, and held from the Light appear'd very lightly discolour'd, and yet
it was a piece knock'd off from a great lump of Glass, to which if we
rejoyn'd it, where it had been broken off, the whole Mass was as green as
Grass. And I have several times us'd Bottles and stopples that were both
made (as those, I had them from assur'd me) of the very same Metall, and
yet whilst the bottle appear'd but inclining towards a Green, the Stopple
(by reason of its great thickness) was of so deep a Colour that you would
hardly believe they could possibly be made of the same materials. But to
satisfie some Ingenious Men, on another occasion, I provided my self of a
flat Glass (which I yet have by me,) with which if I look against the Light
with the Broad side obverted to the Eye, it appeares like a good ordinary
window Glass; but if I turn the Edge of it to my Eye, and place my Eye in a
convenient posture in reference to the Light, it may contend for deepness
of Colour with an Emerald. And this Greeness puts me in mind of a certain
thickish, but not consistent Pigment I have sometimes made, and can show
you when you please, which being dropp'd on a piece of White Paper appears,
where any quantity of it is fallen, of a somewhat Crimson Colour, but being
with ones finger spread thinly on the Paper does presently exhibit a fair
Green, which seems to proceed only from its disclosing its Colour upon the
Extenuation of its Depth into Superficies, if the change be not somewhat
help'd by the Colours degenerating upon one or other of the Accounts
formerly mention'd. Let me add, that having made divers Tryals with that
Blew substance, which in Painters shops is call'd _Litmase_, we have
sometimes taken Pleasure to observe, that being dissolv'd in a due
proportion of fair Water, the Solution either oppos'd to the Light, or
dropp'd upon White paper, did appear of a deep Colour betwixt Crimson and
Purple; and yet that being spread very thin on the Paper and suffer'd to
dry on there, the Paper was wont to appear Stain'd of a Fine Blew. And to
satisfie my selfe, that the diversity came not from the Paper, which one
might suspect capable of inbibing the Liquor, and altering the Colour, I
made the Tryal upon a flat piece of purely White Glass'd Earth, (which I
sometimes make use of about Experiments of Colours) with an Event not
unlike the former.
And now I speak of _Litmass_, I will add, that having this very day taken a
piece of it, that I had kept by me these several years, to make Tryals
about Colours, and having let fall a few drops of the strong Infusion of it
in fair water, into a fine Crystal Glass, shap'd like an inverted Cone, and
almost full of fair Water, I had now (as formerly) the pleasure to see, and
to show others, how these few tincted drops variously dispersing themselves
through the Limpid Water, exhibited divers Colours, or varieties of Purple
and Crimson. And when the Corpuscles of the Pigment seem'd to have equally
diffus'd themselves through the whole Liquor, I then by putting two or
three drops of Spirit of Salt, first made an odd change in the Colour of
the Liquor, as well as a visible commotion among its small parts, and in a
short time chang'd it wholly into a very Glorious Yellow, like that of a
Topaz. After which if I let fall a few drops of the strong and heavy
Solution of Pot-ashes, whose weight would quickly carry it to the sharp
bottome of the Glass, there would soon appear four very pleasant and
distinct Colours; Namely, a Bright, but Dilute Colour at the picked bottome
of the Glass; a Purple, a little higher; a deep and glorious Crimson,
(which Crimson seem'd to terminate the operation of the Salt upward) in the
confines betwixt the Purple and the Yellow; and an Excellent Yellow, the
same that before enobled the whole Liquor, reaching from thence to the top
of the Glass. And if I pleas'd to pour very gently a little Spirit of Sal
Armoniack, upon the upper part of this Yellow, there would also be a Purple
or a Crimson, or both, generated there, so that the unalter'd part of the
Yellow Liquor appear'd intercepted betwixt the two Neighbouring Colours.
My scope in this 3d. Experiment (_Pyrophilus_) is manifold, as first to
invite you to be wary in judging of the Colour of Liquors in such Glasses
as are therein recommended to you, and consequently as much, if not more,
when you imploy other Glasses. Secondly, That you may not think it strange,
that I often content my self to rub upon a piece of White paper, the Juice
of Bodies I would examine, since not onely I could not easily procure a
sufficient Quantity of the juices of divers of them; but in several Cases
the Tryals of the quantities of such Juices in Glasses would make us more
lyable to mistakes, than the way that in those cases I have made use of.
Thirdly, I hope you will by these and divers other particulars deliver'd in
this Treatise, be easily induc'd to think that I may have set down many
Phænomena very faithfully, and just as they appear'd to me, and yet by
reason of some unheeded circumstance in the conditions of the matter, and
in the degree of Light, or the manner of trying the Experiment, you may
find some things to vary from the Relations I make of them. Lastly, I
design'd to give you an opportunity to free your self from the amazement
which possesses most Men, at the Tricks of those Mountebancks that are
commonly call'd Water-drinkers. For though not only the vulgar, but ev'n
many persons that are far above that Rank, have so much admir'd to see, a
man after having drunk a great deal of fair water, to spurt it out again in
the form of Claret Wine, Sack, and Milk, that they have suspected the
intervening of Magick, or some forbidden means to effect what they
conceived above the power of Art; yet having once by chance had occasion to
oblige a Wanderer that made profession of that and other Jugling Tricks, I
was easily confirm'd by his Ingenious confession to me, That this so much
Admir'd Art, indeed consisted rather in a few Tricks, than in any great
Skill, in altering the Nature and Colours of things. And I am easy to be
perswaded; that there may be a great deal of Truth in a little Pamphlet
Printed divers years ago in English, wherein the Author undertakes to
discover, and that (if I mistake not) by the confession of some of the
Complices themselves, That a famous Water-drinker then much Admir'd in
_England_, perform'd his pretended Transmutations of Liquors by the help of
two or three inconsiderable preparations and mixtures of not unobvious
Liquors, and chiefly of an Infusion of Brazil variously diluted and made
Pale or Yellowish, (and otherwise alter'd) with Vinegar, the rest of their
work being perform'd by the shape of the Glasses, by Craft and Legerdemane.
And for my part, that which I marvel at in this business, is, the Drinkers
being able to take down so much Water, and spout it out with that violence;
though Custome and a Vomit seasonably taken before hand, may in some of
them much facilitate the work. But as for the changes made in the Liquors,
they were but few and slight in comparison of those, that the being
conversant in Chymical Experiments, and dextrous in applying them to the
Transmuting of Colours, may easily enough enable a man to make, as ev'n
what has been newly deliver'd in this, and the foregoing Experiment;
especially if we add to it the things contained in the XX, the XXXIX and
the XL. Experiments, may perhaps have already perswaded You.
_EXPERIMENT XLV._
You may I presume (_Pyrophilus_) have taken notice, that in this whole
Treatise, I purposely decline (as far as I well can) the mentioning of
Elaborate Chymical Experiments, for fear of frighting you by their
tediousness and difficulty; but yet in confirmation of what I have been
newly telling you about the possibility of Varying the Colours of Liquors,
better than the Water-drinkers are wont to do, I shall add, that _Helmont_
used to make a preparation of Steel, which a very Ingenious Chymist, his
Sons Friend, whom you know, sometimes employes for a succedaneum to the
Spaw-waters, by Diluting this _Essentia Martis Liquida_ (as he calls it)
with a due proportion of Water. Now that for which I mention to you this
preparation, (which as he communicated to me, I know he will not refuse to
_Pyrophilus_) is this, that though the Liquor (as I can shew you when you
please) be almost of the Colour of a German (not an Oriental) Amethyst, and
consequently remote enough from Green, yet a very few drops being let fall
into a Large proportion of good Rhenish, or (in want of that) White Wine
(which yet do's not quite so well) immediately turn'd the Liquor into a
lovely Green, as I have not without delight shown several curious Persons.
By which _Phænomenon_ you may learn, among other things, how requisite it
is in Experiments about the changes of Colours heedfully to mind the
Circumstances of them; for Water will not, as I have purposely try'd,
concurr to the production of any such Green, nor did it give that Colour to
moderate Spirit of Wine, wherein I purposely dissolv'd it, and Wine it self
is a Liquor that few would suspect of being able to work suddenly any such
change in a Metalline preparation of this Nature; and to satisfie my self
that this new Colour proceeds rather from the peculiar Texture of the Wine,
than from any greater Acidity, that Rhenish or White-wine (for that may not
absurdly be suspected) has in comparison of Water; I purposely sharpen'd
the Solution of this Essence in fair Water, with a good quantity of Spirit
of Salt, notwithstanding which, the mixture acquir'd no Greenness. And to
vary the Experiment a little, I try'd, that if into a Glass of Rhenish Wine
made Green by this Essence, I dropp'd an Alcalizate Solution, or Urinous
Spirit, the Wine would presently grow Turbid, and of an odd Dirty Colour;
But if instead of dissolving the Essence in Wine, I dissolv'd it in fair
Water sharpen'd perhaps with a little Spirit of Salt, then either the
Urinous Spirit of Sal Armoniack, or the solution of the fix'd Salt of
Pot-ashes would immediately turn it of a Yellowish Colour, the fix'd or
Urinous Salt Precipitating the Vitriolate substance contain'd in the
Essence. But here I must not forget to take notice of a circumstance that
deserves to be compar'd with some part of the foregoing Experiment, for
whereas our Essence imparts a Greenness to Wine, but not to Water, the
Industrious _Olaus Wormius_[23] in his late _Musæum_ tells us of a rare
kind of Turn-Sole which he calls _Bezetta Rubra_ given him by an Apothecary
that knew not how it was made, whose lovely Redness would be easily
communicated to Water, if it were immers'd in it; but scarce to Wine, and
not at all to Spirit of Wine, in which last circumstance it agrees with
what I lately told you of our Essence, notwithstanding their disagreement
in other particulars.
[23] Libr. 2do Cap. 34.
_EXPERIMENT XLVI._
We have often taken notice, as of a remarkable thing, that Metalls as they
appear to the Eye, before they come to be farther alter'd by other Bodyes,
do exhibit Colours very different from those which the Fire and the
_Menstruum_, either apart, or both together, do produce in them; especially
considering that these Metalline Bodyes are after all these disguises
reducible not only to their former Metalline Consistence and other more
radical properties, but to their Colour too, as if Nature had given divers
Metalls to each of them a double Colour, an _External_, and an _Internal_;
But though upon a more attentive Consideration of this difference of
Colours, it seem'd probable to me, that divers (for I say not all) of those
Colours which we have just now call'd _Internal_, are rather produc'd by
the Coalition of Metalline Particles with those of the Salts, or other
Bodyes employ'd to work on them, than by the bare alteration of the parts
of the Metalls themselves: and though therefore we may call the obvious
Colours, Natural or Common, & the others Adventitious, yet because such
changes of Colours, from whatsoever cause they be resolv'd to proceed may
be properly enough taken in to illustrate our present Subject, we shall not
scruple to take notice of some of them, especially because there are among
them such as are produc'd without the intervention of Saline _Menstruums_.
Of the Adventitious Colours of Metalline Bodies the Chief sorts seem to be
these three. The first, such Colours as are produc'd without other
Additaments by the Action of the fire upon Metalls. The next such as emerge
from the Coalition of Metalline Particles with those of some _Menstruum_
imploy'd to Corrode a Metall or Precipitate it; And the last, The Colours
afforded by Metalline Bodyes either Colliquated with, or otherwise
Penetrating into, other Bodies, especially fusible ones. But these
(_Pyrophilus,_) are only as I told you, the _Chief_ sorts of the
adventitious Colours of Metalls, for there may others belong to them, of
which I shall hereafter have occasion to take notice of some, and of which
also there possibly may be others that I never took notice of.
And to begin with the first sort of Colours, 'tis well enough known to
Chymists, that Tin being Calcin'd by fire alone is wont to afford a White
_Calx_, and Lead Calcin'd by fire alone affords that most Common Red-Powder
we call _Minium:_ Copper also Calcin'd _per se_, by a long or violent fire,
is wont to yield (as far as I have had occasion to take notice of it) a
very Dark or Blackish Powder; That Iron likewise may by the Action of
Reverberated flames be turn'd into a Colour almost like that of Saffron,
may be easily deduc'd from the Preparation of that Powder, which by reason
of its Colour and of the Metall 'tis made of is by Chymists call'd, _Crocus
Martis per se_. And that _Mercury_ made by the stress of Fire, may be
turn'd into a Red Powder, which Chymists call Precipitate _per se_, I
elsewhere more particularly declare.
_Annotation I._
It is not unworthy the Admonishing you, (_Pyrophilus_,) and it agrees very
well with our Conjectures about the dependence of the change of a Body's
Colour upon that of its Texture, that the same Metall may by the successive
operation of the fire receive divers Adventitious Colours, as is evident in
Lead, which before it come to so deep a Colour as that of _Minium_, may
pass through divers others.
_Annotation II_.
Not only the _Calces_, but the Glasses of Metalls, Vitrify'd _per se_, may
be of Colours differing from the Natural or Obvious Colour of the Metall;
as I have observ'd in the Glass of Lead, made by long exposing Crude Lead
to a violent fire, and what I have observ'd about the Glass or Slagg of
Copper, (of which I can show you some of an odd kind of Texture,) may be
elsewhere more conveniently related. I have likewise seen a piece of very
Dark Glass, which an Ingenious Artificer that show'd it me profess'd
himself to have made of Silver alone by an extreme _Violence_ (which seems
to be no more than is needfull) of the fire.
_Annotation III_.
Minerals also by the Action of the Fire may be brought to afford Colours
very differing from their own, as I not long since noted to you about the
variously Colour'd Flowers of Antimony, to which we may add the Whitish
Grey-Colour of its _Calx_, and the Yellow or Reddish Colour of the Glass,
where into that _Calx_ may be flux'd.
And I remember, that I elsewhere told you, that Vitriol Calcin'd with a
very gentle heat, and afterwards with higher and higher degrees of it, may
be made to pass through several Colours before it descends to a Dark
Purplish Colour, whereto a strong fire is wont at length to reduce it. But
to insist on the Colours produc'd by the Operation of fire upon several
Minerals would take up farr more time than I have now to spare.
_EXPERIMENT XLVII._
The Adventitious Colours produc'd upon Metalls, or rather with them, by
Saline Liquors, are many of them so well known to Chymists, that I would
not here mention them, but that besides a not un-needed Testimony, I can
add something of my own, to what I shall repeat about them, and divers
Experiments which are familiar to Chymists, are as yet unknown to the
greatest part of Ingenious Men.
That Gold dissolv'd in _Aqua Regia_ ennobles the _Menstruum_ with its own
Colour, is a thing that you cannot (_Pyrophilus_,) but have often seen. The
Solutions of Mercury in _Aqua-fortis_ are not generally taken notice of, to
give any notable Tincture to the _Menstruum_; but sometimes when the Liquor
first falls upon the Quick Silver, I have observ'd a very remarkable,
though not durable, Greenness, or Blewness to be produc'd, which is a
_Phænomenon_ not unfit for you to consider, though I have not now the
leisure to discourse upon it. Tin Corroded by _Aqua-fortis_ till the
_Menstruum_ will work no farther on it, becomes exceeding White, but as we
elsewhere note, does very easily of it self acquire the consistence, not of
a Metalline _Calx_, but of a Coagulated matter, which we have observ'd with
pleasure to look so like, either to curdled Milk, or curdled Whites of
Eggs, that a person unacquainted with such Solutions may easily be mistaken
in it. But when I purposely prepar'd a _Menstruum_ that would dissolve it
as _Aqua-fortis_ dissolves Silver, and not barely Corrode it, and quickly
let it fall again, I remember not that I took notice of any particular
Colour in the Solution, as if the more Whitish Metalls did not much Tinge
their _Menstruums_, though the conspicuously Colour'd Metalls as Gold, and
Copper, do. For Lead dissolv'd in Spirit of Vinegar or _Aqua-fortis_ gives
a Solution cleer enough, and if the _Menstruum_ be abstracted appears
either Diaphanous or White. Of the Colour of Iron we have elsewhere said
something: And 'tis worth noting, that though if that Metall be dissolv'd
in oyl of Vitriol diluted with water, it affords a Salt or Magistery so
like in colour, as well as some other Qualities, to other green Vitriol,
that Chymists do not improperly call it _Vitriolum Martis_; yet I have
purposely try'd, that, by changing the _Menstruum_, and pouring upon the
filings of Steel, instead of oyl of Vitriol, _Aqua Fortis_, (whereof as I
remember, I us'd 4 parts to one of the Metall) I obtain'd not a Green, but
a Saffron Colour Solution; or rather a thick Liquor of a deep but yellowish
Red. Common Silver, such as is to be met with in Coines, being dissolv'd in
_Aqua fortis_, yields a Solution tincted like that of Copper, which is not
to be wondred at, because in the coining of Silver, they are wont (as we
elsewhere particularly inform you) to give it an Allay of Copper, and that
which is sold in shops for refined silver, is not (so far as we have tryed)
so perfectly free from that ignobler Metall, but that a Solution of It in
_Aqua fortis_, will give a Venereal Tincture to the _Menstruum_. But we
could not observe upon the solution of some Silver, which was perfectly
refin'd, (such as some that we have, from which 8 or 10 times its weight of
Lead has been blown off) that the _Menstruum_ though held against the Light
in a Crystal Vial did manifestly disclose any Tincture, only it seem'd
sometimes not to be quite destitute of a little, but very faint
Blewishness.
But here I must take notice, that of all the Metalls, there is not any
which doth so easily and constantly disclose its unobvious colour as Copper
doth. For not only in acid _Menstruums_ as _Aqua Fortis_ and Spirit of
Vinegar, it gives a Blewish green solution, but if it be almost any way
corroded, it _appears of one of those_ two colours, as may be observ'd in
Verdigreese made several wayes, in that odd preparation of _Venus_, which
we elsewhere teach you to make with Sublimate, and in the common Vitriols
of _Venus_ deliver'd by Chymists; and so constant is the disposition of
Copper, notwithstanding the disguise Artists put upon it, to disclose the
colour we have been mentioning, that we have by forcing it up with _Sal
Armoniack_ obtain'd a Sublimate of a Blewish Colour. Nay a famous Spagyrist
affirms, that the very Mercury of it is green, but till he teach us an
intelligible way of making such a Mercury, we must content ourselves to
inform you, that we have had a Cupreous Body, that was Præcipitated out of
a distill'd Liquor, that seem'd to be the the Sulphur of _Venus_, and
seem'd even when flaming, of a Greenish Colour. And indeed Copper is a
Metall so easily wrought upon by Liquors of several kinds, that I should
tell you, I know not any Mineral, that will concurr to the production of
such a variety of Colours as Copper dissol'd in several _Menstruums_, as
Spirit of Vinegar, _Aqua fortis_, _Aqua Regis_, Spirit of Nitre, of Urine,
of Soot, Oyls of several kinds, and I know not how many other Liquors, if
the variety of somewhat differing colours (that Copper will be made to
assume, as it is wrought upon by several Liquors) were not comprehended
within the Limits of Greenish Blew, or Blewish Green.
And yet I must advertise you (_Pyrophilus_) that being desirous to try if I
could not make with crude Copper a Green Solution without the Blewishness
that is wont to accompany its Vulgar Solutions, I bethought my self of
using two _Menstruums_, which I had not known imploy'd to work on this
Metall, and which I had certain Reasons to make Tryal of, as I successfully
did. The one of these Liquors (if I much misremember not) was Spirit of
Sugar distill'd in a Retort, which must be warily done, (if you will avoid
breaking your glasses) and the other, Oyl or Spirit of Turpentine, which
affords a fine Green Solution that is useful to me on several occasions.
And yet to shew that the adventitious colour may result, as well from the
true and permanent Copper it self, as the Salts wherewith 'tis corroded, I
shall add, that if you take a piece of good _Dantzick_ Copperis, or any
other Vitriol wherein _Venus_ is prædominant, and having moistened it in
your Mouth, or with fair water, rubb it upon a whetted knife, or any other
bright piece of Steel or Iron, it will (as we have formerly told you)
present'y stain the Steel with a Reddish colour, like that of Copper, the
reason of which, we must not now stay to inquire.
_Annotation I._
I presume you may have taken notice (_Pyrophilus_) that I have borrowed
some of the Instances mention'd in this 47th Experiment, from the
Laboratories of Chymists, and because in some (though very few) other
passages of this Essay, I have likewise made use of Experiments mention'd
also by some Spagyrical Writers, I think it not amiss to represent to you
on this Occasion once for all, some things besides those which I intimated
in the præamble of this present Experiment; For besides, that 'tis very
allowable for a Writer to repeat an Experiment which he invented not, in
case he improve it; And besides that many Experiments familiar to Chymists
are unknown to the generality of Learned Men, who either never read
Chymical processes, or never understood their meaning, or never durst
believe them; besides these things, I say, I shall represent, That, as to
the few Experiments I have borrowed from the Chymists, if they be very
Vulgar, 'twould perhaps be difficult to ascribe each of them its own
Author, and 'tis more than the generality of Chymists themselves can do:
and if they be not of very known and familiar practise among them, unless
the Authors wherein I found them had given me cause to believe, themselves
had try'd them, I know not why I might not set them down, as a part of the
_Phænomena_ of Colours which I present you; Many things unanimously enough
deliver'd as matters of fact by (I know not how many Chymical Writers)
being not to be rely'd on, upon the single Authority of such Authors: For
Instance, as some Spagyrists deliver (perhaps amongst several deceitful
processes) that _Saccarum Saturni_ with Spirit of Turpentine will afford a
Balsom, so _Beguinus_ and many more tell us, that the same Concrete
(_Saccarum Saturni_) will yield an incomparably fragrant Spirit, and a
pretty Quantity of two several Oyles, and yet since many have complain'd,
as well as I have done, that they could find no such odoriferous, but
rather an ill-sented Liquor, and scarce any oyl in their Distillation of
that sweet Vitriol, a wary person would as little build any thing on what
they say of the former Experiment, as upon what they averr of the later,
and therefore I scrupled not to mention this Red Balsom of which I have not
seen any, (but what I made) among my other experiments about redness.
_Annot. II._
We have sometimes had the Curiosity to try what Colours Minerals, as
Tinglass, Antimony, Spelter, &c. would yield in several _Menstruums_, nor
have we forborn to try the Colours of stones, of which that famous one,
(which _Helmont_ calls _Paracelsus's Ludus_) though it be digg'd out of the
Earth and seem a true stone, has afforded in _Menstruums_ capable to
dissolve so solid a stone, sometimes a Yellowish, sometimes a Red solution
of both which I can show you. But though I have from Minerals obtain'd with
several _Menstruums_ very differing Colours, and some such as perhaps you
would be surpriz'd to see drawn from such Bodies: yet I must now pass by
the particulars, being desirous to put an End to this Treatise, before I
put an end to your Patience and my own.
_Annotation III._
And yet before I pass to the next Experiment, I must put you in mind, that
the Colours of Metals may in many cases be further alter'd by imploying,
either præcipitating Salts, or other convenient Substances to act upon
their Solutions. Of this you may remember, that I have given you several
Instances already, to which may be added such as these, That if Quicksilver
be dissolv'd in _Aqua fortis_, and Præcipitated out of the Solution, either
with water impregnated with Sea salt, or with the spirit of that Concrete,
it falls to the Bottom in the form of a white powder, whereas if it be
Præcipitated with an Alcaly, it will afford a Yellowish or tawny powder,
and if there be no Præcipitation made, and the _Menstruum_ be drawn off
with a convenient fire, the corroded Mercury will remain in the bottom, in
the form of a substance that may be made to appear of differing Colours by
differing degrees of Heat; As I remember that lately having purposely
abstracted _Aqua fortis_ from some Quicksilver that we had dissolv'd in it,
so that there remain'd a white _Calx_, exposing that to several degrees of
Fire, and afterwards to a naked one, we obtain'd some new Colours, and at
length the greatest part of the _Calx_ lying at the Bottome of the Vial,
and being brought partly to a Deep Yellow, and partly to a Red Colour, the
rest appear'd elevated to the upper part and neck of the Vial, some in the
form of a Reddish, and some of an Ash-Colour Sublimate. But of the
differing Colours which by differing wayes and working of Quick Silver with
Fire, and Saline Bodies, may be produc'd in Precipitates, I may elsewhere
have occasion to take further notice. I also told you not long since, that
if you corrode Quick-silver with Oyl of Vitriol instead of _Aqua-fortis_,
and abstract the _Menstruum_, there will remain a White _Calx_ which by the
Affusion of Fair Water presently turns into a Lemmon Colour. And ev'n the
_Succedaneum_ to a _Menstruum_ may sometimes serve the turn to change the
Colours of a Metal. The lovely Red which Painters call Vermillion, is made
of Mercury, which is of the Colour of Silver, and of Brimstone which is of
Kin to that of Gold, Sublim'd up together in a certain proportion, as is
vulgarly known to Spagyrists.
_EXPERIMENT XLVIII._
The third chief sort of the Adventitious Colours of Metals, is, that which
is produc'd by associating them (especially when Calcin'd) with other
fusible Bodies, and Principally Venice, and other fine Glass devoid of
Colour.
I have formerly given you an Example, whereby it may appear, that a Metal
may impart to Glass a Colour much differing from its own, when I told you,
how with Silver, I had given Glass a lovely Golden Colour. And I shall now
add, that I have Learn'd from one of the Chief Artificers that sells
Painted Glass, that those of his Trade Colour it Yellow with a preparation
of the _Calx_ of Silver. Though having lately had occasion among other
Tryals to mingle a few grains of Shell-silver (such as is imploy'd with the
Pensil and Pen) with a convenient proportion of powder'd Crystal Glass,
having kept them two or three hours in fusion, I was surpriz'd to find the
Colliquated Mass to appear upon breaking the Crucible of a lovely Saphirine
Blew, which made me suspect my Servant might have brought me a wrong
Crucible, but he constantly affirm'd it to be the same wherein the Silver
was put, and considerable Circumstances countenanc'd his Assertion, so that
till I have opportunity to make farther Tryal, I cannot but suspect, either
that Silver which is not (which is not very probable) brought to a perfect
Fusion and Colliquation with Glass, may impart to it other Colours than
when Neal'd upon it, or else (which is less unlikely) that though Silver
Beaters usually chuse the finest Coyn they can get, as that which is most
extensive under the Hammer, yet the Silver-leaves of which this Shel-silver
was made, might retain so much Copper as to enable it to give the
predominant tincture to the Glass.
For, I must proceed to tell you (_Pyrophilus_) as another instance of the
Adventitious Colours of Metals, that which is something strange, Namely,
That though Copper Calcin'd _per se_ affords but a Dark and basely Colour'd
_Calx_, yet the Glassmen do with it, as themselves inform me, Tinge their
Glass green. And I remember, that when once we took some crude Copper, and
by frequent Ignition quenching it in Water had reduc'd it to a Dark and
Ill-colour'd Powder, and afterward kept it in Fusion in about a 100. times
its weight of fine Glass, we had, though not a Green, yet a Blew colour'd
Mass, which would perhaps have been Green, if we had hit right upon the
Proportion of the Materials, and the Degree of Fire, and the Time wherein
it ought to be kept in Fusion, so plentifully does that Metal abound in a
Venerial Tincture, as Artists call it, and in so many wayes does it
disclose that Richness. But though Copper do as we have said give somewhat
near the like Colour to Glass, which it does to _Aqua-fortis_, yet it seems
worth inquiry, whether those new Colours which Mineral Bodies disclose in
melted Glass, proceed from the Coalition of the Corpuscles of the Mineral
with the Particles of the Glass as such, or from the Action (excited or
actuated by fire) of the Alcalizate Salt (which is a main Ingredient of
Glass,) upon the Mineral Body, or from the concurrence of both these
Causes, or else from any other. But to return to that which we were saying,
we may observe that _Putty_ made by calcining together a proportion of Tin
and Lead, as it is it self a White _Calx_, so does it turn the _Pitta di
Crystallo_ (as the Glassmen call the matter of the Purer sort of Glass,
wherewith it is Colliquated into a White Mass, which if it be opacous
enough is employ'd, as we elsewhere declare, for White Amel. But of the
Colours which the other Metals may be made to produce in Colourless Glass,
and other Vitrifiable Bodies, that have native Colours of their own, I must
leave you to inform your self upon Tryal, or at least must forbear to do it
till another time, considering how many Annotations are to follow, upon
what has in this and the two former Experiments been said already.
_Annotation I._
When the Materials of Glass being melted with Calcin'd Tin, have compos'd a
Mass Undiaphanous and White, this White Amel is as it were the Basis of all
those fine Concretes that Goldsmiths and several Artificers imploy in the
curious Art of Enamelling. For this White and Fusible substance will
receive into it self, without spoyling them, the Colours of divers other
Mineral substances, which like it will indure the fire.
_Annotation II._
So that as by the present (XLVIII.) Experiment it appears, that divers
Minerals will impart to fusible Masses, Colours differing from their own;
so by the making and compounding of Amels, it may appear, that divers
Bodies will both retain their Colour in the fire, and impart the _same_ to
some others wherewith they were vitrifi'd, and in such Tryals as that
mention'd in the 17. Experiment, where I told you, that ev'n in Amels a
Blew and Yellow will compound a Green. 'Tis pretty to behold, not only that
some Colours are of so fix'd a Nature, as to be capable of mixture without
receiving any detriment by the fire, that do's so easily destroy or spoyl
those of other Bodies; but Mineral Pigments may be mingled by fire little
less regularly and successfully, than in ordinary Dyeing Fatts, the vulgar
Colours are wont to be mingled by the help of Water.
_Annotation III._
'Tis not only Metalline, but other Mineral Bodies, that may be imploy'd, to
give Tinctures unto Glass (and 'tis worth noting how small a quantity of
some Mineral substances, will Tinge a Comparatively vast proportion of
Glass, and we have sometimes attempted to Colour Glass, ev'n with Pretious
Stones, and had cause to think the Experiment not cast away. And 'tis known
by them that have look'd into the Art of Glass, that the Artificers use to
tinge their Glass Blew, with that Dark Mineral _Zaffora_, (some of my
Tryals on which I elsewhere acquaint you) which some would have to be a
Mineral Earth, others a Stone, and others neither the one, nor the other,
but which is confessedly of a Dark, but not a Blew Colour, though it be not
agreed of what particular Colour it is. 'Tis likewise though a familiar yet
a remarkable practise among those that Deal in the making of Glass, to
imploy (as some of themselves have inform'd me) what they call Manganess,
and some Authors call _Magnesia_ (of which I make particular mention in
another Treatise) to exhibit in Glass not only other Colours than its own,
(which is so like in Darkness or blackishness to the Load stone, that 'tis
given by Mineralists, for one of the Reasons of its Latine Name) but
Colours differing from one another. For though they use it, (which is
somewhat strange) to Clarifye their Glass, and free it from that Blewish
Greenish Colour, which else it would too often be subject to, yet they also
imploy it in certain proportions, to tinge their Glass both with a Red
colour, and with a Purplish or Murry, and putting in a greater Quantity,
they also make with it that deep obscure Glass which is wont to pass for
Black, which agrees very well with, and may serve to confirm what we noted
near the beginning of the 44th Experiment, of the seeming Blackness of
those Bodies that are overcharg'd with the Corpuscles of such Colours, as
Red, or Blew, or Green, &c. And as by several Metals and other Minerals we
can give various Colours to Glass, so on the other side, by the differing
Colours that Mineral Oars, or other Mineral Powders being melted with Glass
disclose in it, a good Conjecture may be oftentimes made of the Metall or
known Mineral, that the Oar propos'd, either holds, or is most of kin to.
And this easie way of examining Oars, may be in some cases of good use, and
is not ill deliver'd by _Glauber_, to whom I shall at present refer you,
for a more particular account of it: unless your Curiosity command also
what I have observ'd about these matters; only I must here advertise you,
that great circumspection is requisite to keep this way from proving
fallacious, upon the account of the variations of Colour that may be
produc'd by the differing proportions that may be us'd betwixt the Oar and
the Glass, by the Richness or Poorness of the Oar it self, by the Degree of
Fire, and (especially) by the Length of Time, during which the matter is
kept in fusion; as you will easily gather from what you will quickly meet
with in the following Annotation upon this present 48th Experiment.
_Annotation IV._
There is another way and differing enough from those already mention'd, by
which Metalls may be brought to exhibit adventitious Colours: For by This,
the Metall do's not so much impart a Colour to another Body, as receive a
Colour from it, or rather both Bodies do by the new Texture resulting from
their mistion produce a new Colour. I will not insist to this purpose upon
the Examples afforded us by yellow Orpiment, and common Sea Salt, from
which, sublim'd together, Chymists unanimously affirm their White or
Crystalline Arsenick to be made: But 'tis not unworthy our noting, That
though Yellow Orpiment be acknowledg'd to be the Copiousest by far of the
two Ingredients of Arsenick, yet this last nam'd Body being duely added to
the highest Colour'd Metall Copper, when 'tis in fusion, gives it a
whiteness both within and without. Thus _Lapis Calaminaris_ changes and
improves the Colour of Copper by turning it into Brass. And I have
sometimes by the help of Zinck duely mix'd after a certain manner, given
Copper one of the Richest Golden Colours that ever I have seen the Best
true Gold Ennobled with. But pray have a care that such Hints fall not into
any hands that may mis-imploy them.
_Annotation V._
Upon the Knowledge of the differing wayes of making Minerals and Metalls
produce their adventitious Colours in Bodies capable of Vitrification,
depends the pretty Art of making what Chymists by a Barbarous Word are
pleas'd to call _Amanses_, that is counterfeit, or factitious Gemms, as
Emeralds, Rubies, Saphires, Topazes, and the like. For in the making of
these, though pure Sand or Calcin'd Crystal give the Body, yet 'tis for the
most part some Metalline or Mineral _Calx_, mingled in a small proportion
that gives the Colour. But though I have many years since taken delight, to
divert my self with this pleasing Art, and have seen very pretty
Productions of it, yet besides that I fear I have now forgot most of the
little Skill I had in it, this is no place to entertain you with what would
rather take up an intire Discourse, than be comprehended in an Annotation;
wherefore the few things which I shall here take notice of to you, are only
what belong to the present Argument, Namely,
First, That I have often observ'd that Calcin'd Lead Colliquated with fine
White Sand or Crystal, reduc'd by ignitions and subsequent extinctions in
Water to a subtile Powder, will of it self be brought by a due Decoction to
give a cleer Mass Colour'd like a _German_ Amethyst. For though this glass
of Lead, is look'd upon by them that know no better way of making
_Amanses_, as the grand Work of them all, yet which is an inconvenience
that much blemishes this way, the Calcin'd Lead it self does not only
afford matter to the _Amanses_, but has also as well as other Metals a
Colour of its own, which as I was saying, I have often found to be like
that of _German_ (as many call them) not Eastern Amethysts.
Secondly, That nevertheless this Colour may be easily over-powr'd by those
of divers other Mineral Pigments (if I may so call them) so that with a
glass of Lead, you may Emulate (for Instance) the fresh and lovely
Greenness of an Emerald, though in divers cases the Colour which the Lead
it self upon Vitrification tends to, may vitiate that of the Pigment, which
you would introduce into the Mass.
Thirdly, That so much ev'n these Colours depend upon Texture, that in the
Glass of Lead it self made of about three parts of _Lytharge_ or _Minium_
Colliquated with one of very finely Powder'd Crystal or Sand, we have taken
pleasure to make the mixture pass through differing Colours, as we kept it
more or less in the Fusion. For it was not usually till after a pretty long
Decoction that the Mass attain'd to the Amethystin Colour.
Fourthly and lastly, That the degrees of Coction and other Circumstances
may so vary the Colour produc'd in the same mass, that in a Crucible that
was not great I have had fragments of the same Mass, in some of which
perhaps not so big as a Hazel-Nut, you may discern four distinct Colours.
_Annotation VI._
You may remember (_Pyrophilus_) that when I mention'd the three sorts of
adventitious Colours of Metals, I mention'd them but as the chief, not the
only. For there may be other wayes, which though they do not in so strict a
sense belong to the adventitious Colours of Metals, may not inconveniently
be reduc'd to them. And of these I shall name now a couple, without denying
that there may be more.
The first may be drawn from the practise of those that Dye Scarlet. For the
famousest Master in that Art, either in _England_ or _Holland_, has
confess'd to me, that neither others, nor he can strike that lovely Colour
which is now wont to be call'd the _Bow-Dye_, without their Materials be
Boyl'd in Vessels, either made of, or lin'd with a particular Metall. But
of what I have known attempted in this kind, I must not as yet for fear of
prejudicing or displeasing others give you any particular Account.[24]
The other way (_Pyrophilus_) of making Metals afford unobvious Colours, is
by imbuing divers Bodies with Solutions of them made in their proper
_Menstruum's_, As (for Instance) though Copper plentifully dissolv'd in
_Aqua fortis_, will imbue several Bodies with the Colour of the Solution;
Yet Some other Metalls will not (as I elsewhere tell you) and have often
try'd. Gold dissolv'd in _Aqua Regia_, will, (which is not commonly known)
Dye the Nails and Skin, and Hafts of Knives, and other things made of
Ivory, not with a Golden, but a Purple Colour, which though it manifest it
self but slowly, is very durable, and scarce ever to be wash'd out. And if
I misremember not, I have already told you in this Treatise, that the purer
Crystals of fine Silver made with _Aqua fortis_, though they appear White,
will presently Dye the Skin and Nails, with a Black, or at least a very
Dark Colour, which Water will not wash off, as it will ordinary Ink from
the same parts. And divers other Bodies may the Same way be Dy'd, some of a
Black, and others of a Blackish Colour.
[24] See the latter end of the fiftieth Experiment.
And as Metalline, so likewise Mineral Solutions may produce Colours
differing enough from those of the Liquors themselves. I shall not fetch an
Example of this, from what we daily see happen in the powdring of Beef,
which by the Brine imploy'd about it (especially if the flesh be over
salted) do's oftentimes appear at our Tables of a Green, and sometimes of a
Reddish Colour, (deep enough) nor shall I insist on the practise of some
that deal in Salt Petre, who, (as I suspected, and as themselves
acknowledg'd to me) do, with the mixture of a certain proportion of that;
and common Salt, give a fine Redness, not only to Neats Tongues, but which
is more pretty as well as difficult, to such flesh, as would otherwise be
purely White; These Examples, I say, I shall decline insisting on, as
chusing rather to tell you, that I have several times try'd, that a
Solution of the Sulphur of Vitriol, or ev'n of common Sulphur, though the
Liquor appear'd clear enough, would immediately tinge a piece of new Coin,
or other clean Silver, sometimes with a Golden, sometimes with a deeper,
and more Reddish colour, according to the strength of the Solution, and the
quantity of it, that chanc'd to adhere to the Metall; which may take off
your wonder that the water of the hot Spring at _Bath_, abounding with
dissolv'd Substances of a very Sulphureous Nature, should for a while, as
it were gild, the new or clean pieces of Silver coyn, that are for a due
time immers'd in it. And to these may be added those formerly mention'd
Examples of the adventitious Colours of Mineral Bodies; which brings into
my mind, that, ev'n Vegetable Liquors, whether by degeneration, or by
altering the Texture of the Body that imbibes them, may stain other Bodies
with Colours differing enough, from their own, of which very good
Herbarists have afforded us a notable Example, by affirming that the Juice
of _Alcanna_ being green (in which state I could never here procure it)
do's yet Dye the Skin and Nails of a Lasting Red. But I see this Treatise
is like to prove too bulky without the addition of further Instances of
this Nature.
_EXPERIMENT XLIX._
Meeting the other day, _Pyrophilus_, in an _Italian_ book, that treats of
other matters, with a way of preparing what the Author calls a _Lacca_ of
Vegetables, by which the _Italians_ mean a kind of Extract fit for
Painting, like that rich _Lacca_ in English commonly call'd _Lake_, which
is imploy'd by Painters as a glorious Red. And finding the Experiment not
to be inconsiderable, and very defectively set down, it will not be amiss
to acquaint you with what some Tryals have inform'd us, in reference to
this Experiment, which both by our Italian Author, and by divers of his
Countrymen, is look'd upon as no trifling Secret.
Take then the root call'd in Latin _Curcuma_, and in English Turmerick,
(which I made use of, because it was then at hand, and is among Vegetables
fit for that purpose one of the most easiest to be had) and when it is
beaten, put what Quantity of it you please into fair Water, adding to every
pound of Water about a spoonfull or better of as strong a _Lixivium_ or
Solution of Potashes as you can well make, clarifying it by Filtration
before you put it to the Decocting water. Let these things boyl, or rather
simper over a soft Fire in a clean glaz'd Earthen Vessel, till you find by
the Immersion of a sheet of White Paper (or by some other way of Tryal)
that the Liquor is sufficiently impregnated with the Golden Tincture of the
Turmerick, then take the Decoction off the Fire, and Filter or Strain it
that it may be clean, and leisurely dropping into it a strong Solution of
Roch Allum, you shall find the Decoction as it were curdl'd, and the
tincted part of it either to emerge, to subside, or to swim up and down,
like little Yellow flakes; and if you pour this mixture into a Tunnel lin'd
with Cap Paper, the Liquor that Filtred formerly so Yellow, will now pass
clean thorow the Filtre, leaving its tincted, and as it were curdled parts
in the Filtre, upon which fair Water must be so often pour'd, till you have
Dulcifi'd the matter therein contain'd, the sign of which Dulcification is
(you know) when the Water that has pass'd through it, comes from it as
tasteless as it was pour'd on it. And if without Filtration you would
gather together the flakes of this Vegetable Lake, you must pour a great
Quantity of fair Water upon the Decoction after the affusion of the
Alluminous Solution, and you shall find the Liquor to grow clearer, and the
Lake to settle together at the bottom, or emerge to the top of the Water,
though sometimes having not pour'd out a sufficient Quantity of fair Water,
we have observ'd the Lake partly to subside, and partly to emerge, leaving
all the middle of the Liquor clear. But to make this Lake fit for use, it
must by repeated affusions of fresh Water, be Dulcifi'd from the adhering
Salts, as well as that separated by Filtration, and be spread and suffer'd
to dry leisurely upon pieces of Cloth, with Brown Paper, or Chalk, or
Bricks under them to imbibe the Moisture[25].
[Page 372]
_Annotation I._
Whereas it is presum'd that the Magistery of Vegetables obtain'd this way
consists but of the more Soluble and Coloured parts of the Plants that
afford it, I must take the liberty to Question the supposition. And for my
so doing, I shall give you this account.
According to the Notions (such as they were) that I had concerning Salts;
Allom, though to sense a Homogeneous Body, ought not to be reckon'd among
true Salts, but to be it self look'd upon as a kind of Magistery, in regard
that as Native Vitriol (for such I have had) contains both a Saline
substance and a Metall, whether Copper, or Iron, corroded by it, and
associated with it; so Allom which may be of so near a kin to Vitriol, that
in some places of _England_ (as we are assur'd by good Authority the same
stone will sometimes afford both) seems manifestly to contain a peculiar
kind of Acid Spirit, generated in the Bowels of the Earth, and some kind of
stony matter dissolv'd by it. And though in making our ordinary Allom, the
Workmen use the Ashes of a Sea Weed (vulgarly call'd Kelp) and Urine: yet
those that should know, inform us, that, here in _England_, there is
besides the factitious Allom, Allom made by Nature Without the help of
those Additaments. Now (_Pyrophilus_) when I consider'd this composition of
Allom, and that Alcalizate Salts are wont to Præcipitate what acid Salts
have dissolv'd, I could not but be prone to suspect that the Curdled
Matter, which is call'd the Magistery of Vegetables, may have in it no
inconsiderable proportion of a stony substance Præcipitated out of the
Allom by the _Lixivium_, wherein the Vegetable had been decocted, and to
shew you, that there is no necessity, that all the curdl'd substance must
belong to the Vegetable, I shall add, that I took a strong Solution of
Allom, and having Filtred it, by pouring in a convenient Quantity of a
strong Solution of Potashes, I presently, as I expected, turn'd the mixture
into a kind of white Curds, which being put to Filtre, the Paper retain'd a
stony _Calx_, copious enough, very White, and which seem'd to be of a
Mineral Nature, both by some other signes, and this, that little Bits of it
being put upon a live Coal, which was Gently Blown whilst they were on it,
they did neither melt nor fly away, and you may keep a Quantity of this
White substance for a good while, (nay for ought I can guess for a very
long one) in a red hot Crucible without losing or spoiling it; nor did hot
Water wherein I purposely kept another parcel of such _Calx_, seem to do
any more than wash away the looser adhering Salts from the stony substance,
which therefore seem'd unlikely to be separable by ablutions (though
reiterated) from the Præcipitated parts of the Vegetable, whose Lake is
intended. And to shew you, that there is likewise in Allom a Body, with
which the fix'd Salt of the Alcalizate Solution will concoagulate into a
Saline Substance differing from either of them, I shall add, that I have
taken pleasure to recover out of the slowly exhal'd Liquor, that pass'd
through the filtre, and left the foremention'd _Calx_ behind, a Body that
at least seem'd a Salt very pretty to look on, as being very White, and
consisting of an innumerable company of exceeding slender, and shining
Particles, which would in part easily melt at the flame of a Candle, and in
part flye away with some little noise. But of this substance, and its odd
Qualities more perhaps elsewhere; for now I shall only take notice to you,
that I have likewise with Urinous Salts, such as the Spirit of Sal
Armoniack, as well as with the Spirit of Urine it self, Nay, (if I much
mistake not) ev'n with Stale Urine undistil'd, easily Precipitated such a
White _Calx_ as I was formerly speaking of, out of a Limpid Solution of
Allom, so that there is need of Circumspection in judging of the Natures of
Liquors by Precipitations wherein Allom intervenes, else we may sometimes
mistakingly imagine that to be Precipitated out of a Liquor by Allom, which
is rather Precipitated out of Allom by the Liquor: And this puts me in mind
to tell you, that 'tis not unpleasant to behold how quickly the Solution of
Allom (or injected lumps of Allom) do's occasion the severing of the
colour'd parts of the Decoction from the Liquor that seem'd to have so
perfectly imbib'd them.
[25] _The Curious Reader that desires further Information concerning
Lakes, may Resort to the 7th Book of_ Neri's _Art of Glass, Englished (6
or 7 years since the Writing of this 49th Experiment) and Illustrated
with Learned Observations, by the Inquisitive and experienc'd Dr._
Charles Merret.
_Annot. II._
The above mention'd way of making Lakes we have tryed not only with
Turmerick, but also with Madder, which yielded us a Red Lake; and with Rue,
which afforded us an extract, of (almost if not altogether) the same Colour
with that of the leaves.
But in regard that 'tis Principally the Alcalizate Salt of the Pot-ashes,
which enables the water to Extract so powerfully the Tincture of the
Decocted Vegetables, I fear that our Author may be mistaken by supposing
that the Decoction will alwayes be of the very same Colour with the
Vegetable it is made off. For Lixiviate Salts, to which Pot-ashes eminently
belong, though by peircing and opening the Bodies of Vegetables, they
prepare and dispose them to part readily with their Tincture, yet some
Tinctures they do not only draw out, but likewise alter them, as may be
easily made appear by many of the Experiments already set down in this
Treatise, and though Allom being of an Acid Nature, its Solutions may in
some Cases destroy the Adventitious Colours produc'd by the Alcaly, and
restore the former: yet besides that Allom is not, as I have lately shown,
a meer Acid Salt, but a mixt Body, and besides, that its operations are
languid in comparison of the activity of Salts freed by Distillation, or by
Incineration and Dissolution, from the most of their Earthy parts, we have
seen already Examples, that in divers Cases an Acid Salt will not restore a
Vegetable substance to the Colour of which an Alcalizate one had depriv'd
it, but makes it assume a third very differing from both, as we formerly
told you, that if Syrrup of Violets were by an Alcaly turn'd Green, (which
Colour, as I have try'd, may be the same way produc'd in the Violet-leaves
themselves without any Relation to a Syrrup) an Acid Salt would not make it
Blew again, but Red. And though I have by this way of making Lakes, made
Magisteries (for such they seem to be) of Brazil, and as I remember of
Cochinele it self, and of other things, Red, Yellow or Green which Lakes
were enobled with a Rich Colour, and others had no bad one; yet in some the
colour of the Lake seem'd rather inferiour than otherwise to that of the
Plant, and in others it seem'd both very differing, and much worse; but
Writing this in a time and place where I cannot provide my self of Flowres
and other Vegetables to prosecute such Tryals in a competent variety of
Subjects, I am content not to be positive in delivering a judgment of this
way of Lakes, till Experience, or You, _Pyrophilus_, shall have afforded me
a fuller and more particular Information.
_Annotation III._
And on this occasion (_Pyrophilus_) I must here (having forgot to do it
sooner) advertise you once for all, that having written several of the
foregoing Experiments, not only in haste but at seasons of the year, and in
places wherein I could not furnish my self with such Instruments, and such
a variety of Materials, as the design of giving you an Introduction into
the History of Colours requir'd, it can scarce be otherwise but that divers
of the Experiments, that I have set down, may afford you some matter of new
Tryals, if you think fit to supply the deficiencies of some of them
(especially the freshly mention'd about Lakes, and those that concern
Emphatical Colours) which deficiencies for want of being befriended with
accommodations I could better discern than avoid.
_Annotation IV._
The use of Allom is very great as well as familiar in the Dyers Trade, and
I have not been ill pleas'd with the use I have been able to make of it in
preparing other pigments than those they imploy with Vegetable Juices. But
the Lucriferous practises of Dyers and other Tradesmen, I do, for Reasons
that you may know when you please, purposely forbear in this Essay, though
not strictly from pointing at, yet from making it a part of my present work
explicitly and circumstantially to deliver, especially since I now find
(though late and not without some Blushes at my prolixity) that what I
intended but for a short Essay, is already swell'd into almost a Volume.
_EXPERIMENT L._
Yet here, _Pyrophilus_, I must take leave to insert an Experiment, though
perhaps you'l think its coming in here an Intrusion, For I confess its more
proper place would have been among those Experiments, that were brought as
proofs and applications of our Notions concerning the differences of Salts;
but not having remembred to insert it in its fittest place, I had rather
take notice of it in this, than leave it quite unmention'd: partly because
it doth somewhat differ from the rest of our Experiments about Colours, in
the way whereby 'tis made; and partly because the grounds upon which I
devis'd it, may hint to you somewhat of the Method I use in Designing and
Varying Experiments about Colours, and upon this account I shall inform
you, not only What I did, but Why I did it.
I consider'd then that the work of the former Experiments was either to
change the Colour of a Body into another, or quite to destroy it, without
giving it a successor, but I had a mind to give you also a way, whereby to
turn a Body endued with one Colour into two Bodies, of Colours, as well as
consistencies, very distinct from each other, and that by the help of a
Body that had it self no Colour at all. In order to this, I remembred, that
finding the Acidity of Spirit of Vinegar to be wholly destroy'd by its
working upon _Minium_ (or calcin'd Lead) whereby the Saline particles of
the _Menstruum_ have their Taste and Nature quite alter'd, I had, among
other Conjectures I had built upon that change, rightly concluded, that the
Solution of Lead in Spirit of Vinegar would alter the Colour of the Juices
and Infusions of Several Plants, much after the like manner that I had
found Oyl of Tartar to do; and accordingly I was quickly satisfied upon
Tryal, that the Infusion of Rose-leaves would by a small quantity of this
Solution well mingl'd with it, be immediately turn'd into a somewhat sad
Green.
And further, I had often found, that Oyl of Vitriol, though a potently Acid
_Menstruum_, will yet Præcipitate many Bodies, both Mineral and others,
dissolv'd not onely in _Aqua fortis_ (as some Chymists have observ'd) but
particularly in Spirit of Vinegar, and I have further found, that the
_Calces_ or Powders Præcipitated by this Liquor were usually fair and
White.
Laying these things together, 'twas not difficult to conclude, that if upon
a good Tincture of Red Rose-leaves made with fair Water, I dropp'd a pretty
quantity of a strong and sweet Solution of _Minium_, the Liquor would be
turn'd into the like muddy Green Substance, as I have formerly intimated to
You, that Oyl of Tartar would reduce it to, and that if then I added a
convenient quantity of good Oyl of Vitriol, this last nam'd Liquor would
have two distinct operations upon the Mixture, the one, that it would
Præcipitate that resolv'd Lead in the form of a White Powder; the other,
that it would Clarifie the muddy Mixture, and both restore, and exceedingly
heighten the Redness of the Infusion of Roses, which was the most copious
Ingredient of the Green composition, and accordingly trying the Experiment
in a Wine glass sharp at the bottom (like an inverted Cone) that the
subsiding Powder might seem to take up the more room, and be the more
conspicuous, I found that when I had shaken the Green Mixture, that the
colour'd Liquor might be the more equally dispersed, a few drops of the
rectifi'd Oyl of Vitriol did presently turn the opacous Liquor into one
that was cleer and Red, almost like a Rubie, and threw down good store of a
Powder, which when 'twas settl'd, would have appear'd very White, if some
interspers'd Particles of the red Liquor had not a little Allay'd the
Purity, though not blemish'd the Beauty of the Colour. And to shew you,
_Pyrophilus_, that these Effects do not flow from the Oyl of Vitriol, as it
is such, but as it is a strongly Acid _Menstruum_, that has the property
both to Præcipitate Lead, as well as some other Concretes out of Spirit of
Vinegar, and to heighten the Colour of Red Rose-leaves, I add, that I have
done the same thing, though perhaps not quite so well with Spirit of Salt,
and that I could not do it with _Aqua-fortis_, because though that potent
_Menstruum_ does as well as the others heighthen the Redness of Roses, yet
it would not like them Precipitate Lead out of Spirit of Vinegar, but would
rather have dissolv'd it, if it had not found it dissolv'd already.
And as by this way we have produc'd a Red Liquor, and a White Precipitate
out of a Dirty Green magistery of Rose-leaves, so by the same Method, you
may produce a fair Yellow, and sometimes a Red Liquor, and the like
Precipitate, out of an Infusion of a curious Purple Colour. For you may
call to mind, that in the Annotation upon the 39th. Experiment I intimated
to you, that I had with a few drops of an Alcaly turn'd the Infusion of
Logg-wood into a lovely Purple. Now if instead of this Alcaly I substituted
a very Strong and well Filtrated Solution of _Minium_, made with Spirit of
Vinegar, and put about half as much of this Liquor as there was of the
Infusion of Logg-wood, (that the mixture might afford a pretty deal of
Precipitate,) the affusion of a convenient proportion of Spirit of Salt,
would (if the Liquors were well and nimbly stirr'd together) presently
strike down a Precipitate like that formerly mention'd, and turn the Liquor
that swam above it, for the most part into a lovely Yellow.
But for the advancing of this Experiment a little further, I consider'd,
that in case I first turn'd a spoonfull of the infusion of Logg-wood
Purple, by a convenient proportion of the Solution of _Minium_, the
Affusion of Spirit of Sal Armnoniack, would Precipitate the Corpuscles of
Lead conceal'd in the Solution of _Minium_, and yet not destroy the Purple
colour of the Liquor; whereupon I thus proceeded; I took about a spoonfull
of the _fresh_ Tincture of Logg-wood, (for I found that if it were _stale_
the Experiment would not alwayes succeed,) and having put to it a
convenient proportion of the Solution of _Minium_ to turn it into a deep
and almost opacous Purple, I then drop'd in as much Spirit of Sal
Armoniack, as I guess'd would Precipitate about half or more (but not all)
of the Lead, and immediately stirring the mixture well together, I mingled
the Precipitated parts with the others, so that they fell to the bottom,
partly in the form of a Powder, and partly in the form of a Curdled
Substance, that (by reason of the Predominancy of the Ting'd Corpuscles
over the White) retain'd as well as the Supernatant Liquor; a Blewish
Purple colour sufficiently Deep, and then instantly (but yet Warily,)
pouring on a pretty Quantity of Spirit of Salt, the matter first
Precipitated, was, by the above specified figure of the bottome of the
Glass preserv'd from being reach'd by the Spirituous Salt; which hastily
Precipitated upon it a new Bed (if I may so call it) of White Powder, being
the remaining Corpuscles of the Lead, that the Urinous Spirit had not
struck down: So that there appear'd in the Glass three distinct and very
differingly colour'd Substances; a Purple or Violet-colour'd Precipitate at
the bottom, a White and Carnation (sometimes a Variously colour'd)
Precipitate over That, and at the Top of all a Transparent Liquor of a
lovely Yellow, or Red.
Thus you see, _Pyrophilus_, that though to some I may have seem'd to have
lighted on this (50th.) Experiment by chance, and though others may
imagine, that to have excogitated it, must have proceeded from some
extraordinary insight into the nature of Colours, yet indeed, the devising
of it need not be look'd upon as any great matter, especially to one that
is a little vers'd in the notions, I have in these, and other Papers hinted
concerning the differences of Salts. And perhaps I might add upon more than
conjecture, that these very notions and some particulars scatteringly
deliver'd in this Treatise, being skilfully put together, may suggest
divers matters (at least,) about Colours, that will not be altogether
Despicable. But those hinted, _Pyrophilus_, I must now leave such as You to
prosecute, having already spent farr more time than I intended to allow my
self in acquainting You with particular Experiments and Observations
concerning the changes of Colour, to which I might have added many more,
but that I hope I may have presented You with a competent number to make
out in some measure what I have at the beginning of this Essay either
propos'd as my Design in this Tract, or deliver'd as my Conjectures
concerning these matters. And it not being my present Designe, as I have
more than once Declar'd, to deliver any Positive Hypothesis or solemn
Theory of Colours, but only to furnish You with some Experiments towards
the framing of such a Theory; I shall add nothing to what I have said
already, but a request that you would not be forward to think I have been
mistaken in any thing I have deliver'd as matter of Fact concerning the
changes of Colours, in case you should not every time you trye it, find it
exactly to succeed. For besides the Contingencies to which we have
elsewhere shewn some other Experiments to be obnoxious, the omission or
variation of a seemingly unconsiderable circumstance, may hinder the
success of an Experiment, wherein no other fault has been committed. Of
which truth I shall only give you that single and almost obvious, but yet
illustrious instance of the Art of Dying Scarlets, for though you should
see every Ingredient that is us'd about it, though I should particularly
inform You of the weight of each, and though you should be present at the
kindling of the fire, and at the increasing and remitting of it, when ever
the degree of Heat is to be alter'd, and though (in a word) you should see
every thing done so particularly that you would scarce harbour the least
doubt of your comprehending the whole Art: Yet if I should not disclose to
You, that the Vessels, that immediately contain the Tinging Ingredients,
are to be made of or to be lin'd with Tin, You would never be able by all
that I could tell you else (at-least, if the Famousest and Candidest
Artificers do not strangely delude themselves) to bring your Tincture of
Chochinele to Dye a perfect Scarlet. So much depends upon the very Vessel,
wherein the Tinging matters are boyl'd, and so great an Influence may an
unheeded Circumstance have on the Success of Experiments concerning
Colours.
* * * * *
_FINIS._
* * * * *
A SHORT
ACCOUNT
OF SOME
OBSERVATIONS
Made by Mr. _BOYLE_
About a _Diamond_ that _Shines_ in the Dark.
First enclosed in a Letter written to
a Friend,
And now together with it annexed to the Foregoing
Treatise, upon the score of the
Affinity Betwixt
_Light_ and _Colours_.
* * * * *
_LONDON,_
Printed for _Henry Herringman_. 1664
* * * * *
A COPY
OF THE
LETTER
That Mr. _Boyle_ wrote to Sir _Robert Morray_,
to accompany the _Observations_ touching
the _Shining Diamond_.
_SIR,_
Though Sir _Robert Morray_ and Monsieur _Zulichem_ be Persons that have
deserv'd so well of the Commonwealth of Learning, that I should think my
self unworthy to be look'd upon as a Member of it, if I declin'd to Obey
them, or to Serve them; yet I should not without Reluctancy send you the
Notes, you desire for him, if I did not hope that you will transmit
together with them, some Account why they are not less unworthy of his
perusal; which, that you may do; I must inform you, how the writing of them
was Occasion'd, which in short was thus. As I was just going out of Town,
hearing that an Ingenious Gentleman of my Acquaintance, lately return'd
from _Italy_, had a Diamond, that being rubb'd, would shine in the Dark,
and that he was not far off, I snatch'd time from my Occasions to make him
a Visit, but finding him ready to go abroad, and having in vain try'd to
make the Stone yield any Light in the Day time, I borrow'd it of him for
that Night, upon condition to restore it him within a Day or two at
furthest, at _Gresham_ College, where we appointed to attend the meeting of
the Society, that was then to be at that place. And hereupon I hasted that
Evening out of Town, and finding after Supper that the Stone which in the
Day time would afford no discernable Light, was really Conspicuous in the
Dark, I was so taken with the Novelty, and so desirous to make some use of
an opportunity that was like to last so little a while, that though at that
time I had no body to assist me but a Foot-Boy, yet sitting up late, I made
a shift that Night to try a pretty number of such of the things that then
came into my thoughts, as were not in that place and time unpracticable.
And the next Day being otherwise imploy'd, I was fain to make use of a
drowsie part of the Night to set down hastily in Writing what I had
observ'd, and without having the time in the Morning, to stay the
transcribing of it, I order'd the Observations to be brought after me to
_Gresham_ College, where you may remember, that they were together with the
Stone it self shown to the Royal Society, by which they had the good
Fortune not to be dislik'd, though several things were through hast
omitted, some of which you will find in the Margin of the inclosed Paper.
The substance of this short Narrative I hope you will let Monsieur
_Zulichem_ know, that he may be kept from expecting any thing of finish'd
in the Observations, and be dispos'd to excuse the want of it. But such as
they are, I hope they will prove (without a Clinch) Luciferous Experiments,
by setting the Speculations of the Curious on work, in a diligent Inquiry
after the Nature of Light, towards the discovery of which, perhaps they
have not yet met with so considerable an Experiment, since here we see
Light produc'd in a dead and opacous Body, and that not as in rotten Wood,
or in Fishes, or as in the _Bolonian_ Stone, by a Natural Corruption, or by
a Violent Destruction of the Texture of the Body, but by so slight a
Mechanical operation upon its Texture, as we seem to know what it is, and
as is immediately perform'd, and that several wayes without at all
prejudicing the Body, or making any sensible alterations in its Manifest
Qualities. And I am the more willing to expose my hasty Tryals to Monsieur
_Zulichem_, and to You, because, he being upon the Consideration of
Dioptricks, so odd a _Phænomenon_ relateing to the Subject, as probably he
treats of, Light will, I hope, excite a person to consider it, that is wont
to consider things he treats of very well. And for you Sir, I hope you will
both recrute and perfect the Observations you receive, For you know that I
cannot add to them, having a good while since restor'd to Mr. _Clayton_ the
Stone, which though it be now in the hands of a Prince that so highly
deserves, by understanding them, the greatest Curiosities; yet he
vouchsafes you that access to him as keeps me from doubting, you may easily
obtain leave to make further Tryals with it, of such a Monarch as ours,
that is not more inquisitive himself, than a favourer of them that are so.
I doubt not but these Notes will put you in mind of the Motion you made to
the Society, to impose upon me the Task of bringing in, what I had on other
occasions observ'd concerning shining Bodies. But though I deny not, that I
sometimes made observations about the _Bolonian_ Stone, and try'd some
Experiments about some other shining Bodies; Yet the same Reasons that
reduc'd me then to be unwilling to receive ev'n their commands, must now be
my Apology for not answering your Expectations, Namely the abstruse nature
of Light, and my being already over-burden'd, and but too much kept
imploy'd by the Urgency of the Press, as well as by more concerning and
distracting Occasions. But yet I will tell you some part of what I have met
with in reference to the Stone, of which I send you an account. Because I
find on the one side, that a great many think it no Rarity upon a mistaken
perswasion, that not only there are store of Carbuncles, of which this is
one; but that all Diamonds and other Glistering Jewels shine in the Dark.
Whereas on the other side there are very Learn'd Men, who (plausibly
enough) deny that there are any Carbuncles or shining Stones at all.
And certainly, those Judicious men have much more to say for themselves,
than the others commonly Plead, and therefore did deservedly look upon Mr.
_Clayton_'s Diamond as a great Rarity. For not only _Boetius de Boot_, who
is judg'd the best Author on this Subject, ascribes no such Virtue to
Diamonds, but begins what he delivers of Carbuncles, with this passage.[26]
_Magna fama est Carbunculi. Is vulgo putatur in tenebris Carbonis instar
lucere; fortassis quia Pyropus seu Anthrax appellatus a veteribus fuit.
Verum hactenus nemo nunquam verè asserere ausus fuit, se gemmam noctu
lucentem vidisse. Garcias ab Horto proregis Indiæ Medicus, refert se
allocutum fuisse, qui se vidisse affirmarent. Sed iis fidem non habuit._
And a later Author, the Diligent and Judicious _Johannes de Laet_ in his
Chapter of Carbuncles and of Rubies, has this passage. _Quia autem
Carbunculi, Pyropi & Anthraces a veteribus nominantur, vulgo creditum fuit,
Carbonis instar in tenebris lucere, quod tamen nullâ gemmâ hastenus
deprehensum, licet à quibusdam temerè jactetur._ And the recentest Writer I
have met with on this Subject, _Olaus Wormius_, in his Account of his well
furnish'd _Musæum_, do's, where he treats of Rubies, concurr with the
former Writers by these Words.[27] _Sunt qui Rubinum veterum Carbunculum
esse existimant, sed deest una illa nota, quod in tenebris instar Anthracis
non luceat: Ast talem Carbunculum in rerum naturâ non inveniri major pars
Authoram existimant. Licet unum aut alterum in India apud Magnates quosdam
reperiri scribant, cum tamen ex aliorum relatione id habeant saltem, sed
ipsi non viderint._ In confirmation of which I shall only add, that hearing
of a Rubie, so very Vivid, that the Jewellers themselves have several times
begg'd leave of the fair Lady to whom it belong'd, that they might try
their choicest Rubies by comparing them with That, I had the Opportunity by
the Favour of this Lady and her Husband, (both which I have the Honour to
be acquainted with) to make a Trial of this famous Rubie in the Night, and
in a Room well Darkn'd, but not only could not discern any thing of Light,
by looking on the Stone before any thing had been done to it, but could not
by all my Rubbing bring it to afford the least Glimmering of Light.
[26] Boetius de Boot. Gem. & Lapid. Histor. Lib. 3. Cap. 8.
[27] Musæi Wormiani. Cap. 17.
But, Sir, though I be very backward to admit strange things for truths, yet
I am not very forward to reject them as impossibilities, and therefore I
would not discourage any from making further Inquiry, whether or no there
be Really in _Rerum natura_, any such thing as a true Carbuncle or Stone
that without Rubbing will shine in the Dark. For if such a thing can be
found, it may afford no small Assistance to the Curious in the
Investigation of Light, besides the Nobleness and Rarity of the thing it
selfe. And though _Vartomannus_ was not an Eye witness of what he relates,
that the King of _Pegu_, one of the Chief Kings of the _East-Indies_, had a
true Carbuncle of that Bigness and Splendour, that it shin'd very
Gloriously in the Dark, and though _Garcias ab Horto_, the _Indian_
Vice-Roys Physician, speaks of another Carbuncle, only upon the Report of
one, that he Discours'd with, who affirmed himself to have seen it; yet as
we are not sure that these Men that gave themselves out to be Eye-witnesses
speak true, yet they may have done so for ought we know to the contrary.
And I could present you with a much considerabler Testimony to the same
purpose, if I had the permission of a Person concern'd, without whose leave
I must not do it. I might tell you that _Marcus Paulus Venetus_[28] (whose
suppos'd Fables, divers of our later Travellours and Navigatours have since
found to be truths) speaking of the King of _Zeilan_ that then was, tells
us, that he was said to have the best Rubie in the World, a Palm long and
as big as a mans Arm, without spot, shining like a Fire, and he subjoyns,
that the Great _Cham_, under whom _Paulus_ was a considerable Officer, sent
and offer'd the value of a City for it; But the King answer'd, he would not
give it for the treasure of the World, nor part with it, having been his
Ancestours. And I could add, that in the Relation made by two _Russian_
Cossacks of their Journey into _Catay_[29], written to their Emperour, they
mention'd their having been told by the people of those parts, that their
King had a Stone, which Lights as the Sun both Day and Night, call'd in
their Language _Sarra_, which those Cossacks interpret a Ruby. But these
Relations are too uncertain for me to build any thing upon, and therefore I
shall proceed to tell you, that there came hither about two years since out
of _America_, the Governour of one of the Principal Colonies there, an
Ancient _Virtuoso_, and one that has the Honour to be a member of the Royal
Society; this Gentleman finding some of the chief Affairs of his Country
committed to another and me, made me divers Visits, and in one of them when
I enquir'd what Rare Stones they had in those parts of the _Indies_ he
belong'd to, he told me, that the _Indians_ had a Tradition that in a
certain hardly accessible Hill, a pretty way up in the Country, there was a
Stone which in the Night time shin'd very vividly, and to a great distance,
and he assur'd me, that though he thought it not fit to venture himself so
far among those Savages, yet he purposely sent thither a bold _Englishman_,
with some Natives to be his guides, and that this Messenger brought him
back word, that at a distance from the Hillock he had plainly perceiv'd
such a shining Substance as the _Indians_ Tradition mention'd, and being
stimulated by Curiosity, had slighted those Superstitious Fears of the
Inhabitants, and with much ado by reason of the Difficulty of the way, had
made a shift to clamber up to that part of the Hill, where, by a very
heedful Observation, he suppos'd himself to have seen the Light: but
whether 'twere that he had mistaken the place, or for some other Reason, he
could not find it there, though when he was return'd to his former Station,
he did agen see the Light shining in the same place where it shone before.
A further Account of this Light I expect from the Gentleman that gave me
this, who lately sent me the news of his being landed in that Country. And
though I reserve to my self a full Liberty of Believing no more than I see
cause; yet I do the less scruple to relate this, because a good part of it
agrees well enough with another Story that I shall in the next place have
occasion to subjoyn, in order whereunto I shall tell you, that though the
Learned Authors I formerly mention'd, tell us, that no Writer has affirm'd
his having himself seen a real Carbuncle, yet, considering the Light of Mr.
_Claytons_ Diamond, it recall'd into my mind, that some years before, when
I was Inquisitive about Stones, I had met with an old _Italian_ Book highly
extoll'd to me by very competent Judges, and that though the Book were very
scarce, I had purchas'd it at a dear Rate, for the sake of a few
considerable passages I met with in it, and particularly one, which being
very remarkable in it self, and pertinent to our present Argument, I shall
put it for you, though not word for word, which I fear I have forgot to do,
yet as to the Sense, into _English_.
[28] _Purchas_'s Pilgrim. lib. 1. cap. 4. pag. 104.
[29] In the year 1619.
_Having promis'd_ (Says our Author)[30] _to say something of that most
precious sort of Jewels,_ Carbuncles, _because they are very rarely to be
met with, we shall briefly deliver what we know of them. In_ Clement _the
seventh's time, I happen'd to see one of_ _them at a certain_ Ragusian
_Merchants, nam'd_ Beigoio di Bona, _This was a Carbuncle white, of that
kind of whiteness which we said was to be found in those Rubies of which we
made mention a little above,_ (where he had said that those Rubies had a
kind of Livid Whiteness or Paleness like that of a Calcidonian) _but it had
in it a Lustre so pleasing and so marveilous, that it shin'd in the Dark,
but not as much as colour'd Carbuncles, though it be true, that in an
exceeding Dark place I saw it shine in the manner of fire almost gone out.
But as for colour'd Carbuncles, it has not been my Fortune to have seen
any, wherefore I will onely set down what I Learn'd about them Discoursing
in my Youth with a_ Roman _Gentleman of antient Experience in matters of
Jewels, who told me, That one_ Jacopo Cola _being by Night in a Vineyard of
his, and espying something in the midst of it, that shin'd like a little_
glowing Coal, at the foot of a Vine, went near towards the place where he
thought himself to have seen that fire, but not finding it, he said, that
being return'd to the same place, whence he had first descry'd it, and
perceiving there the same splendor as before, he mark'd it so heedfully,
that he came at length to it, where he took up a very little Stone, which
he carry'd away with Transports and Joy. And the next day carrying it about
to show it divers of his Friends, whilst he was relating after what manner
he found it, there casually interven'd a _Venetian_ Embassadour,
exceedingly expert in Jewels, who presently knowing it to be a Carbuncle,
did craftily before he and the said _Jacopo_ parted (so that there was no
Body present that understood the Worth of so Precious a Gemm) purchase it
for the Value of 10. Crowns, and the next day left _Rome_ to shun the being
necessitated to restore it, and (as he affirm'd) it was known within some
while after that the said _Venetian_ Gentleman did in _Constantinople_ sell
that Carbuncle to the then Grand Seignior, newly come to the Empire, for a
hundred thousand Crowns. _And this is what I can say_ concerning
_Carbuncles_, and this is not a little at least as to the first part of
this account, where our _Cellini_ affirms himself to have seen a Real
Carbuncle with his own Eyes, especially since this Author appears wary in
what he delivers, and is inclin'd rather to lessen, than increase the
wonder of it. And his Testimony is the more considerable, because though he
were born a Subject neither to the Pope nor the then King of _France_ (that
Royal _Virtuoso_ _Francis_ the first) yet both the one and the other of
those Princes imploy'd him much about making of their Noblest Jewels. What
is now reported concerning a Shining Substance to be seen in one of the
Islands about _Scotland_, were very improper for me to mention to Sr.
_Robert Morray_, to whom the first Information was Originally brought, and
from whom I expect a farther (for I scarce dare expect a convincing)
account of it. But I must not omit that some _Virtuoso_ questioning me the
other day at _White-Hall_ about Mr. _Claytons_ Diamond, and meeting amongst
them an Ingenious _Dutch_ Gentleman, whose Father was long Embassador for
the Netherlands in _England_, I Learn'd of him, that, he is acquainted with
a person, whose Name he told (but I do not well remember it) who was
Admiral of the _Dutch_ in the _East-Indies_, and who assur'd this Gentleman
_Monsieur Boreel_, that at his return from thence he brought back with him
into _Holland_ a Stone, which though it look'd but like a Pale Dull
Diamond, such as he saw Mr. _Claytons_ to be, yet was it a Real Carbuncle,
and did without rubbing shine so much, that when the Admiral had occasion
to open a Chest which he kept under Deck in a Dark place, where 'twas
forbidden to bring Candles for fear of Mischances, as soon as he open'd the
Trunck, the Stone would by its Native Light, shine so as to Illustrate a
great part of it, and this Gentleman having very civilly and readily
granted me the request I made him, to Write to the Admiral, who is yet
alive in _Holland_, (and probably may still have the Jewel by him,) for a
particular account of this Stone, I hope ere long to receive it, which will
be the more welcome to me, not onely because so unlikely a thing needs a
cleer evidence, but because I have had some suspition of that (supposing
the truth of the thing) what may be a shining Stone in a very hot Countrey
as the _East-Indies_, may perhaps cease to be so (at least in certain
seasons,) in one as cold as _Holland_. For I observ'd in the Diamond I send
you an account of, that not onely rubbing but a very moderate degree of
warmth, though excited by other wayes, would make it shine a little. And
'tis not impossible that there may be Stones as much more susceptible than
that, of the Alterations requisite to make a Diamond shine, as that
appeares to be more susceptible of them, than ordinary Diamonds. And I
confess to you, that this is not the only odd suspition (for they are not
so much as conjectures) that what I try'd upon this Diamond suggested to
me. For not here to entertain you with the changes I think may be effected
ev'n in harder sorts of Stones, by wayes not vulgar, nor very promising,
because I may elsewhere have occasion to speak of them, and this Letter is
but too Prolix already, that which I shall now acknowledge to you is, That
I began to doubt whether there may not in some Cases be some Truth in what
is said of the right Turquois, that it often changes Colour as the wearer
is Sick or Well, and manifestly loses its splendor at his Death. For when I
found that ev'n the warmth of an Affriction that lasted not above a quarter
of a minute, Nay, that of my Body, (whose Constitution you know is none of
the hottest) would make a manifest change in the solidest of Stones a
Diamond, it seem'd not impossible, that certain warm and Saline steams
issuing from the Body of a living man, may by their plenty or paucity, or
by their peculiar Nature, or by the total absence of them, diversifie the
Colour, and the splendor of so soft a Stone as the Turquois. And though I
admir'd to see, that I know not how many Men otherwise Learn'd, should
confidently ascribe to Jewels such Virtues as seem no way competible to
Inanimate Agents, if to any Corporeal ones at all, yet as to what is
affirm'd concerning the Turquois's changing Colour, I know not well how to
reject the Affirmation of so Learned (and which in this case is much more
considerable) so Judicious a Lapidary as _Boetius de Boot_[31], who upon
his own particular and repeated Experience delivers so memorable a
Narrative of the Turquois's changing Colour, that I cannot but think it
worth your Perusal, especially since a much later and very Experienc'd
Author, _Olaus Wormius_,[32] where he treats of that Stone, Confirms it
with this Testimony. _Imprimis memorandum exemplum quod Anshelmus Boetius
de seipso refert, tam mutati Coloris, quam à casu preservationis. Cui &
ipse haud dissimile adferre possum, nisi ex Anshelmo petitum quis putaret._
I remember that I saw two or three years since a _Turcois_ (worn in a Ring)
wherein there were some small spots, which the _Virtuoso_ whose it was
asur'd me he had observ'd to grow sometimes greater sometimes less, and to
be sometimes in one part of the Stone, sometimes in another. And I having
encourag'd to make Pictures from time to time of the Stone, and of the
Situation of the cloudy parts, thatso their Motion may be more
indisputable, and better observ'd, he came to me about the midle of this
very week, and assur'd me that he had, as I wish'd, made from time to time
Schemes or Pictures of the differing parts of the Stone, whereby the
several Removes and motions of the above mentioned Clouds are very
manifest, though the cause seem'd to him very occult: these Pictures he has
promis'd to show me, and is very ready to put the Stone it self into my
hands. But the ring having been the other day casually broken upon his
finger, unless it can be taken out, and set again without any considerable
heat, he is loath to have it medled with, for fear its peculiarity should
be thereby destroy'd. And possibly his apprehension would have been
strengthen'd, if I had had opportunity to tell him what is related by the
Learned _Wormius_[33] of an acquaintance of his, that had a _Nephritick_
stone, of whose eminent Virtues he had often Experience ev'n in himself,
and for that cause wore it still about his Wrist; and yet going upon a time
into a Bath of fair Water only, wherein certain Herbs had been boyl'd, the
Stone by being wetted with this decoction, was depriv'd of all his Virtue,
whence _Wormius_ takes Occasion to advertise the sick, to lay by such
stones whensoever they make use of a Bath. And we might expect to find
_Turcos_ likewise, easily to be wrought upon in point of Colour, if that
were true, which the curious _Antonio Neri_, in his ingenious _Arte
Vetraria_[34] teaches of it, namely, That _Turcois's discolour'd_ and grown
white, will regain and acquire an excellent Colour, if you but keep them
two or three days at most cover'd with Oyl of sweet Almonds kept in a
temperate heat by warm ashes, I say if it were true, because I doubt
whether it be so, and have not as yet had opportunity to satisfie my self
by Tryals, because I find by the confession of the most Skilfull Persons
among whom I have laid out for _Turcoises_, that the true ones are great
rarities, though others be not at all so. And therefore I shall now only
mind you of one thing that you know as well as I, namely, that the rare
Stone which is called _Oculus Mundi_, if it be good in its Kind, will have
so great a change made in its Texture by being barely left a while in the
Languidest of Liquors, common Waters, that from Opacous it will become
Transparent, and acquire a Lustre of which it will again be depriv'd,
without using any other Art or Violence, by leaving it a while in the Air.
And before experience had satisfy'd us of the truth of this, it seem'd as
unlikely that common Water or Air, should work such great changes in that
Gemm, as it now seems that the Effluviums of a human Body should effect
lesser changes in a _Turcois_, especially if more susceptible of them, than
other Stones of the same kind. But both my Watch and my Eyes tell me that
'tis now high time to think of going to sleep, matters of this Nature, will
be better, as well as more easily, clear'd by Conference, than Writing. And
therefore since I think you know me too well to make it needfull for me to
disclame Credulity, notwithstanding my having entertain'd you with all
these Extravagancies; for you know well, how wide a difference I am wont to
put betwixt things that barely _may be_, and things that _are_, and between
those Relations that are but not unworthy to be inquir'd into, and those
that are not worthy to be actually believ'd; without making Apologies for
my Ravings, I shall readily comply with the drowsiness that calls upon me
to release You, and the rather, because Monsieur _Zulichem_ being concern'd
in your desire to know the few things I have observed about the shining
Stone. To entertain those with Suspicions that are accustomed not to
acquiesce but in Demonstrations, were a thing that cannot be look'd upon as
other than very improper by,
SIR,
_Your most Affectionate_
and
_most Faithfull Servant,_
RO. BOYLE.
[30] Benvonuto Cellini _nell Arte del_ Gioiellare, _Lib._ 1. _pag._ 10.
[31] The Narrative in the Authors own words, is this. _Ego_ (sayes he)
_sanctè affirmare possum me unam aureo Annulo inclusam perpetuo gestare,
cujus facultatem (si gemmæ est) nunquam satis admirari potui. Gestaverat
enim ante Triginta annos Hispanus quidam non procula puternis ædibus
habitans. Is cum vitâ functus esset, & ipsius suspellex (ut moris apud
nos est) venum exposita esset, inter cætera etiam Turcois exponebatur.
Verum nemo (licet complures eo concurrissent, ut eam propter Coloris
Elegantiam, quam vivo Domino habuerat emerent) sibi emptam voluit,
pristinum enim nitorem & Colorem prorsus amiserat, ut potius Malachites,
quam Turcois videretur. Aderat tum temporis gemmæ habendæ desiderio etiam
parens & frater meus, qui antea sæpius gratiam & elegantiam ipsius
viderant, mirabundi eam nunc tam esse deformem, Emit eam nihilominus
pater, satisque vili pretio, qua omnibus contemptui erat, ac presentes
non eam esse quam Hispanus gestarat, arbitrarentur. Domum reversus Pater,
qui tam turpem Gemmam gestare sibi indecorum putabat, eam mihi dono dat,
inquiens; Quandoquidem, fili mi, vulgi fama est, Turcoidem, ut facultates
suas exercere possit, dono dari debere tibi eam devoveo, ego acceptam
Gemmam sculptori trado, at gentilitia mea insignia illi, quamadmodum
fieri solet, in Jaspide Chalcedono, aliisque Ignobilioribus Gemmis,
insculperat. Turpe enim existimabam, hujusmodi Gemmâ ornatus gratia, dum
gratiam nullam haberet, uti. Paret Sculptor redditque Gemmam, quam gesto
pro annulo Signatorio. Vix per mensem gestaram, redit illi pristinus
color, sed non ita nitens propter Sculpturam, ac inæqualem superficiem.
Miramur omnes gemmam, atque id præcipuè quod color indies pulchrior
fieret. Id quià observabam, nunquam fere eam à manu deposui, ita ut nunc
adhuc candem gestem._
[32] _Olaus Wormius, in Musæ. 18º pag. 186._
[33] _Musæ. Worm._ pag. 99.
[34] Arte Vetraria, lib. 7 cap. 102.
* * * * *
OBSERVATIONS
Made this 27th.[35]
of _October_ 1663. about
Mr. _Clayton's_
Diamond.[36]
Being look'd on in the Day time, though in a Bed, whose Curtains were
carefully drawn, I could not discern it to Shine at all, though well
Rubb'd, but about a little after Sun-set, whilst the Twilight yet lasted,
Nay, this Morning[37] a pretty while after Sun-rising, (but before I had
been abroad in the more freely inlightned Air of the Chamber) I could upon
a light Affriction easily perceive the Stone to Shine.
[35] These were brought in and Read before the Royal Society, (the Day
following) _Oct._ 28. 1663.
[36] _The Stone it self being to be shown to the Royal Society, when the
Observations were deliver'd, I was willing (being in haste) to omit the
Description of it, which is in short, That it was a Flat or Table
Diamond, of about a third part of an Inch in length, and somewhat less in
breadth, that it was a Dull Stone, and of a very bad Water, having in the
Day time very little of the Vividness of ev'n ordinary Diamonds, and
being Blemished with a whitish Cloud about the middle of it, which
covered near a third part of the Stone._
[37] _Hast made me forget to take notice that I went abroad the same
Morning, the Sun shining forth clear enough, to look upon the Diamond
though a_ Microscope, _that I might try whether by that Magnifying Glass
any thing of peculiar could be discern'd in the Texture of the Stone, and
especially of the whitish Cloud that possest a good part of it. But for
all my attention I could not discover any peculiarity worth mentioning._
Secondly, The Candles being removed, I could not in a Dark place discern
the Stone to have any Light, when I looked on it, without having Rubb'd or
otherwise prepar'd it.
Thirdly, By two white Pibbles though hard Rubb'd one against another, nor
by the long and vehement Affriction of Rock Crystal against a piece of Red
cloath, nor yet by Rubbing two Diamonds set in Ring, as I had Rubb'd this
Stone, I could produce any sensible degree of Light.
Fourthly, I found this Diamond hard enough, not only to enable me to write
readily with it upon Glass, but to Grave on Rock Crystal it self.
Fifthly, I found this to have like other Diamonds, an Electrical
faculty.[38]
[38] V. _For it drew light Bodies like Amber, Jet, and other Concretes
that are noted to do so; But its attractive power seem'd inferiour to
theirs._
Sixthly, Being rubb'd upon my Cloaths, as is usual for the exciting of
Amber, Wax, and other Electrical Bodies, it did in the Dark manifestly
shine like Rotten Wood, or the Scales of Whitings, or other putrified Fish.
Seventhly, But this Conspicuousness was Fainter than that of the Scales,
and Slabber (if I may so call it) of Whitings, and much Fainter than the
Light of a Glow-worm, by which I have been sometimes able to Read a short
Word, whereas after an ordinary Affriction of this Diamond I was not able
to discern distinctly by the Light of it any of the nearest Bodies: And
this Glimmering also did very manifestly and considerably Decay presently
upon the ceasing of the Affriction, though the Stone continued Visible some
while after.
Eighthly, But if it were Rubb'd upon a convenient Body for a pretty while,
and Briskly enough, I found the Light would be for some moments much more
considerable, almost like the Light of a Glow-worm, insomuch after I ceased
Rubbing, I could with the Chaf'd stone exhibit a little Luminous Circle,
like that, but not so bright as that which Children make by moving a stick
Fir'd at the end, and in this case it would continue Visible about seven or
eight times as long as I had been in Rubbing it.
Ninthly, I found that holding it a while near[39] the Flame of a Candle,
(from which yet I was carefull to avert my Eyes) and being immediately
remov'd into the Dark, it disclosed some faint Glimmering, but inferiour to
that, it was wont to acquire by Rubbing. And afterward holding it near a
Fire that had but little Flame, I found the Stone to be rather less than
more excited, than it had been by the Candle.
[39] IX. _We durst not hold it in the Flame of a Candle, no more than put
it into a naked Fire; For fear too Violent a Heat (which has been
observ'd to spoil many other precious Stones) should vitiate and impair a
Jewel, that was but borrow'd, and was suppos'd to be the only one of its
Kind._
Tenthly, I likewise indeavour'd to make it Shine, by holding it a pretty
while in a very Dark place, over a thick piece of Iron, that was well
Heated, but not to that Degree as to be Visibly so. And though at length I
found, that by this way also, the Stone acquired some Glimmering, yet it
was less than by either of the other ways above mention'd.
Eleventhly, I also brought it to some kind of Glimmering Light, by taking
it into Bed with me, and holding it a good while upon a warm part of my
Naked Body.
Twelfthly, To satisfie my self, whether the Motion introduc'd into the
Stone did generate the Light upon the account of its producing Heat there,
I held it near the Flame of a Candle, till it was qualify'd to shine pretty
well in the Dark, and then immediately I apply'd a slender Hair to try
whether it would attract it, but found not that it did so; though if it
were made to shine by Rubbing, it was as I formerly noted Electrical. And
for further Confirmation, though I once purposedly kept it so near the hot
Iron I just now mention'd, as to make it sensibly Warm, yet it shin'd more
Dimly than it had done by Affriction or the Flame of a Candle, though by
both those ways it had not acquir'd any warmth that was sensible.
Thirteenthly, Having purposely rubb'd it upon several Bodies differing as
to Colour, and as to Texture, there seem'd to be some little Disparity in
the excitation (if I may so call it) of Light. Upon White and Red Cloths it
seem'd to succeed best, especially in comparison of Black ones.
Fourteenthly, But to try what it would do rubb'd upon Bodies more hard, and
less apt to yield Heat upon a light Affriction, than Cloath, I first rubb'd
it upon a white wooden Box, by which it was excited, and afterwards upon a
piece of purely Glazed Earth, which seem'd during the Attrition to make it
Shine better than any of the other Bodies had done, without excepting the
White ones, which I add, lest the Effect should be wholly ascrib'd to the
disposition White Bodies are wont to have to Reflect much Light.
Fifteenthly, Having well excited the Stone, I nimbly plung'd it under
Water[40], that I had provided for that purpose, and perceiv'd it to Shine
whilst it was beneath the Surface of that Liquor, and this I did divers
times. But when I indeavour'd to produce a Light by rubbing it upon the
lately mentioned Cover of the Box, the Stone and it being both held beneath
the Surface of the Water, I did not well satisfie my self in the Event of
the Trial; But this I found, if I took the Stone out, and Rubb'd it upon a
piece of Cloath, it would not as else it was wont to do, presently acquire
a Luminousness, but needed to be rubb'd manifestly much longer before the
desired Effect was found.
[40] XV. _We likewise Plung'd it as soon as we had excited it, under
Liquors of several sorts, as Spirit of Wine, Oyl both Chymical and
express'd, an Acid Spirit, and as I remember an Alcalizate Solution, and
found not any of those various Liquors to destroy its Shining property._
Sixteenthly, I also try'd several times, that by covering it with my warm
Spittle (having no warm Water at hand) it did not lose his Light.[41]
[41] XVI. _Having found by this Observation, that a warm Liquor would not
extinguish Light in the Diamond, I thought fit to try, whether by reason
of its warmth it would not excite it, and divers times I found, that if
it were kept therein, till the Water had leisure to communicate some of
its Heat to it, it would often shine as soon as it was taken out, and
probably we should have seen it Shine more, whilst it was in the Water,
if some degree of Opacity which heated Water is wont to acquire, upon the
score of the Numerous little Bubbles generated in it, had not kept us
from discerning the Lustre of the Stone._
Seventeenthly, Finding that by Rubbing the Stone with the Flat side
downwards, I did by reason of the Opacity of the Ring; and the sudden Decay
of Light upon the ceasing of the Attrition, probably lose the sight of the
Stones greatest Vividness; and supposing that the Commotion made in one
part of the stone will be easily propagated all over, I sometimes held the
piece of Cloath upon which I rubb'd it, so, that one side of the Stone was
exposed to my Eye, whilst I was rubbing the other, whereby it appear'd more
Vivid than formerly, and to make Luminous Tracts by its Motions too and
fro. And sometimes holding the Stone upwards, I rubb'd its Broad side with
a fine smooth piece of Transparent Horn, by which means the Light through
that Diaphanous Substance, did whilst I was actually rubbing the Stone,
appear so Brisk that sometimes and in some places it seem'd to have little
Sparks of fire.
Eighteenthly, I took also a piece of flat Blew Glass, and having rubb'd the
Diamond well upon a Cloath, and nimbly clapt the Glass upon it, to try
whether in case the Light could peirce it, it would by appearing Green, or
of some other Colour than Blew, assist me to guess whether it self were
sincere or no. But finding the Glass impervious to so faint a Light, I then
thought it fit to try whether that hard Bodies would not by Attrition
increase the Diamonds Light so as to become penetrable thereby, and
accordingly when I rubb'd the Glass briskly upon the Stone, I found the
Light to be Conspicuous enough, and somewhat Dy'd in its passage, but found
it not easie to give a Name to the Colour it exhibited.
Lastly, To comply with the Suspition I had upon the whole Matter, that the
chief manifest Change wrought in the Stone, was by Compression of its
parts, rather than Incalescence, I took a piece of white Tile well Glaz'd,
and if I press'd the Stone hard against it, it seem'd though I did not rub
it to and fro, to shine at the Sides: And however it did both very
manifestly and vigorously Shine, if whilst I so press'd it, I mov'd it any
way upon the Surface of the Tile, though I did not make it draw a Line of
above a quarter of an Inch long, or thereabouts. And though I made it not
move to and fro, but only from one end of the short Line to the other,
without any return or Lateral motion. Nay, after it had been often rubb'd,
and suffer'd to lose its Light again, not only it seem'd more easie to be
excited than at the beginning of the Night; but if I did press hard upon it
with my Finger, at the very instant that I drew it briskly off, it would
disclose a very Vivid but exceeding short Liv'd Splendour, not to call it a
little Coruscation.[42] So that a _Cartesian_ would scarce scruple to think
he had found in this Stone no slight Confirmation of his Ingenious Masters
_Hypothesis_, touching the Generation of Light in Sublunary Bodies, not
sensibly Hot.
[42] _I after bethought my self of imploying a way, which produc'd the
desir'd Effect both sooner and better. For holding betwixt my Fingers a
Steel Bodkin, near the Lower part of it, I press'd the point hard against
the Surface of the Diamond, and much more if I struck the point against
it, the Coruscation would be extremely suddain, and very Vivid, though
very Vanishing too, and this way which commonly much surpris'd and
pleas'd the Spectators, seem'd far more proper than the other, to show
that pressure alone, if forcible enough, though it were so suddain, and
short, that it could not well be suppos'd to give the Stone any thing
near a sensible degree of Warmth, as may be suspected of Rubbing, yet
'tis sufficient to generate a very Vivid Light._
* * * * *
A Postscript.
Annexed some Hours after the Observations were Written.
_So many particulars taken notice of in one Night, may make this Stone
appear a kind of Prodigie, and the rather, because having try'd as I
formerly noted, not only a fine Artificial Crystal, and some also that is
Natural, but a Ruby and two Diamonds, I did not find that any of these
disclos'd the like Glimmering of Light;[43] yet after all, perceiving by
the Hardness, and the Testimony of a Skilfull Goldsmith, that this was
rather a Natural than Artificial Stone; for fear lest there might be some
difference in the way of Setting, or in the shape of the Diamonds I made
use of, neither of which was like this, a flat Table-stone, I thought fit
to make a farther Trial of my own Diamonds, by such a brisk and assiduous
Affriction as might make amends for the Disadvantages above-mention'd, in
case they were the cause of the unsuccessfulness of the former Attempts:
And accordingly I found, that by this way I could easily bring a Diamond I
wore on my Finger to disclose a Light, that was sensible enough, and
continued so though I cover'd it with Spittle, and us'd some other trials
about it. And this will much lessen the wonder of all the formerly
mention'd Observations, by shewing that the properties that are so strange
are not peculiar to one Diamond, but may be found in others also, and
perhaps in divers other hard and_ Diaphanous _Stones. Yet I hope that what
this Discovery takes away from the Wonder of these Observations, it will
add to the Instructiveness of them, by affording pregnants Hints, towards
the Investigation of the Nature of Light._
[43] We afterwards, try'd precious Stones, as Diamonds, Rubies, Saphires,
and Emeralls, &c. but found not any of them to Shine except some
Diamonds, and of these we were not upon so little practice, able to
fore-tell before hand, which would be brought to Shine, and which would
not; For several very good Diamonds, either would not Shine at all, or
much less than others that were farr inferiour to them. And yet those
Ingenious Men are mistaken, that think a Diamond must be foul and cloudy,
as Mr. _Claytons_ was, to be fit for Shining; for as we could bring some
such to afford a Glimmering Light, so with some clear and excellent
Diamonds, we could do the like. But none of those many that we try'd of
all Kinds, were equal to the Diamond on which the Observations were made,
not only considering the degree of Light it afforded, but the easiness
wherewith it was excited, and the Comparatively great duration of its
Shining.
FINIS.
* * * * *
Transcriber's notes.
The Errata of the printed book have all been corrected.
They were as follows:
Pag. 142. l. 20. These words, And to manifest, with the rest of what is by
a mistake further printed in this fourth Experiment, belongeth, and is to
be referred to the end of the second Eperiment, p.137. pag. 145. l. 1. leg.
matter. 146. l. 4. leg. Bolts-head. pag 161. in the marginal note l. 2.
dele de ib. l. 3. lege lib 1. p 163. l. ult. insert where between the words
places and the. p. 164 l. 1. dele that. ibid, l. 8. leg Epidermis. ibid. l.
19 leg. 300. for 200. p. 169. l. 22. leg. into it. p. 170. l. 23. & 24.
leg. Some Solutions hereafter to be mentioned, for the Solutions of
Potashes, and other Lixiviate Salts. p. 171. l. 6. insert part of between
the words most and dissolved p. 176. l. ult. insert the participle it
between the words Judged and not p. 234. l. 4. leg. Woud-wax or Wood-wax.
p. 320 l. 29. leg. urine for urne.
In addition I have corrected the following original typos:
The preface: I devis'd tbem -> I devis'd them
The preface: make Expements -> make Experiments
The Publisher to the reader: made of Eperiments -> made of Experiments
I. Ch. III.6 divers Expements -> divers Experiments
I. Ch. III.13 epecially with some sorts -> especially with some sorts
II. Ch. II.8 Slightet Texture -> Slightest Texture
II. Exp. I two Colonrs -> two Colours
II. Exp. XIII were the change of Colour -> where the change
III. Exp. XII avoiding of Ambignity -> avoiding of Ambiguity
III. Exp. XXIX Juice of this Sipce -> Juice of this Spice
III. Exp. XL forty second Expement -> forty second Experiment
III. Exp. XLIV keep them swimning -> keep them swimming
III. Exp. XLVI it seem'd propable to me -> it seem'd probable to me
III. Exp. XLVII where not comprehended -> were not comprehended
III. Exp. XLVIII frequent Igintion -> frequent Ignition
III. Exp. L I could tell yon -> I could tell you
A Copy of the Letter: nemo unqnam vere -> nemo nunquam vere
(ib.): what is reladed -> what is related
Observations: carefulsy drawn -> carefully drawn
- and emended
Phoenomenon/a to Phaenomenon/a 10 times and
Coeruleous etc. -> Caeruleous 20 times
*** End of this LibraryBlog Digital Book "Experiments and Considerations Touching Colours (1664)" ***
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