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,_