Chapter 1

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.

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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.

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_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._

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THE CONTENTS.

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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.)