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 ...

A COPY OF THE LETTER That Mr. Boyle wrote to Sir Robert Morray, to accompany the Observations touch∣ing 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 re∣turn'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 fur∣thest, at Gresham College, where we ap∣pointed to attend the meeting of the Socie∣ty, 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 Conspi∣cuous 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 lit∣tle 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 im∣ploy'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 with∣out 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 remem∣ber, 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 dis∣pos'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 Na∣ture 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 opa∣cous 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 opera∣tion upon its Texture, as we seem to know what it is, and as is immediately perform'd, and that several wayes without at all pre∣judicing 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 Phoenomenon relate∣ing to the Subject, as probably he treats of, Light will, I hope, excite a person to con∣sider 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 under∣standing 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 some∣times 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 unwil∣ling 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 perswa∣sion, that not only there are store of Car∣buncles, 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 Dia∣mond

as a great Rarity. For not only Boetius de Boot, who is judg'd the best Au∣thor on this Subject; ascribes no such Virtue to Diamonds, but begins what he delivers of Carbuncles, with this passage. Magna fama est Carbunculi. Is vulgo putatur in tenebris Carbonis in∣star * 1.1 lucere; fortassis quia Pyro∣pus seu Anthrax appellatus à veteribus fuit. Verum hactenus nemo unqnam verè asserere ausus fuit, se gem∣mam noctu lucentem vidisse. Garcias ab Horto proregis Indiae Medicus, refert se allo∣cutum fuisse, qui se vidisse affirmarent. Sed tis fidem non habuit. And a later Author, the Diligent and Judicious Johannes de Laet in his Chapter of Carbuncles and of Ru∣bies, has this passage. Quia autem Carbun∣culi, Pyropi & Anthraces à veteribus nomi∣nantur, vulgo creditum fuit, Carbonis instar in tenebris lucere, quod tamen nullâ gemmâ hastenus deprehensum, licet à quibusdam te∣merè jactetur. And the recentest Writer I have met with on this Subject, Olaus Wor∣mius, in his Account of his well furnish'd Musaeum, do's, where he treats of Rubies, concurr with the former Writers by these Words. Sunt qui Rubinum ve∣terum Carbunculum esse existi∣mant, * 1.2 sed deest una illa nota, quod

in tenebris instar Anthracis non luceat: Ast talem Carbunculum in rerum naturâ non inve∣niri major pars Authorum existimant. Licet unum aut alterum in India apud Magnates quosdam reperiri scribant, cum tamen ex alio∣rum 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 ac∣quainted with) to make a Trial of this famous Rubie in the Night, and in a Room well Darkn'd, but not only could not dis∣cern 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.

But, Sir, though I be very backward to admit strange things for truths, yet I am not very forward to reject them as impossi∣bilities, and therefore I would not discou∣rage 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 Car∣buncle 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 Car∣buncle, 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 con∣trary. 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 (whose suppos'd Fa∣bles, divers of our later Tra∣vellours * 1.3 and Navigatours have since found to be truths) speak∣ing 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 considera∣ble 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 Re∣lation made by two Russian Cons∣sacks of their Journey into Ca∣ray, * 1.4 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 Surra, which those Cossacks interpret a Ru∣by. 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 Ameri∣ca, 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 Rate 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 Tra∣dition 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 Ob∣servation, 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 fur∣ther 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 Wri∣ter 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 con∣siderable passages I met with in it, and par∣ticularly one, which being very remarkable in it self, and pertinent to our present Ar∣gument, I shall put it for you, though not word for word, which I fear I have for∣got to do, yet as to the Sense, into Eng∣lish.

Having promis'd (says our Author) 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 Cle∣ment * 1.5 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 Calci∣donian) 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 he 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 Gentle∣man of antient Experience in matters of Jew∣els, 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 des∣cry'd it, and perceiving there the same splen∣dor 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 a∣way 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, exceed∣ingly expert in Jewels, who presently know∣ing 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 neces∣sitated 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 Seig∣nior, newly come to the Empire, for a hun∣dred 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 ap∣pears wary in what he delivers, and is in∣clin'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 far∣ther (for I scarce dare expect a convin∣cing) account of it. But I must not omit that some Virtuoso questioning me the other day at White-Hall about Mr. Claytons Dia∣mond, and meeting amongst them an In∣genious 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 Gen∣tleman having very civilly and readily gran∣ted me the request I made him, to Write to the Admiral, who is yet alive in Hol∣land, (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 cer∣tain 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 suscep∣tible than that, of the Alterations requisite to make a Diamond shine, as that appeares to be more susceptible of them, than ordi∣nary 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 har∣der sorts of Stones, by wayes not vulgar, nor very promising, because I may else∣where 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 ma∣nifest change in the solidest of Stones a Di∣amond, it seem'd not impossible, that cer∣tain warm and Saline steams issuing from the Pody of a living man, may by their plen∣ty 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 ad∣mir'd to see, that I know not how many Men otherwise Learn'd, should confident∣ly 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 considera∣ble) so Judicious a Lapi∣dary as Boetius de Boot * 1.6, who upon his own par∣ticular and repeated Ex∣perience delivers so me∣morable

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, where he treats of that Stone, Confirms it with this * 1.7 Testimony. Imprimis memorandum exemplum quod Anshelmus Boëtius de seipso refert, tam mutati Coloris, quam à casu preservationis. Cui & ipse haud dis∣simile adferre possum, nisi ex Anshelmo peti∣tum 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 Situ∣ation of the cloudy parts, that so their Mo∣tion 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 Re∣moves and motions of the above mention∣ed Clouds are very manifest, though the cause seem'd to him very occult: these Pic∣tures

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 streng∣then'd, if I had had opportunity to tell him what is reladed by * 1.8 the Learned Wormius of an ac∣quaintance 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 Ve∣traria teaches of it, namely, That * 1.9 Turcois's discolourd 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 Lan∣guidest 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 Tur∣cois, 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 bet∣ter, as well as more easily, clear'd by Con∣ference, 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 ra∣ther, 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.

Notes

• * 1.1

  Boetius de Boot. Gem. & Lapid. Histor. Lib. 2. Cap. 8.
• * 1.2

  Musaei Wor∣miani, Cap. 17.
• * 1.3

  Purchas's Pilgrim. lib. 1. cap. 4. pag. 104.
• * 1.4

  In the year 1619.
• * 1.5

  Behvonu••o Cellini nell Aree del Gioiellar's Lib. 1. pag. 10.
• * 1.6

  The Narrative in the Authors own words, is this, Ego (sayes he) sanctè af∣firmare possum me unam aureo Annulo inclusam perpetuo gestare, cujus facultatem (si gemmae est) nunquam satis admirari potui. Gestaverat enim ante Triginta annos Hispa∣nus quidam non procula puternis aedibus habitans. Is cum vitâ-functus esset, & ipsius suspellex (ut moris apud nos est) venum exposita esset, inter caetera etiam Turcois expone∣batur. Verum nemo (licet complures co 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 gemmae habendae desiderio etiam parens & frater meus, qui antea saepius gra∣tiam & elegantiam ipsius viderant, mirabundi cam nunc tam esse deformem, Emit cam nihilominus pater, satis•••• vili pretio, qua omnibus contemptui crat, ac presentes non eam esse quam Hispanus gestaral, arbitrarentur. Domum reversus Pater, qui tam turpem Gemmam gestare sibi indecorum puta∣bat, 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, quamadmodam fieri solet, in Jaspide Chalcedonio, aliis{que} Ignobilioribus Gem∣mis, insculper l. Turpe enim existimabam, hujusmodi Gem∣mâ ornatus gratia, dum gratiam nullam haberet, uti. Paret Sculptor redditque Gemmam, quam gesto pro annulo Signa∣torio. Vix per mensem gestaram, redit illi pristinus color, sed non it a nitens propter Sculpturam, ac inaequalem superfi∣ciem. Miramur omnes gemmam, atque id praecipuè quod color indies pulchrior fieret. Id quià observabam, nunquam fere ••am à manu deposui, ita ut uunc adhuc candem gestem.
• * 1.7

  Olaus Wormius in Musae. 18^o. pag. 186.
• * 1.8

  Musae. Worm, pag. 99.
• * 1.9

  Arte Vetra∣tia, lib. 7. cap. 102.