Experiments and Considerations Touching Colours (1664) Part 9

Thirdly, That so much ev'n these Colours depend upon Texture, that in the Gla.s.s 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 pa.s.s 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 Ma.s.s attain'd to the Amethystin Colour.

Fourthly and lastly, That the degrees of Coction and other Circ.u.mstances may so vary the Colour produc'd in the same ma.s.s, that in a Crucible that was not great I have had fragments of the same Ma.s.s, 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 advent.i.tious 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 advent.i.tious 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 un.o.bvious 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 quant.i.ty 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 advent.i.tious 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 _Curc.u.ma_, 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 Quant.i.ty 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 pa.s.s 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 pa.s.s'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 Quant.i.ty 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 Quant.i.ty 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 h.o.m.ogeneous 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 a.s.sociated with it; so Allom which may be of so near a kin to Vitriol, that in some places of _England_ (as we are a.s.sur'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 fact.i.tious 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 Praecipitate what acid Salts have dissolv'd, I could not but be p.r.o.ne 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 Praecipitated 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 Quant.i.ty 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 Quant.i.ty 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 Praecipitated 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 pa.s.s'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 Circ.u.mspection 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 Gla.s.s, Englished (6 or 7 years since the Writing of this 49th Experiment) and Ill.u.s.trated 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 Princ.i.p.ally 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 Advent.i.tious 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 a.s.sume 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 en.o.bled 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 circ.u.mstantially 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 quant.i.ty 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 Praecipitate 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 Praecipitated 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 quant.i.ty 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 quant.i.ty of good Oyl of Vitriol, this last nam'd Liquor would have two distinct operations upon the Mixture, the one, that it would Praecipitate 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 gla.s.s 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 Praecipitate 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 subst.i.tuted 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 Quant.i.ty of Spirit of Salt, the matter first Precipitated, was, by the above specified figure of the bottome of the Gla.s.s 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 Gla.s.s 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 circ.u.mstance, 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 ill.u.s.trious 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 Circ.u.mstance 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 s.n.a.t.c.h'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 a.s.sist 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 _Phaenomenon_ 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 pa.s.sage.[26]

_Magna fama est Carbunculi. Is vulgo putatur in tenebris Carbonis instar lucere; forta.s.sis quia Pyropus seu Anthrax appellatus a veteribus fuit.

Verum hactenus nemo nunquam vere a.s.serere ausus fuit, se gemmam noctu lucentem vidisse. Garcias ab Horto proregis Indiae 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 pa.s.sage. _Quia autem Carbunculi, Pyropi & Anthraces a veteribus nominantur, vulgo creditum fuit, Carbonis instar in tenebris lucere, quod tamen nulla gemma hastenus deprehensum, licet a quibusdam temere jactetur._ And the recentest Writer I have met with on this Subject, _Olaus Wormius_, in his Account of his well furnish'd _Musaeum_, 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 natura non inveniri major pars Authoram existimant. Licet unum aut alterum in India apud Magnates quosdam reperiri scribant, c.u.m 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.