changing Colour, I know not well how to reject the Affirmation of so Learned (and which in this case is much more considerable) so Judicious a Lapidary as Boetius de Boot[31], who upon his own particular and repeated Experience delivers so memorable
a Narrative of the Turquois's changing Colour, that I cannot but think it worth your Perusal, especially since a much later and very Experienc'd Author, Olaus Wormius,[32] where he treats of that Stone, Confirms it with this Testimony. Imprimis memorandum exemplum quod Anshelmus Boetius de seipso refert, tam mutati Coloris, quam à casu preservationis. Cui & ipse haud dissimile adferre possum, nisi ex Anshelmo petitum quis putaret. I remember that I saw two or three years since a Turcois (worn in a Ring) wherein there were some small spots, which the Virtuoso whose it was asur'd me he had observ'd to grow sometimes greater sometimes less, and to be sometimes in one part of the Stone, sometimes in another. And I having encourag'd to make Pictures from time to time of the Stone, and of the Situation of the cloudy parts, thatso their Motion may be more indisputable, and better observ'd, he came to me about the midle of this very week, and assur'd me that he had, as I wish'd, made from time to time Schemes or Pictures of the differing parts of the Stone, whereby the several Removes and motions of the above mentioned Clouds are very manifest, though the cause seem'd to him very occult: these Pictures
he has promis'd to show me, and is very ready to put the Stone it self into my hands. But the ring having been the other day casually broken upon his finger, unless it can be taken out, and set again without any considerable heat, he is loath to have it medled with, for fear its peculiarity should be thereby destroy'd. And possibly his apprehension would have been strengthen'd, if I had had opportunity to tell him what is related by the Learned Wormius[33] of an acquaintance of his, that had a Nephritick stone, of whose eminent Virtues he had often Experience ev'n in himself, and for that cause wore it still about his Wrist; and yet going upon a time into a Bath of fair Water only, wherein certain Herbs had been boyl'd, the Stone by being wetted with this decoction, was depriv'd of all his Virtue, whence Wormius takes Occasion to advertise the sick, to lay by such stones whensoever they make use of a Bath. And we might expect to find Turcos likewise, easily to be wrought upon in point of Colour, if that were true, which the curious Antonio Neri, in his ingenious Arte Vetraria[34] teaches of it, namely, That Turcois's discolour'd and grown white, will regain and acquire
an excellent Colour, if you but keep them two or three days at most cover'd with Oyl of sweet Almonds kept in a temperate heat by warm ashes, I say if it were true, because I doubt whether it be so, and have not as yet had opportunity to satisfie my self by Tryals, because I find by the confession of the most Skilfull Persons among whom I have laid out for Turcoises, that the true ones are great rarities, though others be not at all so. And therefore I shall now only mind you of one thing that you know as well as I, namely, that the rare Stone which is called Oculus Mundi, if it be good in its Kind, will have so great a change made in its Texture by being barely left a while in the Languidest of Liquors, common Waters, that from Opacous it will become Transparent, and acquire a Lustre of which it will again be depriv'd, without using any other Art or Violence, by leaving it a while in the Air. And before experience had satisfy'd us of the truth of this, it seem'd as unlikely that common Water or Air, should work such great changes in that Gemm, as it now seems that the Effluviums of a human Body should effect lesser changes in a Turcois, especially if more susceptible of them, than other Stones of the same kind. But both my Watch and my Eyes tell me that
'tis now high time to think of going to sleep, matters of this Nature, will be better, as well as more easily, clear'd by Conference, than Writing. And therefore since I think you know me too well to make it needfull for me to disclame Credulity, notwithstanding my having entertain'd you with all these Extravagancies; for you know well, how wide a difference I am wont to put betwixt things that barely may be, and things that are, and between those Relations that are but not unworthy to be inquir'd into, and those that are not worthy to be actually believ'd; without making Apologies for my Ravings, I shall readily comply with the drowsiness that calls upon me to release You, and the rather, because Monsieur Zulichem being concern'd in your desire to know the few things I have observed about the shining Stone. To entertain those with Suspicions that are accustomed not to acquiesce but in Demonstrations, were a thing that cannot be look'd upon as other than very improper by,
SIR,
Your most Affectionate
and
most Faithfull Servant,
RO. BOYLE.
