[a]34] Arte Vetraria, lib. 7 cap. 102.
[a]35] Theſe were brought in and Read before the Royal Society, (the Day following) Oct. 28. 1663.
[a]36] The Stone it ſelf being to be ſhown to the Royal Society, when the Obſervations were deliver'd, I was willing (being in haſte) to omit the Deſcription of it, which is in ſhort, That it was a Flat or Table Diamond, of about a third part of an Inch in length, and ſomewhat leſs in breadth, that it was a Dull Stone, and of a very bad Water, having in the Day time very little of the Vividneſs of ev'n ordinary Diamonds, and being Blemiſhed with a whitiſh Cloud about the middle of it, which covered near a third part of the Stone.
[a]37] Haſt made me forget to take notice that I went abroad the ſame Morning, the Sun ſhining forth clear enough, to look upon the Diamond though a Microſcope, that I might try whether by that Magnifying Glaſs any thing of peculiar could be diſcern'd in the Texture of the Stone, and eſpecially of the whitiſh Cloud that poſſeſt a good part of it. But for all my attention I could not diſcover any peculiarity worth mentioning.
[a]38] V. For it drew light Bodies like Amber, Jet, and other Concretes that are noted to do ſo; But its attractive power ſeem'd inferiour to theirs.
[a]39] IX. We durſt not hold it in the Flame of a Candle, no more than put it into a naked Fire; For fear too Violent a Heat (which has been obſerv'd to ſpoil many other precious Stones) ſhould vitiate and impair a Jewel, that was but borrow'd, and was ſuppos'd to be the only one of its Kind.
[a]40] XV. We likewiſe Plung'd it as ſoon as we had excited it, under Liquors of ſeveral ſorts, as Spirit of Wine, Oyl both Chymical and expreſs'd, an Acid Spirit, and as I remember an Alcalizate Solution, and found not any of thoſe various Liquors to deſtroy its Shining property.
[a]41] XVI. Having found by this Obſervation, that a warm Liquor would not extinguiſh Light in the Diamond, I thought fit to try, whether by reaſon of its warmth it would not excite it, and divers times I found, that if it were kept therein, till the Water had leiſure to communicate ſome of its Heat to it, it would often ſhine as ſoon as it was taken out, and probably we ſhould have ſeen it Shine more, whilſt it was in the Water, if ſome degree of Opacity which heated Water is wont to acquire, upon the ſcore of the Numerous little Bubbles generated in it, had not kept us from diſcerning the Luſtre of the Stone.
[a]42] I after bethought my ſelf of imploying a way, which produc'd the deſir'd Effect both ſooner and better. For holding betwixt my Fingers a Steel Bodkin, near the Lower part of it, I preſs'd the point hard againſt the Surface of the Diamond, and much more if I ſtruck the point againſt it, the Coruſcation would be extremely ſuddain, and very Vivid, though very Vaniſhing too, and this way which commonly much ſurpris'd and pleas'd the Spectators, ſeem'd far more proper than the other, to ſhow that preſſure alone, if forcible enough, though it were ſo ſuddain, and ſhort, that it could not well be ſuppos'd to give the Stone any thing near a ſenſible degree of Warmth, as may be ſuſpected of Rubbing, yet 'tis ſufficient to generate a very Vivid Light.
[a]43] We afterwards, try'd precious Stones, as Diamonds, Rubies, Saphires, and Emeralls, &c. but found not any of them to Shine except ſome Diamonds, and of theſe we were not upon ſo little practice, able to fore-tell before hand, which would be brought to Shine, and which would not; For ſeveral very good Diamonds, either would not Shine at all, or much leſs than others that were farr inferiour to them. And yet thoſe Ingenious Men are miſtaken, that think a Diamond muſt be foul and cloudy, as Mr. Claytons was, to be fit for Shining; for as we could bring ſome ſuch to afford a Glimmering Light, ſo with ſome clear and excellent Diamonds, we could do the like. But none of thoſe many that we try'd of all Kinds, were equal to the Diamond on which the Obſervations were made, not only conſidering the degree of Light it afforded, but the eaſineſs wherewith it was excited, and the Comparatively great duration of its Shining.