Page:Theophrastus - History of Stones - Hill (1774).djvu/177

  blue Turquoie. This Colour it is ometimes found beautifully and equally tinged with all through; and ometimes only in Spots and Lines of a very deep Blue, but which the Aitance of Heat will diffue through the whole Mas, and make it as beautifully palely, and uniformly blue, as that found naturally o.

The Word in this Place has been always tranlated black; and Pliny copies it in that Sene from this Author; for he ays, Theophratus auctor et & ebur foile candido & nigro colore inveniri. If we may be allowed to undertand it as I have done, only in the very Sene in which he ues it in the next Line; and judge that he means by it no more than a deep Blue; as 'tis certain he there does, where he applies it to the Sapphire; for Nobody can imagine he intended to call that black; if we receive the Word, in this Sene, and determine that the Author means to ay, that foile Ivory was white variegated with blue; and remember what is jut before oberved of the Turquoies only potted and veined with a very deep Blue, as thoe of France all are; and many of many other Places, till brought to the Fire; we hall undertand this Paage, the Meaning of which has never yet been gues'd at, in a very clear and very particular Light: and find, that the Subtance here decribed is the genuine rough Turquoie, which our Author has very properly called no other than foile Ivory, as perhaps all he had een was of Elephants Teeth; and eems very well acquainted with it in its rough State. Whether the manner of diffuing its Colour by Fire was known at that Time, is more than can now be poitively determined: Mot probably it was not, and they looked upon the native blue Turquoie, which they called Callais, as a different Subtance.

That the Sytem of the Turquoies owing their Colour to Copper diolved in a proper Alcali, is jut, I have this to prove; that by a imilar Operation I have myelf made Turquoies, many of which I have now by me, and which have been acknowledged true ones by our bet Lapidaries. white and a dark Colour; and the Sapphire, which is of a dark Dye, and not