tive Zaffer, there is in the Arguments founded on its ſuppoſed Effects.
And to the Firſt, That the Turquoiſe and Sapphire are coloured by the ſame Matter, and that this Matter is univerſally allowed to be a native Zaffer: I ſhall anſwer, That I allow the Sapphire and Turquoiſe to be coloured by Particles of the ſame Kind; that I know it to be the common Opinion, that the Turquoiſe is coloured by Zaffer, and not by Copper: But that I alſo know it to be an erroneous one. I know the Turquoiſe owes its Colour to Copper only; having ſucceeded in a Courſe of Experiments, by which I have been able to diveſt the Turquoiſe wholly of its Colour; to precipitate and preſerve that Colour ſeparate and alone; to prove that Colour, by the Effects of different Menſtruums, to be abſolute Copper; and, by Experiments founded on this Proceſs, to give, by a Solution of Copper in a volatile Alkali, the true Turquoiſe Colour to the Subſtance of the native Turquoiſes, which is abſolutely no other than animal Bone; and to make, by that means, thoſe factitious Turquoiſes, which have been put, before a judicious Aſſembly, to the ſevereſt Trials; and gave all the Marks of the genuine.
To the Second Argument, That Copper is not capable of giving ſo deep a Blue as that of ſome of theſe Gems; I have a Solution of Copper, the very one with which I tained the factitious Turquoiſes, which is of the true Colour
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