firſt, fairly to give the Arguments uſed in Support of the other Opinion; which are principally three, and have the Appearance of being of ſome Weight. They are:
1, That the Turquoiſe is evidently coloured by the ſame Matter with the Sapphire, and that the Matter of its Colour is known to be a Native Zaffer.
2. That Copper is not capable of giving the deep Blue of ſome of the deeper Sapphires; and of the Veins and Striæ of the rough native Turquoiſes.
3. That Zaffer is the Subſtance which colours the common blue Glaſs; and that it is capable of giving it the Colour of the deepeſt native Sapphires; as is evident from the counterfeit ones which are coloured with it, and are of all the Degrees of Colour of the genuine.
To which permit me to anſwer,
Firſt, That it was incumbent on the Aſſertors of this Doctrine, to have proved the Exiſtence of this Native Zaffer, before they attributed ſuch great Effects to it. I am not aſhamed to ſay, that I don't know what Native Zaffer is; that I never yet ſaw any ſuch Foſſil, nor believe I ever ſhall: And, notwithſtanding that Dr. Woodward, and ſome other able Naturaliſts have ventured to name ſome of their unknown Specimens native Zaffers, I cannot bring myſelf to think that Nature
ever
