As for silver, I never could see any degree of fire make it part with any of its three principles.... But admitting, that some parts of the silver were driven away by the violence of the fire, what proof is there, that it was either the salt, the sulphur, or the mercury of the metal, and not rather a part of it homogeneous to what remained? for besides that the silver, that was left, seemed not sensibly altered, which probably would have appeared, had so much of any one of its principles been separated from it.

Part I - The Sceptical Chymist (1661)