Page:Theophrastus - History of Stones - Hill (1774).djvu/205

 LXXIX. It is aid alo, that there is a much better Kind of this Stone now found out, than that which was formerly ued; inomuch, that it now erves not only for the Trial of the refined Gold, but alo of Copper or Silver coloured with Gold; and hews how much of the adulterating Matter by Weight is mixed with Gold: This has Signs which it yields from the mallet Weight of the adulterating Matter, which is a Grain, from thence a Colybus, and thence a Quadrans or Semi-Obolus; by which it is eay to ditinguih if, and in what Degree, that Metal is adulterated.