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bring another into fusion, though both are of themselvesinfusible ; and the earthy parts of different ores are madefluid in the furnace of the smelter by the addition ofother earths.

V. Extraliion of gold from the ores of other metals.

When gold is intimately combined with other metalsin their ores, the ore is to be run down in the fame man-ner as the fame kind of ore without gold. The goldcommonly melts out with the proper metal of the ore,from which it may be afterwards separated by differentprocesses according to the nature of the metal. Thereare grounds to believe that most metallic bodies, as ex-tracted from their ores, contain generally a portion of gold,though rarely sufficient to bear the expences of its sepa-ration.

Zinc, arsenic, and mercury, are obtained from theirores by a kind of sublimation : hence if the ores of thesecontain gold, the gold is to be sought for, not in the me-tallic substance separated, but in the remaining matter.There are some other cases also, in which the gold, in-stead of accompanying the metal in its fusion, is thrownoff in the flag: but the ores and flags of this kingdomhave been so seldom examined for gold, that at present Ican say little satisfactory on this subject.

SECT XII.

Of the alchemical history of gold.

S OME of the Greek writers, in the fourth and fifthcenturies, speak of an art, as being then known, oftransmuting the baser metals into gold ; and towards theend of the thirteenth century, when the learning of theeast had been brought hither by the Arabians, the fame

pretensions