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IV. "Refining ofi gold firom silver and base metals by

antimony.

Antimony consists of a metallic substance unitedwith sulphur. Sulphur has less affinity to the antimonialmetal than to silver, copper, or the other metals com-monly mixed with gold : and accordingly when antimonyand alloyed gold are melted together, the sulphur of theantimony unites with and scorifies the alloy of the gold,while the gold falls to the bottom blended with themetal of the antimony, which last may be afterwards dissi-pated from it by fire.

One of the greatest difficulties in this process regardsthe crucibles, which are very liable to crack, and to be cor-roded by the sulphureous matter. Scheffer relates, that thecrucibles he has found to be most durable are those whichhad been steeped several days in linseed oil; then clearedfrom the oil, so as to remain only of such a degree ofmoistnefs, that some borax in fine powder may adhereand be spread all over the inner surface; and afterwardsset by to dry slowly : in a crucible thus prepared he fayshe can perform two or three hundred fusions. It isnevertheless advisable, in a case where the vessel is so aptto fail, to take precautions for preserving its contents incafe of such an accident; as inserting it into another cru-cible, or placing a bason underneath.

The gold being melted in the crucible, about twice itsweight of powdered antimony is thrown upon it, in dif-ferent parcels, one parcel after another is melted ; withcare to prevent the falling in of any pieces of charcoal,which would occasion the antimony to swell and frothup, so as to be apt to run over the vessel: as this swellingup cannot be wholly avoided, the crucible ought to belarge. If the gold is very impure, or contains above one

fourth