ANALYSIS OF ORES OF ZINC.

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mine or ore employed, and upon the whole lay another equalquantity of grains or plates of copper, and lastly, cover this latterportion with charcoal powder. Lute a cover upon the crucible,and apply a red heat during one or two hours. The volatilizedzinc will thus combine with the copper and convert it into brass.By comparing the weight of the metal after tire operation, withthe weight of the copper employed; the quantity of zinc unitedwith the copper will be known.

The copper which has not been converted into brass, or morecopper with fresh charcoal powder may be again added in thesame manner to the remaining ore, and the operation repeatedwith a heat somewhat more intense, in order that any zinc re-maining in the ore may be thus extracted. A curious circum-stance is, that a much greater heat is required to obtain zincfrom its ore without the interposition of copper, than in theprocess now described of making brass; in which the separationof the zinc from its ore is certainly facilitated by the interpositionof the copper.