This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1898 Excerpt: ...The weighed portion of the ore is mixed with. 1 A. T. to т i A. T. of granulated test lead, and a little borax--slHca being added when the ore is basic--and the whole submitted to scoriflcation. The molten lead ab sorbs the gold and silver and the Impurities of the ore are oxidized, volatilized or slagged off. ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1898 Excerpt: ...The weighed portion of the ore is mixed with. 1 A. T. to т i A. T. of granulated test lead, and a little borax--slHca being added when the ore is basic--and the whole submitted to scoriflcation. The molten lead ab sorbs the gold and silver and the Impurities of the ore are oxidized, volatilized or slagged off. When the lead becomes covered with a layer of litharge and slag the contents of the scorifier are poured into an iron mould and allowed to cool. The lead button is separated from the slag by hammering, and if it is not malleable or is too large to cupel it is put back into the scorifler and the operation repeated till a malleable button is obtained of proper size. CUPEUUATION.--By the operations thus far considered the precious metals of the ore have been obtained alloyed with a relatively large quantity of lead, but free from impurities. The separation of the gold and silver from the lead is accomplished by cupellation, an oxidation process somewhat similar to scorification except that the dish (cupel) used is made of bone ash which has the property of absorbing lead oxide, at a red heat, to the extent of a little more than its own weight. A cupel Щ inches in diameter and weighing about 20 grams is the size most commonly used in practice. The lead button to be cupeled should therefore not weigh more than 20 grams. The cupel should be placed in the muffle and heated to full redness. The lead button is then plaped in it and the muffle door closed until the cupellation is well started After this care must be taken to keep the temperature neither too high nor too low. The formation of crystals of litharge or "feathers" on the edge of the cupel is a safe indication that the cupel is not too hot. On the other hand, the surface of the ...
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Add this copy of Chemical and Metallurgical Handbook: Containing Tables, to cart. $56.22, good condition, Sold by Bonita rated 4.0 out of 5 stars, ships from Newport Coast, CA, UNITED STATES, published 2012 by Nabu Press.
