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ANALYSIS OF ORES OF COFPER.

Red copper ore may be dissolved in muriatic acid, and then im-mersing into this solution polished plates of iron, so long as a filmof copper is precipitated upon them. 88 parts of the precipitatedCopper being equivalent to 100 of the oxid of which the ore iscomposed.

Arseniate of copper was analyzed by Chenevix * in the follow-ing manner:

The ore was dissolved in diluted nitric acid, and then decom-posed by nitrate of lead. The solution was evaporated till aprecipitate began to appear, and then mingled with alcohol. Theproduct which became precipitated was arseniate of lead; 100parts of which indicate 33 of arsenic acid. The copper mustthen be separated from the nitric acid by boiling it with potashas directed above.

Native copper sometimes contains gold, • silver, or iron. Ifthe ore therefore be dissolved in nitric acid, the gold will not beacted upon by this acid, but the other metals will be dissolved.The silver may be separated by immersing into the solution apolished plate of copper, (or it may be precipitated from a separateportion of the solution by muriatic acid, or common salt) ; tireiron may be separated by boiling the solution to dryness, andtreating the residuum with water. By this process the nitrate ofiron is decomposed; the oxid of iron remains wdiile the waterdissolves the nitrate of copper. This nitrate may be decomposedby boiling it wdth potash, and its quantity of metal estimated asstated above.

In order to obtain pure copper, let the copper of commercebe dissolved in muriatic acid, and precipitate it by a polishedplate of iron; or the black oxid of copper obtained by decom-posing cuprated ammonia may be melted with its ow'n weightof pounded glass and pitch.

Philosoph. Trans. iSoi, p. 195;