Sources. - Its chief source is copper pyrites, which is a double sulphide of copper and iron.

General Reactions. - Ammonia throws down a pale blue precipitate of hydrate, which is soluble in excess, forming a deep blue solution. Potassium ferrocyanide gives a maroon red precipitate.

Prepared from

By

Copper, B.P. .

Copper pyrites

Roasting with sand and coal.

Copper sulphate, B. and U.S.P.

Copper ...........

Heating copper or its oxide with sulphuric acid, dissolving in water and crystallising.

Copper nitrate, B.P.

Ditto

Dissolving in nitric acid, evaporating and crystallising.

Copper acetate, B. and U.S.P.

Copper sulphate

Precipitating with acetate of lead.

General Impurity. - Iron.

General Test. - If an aqueous solution of a copper salt be mixed with twice its volume of chlorine water, any iron present is converted into a ferric salt. If solution of ammonia be now added, cupric hydrate will fall as a precipitate of a pale blue colour, but is redissolved by excess, forming a deep blue solution. If iron be present, it will be precipitated by the ammonia and not redissolved.

Cuprum, Cu = 63.4. B.P. Copper. - Fine copper wire, about No. 25 wire gauge, or 0.02 inch.

Use. - To detect the presence of metals, as silver, mercury, and arsenic, by their being precipitated on its surface and forming a stain. It is employed in the preparation of sulphate and nitrate of copper and of spirit of nitrous ether.