Prop., Uses, &c. A superb red powder, with a metallic lustre. It often occurs in beautiful transparent, ruby-red crystals, associated with other ores of copper, and can be obtained in this state by artificial means. It is used as a pigment and a bronze, and as a stain for glass and enamels, to which it gives a rich red colour. By heat it is converted into the black oxide. With ammonia it forms a colourless solution, which rapidly becomes blue from the action of the air.
Cupric Oxide. CuO. Syn. Ox′ide of copper, Black oxide, Protoxide; Cu′pri protox′ydum. Prep. By heating the nitrate or carbonate of copper to redness. When it ceases to lose weight the conversion is completed, and the oxide appears as a heavy, black powder.
By heating in the air the hydrated oxide thrown down from solutions of copper by pure potassa.
By adding caustic potassa, in excess, to a solution of a cupric salt, and heating the whole to a boiling-point; the precipitate is then collected, washed, and dried. A heavy, dark-brown powder.
Uses, &c. Protoxide of copper is unchanged by heat unless combustible matter is present, when it readily parts with its oxygen; hence its general use in ORGANIC ANALYSIS as a
source of that element. It communicates a beautiful green colour to glass and enamels. With the acids it produces the ordinary salts of copper.
Cupric Sulphate. CuSO4.5Aq. Syn. Sulphate of copper, Blue cop′peras, B. vit′riol; Cu′pri sul′phas, L.; Sulfate de cuivre, Fr.; Kupfer vitriol, Ger.; Neela tootia, Hind. Prep. (Commercial.) The sulphate of copper of commerce is obtained by the oxidation of native sulphide of copper (COPPER PYRITES); by the joint action of air, heat, and moisture, the copper is converted into an oxide, and the sulphur into sulphuric acid. The resulting salt is washed out, and the solution evaporated and crystallised. The water found in and issuing from copper mines often furnishes such a solution ready to the hands of the manufacturers. A large quantity of sulphate of copper is also obtained as a secondary product in the refining of silver, and is occasionally prepared by dissolving in sulphuric acid an oxychloride of copper, made for the purpose by exposing sheets of copper to the joint action of air and hydrochloric acid.
(Pure.) By the direct solution of the metal, or preferably, of its oxide or carbonate in sulphuric acid, or by purifying the commercial salt by recrystallisation, &c.
Prop., Uses, &c. Fine blue crystals, slightly efflorescent, having an intensely styptic and metallic taste. By heat the blue salt loses its water of crystallisation, and becomes a white, anhydrous powder. It dissolves in 4 parts of water at 60° Fahr., and in 2 parts at 212°; is insoluble in alcohol and ether; and is decomposed at an intense heat into protoxide of copper, sulphurous acid, and oxygen. It has been used to prevent the dry rot in timber and in dyeing. It is largely employed as a source of metallic copper in the ELECTROTYPE. Grain is steeped in a weak solution of it by the farmer, to prevent the ‘smut,’ As a medicine, it is employed chiefly as a styptic (in solution) and caustic (in substance) to destroy ‘proud flesh,’ and, less frequently, as an astringent or tonic (from 1⁄4 gr. to 2 gr.), and an emetic (3 or 4 gr. to 10 or 12 gr). It is exceedingly poisonous.
COP′PERAS. This is a generic name for the CRUDE METALLIC SULPHATES. When used without a qualifying adjective, it generally means sulphate of iron.