4092. Protoxide of Copper

4092. Protoxide of Copper—also known as black oxide of copper - may be formed by calcining metallic copper, nitrate of copper, or the hydrate, thrown down from solutions of the salts of copper by means of pure potassa. This preparation was formerly called the deutoxide of copper. It is not changed by heat, but readily gives out its oxygen when heated with combustible matter; hence its general use in organic analysis for supplying oxygen. It communicates a beautiful green color to glass and enamels.

4093. Sulphite of Copper

4093.    Sulphite of Copper. To a concentrated solution of bisulphite of potash add a cold solution of sulphate of copper, filter, and heat gently.

4094. Suboxide of Copper

4094.    Suboxide of Copper. This is the red oxide of copper, obtained by heating together in a covered crucible 4 parts copper filings, and 5 parts black oxide of copper. (See No. 4092 (Protoxide of Copper).) Or: Mix 100 parts sulphate of copper with 57 parts carbonate of soda, (both in crystals), and fuse them at a gentle heat; cool, pulverize, add 25 parts fine copper filings, ram the mixture into a crucible, cover it over, and expose it for 20 minutes to a white heat. It consists of a superb red powder with a metallic lustre. It is used as a pigment and a bronze, and as a stain for glass and enamel, to which it gives a rich red color. Heat converts it into the black oxide. "With ammonia it forms a colorless solution, which rapidly becomes blue from the action of the air. (Cooley.)

4095. Peroxide of Copper

4095.    Peroxide of Copper. An oxide formed by the action of peroxide of hydrogen water on the hydrated black oxide.

4096. Sulphate of Copper

4096.    Sulphate of Copper. The blue vitriol of commerce is obtained from the native sulphuret of copper (copper pyrites). Pure sulphate of copper is made by the direct solution of the metal, or preferably, of its oxide or carbonate, in sulphuric acid. It consists of fine blue crystals, slightly efflorescent in the air. By heat it loses its water of crystallization and crumbles into a white powder. (See No. 120 (To make Blue Stone).)

4097. Chloride of Copper

4097.    Chloride of Copper. Dissolve black oxide of copper in muriatic acid; evapMISCELLANEOUS CHEMICALS.

orate and crystallize. It forms green, deliquescent crystals, soluble in alcohol, the flame of which it turns green; exposed to a heat under 400° Fahr. it becomes anhydrous, assuming the form of a yellow powder.

4098. Ferrocyanide of Copper

4098.     Ferrocyanide of Copper. Called also Prussiate of Copper. Precipitate a solution of a salt of copper (sulphate of copper, for instance,) with another of yellow prussiate of potash ; collect the powder, wash it with water, and dry. Has a beautiful reddish-brown color, and is sometimes used as a pigment.