This salt, also called Corrosive Sublimate, and sometimes Chloride of Mercury (the atomic weight of Mercury being halved), may be formed by heating Mercury in excess of Chlorine, or more economically, by subliming a mixture of Persulphate of Mercury and Chloride of Sodium.
Properties.—A very corrosive and poisonous salt, usually sold in semi-transparent, crystalline masses, or in the state of powder. Soluble in 16 parts of cold, and in 3 of hot water; more abundantly so in Alcohol, and also in Ether. The solubility in water may be increased by the addition of free Hydrochloric Acid, or of Chloride of Ammonium.
The Protochloride of Mercury is an insoluble white powder, commonly known under the name of Calomel.
METHYLIC ALCOHOL.
This liquid, known also by the names of wood naphtha and pyroxylic spirit, is one of the volatile products of the destructive distillation of wood. It is very volatile and limpid, with a pungent odour.
By a recent excise regulation, ordinary Spirit mixed with ten per cent, of wood naphtha is sold free of duty, under the name of "Methylated Spirit."
The Milk of herbivorous animals contains three principal constituents—Fatty matter, Caseine, and Sugar; in addition to these, small quantities of the Chloride of Potassium, and of Phosphates of Lime and Magnesia, are present.
The fatty matter is contained in small cells, and forms the greater part of the cream which rises to the surface of the milk on standing; hence shimmed milk is to be preferred for Photographic use.