Prep. Made by dissolving granulated zinc in hydrochloric acid, digesting for some hours with heat, filtering, and adding solution of chlorine, until the fluid acquires a permanent odour of that gas; afterwards adding carbonate of zinc in small quantities at a time, until a brown sediment appears; this is separated, and the fluid evaporated to a proper consistence and poured into moulds to solidify.

The use of the chlorine, and carbonate of zinc is to peroxidize and precipitate any iron.

Prop. & Comp. A white, crystalline, semi-transparent mass, in rods or tablets, rapidly absorbing water if exposed to the air, and deliquescing; soluble in rectified spirit, in water and in ether. The watery solution is precipitated white by hydrosulphuret of ammonia and nitrate of silver, but if first acidulated with hydrochloric acid, it is not affected by sulphuretted hydrogen. The aqueous solution is likewise precipitated by ammonia and potash but the precipitate is redissolved by excess of these reagents; also precipitated by carbonate of soda, or potash, but not redissolved by excess of these reagents. Composition (Zn Cl). The following are the tests for the purity of this salt: its watery solution is not affected by chloride of barium or oxalate of ammonia and is not tinged blue by the ferrocyanide or the ferridcyanide of potassium, showing the absence of sulphates, lime, and iron. The white precipitate thrown down by ammonia is entirely soluble in excess of that reagent.

Therapeutics. When applied externally in substance, or made into a paste with flour or gypsum, it acts as a powerful escharotic; in solution, as a stimulant and astringent; internally in small doses, as a nervine tonic. A solution of chloride of zinc, sp. gr. 2.0, is used as a deodorizer and disinfectant, under the name of Sir W. Burnett's Solution.

Dose. Internally, 1/2 gr. to 1 gr. or 2 gr.