Characters. - A white, crystalline powder, permanent in the air, odourless, has a sweet, and afterwards an astringent taste, and an acid reaction.

Solubility. - Soluble, without leaving more than a trifling residue, in 1.2 parts of water at 15° C. (59° F.), and very soluble in boiling water; almost insoluble in alcohol.

Reactions. - The aqueous solution of the salt yields the reactions of aluminium (p. 654) and of a sulphate (p. 595).

Uses. - It is a powerful antiseptic. A saturated solution has been used as a mild caustic in enlarged tonsils, nasal polypi, naevi, scrofulous and cancerous ulcers, diseases of the os uteri, and various chronic enlargements. Weaker solutions are used as lotions to ulcers, and as injections in gonorrhoea, leucorrhoea, and foetid discharges from the vagina.

A solution of the sulphate dissolves recently precipitated gelatinous alumina, and thus a benzoated solution of alumina can be prepared by saturating with gelatinous alumina 8 oz. of the sulphate in 1 pint of water, adding 6 drms. of powdered benzoin, keeping it at a temperature of 150° F. for six hours, and putting in a cool place for several days to allow the deposition of crystals. This solution is remarkable for its sweet odour and astringent balsamic taste.1