Characters. - Small, shining, pearly or translucent scales, becoming opaque on exposure to air, odourless, having a slightly acidulous and metallic taste, and a neutral or faintly alkaline reaction.

Reactions. - The aqueous solution of the salt gives the reaction of bismuth, of ammonia (p. 634) and of a citrate (p. 594).

Dose. - 2 to 4 grains.

Uses. - The solution of bismuth and ammonium, B.P., and the soluble salt, U.S.P., are more astringent and irritant in their action than the insoluble subnitrate, oxide, or carbonate. They may be used as astringents, but are inferior to the insoluble preparations as a means of allaying irritation.