Definition. - Bismuth subgallate should yield not less than 52 per cent. nor more than 57 per cent. of pure bismuth oxide.

Official in the German Pharmacopoeia as Bismutum Subgallicum; also known as dermatol.

Description and Properties. - Although somewhat variable in chemical composition, bismuth subgallate approximates the following formula: C6H1(OH)3 CO2Bi(OH)2, which contains 56.49 per cent. of bismuth oxide, Bi2O3. An amorphous, bright yellow powder, odorless, tasteless, and permanent in the air. Insoluble in water, alcohol, and in very dilute mineral acids. Readily soluble with decomposition in hydrochloric, nitric, and sulphuric acids, if these be heated, Alkalies dissolve it readily, forming clear, yellow-colored solutions, which rapidly change to deep red.

Dose. - Average dose: 4 grains (0.250 Gm. = 250 milligrammes), U. S. P.