This section is from the "A Handbook of Useful Drugs" book, by State Medical Examining and Licensing Boards.
A basic carbonate of bismuth of somewhat varying composition, some specimens being more basic than others.
Properties : Bismuth subcarbonate is practically insoluble in water or alcohol. It is decomposed by hydrochloric or nitric acid giving a copious effervescence of carbondioxid and producing a chlorid or nitrate of bismuth which enters into solution. When such a solution is diluted with water the insoluble basic chlorid (oxychlorid or subchlorid) or basic nitrate of bismuth is precipitated. Bismuth subcarbonate is readily decomposed by the acid of the gastric juice, but in this case while the acid is neutralized, an insoluble oxychlorid of bismuth remains, coating the stomach and thus acting therapeutically in the same manner as the original subcarbonate would.
Incompatibilities: It is incompatible with sulphids, sulphur, acids and acid salts.
Action and Uses: Bismuth subcarbonate acts like other insoluble salts of bismuth. For its uses see Bismuth Subnitrate. In roentgenography it is to be preferred to bismuth subnitrate because of the fact that it cannot give rise to nitrite poisoning, which has occasionally happened when large doses of the subnitrate were used.
Dosage: 0.5 Gm. or 7½ Grains.