Origin.—Bicarbonate of soda may be obtained by exposing crystals of sodium carbonate to carbonic anhydride, or by the interaction of sodium chloride and ammonium bicarbonate.

Properties.—Bicarbonate of soda is a white, opaque powder, odorless and having a cooling, mildly alkaline taste. It is permanent in dry, but slowly decomposes in moist air. Soluble in twelve parts of water at 15° C. (59° F.); above this temperature the solution gradually loses carbon dioxide, and at boiling heat the salt is entirely converted into normal carbonate, insoluble in alcohol.

Actions.—Antacid, peristaltic stimulant, carminative, alterative and mildly anodyne externally. It also increases fluidity of and secretion of gastric juice.

Uses.—In disorders of the digestive organ administered half hour before meals, to increase the flow of gastric juice, or as an antacid after meals. Young calves when fed on stale skim milk, suffering from dyspepsia, are benefited by one to two drams of bicarbonate of soda, dissolved in each meal of milk. Bicarbonate of soda has become a very popular medicine in the treatment of azoturia in about four ounce doses every four hours. Bicarbonate of soda is used to lessen the irritation of itching skin disorders, as nettle-rash and urticaria, one ounce to a quart of water. Also used as an injection for leucorrhoea. It is an antidote for acid poisoning.

Doses.—Horses, 2 dr. to 4 oz.; cattle, 2 dr. to 2 oz.; sheep and pigs, ¹/₂ to 1 dr.; dogs, 10 to 30 gr.