Prep. Made by passing a stream of carbonic acid through a solution of the carbonate in water unto saturation, and subsequent crystallization.

Prop. & Comp. The bicarbonate occurs in large transparent colourless rhombic prisms, not deliquescent, with a mild alkaline taste; soluble in about four times its weight of water. The solution, when cold, does not precipitate sulphate of magnesia; effervesces with nitric acid; and the supersaturated solution is not precipitated by chloride of barium, or scarcely by nitrate of silver. With dilute hydrochloric acid it forms a solution with which bichloride of platinum gives a yellow precipitate (double chloride of platinum and potassium). Composition (KO, HO, 2 Co2). Fifty grains exposed to a low red heat leave 34 1/2 grains of a white residue, which require for exact saturation 50 measures of the volumetric solution of oxalic acid, equivalent to 23.5 grains of potash.

Therapeutics. Bicarbonate of potash acts as a direct antacid, but does not produce the sedative effect of liquor potassae upon the stomach; it may be taken in very large doses, and is readily absorbed. It renders the blood and urine, and probably many other secretions, strongly alkaline; hence it is a powerful alterative; the action of the kidneys is likewise often increased. It is used in dyspepsia as an antacid; also in urinary affections where there is excessive deposit of uric acid. Bicarbonate of potash may be also employed with great advantage in the treatment of inflammatory affections, as acute rheumatism, etc.

Dose. 10 gr. to 30 gr. as an antacid, etc.; in acute rheumatism, 30 gr. to 40 gr. every four hours, freely diluted with water.

Adulteration. It is apt to contain carbonate of potash, which can be detected by its precipitating sulphate of magnesia.