with about 16 per cent. of water of crystallisation, B.P. (K2CO3) 3H2O; 330, U.S.P.

Characters. - A white crystalline powder, alkaline, and caustic to the taste, very deliquescent.

Solubility. - It is readily soluble in water, but insoluble in spirit. Reaction. - It gives the reactions of a carbonate (p. 594) and of potassium (p. 603).

20 grains Carbonate of Potassium neutralise

17 grains Citric Acid, or

18 grains Tartaric Acid.

Dose. - 10 to 30 grains.

Action. - When taken internally it acts as an irritant poison. It is rarely used internally, but may be given instead of liquor potassae, or of bicarbonate, or in an effervescent form with citric or tartaric acid. It is chiefly employed in the preparation of other potassium salts. A dilute solution of it may be used as an application to the skin to relieve itching, and for this purpose may be alternated with dilute acid. Carbonate of potassium is also used as an ingredient in sulphur ointments (Ung. Sulph. Alk. U.S.P. p. 544) in cases of indurated acne: the strength may be half a drachm to a drachm in the ounce of ointment.