An acid salt obtained from the crude tartar which is deposited during the fermentation of grape-juice, B.P.

Characters. - A gritty white powder, or fragments of cakes crystallised on one surface; of a pleasant acid taste.

Solubility. - Sparingly soluble in water, insoluble in spirit.

Reactions and Tests. - Heated in a crucible it evolves inflammable gas and the odour of burnt sugar, and leaves a black residue (tartrate). The calcined residue consists of potassium carbonate and gives its reactions.

Dose. - 20 to 60 grains as a diuretic; 1/4-1/2 oz. as purgative.

Preparations in which Acid Tartrate of Potassium is used.

B.P

Acidum Tartaricum. Antimonium Tartaratum. Confectio Sulphuris. Ferrum Tartaratum. Potassii Tartras. Pulvis Jalap ae Compositus. Soda Tartarata.

U.S.P

Pulvis Jalapae Compositus.

Uses. - From there being two equivalents of tartaric acid to one of potassium it has a somewhat acid taste, and is used instead of tartaric or other acids for making cooling drinks in fevers, etc. A refreshing drink called Potus Imperialis, or Imperial, is made by dissolving 1 to 1 1/2 drachm of acid tartrate and a little sugar in a pint of boiling water and infusing with half the fresh peel of a lemon.

In small doses it is absorbed, oxidised in the blood to carbonate, and acts like the acetate as a diuretic.

In larger doses it retains water with great avidity, and prevents its absorption into the blood for a long time. It therefore causes the stools to be very watery, by detaining water in the intestine, but it has no irritating action on the intestine, and produces no increased peristalsis. If no other medicine be given to cause peristalsis, the salt and the water it has been retaining will be absorbed. Its action is thus very much like that of a simple enema of water going along the whole intestine, and like a simple enema it produces no depressing effect.

It is much used in dropsies as a purgative, generally in combination with jalap or scammony to produce peristalsis, whether the dropsy be due to affections of the heart or kidneys, and also in Bright's disease, even when unaccompanied by dropsy. It has also been employed as a laxative in dysentery, piles, and prolapsus ani.