Prep. Made by boiling the acid or bitartrate with carbonate of potash, when an equivalent of water in the acid salt is replaced by one of potash, and carbonic acid given off.

Prop. & Comp. Small granular crystals, usually without distinguishable shape; its real form is a right rhombic prism; neutral, deliquescent, and very soluble in water; bitartrate of potash is precipitated on the addition of hydrochloric acid to the solution. Heated with sulphuric acid it forms a black tarry fluid, evolving inflammable gas, and the odour of burned sugar. It is entirely dissolved by its own weight of water. 113 grains heated to redness, till gases cease to be evolved, leave an alkaline residue, which requires for exact saturation 100 measures of the volumetric solution of oxalic acid, equivalent to 47 grains of potash. Composition (2 KO, C8 H4 Ol0), tartaric acid being bibasic.

Therapeutics. In small doses it acts as a diuretic, and is changed into the carbonate in the same way as the acetate: in larger doses it is purgative, producing watery evacuations.

Doses. As a diuretic and alterative, 20 gr. to 60 gr.; as a purgative, 120 gr. to 200 gr.

Adulteration. Some sulphates may be present, which may be detected by the tests already given for them.