Prep. By passing a stream of chlorine gas through a mixture of carbonate of potash and slaked lime: when saturation has taken place, chlorate of potash and chloride of potassium are formed; the former readily crystallizing out on account of its sparing solubility.

Prop. & Comp. Colourless transparent tabular crystals with four or six sides; have a cooling taste; sparingly soluble in water, especially when cold: the solution gives no precipitate with nitrate of silver; when a few drops of sulphuric acid are dropped upon the crystals, they become orange-red, and give off yellow vapours of peroxide of chlorine; when the salt is rubbed with sulphur in a mortar, it detonates. Composition (KO, Cl O5); when heated, it first liquefies and then gives off nearly 39 per cent. of oxygen, and leaves a white residue, chloride of potassium (K Cl), readily forming with water a neutral solution, which is precipitated white by nitrate of silver, and yellow by bichloride of platinum. The solution of chlorate of potash is not affected by nitrate of silver or oxalate of ammonia.

Therapeutics. Chlorate of potash acts as a refrigerant and diuretic, in a manner similar to nitre; it has been supposed to give oxygen to the system, but this is doubtful: it has, however, been employed in low fevers, as scarlatina maligna, typhus and typhoid fevers, also in cancrum oris and other sloughing ulcers about the mouth and fauces.

Dose. 10 gr. to 20 gr., or more. About 16 parts of cold water dissolve 1 part of the salt.

Adulteration. Chloride of potassium may be present; detected by nitrate of silver.