Origin. - Iodine is dissolved in a solution of potassa in hot distilled water. The solution is evaporated, and the residue heated with charcoal. Dissolve in boiling water, filter, wash the filtrate, and crystallize.

Description and Properties. - Colorless, transparent or translucent, cubical crystals, or a white, granular powder, having a peculiar, faint, iodine-like odor, and a pungent, saline, and afterward bitter taste. Permanent in dry air and but slightly deliquescent in moist air. Soluble in 0.7 part of water and in 12 parts of alcohol; also soluble in 2.5 parts of glycerin. Potassium iodide should be kept in well-stoppered bottles.

Dose. - 2-30 grains (0.12-2.0 Gm.) [7 1/2 grains (0.5 Gm.), U. S. P.].

Official Preparation

Unguentum Potassii Iodidi - Unguenti Potassii Iodidi - Ointment of Potassium Iodide. - Potassium iodide, 10; potassium carbonate, 0.6; water, 10; benzoinated lard, 88. For external use.