Origin. - Prepared from a solution of soda in a manner similar to the preparation of potassium iodide.

Description and Properties. - Colorless, cubical crystals, or a white, crystalline powder, odorless, and having a saline and slightly bitter taste. In moist air it deliquesces and becomes partially decomposed into sodium carbonate and free iodine, assuming thereby a reddish color. Soluble in 0.5 part of water and in about 3 parts of alcohol. It 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.].