Colorless, hard, six-sided, rhombic prisms, permanent in the air, odorless, having a sharp, saline, slightly bitter taste, and a neutral reaction. Soluble in 9 parts of water at 15° C. (59° F.), and in 4 parts of boiling water; insoluble in alcohol. When heated, the crystals decrepitate, and at a white heat they fuse, solidifying on cooling to a crystalline mass of an alkaline reaction. Is best dissolved in half its weight of boiling water for immediate use. Where it is desired to keep a ready-made solution in stock, dissolve one part by weight in 99 parts of water (1 per cent, solution), specific gravity 1.008 at 15° C, to avoid separating crystals in cold weather, which may happen if only dissolved in the proportion of one to ten (10 per cent, solution). Proportion of a one per cent, solution 100 to 1.