AMMONIA

(NH:), colorle gas which does not support combustion, with characteristic pungent smell, occurring naturally in minute quantities in the atmosphere. in water, and in decomposition of nitregenous organic matter; liquified a. boils —33.7°C. and solidifies ~75°O. It is readily soluble in water, forming ammonia water (NH.O8), which may be regarded as containing the ionized radicals, ammonium (NH,), and hydroxyl (OH), and, owing to the latter, has a strongly alkaline reaction. The group ammonium has not been isolated, but behaves chemically very much in the same way as the alkali metals. The most important salts largely obtained in the manufacture of coal gas are ammonium sulphate, used for the preparation of the numerous other salts and as a fertilizer, ammonium carbonate (sal volatile), and ammonium chloride (sal ammoniac, g.v.) The preparation of ammonia from the nitrogen of the air is an important, but hitherto unsolved, economical problem. Ammonia is used in pharmacy, in dyeing, in the soda-manufacturing proce , and in ice-making.