CHLOROUS ACID

HClO 2 . Syn. Acidum chloro′sum , L. Prep. From chlorate of pota ium, 4 parts; arsenious anhydride, 3 parts; nitric acid, 12 parts; (diluted with) water, 4 parts; heated together in a gla flask, furnished with a bent tube, and placed in a water bath. It must be collected in the same way as chlorine, or pa ed into water, when it forms a solution of chlorous acid. Prop., . Chlorous acid is a greenish-yellow gas, non-condensable by a freezing mixture of salt and ice, but liquefiable by extreme cold. The aqueous solution undergoes gradual decomposition, yielding chloric acid and chlorine. Chlorous acid po e es powerful oxidising and bleaching properties; with the bases it forms salts called CHLORITES . These are all soluble in water, and bleach like the acid. They may be recognised by the evolution of chlorous acid gas when acted on by an acid. The use of the arsenious acid is to deoxidise the nitric acid employed in the proce . Tartaric acid, or other deodorising agent, may be substituted for it.