HYPOCHLOROUS ACID, an acid hav ing the chemical formula HCIO, which is formed when chlorine monoxide, C1,0, is dis solved in water. The most convenient method of preparing it is by distilling a mixture of dilute nitric acid and a salt of hypochlorous acid. The sodium salt of hypochlorous acid known as sodium hypochlorite, NaCIO, may be prepared by passing a stream of chlorine gas through a cold dilute solution of caustic soda, NaOH ; the reaction being 2NaOH -E. 2C1= NaCIO NaCI H2O. Potassium hypochlo rite may be prepared in a similar manner. Crude calcium hypochlorite, Ca (C10),, known in the trade as "bleaching powder,* is prepared by acting upon slaked lime with chlorine gas. Hypochiorous acid and the hypochlorites possess powerful bleaching properties, owing to the readiness with which they part with a portion of their chlorine or of their oxygen. (See BLEACHING). Hypochlorous acid is only known in its aqueous solution, which is a colorless liquid, with a peculiar smell. It decomposes
readily with the liberation of chlorine, and the formation of chloric acid, HCIO,, the decompo sition proceeding rapidly in the sunlight. Hy drochloric and sulphuric acids also decompose it with liberation of chlorine, the reaction in the case of hydrochloric acid being HCIO HCl === H2O 2CI. Heat decomposes the hypochlo rites, with formation of the corresponding chlo rates and chlorides.
HYPOCHcERIS, hi-po-keris, a genus of plants of the family Composite. The leaves re semble those of the dandelion, with more hairy surface, and the flowers are arranged and formed like the dandelion, but are smaller. It is generally relished by cattle. The most com mon species is Hytochceris radicata, found abundantly in fields in Great Britain and Eu rope, and in the eastern United States. The common name is long-rooted cat's ear.