Thus the chlorine oxyacids enumerated above form salts named respectively hypochlorites, chlorites, chlorates and perchlorates.
Balard discovered chlorine monoxide in 1834, investigating its properties and reactions; and his observations on hypochlorous acid and hypochlorites led him to conclude that " bleaching-powder " or " chloride of lime " was a compound or mixture in equimolecular proportions of calcium chloride and hypochlorite, with a little calcium hydrate.
It is also prepared by heating ammonium nitrite (or a mixture of sodium nitrite and ammonium chloride): NH 4 NO 2 =2H20+N21 by heating a mixture of ammonium nitrate and chloride (the chlorine which is simultaneously produced being absorbed by milk of lime or by a solution of sodium hydroxide): 4NH4N03+2NH4C1=5N2 +C1 2 +12H 2 O; by heating ammonium dichromate (or a mixture of ammonium chloride and potassium dichromate): (NH4)2Cr207 = Cr203+4H20+ N2; by passing chlorine into a concentrated solution of ammonia (which should be present in considerable excess): 8NH3+3C12=6NH4C1-F-N2; by the action of hypochlorites or hypobromites on ammonia: 3NaOBr-+2NH 3 =3NaBr+3H 2 OH-N 2; and by the action of manganese dioxide on ammonium nitrate at 180-20o° C. It is also formed by the reduction of nitric and nitrous oxides with hydrogen in the presence of platinized asbestos at a red heat (G.
Nascent hydrogen reduces it to hydroxylamine (q.v.), whilst solutions of hypochlorites oxidize it to nitric acid.
It is obvious that, with suitable methods and apparatus, the electrolysis of alkaline chlorides may be made to yield chlorine, hypochlorites (bleaching liquors), chlorates or caustic alkali, but that great care must be exercised if any of these products is to be obtained pure and with economy.