The hexammine salts are formed by the oxidizing action of air on dilute ammoniacal solutions of cobaltous salts, especially in presence of a large excess of ammonium chloride.
Cadmium salts can be recognized by the brown incrustation which is formed when they are heated on charcoal in the oxidizing flame of the blowpipe; and also by the yellow precipitate formed when sulphuretted hydrogen is passed though their acidified solutions.
Molybdenum trioxide, Mo03, is prepared by oxidizing the metal or the sulphide by heating them in air, or with nitric acid.
Oxidizing agents rapidly attack sulphuretted hydrogen, the primary products of the reaction being water and sulphur.
Dessaignes, who obtained it by oxidizing malic acid (Ann., 1858, 107, p. 251).
