Note 36 — Chapter XXII · IRON, COBALT, AND NICKEL
George Kamensky translation
The action of an alkaline hypochlorite or hypobromite upon a boiling solution of cobaltous salts, according to Schroederer (1889), produces oxides, whose composition varies between Co3O5 (Rose's compound) and Co2O3, and also between Co5O8 and Co12O19. If caustic potash and then bromine be added to the liquid, only Co2O3 is formed. The action of alkaline hypochlorites or hypo-bromites, or of iodine, upon cobaltic salts, gives a highly-coloured precipitate which has a different colour to the hydrate of the oxide Co2(OH)6. According to Carnot the precipitate produced by the hypochlorites has a composition Co10O16, whilst that given by iodine in the presence of an alkali contains a larger amount of oxygen. Fortmann (1891) re-investigated the composition of the higher oxygen oxide obtained by iodine in the presence of alkali, and found that the greenish precipitate (which disengages oxygen when heated to 100°) corresponds to the formula CoO2. The reaction must be expressed by the equation: CoX2 + I2 + 4KHO = CoO2 + 2KX + 2KI + 2H2O.