1835. Decolourizing Compounds of Chlorine. 433 



position of hypo-chlorite of lime, by persulphate of iron, 

 sulphate of lime and peroxide precipitated. Chlorine is 

 slowly absorbed, as Grouvelle states, by hydrate of iron, 

 and the liquor, after ebullition for a quarter of an hour, pos- 

 sesses strong decolourizing properties. During the ebulli- 

 tion, chlorine and chlorous acid are disengaged. The liquid, 

 before boiling, contained a salt of peroxide of iron, but 

 during the distillation almost the whole of this peroxide was 

 deposited in a state of purity. Hence, it appears that in 

 the action of peroxide of iron upon chlorine, peroxide of iron 

 and chlorous acid are formed, compounds which may co- 

 exist on account of the state of dilution in which they may 

 both be. The intervention of heat destroys what was formed 

 in the cold, and induces an inverse re-action, from which 

 peroxide of iron and chlorine result, and some chlorous acid 

 escapes. 



Solutions of sulphates of zinc and copper are decomposed 

 by hypo-sulphate of lime, while sulphate of lime, and 

 metallic oxide precipitate. 



If the chlorate of lime is in excess, no metal remains in 

 solution, and hypo-chlorous acid is obtained by distillation. 



When the hydrates of zinc and copper are treated by 

 hypo-chlorous acid, a certain quantity is dissolved, and the 

 liquid possesses decolourizing properties. Now, since free 

 chlorous acid dissolves these oxides, and these compounds 

 are precipitated in solutions of alkaline chlorites which 

 contain an excess of chlorous acid, it is natural to think 

 that in this case the chlorous acid does not exist free. It 

 is then probable that some alkaline oxides, as of lime, for 

 example, are capable of forming bihypo-chlorites, which de- 

 compose by evaporation in a vacuum, into neutral hypo- 

 chlorites, and hypo-chlorous acid. The hypo-chlorites of 

 zinc and copper are easily decomposed ; when distilled, 

 hypo-chlorous acid and a little oxygen pass over, and they 

 are changed into chlorides of oxides. The chloride of the 

 oxide of copper is a beautiful green; that of zinc, white. 

 The latter decomposes into chloride and chlorate, with dis- 

 engagement of oxygen, mixed with a little chlorine. These 

 chlorites, mixed with chlorides, may be obtained by agi- 

 tating with chlorine one or other of these hydrates diluted 

 iwith water. The gas is rapidly absorbed, especially by the 



VOL. II. 2 F 



