THE BLEACHING COMPOUNDS OF CHLORINE. 307 



the chlorous acid escaped decomposition and -was disengaged in the 

 form of vapour. 



The phaenomena are rather different when oxide of copper or of zinc 

 is employed ; the solutions of the sulphates of these metals are decom- 

 posed by hypochlorite of lime, and sulphate of lime and the metallic 

 oxide are precipitated together. If the chlorite of lime is in excess, the 

 liquor does not retain the slightest portion of either metal, and by dis- 

 tillation hypoehlorous acid only is obtained. 



When however the hydrates of zinc and copper are treated with 

 chlorous acid, a certain quantity of them is dissolved, and the liquid 

 possesses decolorizing properties. Since, then, perfectly free chlorous 

 acid dissolves these oxides, and these compounds are precipitated by 

 solutions of alkaline chlorites, which contain an excess of chlorous acid, 

 it is natural to suppose that in these cases this chlorous acid is not in a 

 perfectly free state. It is therefore probable that some alkaline oxides, 

 lime for example, are susceptible of forming bihypochlorites, which 

 are decomposed by evaporation in vacuo into neutral hypochlorites and 

 hypoehlorous acid. 



The hypochlorites of zinc and copper, the existence of which is ren- 

 dered probable by what I have stated, suffer decomposition very readily. 

 When they are distilled they evolve hj^pochlorous acid, and probably a 

 little oxygen, and they are converted into oxichlorides. The oxichloride 

 of copper is of a fine green colour ; that of zinc is white, with an agree- 

 able pearly lustre ; it decomposes spontaneously into chloride and chlo- 

 rate, with the disengagement of oxygea and a little chlorine. As to 

 thajt of copper, it is decomposed by an excess of oxide, M'hioh it con- 

 verts into insoluble oxichloride^ also disengaging a mixture of oxygen 

 and chlorine. «. . ,.-•, : v. 



These chlorites, mixed with chlorides, may be obtained as mentioned 

 ■by M. Grouvelle, by agitating either of these oxides, diffused through 

 water, with chlorine. The absoi^ition of the gas is rapid, especially by 

 -the oxide of zinc ; the distilled liquor precipitates an oxichloride, as ob- 

 served by M. Grouvelle, and it contains a metallic chloride in solution. 

 A portion of dilute hypoehlorous acid is condensed. In the absence of 

 peroxide of mercury, the oxide of zinc and that of copper may serve for 

 the preparation of this acid. The hypochlorites of powerful bases pos- 

 sess the following properties : their odour and colour are identically the 

 same as the corresponding decolorizing compounds of chlorine, from 

 which it is impossible to distinguish them by their physical properties ; 

 they are salts of a very changeable constitution. A slight increase of 

 temperature, the influence of solar light, even of diffused light, converts 

 them into chlorides and chlorates. I have not estimated the relation 

 between the atomic quantities of these two salts. 

 •o..Thi8 change is effected in the greatest number of cases with the dis- 



