272 balard's researches concerning the nature of 



mitted, that it is not only chlorine and the analogous bodies which pos- 

 sess decolorizing power ; the same property was found in oxygenated 

 water, and the hyperraanganates ; and at present everything tends to 

 the opinion that oxygenating agents are as effective as chlorine in pro- 

 ducing decoloration. Perhaps indeed, as many chemists suppose, chlo- 

 rine, when acting with water on coloured bodies, produces this effect by 

 indirect oxidation, induced by its tendency to combine with hydrogen. 



Welter had, however, made an experiment on this subject which 

 seemed to prove the existence of chlorides of oxides ; he found that the 

 decolorizing power of chlorine was constant, whether it was free, dis- 

 solved in water, or combined with an oxide. 



This remarkable fact could scarcely be explained but by supposing 

 that the chlorine existed in the two cases in analogovis conditions. Sup- 

 posing, therefore, that it was in a state of solution in water saturated 

 with chlorine, it must be admitted that it existed in the state of a chlo- 

 ride of oxide in the decolorizing compound ; or, if the latter was a 

 chlorite, it followed that the solution of chlorine in water wa^ a mix- 

 ture of chlorous and hydrochloric acid ; for how can it be supposed 

 that two different bodies, producing decoloration by different causes, 

 can effect it with precisely the same efficacy ? The greater number of 

 chemists adopted the first supposition ; Berzelius alone preferred the 

 second, although it appeared to be less probable. 



The experiments of Soubeiran have since explained these facts. They 

 have shown that Welter's statement was correct only Avhen a solution of 

 sulphate of indigo was used, which, on account of the sulphuric acid it 

 contained, decomposed the decolorizing chloride, and evolved all the 

 chlorine which had served to form it. But if an ink Avhich is not acid 

 or a vegetable infusion be employed as a chlorometric liquor, it is found 

 that the decolorizing power is no longer the same, and that it may al- 

 ways be increased by more than half, by means of an acid which sets 

 free the chlorine contained in the solution of the chlorides. 



The propei'ty which is possessed by the decolorizing chlorides, of 

 yielding the whole of the chlorine which they contain by the action of 

 the weakest acids, such, for example, as the carbonic acid, has been re- 

 garded as a strong proof in favour of their being chlorides of oxides ; 

 and it must be admitted that these phsenomena of decomposition are 

 much more easily explained by this hypothesis than the other. Nothing 

 is in fact more easily conceivable than the action of an acid combining 

 with a base, and thus disengaging the simple body with which it had 

 formed an ephemeral compound. But this disengagement of chlorine 

 is also easily explained by the hypothesis of chlorites ; for it may be 

 conceived that the chlorous acid, set free by the acids themselves, de- 

 termines a double decomposition, by reacting upon the metallic chlo- 

 rides with which the chlorites are necessarily mixed by the very mode 



