THE BLEACnrNG COMPOUNDS OF CHLORINE. 299- 



more dilute. I am ignorant of the state in which this chlorine exists : 

 perhaps it forms alittle of the chloroxalic acid, which M.Dumas obtained 

 by exposing acetic acid and chlorine to the influence of the solar rays ; 

 perhaps also it existed in the state of hydrochloric acid, a state to which 

 it might be reduced by the decomposition Of water, the oxygen of which 

 would contribute to the formation of the carbonic acid. 



Inexact as this method of analysis is, it renders it very probable that 

 chlorous acid is formed of two volumes of chlorine and one volume of 

 oxygen. But the manner of its action with hydrochloric acid leaves 

 no doubt on this subject. 



Chlorous acid and hydrochloric acid produce, by their double decom- 

 position, water and chlorine, as already mentioned. Then if an excess 

 of chlorous acid be made to act upon a given quantity of hydrochloric 

 acid, the relation between the volumes of the acid gas decomposed and 

 of the chlorine obtained, will allow the composition of the chlorous acid 

 to be inferred from that of the hydrochloric acid. 



I attempted to eflTect this decomposition, both by passing hydrochloric 

 acid gas over mercury into a graduated tube containing in its upper 

 part a little very concentrated chlorous acid, and by introducing 

 chlorous acid into a tube already containing hydrochloric acid gas. 

 But the decomposition was in both cases produced in a very imperfect 

 manner. The chlorine gas which is disengaged at first renders the so- 

 lution of the hydrochloric acid gas difficult. In order that it may be 

 complete, recourse must be had to agitation, which cannot be effected 

 without a portion of the chlorine being absorbed by the mercury. 



The following mode of operating, however, succeeded perfectly : 

 after having filled a stopped bottle with hydrochloric acid gas in the 

 mercurial apparatus, I introduced a small phial of glass filled with 

 chlorous acid and hermetically sealed ; I stopped the bottle, and I 

 shook it so as to break the small phial. As soon as the chlorous and 

 hydrochloric acid came into contact, decomposition took place with 

 disengagement of heat, and the interior of the bottle assumed a yellow 

 tint. When this had returned to the temperature of the atmosphere I 

 was able to open the phial over the mercurj"^ without a drop of this liquid 

 metal entering or a bubble of gas escaping. The gas which thus filled 

 it was entirely absorbed by mercury. 



In its decomposition by chlorous acid, the hydrochloric acid had 

 been converted into an equal volume of chlorine. Then in this vo- 

 lume of hydrochloric acid there was half a volume of hydrogen : the 

 chlorous acid which had converted this hydrogen into water had 

 yielded a quarter of a volume of oxygen. On the other hand, the hy- 

 drochloric acid decomposed could give only half a volume of chlorine ; 

 and, as a whole volume had been produced, the other half volume must 



