XATURK OF THE BI.KACHIXG COMPOUNDS OF CHLORINE. 277 



acid, which is in this case set at liljerty, exerts the same re-action on 

 the chloride of silver which it produces on the other chlorides, and 

 that the presence of a small excess of nitric acid much accelerates this 

 decomposition. 



It will be observed, then, that in order to have a chance of success 

 in this operation, it is requisite to make use of a decolorizing chloride 

 which is perfectly neutral. It is impossible to prove that it is in this 

 state by means of coloured tests, for their tint is not merely modified 

 but completely destroyed by the chlorides. It is preferable to prepare 

 it by adding nitric acid drop by drop, and until the precipitate formed 

 by the chloride in the solution of silver ceases to have the brown tint 

 which the oxide of silver communicates to it when they are mixed. 



When this perfect neutralization is attained, and not exceeded, the 

 metallic chloride and the alkaline chlorite are decomposed, chloride of 

 silver is deposited, and the liquid possesses decolorizing power in a very 

 high degree, which is undoubtedly due to the chlorite of silver remain- 

 ing in the liquor. 



But the substance which it contains is extremely easy of decomposi- 

 tion ; it was impossible to obtain the liquid clear even by filtration ; it 

 becomes turbid, precipitates, and deposits much chloride of silvei-. The 

 liquor gradually ceases to be decolorizing, and it then contains chlorate 

 of silver. Thus the attempts which I made to separate chlorous acid 

 have almost always been fruitless, and therefore it was necessary to make 

 fresh ones. 



According to what I have stated as to the action of the salts of silver 

 on the decolorizing compounds of chlorine, it appears to me that it 

 must be admitted that the oxide of this metal can form with chlorine 

 compounds similar to those which it yields with the alkalis, though they 

 are less permanent. It seemed to me therefore proper, as I had so 

 little success in treating the alkaline chlorides with the salts of silver, 

 to try the action of oxide of silver upon chlorine itself. 



Chemists are generally of opinion that, when chlorine acts upon the 

 «alts of silver, it converts them into chlorate and chloride. Vauquelin 

 mentions having observed the same phaenomena in treating chlorine 

 with free oxide of silver simply diff'used in water. But I had eveiy 

 reason to think, according to the facts above stated, that these two 

 compounds were formed only by the decomposition of a chlorite. 



Some pure oxide of silver was therefore suspended in distilled water, 

 and agitated with chlorine. This was absorbed. The portion of oxide 

 which was in contact with the chlorine formed a white compound, and 

 the other portion became of a very deep black colour. I ascertained 

 that the first was chloride of silver ; as to the second, it possessed all 

 the characters of peroxide of silver. During this re-action heat was 

 evolved, but I did not perceive any disengagement of oxygen. This 

 liquid immediately after filtration Mas limpid and strongly ^lecolorizing; 



Vol. I — Pa in II. v 



