284 balard's researches concerning the 



It is probable that tlie disposition of oxide of copper to combine 

 with tlie chloride of this metal to form an oxichloride, contributed to 

 render copper, though less oxidizable than zinc or tin, proper to produce 

 the decomposition of chlorous acid, — an operation which these two last 

 metals cannot effect. 



This is probably also the cause which rendei-s the action of mercury 

 so prompt. When a few globules of this metal are shaken with chlo- 

 rous acid, it is almost instantaneously decomposed, without any appa- 

 rent disengagement of gas of any kind, and oxichloride of mercury is 

 found to be the product of this re-action. The disposition which the two 

 products of this decomposition have to combine is undoubtedly the 

 reason which renders it so easy of execution. 



The kind of alteration which silver causes chlorous acid to undergo, 

 is precisely the reverse of that of the bodies whose action upon this 

 acid has been hitherto described. When very finely divided silver is 

 put into contact with chlorous acid, a brisk effervescence takes place, 

 which is produced by a disengagement of oxygen gas, without any 

 trace of chlorine, and the whole of this combines with the silver and 

 converts it into chloride. 



To recapitulate: — The bodies which I have tried, chlorine and the 

 metals of the last section of Thenard excepted, decompose chlorous 

 acid; they are oxigenated at its expense, and set some chlorine at 

 liberty, which can be only partially absorbed by the combustible, 

 except in some peculiar circumstances. Silver alone is an exception to 

 this law of disengaging oxygen : and this phaenomenon, as well as the 

 decomposition of fluoride of silver by chlorine, indicates the very 

 peculiar affinity which exists between these two bodies. 



Chlorous acid is therefore one of the most energetic oxidizing 

 agents. The property which it has of converting bromine into bromic 

 acid, and selenium into selenic, and not selenious acid, gives it in this 

 respect an incalculable advantage over nitric acid, and up to a certain 

 point over oxigenated water. 



To judge of its effects as an oxidizing agent only by its action on the 

 metals, it might perhaps be ranged below nitric acid ; but it must be 

 remembered, that the action of nitric acid on metallic substances does 

 not depend on their oxidability alone, and the easy decomposition of 

 the acid, but also on their disposition to form a nitrate, and a nitrate 

 soluble in acid, of the degree of concentration employed. This is 

 proved by the singular action which it exerts upon iron and tin in 

 certain cases. 



Chlorous acid not having much power to form salts, except with the 

 oxides of those metals which yield energetic bases, it ought not to 

 cause surprise that they excite so little definite action upon the otliers. 



This power of oxidizement possessed by chlorous acid is a perfectly 



