266 ' M. Balard on the Nature of the [Oct. 



acid set at liberty by the acids themselves, produces a double 

 decomposition, by re-acting upon the metallic chlorides, 

 with which the chlorites are necessarily mixed, in conse- 

 quence of the mode in which they are prepared. 



From this double decomposition will thus result, on the 

 one side, the oxidation of the metal of the chloride, which 

 in this new state would saturate the acid employed, like 

 the base of the chlorite ; and, on the other, a disengagement 

 of the chlorine gas, which would proceed from two sources, 

 the chlorous acid and the metallic chloride. 



Although this explanation is more complex than the first, 

 still it is supported by analogous chemical facts. If we 

 ignite, for example, a mixture of phosphuret of lime and 

 phosphate of lime, pure lime is the only residue. Phos- 

 phorus is disengaged, which led to the idea upheld for a 

 long time, that this mixture consisted of a phosphuret of 

 the oxide, which is, however, contrary to the fact. 



We owe to Liebig some experiments which appear to 

 support the hypothesis of the chlorides. This able chemist 

 observed that chlorine can take the place of carbonic acid, 

 in acting upon the bi-carbonates, and also acetic acid, so 

 as to form decolourizing compounds. Now, it is difficult 

 to conceive that a simple body can thus drive away an acid 

 from its combination with a base. It is more natural to 

 suppose that another acid overcame the affinity of the acetic 

 acid ; and this circumstance appears to justify the supposi- 

 tion of the existence of chlorous acid. 



It may appear astonishing, at first sight, that an acid so 

 weak as chlorous acid, and which may be expelled from its 

 combinations by carbonic acid, should be able to take the 

 place of acetic acid ; but we are acquainted with other facts 

 equally singular : Acetic acid, for example, decomposes 

 the carbonates, and yet carbonic acid, in acting upon acetate 

 of lead, precipitates the carbonate and sets the acetic acid 

 at liberty, which may be distilled over. 



Berzelius investigated this subject, and we owe to him an 

 experiment which, although it has not solved the question, 

 has thrown considerable light on it. In passing a current 

 of chlorine through a solution of carbonate of potash, satu- 

 rated with chloride of potassium, he observed that, at first, 

 the liquid acquired a strong bleaching powder, and much 



