1835.] Decolourizing Combinations of Chlorine. 347 



ment of chlorine, mixed with variable proportions of car- 

 bonic acid gas. When the substance contains azote, the 

 latter is disengaged in the form of chloride of azote. This 

 happens with urea, uric acid, and the vegetable alkalies 

 which do not appear susceptible of forming chlorites. In 

 some cases the quantity of carbonic acid represents the 

 oxygen which enters into the composition of chlorous acid. 

 This occurs with indigo, which chlorous acid transforms 

 into a bitter yellow matter, soluble in alcohol. In most 

 cases little carbonic acid is obtained, a notable portion of 

 the oxygen disappearing, and contributing to form more 

 oxidized compounds. Thus, the products of its action upon 

 sugar, gum, and starch, &c., are strongly acid. Sometimes, 

 however, the decomposition is latent, and the two elements 

 of the chlorous acid are absorbed at the time by the organic 

 matter. This is what happens with alcohol. By its mix- 

 ture with chlorous acid this liquid is changed into acetic 

 acid, and, at the same time, a certain quantity of oily liquid 

 is formed, the product of the action of chlorine upon alcohol. 



These observations are sufficient to prove that, in its 

 action upon organic matter, chlorous acid acts principally 

 by the oxygen which it contains. Hence, it is natural to 

 infer that our knowledge of chlorous acid may, in an indi- 

 rect manner, contribute to the progress of organic chemistry. 



4. Of Chlorous Acid Gas. — I had observed, in several 

 trials, that the aqueous solution of chlorous acid, when 

 exposed to the contact of air, lost, in a short time, its 

 colour, and a great portion of its smell. These changes 

 made me suppose that it was very volatile, and might admit 

 of its readily being obtained in the gaseous state. 



I tried, at first, the action of heat upon concentrated 

 liquid chlorous acid. At a temperature a little below that 

 of ebullition, a small quantity of a yellow coloured gas was 

 discharged through the mercury in small bubbles, was 

 absorbed, and left a residue of oxygen. The liquid pre- 

 served even after exposure to a temperature near that of 

 ebullition, the power of acting upon combustibles with the 

 same activity as before. 



Hence, I concluded that chlorous acid had a great affinity 

 for water, and that, by the action of a substance possessing 

 a strong disposition for water, the chlorous acid might be 



