THE BLEACHING COMPOUNDS OF CHLORINE. 297 



gas has the penetrating odour of chlorocarbonic acid. Nitrous oxide 

 gas does not appear to undergo any alteration by chlorous acid ; but 

 with nitric oxide gas this acid occasions a violent detonation. This is 

 accompanied with the production of nitrous gas, which fresh bubbles of 

 chlorous acid are susceptible of converting into nitric acid. 



Sulphurous acid gas, when dry, is but slowly attacked by chlorous 

 acid ; yet, after some hours, the gaseous mixture placed over mer- 

 cury disappears, and the sulphurous acid is converted into sulphuric 

 acid. 



Filtering paper and indigo are the only organic matters which I have 

 put in contact with chlorous acid gas. The first occasioned detonation, 

 but very little carbonic acid was produced. The receiver, after the 

 explosion, was found full of oxygen and chlorine, nearly in the propor- 

 tions which constitute chlorous acid ; this indicates that it was chiefly 

 bj' the heat disengaged in its action on the pajjer that the gas detonated. 



Indigo also decomposes chlorous acid without detonation, and con- 

 verts it into a compound of a yellow colour. The volume of carbonic 

 acid produced is much smaller than that of the oxygen contained in 

 the acid employed; and the chlorine evolved is in part absorbed by the 

 mercury, and partly retained in the pores of the vegetable matter, 

 which yields, undoubtedly from this cause, acid vapours Avhen heated. 



The facts which I have now detailed prove, as it appears to me, 

 that chlorous acid in the state of gas acts nearly in the same Avay as 

 when it is liquid. If its two elements are absorbed together when 

 the temperature is but little raised, it is on the other hand principally 

 owing to the oxygen gas which it contains that it acts whenever much 

 heat is emitted. The disengagement of chlorine gas which accompanies 

 the greater number of its re-actions appears to me to be a sufficient 

 proof of the truth of this assertion. 



It may be thought at first that the chlorine comes from the decom- 

 position of a portion of the gas, occasioned by the high temperature 

 which the action of a combustible body most commonly develops ; 

 but only one portion of the chlorine can be attributed to such au 

 origin. In fact, the quantity of oxygen with which it is mixed, is al- 

 most always smaller than that which in chlorous acid is united with 

 the volume of chlorine obtained ; which induces the opinion, that in 

 these cases the two combustible elements of the compound are princi- 

 pally combined with oxygen. 



ij .5. Composition of Chlorous Acid. 



The experiments which I have now related are sufl[icient to determine 

 that the new compound, which I have described under the name of 

 chlorous acid, is uniformly composed of chlorine and oxygen ; but they 

 do not determine the i)r<ii)(^rtions in which these two elements are united. 



