348 M. Balard on the Nature of the [Nov. 



obtained in a gaseous state. Sulphuric acid was used for 

 this purpose ; a gas was procured, but, instead of being 

 of the deep yellow colour, and having the smell of liquid 

 chlorous acid, it rather resembled deutoxide of chlorine. 

 The acid was changed into deutoxide of chlorine, chlorine, 

 and oxygen. 



I had nearly concluded that chlorous acid, like nitric, 

 chloric, and bromic acids, could not exist without water ; 

 but, before being satisfied with"^this idea, I considered it pro- 

 per to try the effect of an agent, which, though possessing 

 an affinity for water, was less powerful than sulphuric acid. 

 Nitrate of lime was adopted. When a mixture is made of 

 equal parts of liquid chlorous acid, and dry nitrate of lime, 

 a lively effervescence takes place ; a gas is disengaged, which 

 re-dissolves in the water, and possesses all the properties 

 of liquid chlorous acid. The same result was obtained by 

 using phosphoric acid (not prepared from the phosphate of 

 ammonia, because, the ammonia which the acid, in this 

 case, always contains, would produce chloride of azote, and 

 consequently explosions). If the gas is collected in a mer- 

 curial trough, in the usual way, it acts upon the metal, and 

 nothing remains but oxygen. The following method was, 

 therefore, adopted ; 



After having introduced into the upper part of a vessel 

 filled with mercury, about yV ^^ its volume of concentrated 

 chlorous acid, fragments of dry nitrate of lime were gradu- 

 ally passed up. The gas was disengaged in the effervescence, 

 and, as it did not touch the mercury, from which it was 

 separated by the solution of the nitrate, it was preserved in 

 the jar for a long time. It may be transferred from one 

 vessel to another, when the manipulation is performed 

 rapidly, because it is not decomposed by the metal when it 

 passes through it rapidly, and in large bubbles. 



Chlorous acid gas possesses a yellow colour, which is 

 somewhat darker than that of chlorine, with which it 

 is apt to be confounded. Its odour resembles that of the 

 liquid acid. It is completely absorbed by mercury, which 

 is converted into muriate and oxide (oxido-chlorure). Water 

 absorbs a hundred times its volume of the gas. A some- 

 what elevated temperature suffices to separate the elements 

 with an explosion, much heat and light being disengaged. 



