294 BALARD’S RESEARCHES CONCERNING THE NATURE OF 
course to nitrate of lime, a very deliquescent calcareous salt, the action 
of which changed my idea on the subject. 
When a mixture is made of nearly equal volumes of sdenccrtaiell 
liquid chlorous acid, and very dry solid nitrate of lime, a brisk effer- 
vescence ensues, and a gas is produced, which re-dissolyed in water 
gives a product possessed of all the properties of liquid chlorous acid, 
and which ought consequently to be considered as pure chlorous acid 
gas. Thesame results are obtained by using vitreous phosphoric acid* 
instead of nitrate of lime. 
If an attempt be made to collect chlorous acid gas in the mercurial 
trough in the usual way, the metal is attacked, and oxygen alone re- 
mains; sometimes indeed the absorption is complete. It is then neces- 
sary, in order to obtain it, to operate in a peculiar manner. The fol- 
lowing method has always succeeded. 
After having introduced into a receiver filled with mercury about 
xvth of its volume of concentrated chlorous acid, I gradually passed up 
fragments of dry nitrate of lime. The gas is disengaged with effer- 
vescence, and, as it does not touch the mercury, being separated from 
it by the solution of nitrate of lime, it may be kept in the trough for a 
long time. Afterwards it may be transferred from one receiver to an- 
other, provided this operation be effected rapidly ; for it is but slightly 
decomposed by the metal, when it passes through it in large bubbles. 
Chlorous acid gas is of a yellow colour, and but little deeper than 
that of chlorine, with which in the course of my researches I had long 
confounded it, on account of this similarity of tint. Its, smell is ex- 
tremely pungent, and like that of the liquid acid; it is completely ab- 
sorbable by mercury, which it converts into red oxichloride. 
Water dissolves many times its volume. I have not determined this 
solubility very exactly, but I believe it to be more than 100. The so- 
lution is very slightly coloured, and has the properties of liquid chlo- 
rous acid. The solution of chlorous acid in water takes place very 
rapidly, but there always remains, after the operation is over, a very 
small residue of chlorine and oxygen, which indicates a very slight de- 
composition of this gas during its preparation. A small increase of 
temperature separates its elements with explosion, and a very conside- 
rable disengagement of, heat and light. Although it appears to me 
more difficultly decomposable by increase of temperature than the ox- 
ides of chlorine, it has happened to me that it has exploded during 
transfer. On this account, care should be taken to add the nitrate of 
* Care mnst be taken touse phosphoric acid which is not prepared by the de- 
composition of phosphate of ammonia by heat. As this often retains a little 
ammonia, it produces chloride of azote, which, by the slightest increase of tem- 
perature, gives rise to detonations, which are the more speci as not being 
foreseen, 
