298 BALARD S RESEARCHES CONCERNING THE NATURE OF 
It was necessary therefore to attempt some more exact experiments, iu 
order to proceed to its exact analysis. , 
I first made them upon chlorous acid in the state of aqueous solution. 
When I had afterwards sueceeded in extracting pure chlorous acid gas, 
I verified by direct analysis the results which I had obtained with the 
aqueous acid. . 
Several methods suggest themselves for analysing chlorousacid diluted 
with water. It may, in fact, be decomposed by a combustible, which sets 
the chlorine free, and then appreciating together the proportions of this 
gas and those of the oxigenated compound which is produced at the same 
time with it. On the contrary, it may be treated with metallic silver, and 
the quantities of oxygen and of chloride of silver formed may be ascer- 
tained; ‘but in both these methods only one of the elements of the 
chlorous acid is obtained in the state of gas: it is requisite to determine 
the volume of the other by weighings and ealéulation, which render 
these analytic processes rather long in executing. I therefore endea- 
-voured to find another, which would allow of my attaching the compo- 
sition of chlorous acid to the nature of some well-known combination, 
and to reduce its analysis to that of a gaseous mixture, a kind of ope- 
ration which unites the double advantage of accuracy and brevity. 
The action‘which chlorous acid exerts on oxalic acid, and in which 
these two bodies are converted into chlorine and carbonic acid, ap- 
peared to offer an easy method. It is well known that oxalic, acid 
yields, by decomposition, equal volumes of carbonic acid and oxide of 
carbon, and that the latter requires half its volume of oxygen to con- 
vert itintoa volume of carbonic acid equal to its own. It results from 
this, that when oxalic acid is changed into carbonic acid, the quarter 
of the volume of this gas obtained represents that of the additional 
oxygen necessary for this alteration. 
The analysis of chlorous acid is brought by this method to that of 
a mixture of chlorine and carbonic acid, which is easy of execution by 
means of mercury. 
I made in this way various attempts, which, although they indicated 
that the volume of chlorine was almost double that of the oxygen, 
differed however too much from this result, and did not besides agree 
sufficiently together to inspire me with confidence. I persevered ne- 
vertheless, for the method is easy and it appeared to me to be certain. 
Convinced, however, at last that the results obtained were not attribu- 
table to any fault in the execution, I examined by nitrate of silver the 
residue of a re-action of this kind in which the oxalic acid was in 
excess, and the quantity of chloride of silver insoluble in nitric acid 
which I obtained proved that a notable portion of chlorine remained 
in the liquid. I have since convinced myself that the quantity which 
is not disengaged in.a gaseous form is greater as the chlorous acid is 
