298 BALARp'iS 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 succeeded 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 chlorous acid 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 'ajiid those of the oxigenated compound which is produced at the same 

 time with it. On the contraiy, 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 methotls 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 calculation, 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 it into a volume of cai'bonic 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 brotight 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 



