AND ON THE CONSTITUTION OF HYPONITRIC ACID. 417 
heat from its solution in sulphuric acid, red vapours begin to 
be disengaged. ‘These vapours would, on being passed through 
an aqueous solution of chlorine, again form hydrochloric and 
nitric acids. 
10. In the present case, therefore, the hydrochloric acid must 
be determined according to the process which I have described 
in a previous communication *, 
After these preliminary observations I might pass on to the 
description of the apparatus I employed, the processes I adopted, 
and to an infinity of precautionary measures I took in order to 
determine accurately the quantity of hydrochloric acid which 
escaped the action of the nitric acid, the amount of actual acid 
in which had been previously ascertained ; but since the analyses 
made with various quantities of substances led to no results 
agreeing with the above theory, their description would be su- 
perfluous. For although it is without contradiction to be ex- 
pected that in analyses of this kind very perceptible losses must 
occur, it is not the less true that when it is a question of a loss 
of more than half an equivalent of hydrochloric acid, the cause 
must be sought for elsewhere than in the complication of the 
apparatus, or of the analysis. 
11. Since the cause of this might be supposed to be owing to 
the deoxidation which the hyponitric acid experiences under the 
influence of the action of the hydrochloric acid, vapours of hypo- 
nitric acid were passed into 100 grammes of pure concentrated 
sulphuric acid. ‘They were prepared by heating 5 grammes of 
well-dried nitrate of lead. Afterwards gaseous hydrochloric 
acid was passed into the acid solution. It liberated a consi- 
derable quantity of chlorine from the solution of the sulphate 
of potash (10.). 
To ascertain whether the nitrous acid had been decomposed 
by the hydrochloric acid, the following method was adopted. 
12. A current of hydrochloric acid was passed for half an 
hour into a solution of 100 grammes of pure sulphuric acid, and 
2°1 grammes hyponitric acid; and after the chlorine and hydro- 
chloric acid had been expelled by heat, one-half of it was again 
subjected to the action of hydrochloric acid, but this time no 
chlorine was formed. A portion of the other half was mixed 
with a sixth of its volume of water, from which all air had been 
* Poggendorff’s Annalen, vol. Ixiy. p. 404. 
