AND ON THE CONSTITUTION OF HYPONITRIC ACID. 421 
Hyponitric Acid considered as an Oxidizing Agent. 
20. We have just seen that the action between the hydro- 
chloric and nitric acid ceases as soon as the latter is reduced to 
nitrous acid. This evidently arises from the circumstance that 
the oxygen in the latter acid is more intimately combined than 
in the nitric and hyponitric acids. The nitrous acid is conse- 
quently the most stable, and therefore the least oxidizing of the 
three oxy-acids of nitrogen. 
This conclusion, deduced from the reactions to which hydro- 
chloric, nitric and hyponitric acids give rise in concentrated sul- 
phuric acid, is widely different from that which M. Millon has 
drawn from his experiments. According to this chemist, the 
general course in oxidations by means of nitric acid is, that the 
nitrous acid which first originates forms nitrite of copper, mer- 
cury, silver, &c., that these are destroyed as they are formed, 
and that this destruction gives rise to the production of nitric 
oxide, which again forms nitrous acid with the nitric acid pre- 
sent, whence proceeds a fresh action and a fresh destruction*. 
21. We are not aware whether, in the action of a metal upon 
nitric acid, the formation of nitrite always precedes that of ni- 
trate; however, it appears to me that the origin of a nitrite by 
the action of an alkali on a saturated solution of nitric oxide in 
nitric acid does not admit of our adopting the hypothesis of 
M. Millon+, because the formation of the hyponitric acid pre- 
cedes that of the nitrous acid, and because, when the nitric acid 
is present, as is usually the case, in excess, only hyponitric acid 
is formed. Nor can we conceive how nitrous acid, considered 
as one of the most powerful oxidizing agents, could combine 
with protoxide of mercury. 
The existence of the protonitrate of mercury, the circum- 
among others, that of parting with nitrous acid to sulphuric acid (see the de- 
tails of my experiments), of not combining with the elements of water, but 
yielding with the metalloids, nitrates and chlorides ; acting upon gold, and pro- 
ducing an explosion with pulverulent silver, but only acting slowly upon po- 
tassium, producing an intense evolution of heat and light with powdered anti- 
mony or arsenic, without giving rise to the same phenomena with fused phos- 
phorus.—Annal. der Chem. und Pharm., vol, xlviii. p. 202, and Traité de Chimie 
générale, par A. Baudrimont, vol. i. p. 616. 
If the French chemist, instead of using the crude products of commerce, had 
worked with dry hydrochloric acid and monohydrated nitric acid; if, moreover, 
he had dried the chlorazotic gas, and had assured himself of the absence of hy- 
drochloric acid, we should be in a condition to judge of the value of an inves- 
tigation the statements of which require a most minute study. 
* Comptes Rendus, vol. xiv. p. 912. + Ibid, p. 911. 
