66 PROVOSTAYE ON THE ACTION OF 
with the red vapours produced in the distillation of dry nitrate 
of lead; and when these vapours were put in contact with sul- 
phuric acid, crystals were soon produced; an apparently con- 
vincing proof of the justness of the proposed views. But shortly 
afterwards a clear distinction was drawn between nitrous acid 
(N O,) and hyponitric acid (N O,) by M. Dulong, when it be- 
came necessary to decide which of these two acids was centained 
in the crystals. The experiment just cited produced a general 
admission of their containing hyponitric acid. More lately, Dr. 
William Henry* analysed some crystals found in a pipe em- 
ployed in renewing the air in the leaden chambers; his analysis 
gave 
Dry sulphuric acid . 68°800 
Nitrous acid ... . 13°:073 
Watercress ana) Coen 18°927 
Assuming the identity of these crystals with those of the cham- 
ber, he was induced to give them the formula N O,, 5 S O,; 
+5 HO. The above numbers indeed agree better with six 
equivalents of water, but perhaps the author considered an 
excess of water would be probable in the analysis of so highly a 
hygrometric substance. A little later, M. Berzelius, in his 
Traité de Chimie, and M. Bussy, in a note inserted in the 
16th vol. of the Journal de Pharmacie (1830), supported the 
results of this analysis; the one, by showing that sulphuric 
acid completely absorbed a mixture of nitric oxide and oxygen, 
when in the proper proportions to form nitrous acid, but left a 
residue undissolved if the proportions were different; and the 
other, by the observation that liquid hyponitrous acid introduced 
into a tube containing sulphuric acid, is decomposed into nitrous 
acid which is absorbed, and nitric acid which is diffused in white 
and pungent fumes. 
In the same year, M. Gaultier de Claubry made an analysis 
of the crystals produced by the combination of sulphuric acid 
and hyponitric acid under the influence of water. He found in 
them— 
Anhydrous sulphuric acid 5 equivalents. 
Nitrousacid .... . . 2 equivalents. 
Water ......... . 4 equivalents. 
His numbers, however, really give 3} equivalents of water. 
* Annals of Philosophy, May 1826, 
