PELOUZE ON CERTAIN COMBINATIONS OF A NEW ACID. 471 



this operation several times, the deutoxide of azote is completely ab- 

 sorbed bj' the sulphite ; and these two bodies, upon disappearing, give 

 birth to e very remarkable new salt, to which I shall revert piesentlv. 



If, instead of causing the deutoxide of azote to act upon the sulphite 

 at — 15°, we bring them in contact at zero, or rather at the ordinary 

 temperature, the result is very diflerent : the deutoxide of azote is com- 

 pletely destroyed, it is true, bot it is replaced by hair its volume of prot- 

 oxide of azote, and instead of a new salt we obtain the neutral sulphate 

 of ammonia. 



I am not aware that chemistry presents a single similar instance 

 namely, an example of actions so different at temperatures so nearly 

 equal, above all within the lower limits of the thermometiical scale. 

 It is probable that facts of this nature will eventually multinlv, and 

 that by the aid of freezing mixtures we shall succeed in obtaininp- com- 

 binations which, though little stable, may nevertheless offer a compo- 

 sition and definite properties. 



To return to the experiment above described : If, when all the 

 deutoxide of azote has been absorbed by the sulphite we leave the so- 

 lution to itself, at the ordinary temperature, the new salt is gradually 

 destroyed, puie protoxide of azote is disengaged, and the liquid retains 

 only &u'phc>i,c of ammonia. The volume of the new gas collected is 

 found to be precisely equal to half the volume of deutoxide of azote 

 emoloyed. 



I'he instability of the new substance scarcely allowed me to examine 

 it completely : at zero, it is converted into protoxide of azote and into 

 sulphate of ammonia : at the ordinary temperature, its decomposition is 

 rapid; at 40° and above, its action is violent, and appears like a brisk 

 effervescence ; farther than this, it is not easy, especially in summer, to 

 operate on the gases in refrigerating mixtures. It was necessary then 

 to contrive anoiher mode of preparation, and the following was the rea- 

 soning which led me to discover It. " The salt cannot be what Davy 

 has said, namely a combination of protoxide of azote and an alkali ; for, 

 since it is possible to obtain it with a neutral sulphite, the sulphurous 

 acid eliminated from its base by the deutoxide of azote, and converted 

 into sulphuric acid by the absorption of half the oxygen of the latter 

 gas, would infallibly decompose it, and a disengagement of protoxide of 

 azote would be the result ; but, on the other hand, Davy obtained these 

 combinations, although impure, at the ordinary temperature ; he ob- 

 tained them with sulphites mixed with free alkalies ; the alkalies must 

 therefore increase the stability of the salts in question, and it is proba- 

 ble that by modifying more or less the process of Davy I shall obtain 

 •them pure." 



This is in fact what takes place. The presence of a free alkali re- 

 tards in a remarkable manner the decomposition of the precipitated 



