On the Decomposition ofCuminate of Ammonia hy Heat. 459 



The acid had a density of 1*424 at 60°; it began to boil at 

 250°, and distilled over perfectly colourless and unchanged ; 

 towards the end, when slight decomposition commenced, the 

 temperature rose to 260°. 



Five or six ounces of very weak acid, of the density of 1*180, 

 were introduced into a retort and kept heated just below its 

 boiling-point for two or three hours ; the heat was increased 

 from time to time so as to make it boil briskly, and a ther- 

 mometer introduced through the tubulure ; when that which 

 remained in the retort boiled uniformly at 250°, the heat was 

 withdrawn and it was allowed to cool. 



When the specific gravity of this acid was taken, it was 

 found to be close upon that of the tetra-hydrate, but not 

 exactly ; probably if I had operated upon a large quantity, 

 and carried it on for a longer time, it would have been more 

 so; as found, its density was 1*412 instead of 1*424, which 

 would make a difference of rather less than 1^ per cent, de- 

 ficiency in the acid. 



This is, I have no doubt, the proper hydrate of nitric acid, 

 HO, NO5 + 3HO, as it is generally considered; and as Dr. 

 Dalton correctly observed, acids which are either stronger or 

 weaker than this acid, are brought to this strength by conti- 

 nued ebullition, the former losing acid and the latter water. 



LXX. On the Products of the Decomposition of Cuminate of 

 Ammonia by Heat. By Mr. Frederick Field*. 



THE peculiar mode of decomposition which the ammonia 

 salts of inorganic acids exhibit when exposed to the ac- 

 tion of heat, occurs likewise in the ammonia compounds of 

 organic acids, although the results in the latter instances are 

 usually of a more complicated nature. In most of these cases 

 a formation of water takes place, the hydrogen of which is 

 derived from the volatile alkali, while the acid furnishes the 

 oxygen, the residue of which combines in a more intimate 

 manner with the nitrogen of the ammonia. In decompositions, 

 however, of inorganic compounds this reduction seems to be 

 carried at once as far as it can go, the Avhole of the hydrogen 

 contained in the ammonia being converted into water ; while 

 in organic salts this hydrogen is eliminated only by degrees, 

 an intermediate body being produced between the original 

 ammonia salt and the final product of the decomposition. 

 Thus we find that nitrite and nitrate of ammonia, when ex- 

 posed to heat, are at once converted into water, and respect- 

 ively into nitrogen and nitrous oxide. Oxalate of ammonia, 



* Coramunicated by the Chemical Society; having been read June 7. 



1847. 



