122 IIEINRICH ROSE ON THE COMBINATIONS OF 



acid over mercury, gave 934*5 cub. centim. of carbonic acid gas. 



The following composition is the result : 



Ammonia 31*13 



Carbonic acid 52*92 



Water 15*95 



100*00 



This coiTesponds to the following chemical composition : 5 C 

 4- 4 NH^ + 4 H, or, 5 C + 4 NH*. The composition, calculated 

 according to this formula, gives in the hundred, 



Ammonia 31*85 



Carbonic acid 51*38 



Water 16*77 



100*00 



Being obtained by sublimation, and not by crystallization 

 from a solution, it is not of uniform composition. If the heat- 

 ing be further continued, so that considerably more water is 

 evaporated, some of the salt described in the preceding section 

 is obtained, which I shall have occasion subsequently to refer 

 to. Besides, the quantity of this salt obtained is very consi- 

 derable, being more than half of the sesquicarbonate employed, 

 so that it is impossible that all specimens can be of the same 

 purity. That it is not a mixture of several salts, but a distinct 

 salt, is shown by its crystalline cleavage. 



If we reflect on the composition of this salt, we shall imme- 

 diately perceive that it may be regarded as a double salt of the 

 common sesquicarbonate, and of the neutral carbonate of the 

 oxide of ammonium, which cannot be prepared separately ; for, 



5 C + 4 NH4 = (3 C + 2 NH^) + 2 (C + NH^). 

 Since, however, as is evident from what precedes, it is highly 

 probable that the sesquicarbonate itself must be considered as a 

 double salt, it is far better to regard the salt as a combination of 

 the carbonate of ammonia with the bicarbonate of the oxide of 

 ammonium, the chemical formula of which would be 

 3(C + NTP) + (2C + NH-i + 3H). 

 The combinati(*n of the bicarbonate of the oxide of ammonium 

 with 3 atoms of water, or of the bicarbonate of ammonia with 4 

 atoms of water, has not, it is true, been as yet prepared separately, 

 but very probably it exists amongst the numerous combinations 



