AMMONIA WITH CARBONIC ACID. 135 



which correspond best with the chemical formula 7 C + 4 NH ^ 

 + 12 H, or rather, 7 C + 4 NH^ + 8 H . When the composi- 

 tion is calculated according to this we obtain in the hundred. 



Ammonia 20'7l 



Carbonic acid 46* 71 



Water 32-58 



100-00 

 The preparation of this salt, like that of the bicarbonate with 

 the greatest quantity of water, should be repeated ; for the experi- 

 ments Avith these two salts were the last which I made on the 

 combinations of ammonia with carbonic acid, and, moreover, at 

 a time when I had already resolved to discontinue these examina- 

 tions. 



I have, however, made especial mention of this salt, be- 

 cause, if it be regarded as a double salt, in which the anhy- 

 drous neutral carbonate forms the one constituent, we are then 

 compelled to consider the other constituent as a combination 

 of 4 atoms of carbonic acid, and 1 atom of ammonia or the oxide 

 of ammonium, — a combination which has never yet been pre- 

 pared isolated. According to this view the composition of the 

 salt would be expressed by the formula 3 (C + NH^) + (4 C5 

 + NH3 + 12 H), or rather, 3 (C + NH ^) + (4 C~+ NH^ + 

 11 H), or 3 (C + NH4) + (4 C + W + 8 H). 



XII. Nine-four Carbonate of Ammonia. 



When a solution of the common sesquicarbonate is evaporated 

 over sulphuric acid in vacuo, and too much pumping is avoided, 

 so that the solution may not boil, small crystals are obtained, 

 which, immediately on their formation, must be withdrawn from 

 the influence of the sulphuric acid, otherwise they effloresce and 

 pass into the common bicarbonate. 



1-507 grm. of these crystals gave 1-657 of platina, and 1-176 

 grm. of crystals from the same preparation gave, treated with 

 chloride of barium and ammonia, 2-929 grm. of carbonate of ba- 

 rytcs, which gives the following composition : 



Ammonia 19*12 



Carbonic acid 55-83 



Water 25-05 



100-00 



