AMMONIA WITH CARBONIC ACID. 121 



0"714 grm. of the salt, treated with muriatic acid, gave 160*9 

 cub. centim. of carbonic acid gas; 0*598 grm. of the crystals, 

 w hich were deposited in beautiful tables, after a long time, from 

 the mother-liquor, gave, treated in a similar manner, 135 cub. 

 centim. of carbonic acid gas. The first determination answers 

 to 44*61 per cent.; the last to 44*69 per cent, of carbonic acid. 



The proportion of the carbonic acid to the ammonia is the 

 same as in the common sesquicarbonate ; only the water is much 

 greater. This salt corresponds to the combination 3C + 

 2 NH^ + 5 H, which, according to the calcidation in the hun- 

 dred, consists of. 



Ammonia 23*56 



Carbonic acid 45*55 



Water 30*89 



100*00 

 Considered as a double salt, the composition would be repre- 

 sented by the formula (C + NH«) + (2 C + NH") + 4H; or 

 if we suppose the oxide of ammonium to be present in the 

 carbonate, by (C + NH^) + (2 C + NH^) + 3 H. 



The crystals do not retain their forms long when exposed to 

 the air, but in closed glasses they do. Exposed to the air they 

 lose water, and effloresce, and probably change in time, like the 

 common sesquicarbonate, into the bicarbonate of ammonia, 



V. The five-four Carbonate of Ammonia. 



I have mentioned, that during the slow sublimation of the com- 

 mon sesquicarbonate in the neck and in the throat of the retort 

 a subUmate is formed, which differs from that of the hydrous 

 neutral salt, by its less degree of volatility, and also by its being 

 formed in a much larger quantity. The sublimation must, how- 

 ever, be discontinued, when the contents of the retort have 

 changed into a perfectly clear liquid in which no more solid salt 

 can be perceived ; if the heating be continued longer, much w^ater 

 passes over at the same time, and the sublimate changes in its 

 composition. 



The sublimate forms crystalline incrustations and masses. In 

 its outward appearance it does not differ from the sesquicarbo- 

 nate of commerce, but it does in its composition. 



1 *66Sgrm. of the salt gave, on experiment, 2*980 grm. of metallic 

 l)latina ; 3*496 grm. from the same specimen, treated with muriatic 



