AMMONIA WITH CARBONIC ACID. 131 



drate of sulphiiric acid ; just so those might be regarded as double 

 salts of the carbonate of potash and of oxide of ammonium, with 

 hydrate of carbonic acid, if the latter were known in the isolated 

 condition *. If this view could be maintained, and if, at the same 

 time, it were to be admitted that hydrate of carbonic acid, and car- 

 bonate of ammonia (C + NH^) might replace one another, the 

 formulae of some double salts would tm-n out to be very simple. 

 The neutral hydrous carbonate of ammonia, which is produced 

 by the sublimation of the sesquicarbonate and other salts, would 

 thus be analogous to the bicarbonate, only that the carbonate of 

 ammonia of the former would be replaced in the latter by the 

 hydrate of carbonic acid ; both would be then united with the 

 carbonate oxide of ammonium, 



for the formula of the bicarbonate would then be C H i- C NH*, 

 and that of the hydrous neutral carbonate of 



ammonia CNH^ + CNH^. 



The common sesquicarbonate would then be a combination of 

 carbonate oxide of ammonium, with carbonate of ammonia, and 

 hydrate of carbonic acid. In general all combinations of car- 

 bonic acid and ammonia might then be considered as combina- 

 tions of the carbonate oxide of ammonium, either with hydrate of 

 carbonic acid, or with carbonate of ammonia, or -with both ; but 

 some salts would still contain a superfluous quantity of water. 

 In a table annexed to this memoir the compositions of all the 

 salts described in this paper will be enumerated in formulae, ac- 

 cording to this view. 



IX. Bicarbonate of Ammonia, with a greater proportion of 

 Water. 



If common sesquicarbonate be powdered, and as much boiling 

 water poured upon it as is necessary to dissolve it ; and if the 

 glass, directly after the water has been added to it, is carefully 

 closed, so that no carbonic acid gas, which is violently evolved 

 from the sesquicarbonate by the boiling M^ater, when the expe- 

 riment is made in an open vessel, be lost, and is again ab- 

 sorbed by the solution as it cools ; crystals of a large size are 

 produced on the surface on cooling, which increase for many 

 days. The greater the quantity of boiling water employed for 

 the solution of the sesquicarbonate, the longer the time before 



* It is perhaps possible tliat the soUd carbonic acid, prepared by Thilorier, 

 may be a hydrate of it. 



I 2 



