AMMONIA WITH CARBONIC ACID. 107 



cated any trace of chloride of nitrogen. When the anhydrous 

 carbonate of ammonia is treated with dry sulphurous acid, it 

 assumes, even in the cold, a pale yellowish colour. If it is 

 heated in an atmosphere of sulphurous acid gas, it changes en- 

 tirely into an orange sublimate of anhydrous sulphite of am- 

 monia. The solution acts with acids, solution of the nitrate of 

 silver, and solution of chloride of mercmy, &c., quite in the 

 same way as the solution of the anhydrous sulphite of ammonia, 

 which has been directly prepared from dry ammoniacal gas and 

 dry sulphurous gas*. When the common sesquicarbonate is 

 treated with dry sulphurous gas, no change is perceptible in the 

 cold. But if the salt be slightly heated in the sulphurous gas, 

 a yellow sublimate of anhydrous sulphite of ammonia is pro- 

 duced on the first action of caloric ; but if the heat is continued, 

 a white sublimate of the usual hydrous sulphite of ammonia is 

 formed. If the whole is left to cool, and then suddenly heated 

 anew, the same phaenomena occur, and this may be repeated 

 three or four times in the same way. But at last only white 

 sublimate of anhydrous sulphite of ammonia is apparent. This 

 decomposition of the salt into anhydrous and hydrous sulphite 

 of ammonia is very easily explained if we regard the sesquicar- 

 bonate as being composed of anhydrous carbonate and of hydrous 

 bicarbonate of ammonia. 



When the anhydrous carbonate of ammonia is treated in the 

 cold with dry sulphuretted hydrogen gas, no effect is produced. 

 On the application of heat sulphuret of ammonia is formed with- 

 out any evolution of water. The sesquicarbonate is likewise not 

 affected by sulphuretted hydrogen gas in the cold, and even 

 when heated it changes with difficulty, and partially only, with 

 production of water, into sulphuret of ammonia ; the greatest 

 portion of the salt, however, may be sublimed in sulphuretted 

 hydrogen gas. 



An important difference between the anhydrous neutral and 

 the hydi'ous sesquicarbonate of ammonia, is manifested in their 

 respective actions with anhydrous sulphuric acid. When the 

 vapours of this acid are passed over some powdered sesquicar- 

 bonate, it is decomposed, even when kept cold by a refrigerating 

 mixture, with effervescence and evolution of carbonic acid, and 

 the common hydrous sulphate of ammonia is formed. The neu- 



* Poggendorff's Annalen, vol. xxxiii. p. 235. 



