78 Dr. Kane on the Compounds oj" Ammonia. 



stance free from ammonia has occurred, some fundamental distinction must 

 necessarily be drawn between the resulting ammonia bodies of the mercurial 

 series and those containing copper, zinc, or nickel. 



A remarkable example of this kind is furnished by nitrate of silver. When 

 dry ammonia is passed over nitrate of silver it is absorbed in quantity, but by the 

 application of a moderate heat it can be all again expelled. If an excess of water 

 of ammonia be added to nitrate of silver there is obtained the crystalline com- 

 pound analyzed by Mitscherlich and myself, and which, when heated, gives 

 common nitrate of ammonia, metallic silver, and the elements of amidogene. 

 Thus there are two bodies, 



1. Ag-CNOj-j-^NHj. 



2. HO.NO5.NH3-I- A^-,A</. 



And in the latter case the formation of the common ammoniacal salt and of the 

 metallic amidide becomes quite manifest. 



Recurring to the constitution of the ammonia sulphate of copper, there is 



1. HO.sO3.HAj4~CMO.HA6?. 

 In the zinc series there is 



2. HO.sO3.HA6J-j~zrao.HArf 4" 2 HO. 



In the nickel series, 



3. Ho.sOyUAd-\-mo.uAd-\-HO. 



Here a property is found fully displayed, which in the ordinary aminonla salts is 

 either latent, or else but feebly manifested, except when in combination ; that is, 

 the power of combining with water of crystallization, or with a group of equiva- 

 lents of the same type, and capable of representing such. If we set out from the 

 common sulphate of potash, and one form of sulphate of ammonia, quite anhydrous, 

 the second gives to us in HO.so3.HArf4- ho the commencement of the series, the 

 completion of which, for the ordinary salts of ammonia, must be sought in the 

 common alums, where there is 



(H0.SO3.HArf-|-6H0)4-(A403.3sO3+ 18ho), 



and in which KO.SO3 is similarly circumstanced. 



The complex group, partly metallic oxide and partly ammonia, which oecu- 



