CONTAINING AMMONIA. 421 



in about three times its weight of water at 60 ; 

 it has a taste very similar to that of alum, and 

 may in fact be considered as an ammoniacal 

 alum, with persulphate of iron substituted for 

 sulphate of alumina. I analyzed it in the same 

 wav as soda alum, and found its constituents to 

 be 



2 atoms persesquisulphate of iron 25 



1 atom sulphate of ammonia 7*125 



atoms water . . . 28-125 



60-25 



Jt comes therefore as near as possible to the 

 atomical weight of ammoniacal alum. Yet it is 

 not analogous to that alum in its composition : 

 for the alum consists of 3 atoms of sulphate of 

 alumina united to 1 atom of sulphate of ammo- 

 nia ; whereas this salt contains only 2 atoms of 

 sesquisulphate of iron united to 1 atom of sul- 

 phate of ammonia. The quantity of sulphuric 

 acid in an integrant particle of both salts is the 

 same, namely 4 atoms ; 2 atoms of peroxide of 

 iron are substituted for 3 atoms of ahftnina. 



7. Ammonio-sulphate of nickel. This is a 

 beautiful green coloured salt, crystallized in flat nickel. 

 rhombs. It dissolves readily in water, and crys- 

 tallizes with facility ; its specific gravity is 1-801. 

 Its constituents are 



Dd3 



