222 



The followiuj? table shows the quantities of materials used, the salts 

 formed and the yields : 



The following table shows the volume of the solution used in the prepara- 

 tion of each selenate, the amount of selenate present, and the amount which 

 crystallized upon standing over night. This table gives an idea of the relative 

 s )lubility of those selenates and shows the volumes of solution to use in prepar- 

 iag them: 



TABLE IV. 



The following table gives the results of analyses which were made to de- 

 t3rmine the formulas of the salts: 



Formula. 



CuSe04.)5H.O 



NH.).Ni{SeO,),6H,0.. 

 NH.),Co(Se().),6H,0.. 

 NH.).Mn(Se().).6H,0. 

 NH.),ZnrSeO.).6H,0.. 

 NH,Al(Se04).12HiO.. 



Per cent Found 



NH, 



6.7 

 6.8 

 6.9 

 6.6 

 3 1 



Metal. 

 21.5 

 11.9 

 12.3 

 11.3 

 13.2 

 4.9 



Per cent. From Theory. 



NHi 



6.9 

 6.7 

 7.0 

 7.1 

 3.1 



Metal. 

 21.4 

 12. 

 12. 

 11.3 

 13.6 

 4.9 



2. Ammonium selenate can be decomposed by basic metallic oxides 

 with the formation of the metallic selenate and volatilization of the free 

 ammonia. For example : 



ZnO + XII, ),SeC\ = ZnSeC), -f 2XII, + II.,0 



