X906.J SULPHURIC ACID ON DEPOSITION OF METALS. 265 



communicate a few results obtained in this direction. The idea 

 will, however, be pursued in detail as far as it can be carried out. 



Cadmium from Aluminium. 



The aluminium salt appears to retard the complete deposition of 

 cadmium. In the presence of a few (4) drops of concentrated sul- 

 phuric acid with a current of two amperes and seven volts, consid- 

 erable cadmium remained undeposited after the current had acted 

 fifteen minutes. A higher current was, therefore, employed. The 

 separation was complete in twenty minutes, using a current of three 

 amperes and seven volts. The cadmium in solution was 0.25 gram, 

 while the aluminium sulphate was equivalent to o.i gram of alumin- 

 ium. The total volume of the solution was ten cubic centimeters. 

 The increase in the weight of the mercury in the first experiment 

 was 0.2502 gram and in the second 0.2495 gram. 



Cadmium from Magnesium. 



This separation was accomplished under the same conditions 

 as the previous separation (cadmium from aluminium). 



Conditions. 



Volume of solution = 10 cubic centimeters. 



Magnesium sulphate =c= o.i gram magnesium. 



Cadmium sulphate =c= 0.25 gram cadmium. 



Sulphuric acid = 4 drops (40 drops = icc.). 



Current = 2-3 amperes. 



Pressure =11-9 volts. 



Time = 25 minutes. 



Cadmium found (first experiment) = 0.2505 gram. 

 Cadmium found (second experiment) = 0.249/ gram. 



Cadmium from Chromium. 

 Inasmuch as chromium is deposited from its sulphate from 

 slightly acidulated solution, the separation of chromium from cad- 

 mium was carried out in the presence of three cubic centimeters of 

 concentrated acid. The conditions were as follows : 



Volume = 10 cubic centimeters. 



Chromium sulphate =c= 0.1 gram chromium. 



Cadmium sulphate --= 0.25 gram cadmium. 



Sulphuric acid = 3 cubic centimeters. 



