266 KOLLOCK AND SMITH— EFFECT OF [Novembers, 



Current = 2-3 amperes. 



Pressure . = 3-5-4 volts. 



Time ^^^25 minutes. 



Cadmium found (first experiment) = 0.2499 gram. 



Cadmium found (second experiment) '=■ 0.2492 gram. 



Copper from Aluminium. 



This separation was accomplished in the presence of 0.5 cubic 

 centimeters of sulphuric acid (i.i). The current registered i am- 

 pere and 4 volts. In four minutes the solution was colorless. The 

 current was allowed to act for ten minutes. 



Volume of the solution = 10 cubic centimeters. 



Copper sulphate <:= 0.1150 gram copper. 



Aluminium sulphate =c= q.i gram aluminium. 



Sulphuric acid (i.i) = 0.5 cubic centimeter. 



Current = 1-1.6 ampere. 



Pressure = 4-4.5 volts. 



Time = 10 minutes. 



Copper found = 0.1150 gram, 0.1153 gram, 0.1152 gram. 



A low current (o.oi ampere and 2 volts) was passed through 

 zinc sulphate in the presence of 0.25 cubic centimeter of sulphuric 

 acid. In twenty minutes the mercury had increased 0.0006 gram 

 in weight. 



Iron sulphate containing o.iiio gram of iron, acidulated with 

 0.5 cubic centimeter of acid, with a current of 0.0 1 ampere and a 

 pressure of 2 volts gave in thirty minutes 0.0434 gram of iron. 

 When one cubic centimeter of acid was present, a current of o.i 

 ampere with a pressure of 2 volts gave 0.0991 gram of metal. 



The separation of copper from zinc was attempted but it was not 

 successful. A copper solution containing 0.1150 gram of copper, in 

 the presence of 2.5 cubic centimeters of acid and a current of 0.6 

 ampere and three volts, caused the mercury to increase in weight 

 0.1360 gram, showing that 0.0212 gram of zinc had also been 

 deposited. 



The separation of copper from iron was tried, but this, too, 

 failed. With a current (like that given in the preceding paragraph) 

 iron was detected in the mercury, and in thirty minutes the solution 

 still showed the presence of copper. 0.25 cubic centimeter of acid 

 was present. The iron seemed to hold back the copper. 



