﻿2 EVANS, Electrolytic Preparation of Titanous Sulphate. 



apart. Moreover, the P.D. required is much lower owing 

 to the smaller resistance of the cell (2*5 to 3*5 volts instead 

 of 4 to 5 volts). 



Effect of Varying the Current Density. 



With a solution containing 408 gms. titanium sul- 

 phate per litre in a beaker containing 400 c.c, with a 

 current of 3*5 amperes = (14 amperes per 100 sq. cms.), the 

 yield at 20 minutes after starting was 31 per cent, after 

 33 minutes 22 per cent. 



With the same solution, but with only 17 amperes 

 ( = 6'8 amperes per 100 sq. cms.), the yield at corresponding 

 times was 62 and 50 per cent, respectively. That the 

 yield falls rapidly with increase of current density was 

 fully borne out by the results of a series of preliminary 

 experiments, using a porous pot. 



Influence of Temperature. 



It was found that by raising the temperature at which 

 electrolysis was carried out the yield could be considerably 

 increased. The comparative experiments were arranged 

 by connecting two electrolytic cells containing the same 

 solutions (8 1 '6 gms. Ti(S0 4 ) 2 per litre) in series. One cell 

 was kept at 70°C, the other as near o°C. as possible. At 

 the higher temperature, with a current density of 4*5 

 amperes per 100 sq. cms., the yield could be kept above 

 70 per cent, until quite half of the titanium sulphate had 

 been reduced. 



In the cold solution, on the other hand, the yield was 

 only about 45 per cent, of the theoretical ; the difference 

 in the two cases was very clearly seen in the fact that 

 there was no visible evolution of hydrogen at the cathode 

 in the hot solution, whereas in the cold a considerable 

 amount of hydrogen was given off. 



