412 



MR. F. E. SMITH ON THE NORMAL VVESTON CADMIUM CELL. 



5 hours. Much, however, depends on the construction of the cell. An extreme 

 case is illustrated in fig. 12. Here a cell was maintained at a temperature of 55 C. 

 for 12 hours and was then plunged into a bath of paraffin oil at 17 C. The oil 

 was stirred, and observations of the E.M.F. were frequently made. At 1 1.20 A.M. (see 



E.M.F. 

 TOI825 



roiSOO 



1-0177-5 



TOI750 



z 



II- 20 a.m. 



11-40 



12-20 p.m. 



12-40 



12-0 

 TIM C 



Fig. 12. Recovery curve of cell suddenly cooled from 55 C. to 17 C. 



fig. 12) the cell was at a temperature of 55 C. and was then immersed in the oil at 

 17 C. Twenty minutes afterwards the E.M.F. was normal to 1 part in 4000; after 

 a total interval of 40 minutes it was right to 1 in 10,000, and after 1 hour to about 

 7 parts in 100,000. Fourteen days elapsed, however, before the cell was within 

 2 parts in 100,000. 



Recovery after Short-circuiting. 



In order to test the recuperative power of the Weston cadmium cell, one of the 

 cells was short-circuited for 1 minute, another for 5 minutes, a third for 5 hours, 



