on Secondary Batteries. 



169 



Time, after stopping the 

 charging current. 



Electromotive force, in volts. 



Exp. I. 



Exp II. 



Exp III. 



Exp. IY. 





2-58 



216 



2-13 

 2-06 

 201 

 200 



2-18 



2-17 

 210 

 2-04 

 201 



2-17 



216 

 2-10 

 2-02 

 2-01 



2-58 

 2-28 

 2-14 

 212 

 2-06 

 205 









5 



10 „ 



15 „ 



Peroxide plate no 



w put into the jar of stronger acid. 



lime after change of acid Acid 34 per Acid 34 per 

 round peroxide. cent.* cent.* 



Acid 34 per 

 cent.* 



Acid 58 per 

 cent.* 



h minute 



1 „ 



1 2-05 volts. 

 207 „ 

 2-07 „ 

 2-09 „ 



2-06 volts. 

 2-09 „ 

 2-12 „ 



2-05 volts. 

 2-09 „ 

 2-12 „ 



1 2-13 „ 



2- 16 volts. 

 2-20 „ 

 2-21 „ 

 2-24 „ 



2 „ 



4 „ 



5 „ 



2-10 „ 



1 2*13 „ 



From this Table it is evident that the rate of fall in the 

 various experiments is fairly uniform, and also that an 

 increase in the strength of the acid round the positive plate 

 (peroxide) is able to give a large increase in the E.M.F. of 

 the cell. We further see that the greater portion of the fall 

 in E.M.F. takes place in the first few seconds after stopping 

 the charging current. This we should expect if the action 

 depends on differences of density in acid, for these differences 

 will be greatest and diffusion most marked in the early stages. 

 In the following set of experiments the spongy lead stood in 

 18*5 per cent, acid, while the porous jar containing the per- 

 oxide plate was filled with acid whose strength in Exps. I. 

 and II. was 34 per cent., and in Exp. III. 58 per cent. The 



Time, after stopping the 

 charging current. 



Electromotive force, in volts. 



Exp. I. 



Exp. II. 



Exp. III. 



261 

 2-44 

 2-33 

 231 



2-28 

 2-28 

 2-27 

 2-27 

 2-25 



At once 



2-61 



2 : 22 

 221 

 2-18 

 2-17 

 2-14 



2-24 

 223 



2-21 

 2-20 

 216 



5 seconds 



1 minute 



2 minutes 



5 „ 



10 „ 



15 „ 



25 „ 



30 „ 





* These strengths refer to the acid in the porous jar. That in the 

 general body of the cell remained as before— 18*5 per cent. 



