Reversibility of Voltaic Cells. 

 (3) Chi, CuCl 2 , ZnGl 2 , Zn. 



495 



i 



E. 



r (direct 

 experi- 

 ment). 



r (reverse 

 experi- 

 ment). 



(observed). 



(calculated). 



D 2 



(observed). 



D 2 



(calculated). 



4000... 



ohms. 

 3049 



ohms. 

 301-4 



volt. 

 0-997 



volt. 

 0-9997 



volt. 

 1141 



volt. 

 1-1392 



6000... 



286-8 



298-5 



1025 



10230 



1119 



1-1182 



12000... 



262-0 



304-3 



1-051 



1-0474 



1-097 



1-0961 



For this cell D = 1-073 at 23° C, B = 2*0434. 

 Mean value of r= 293*1. 



(4) Cu, CuCl 2 , CdCl 2 , Cd. 



E. 



r (direct 

 experi- 

 ment). 



r (reverse 

 experi- 

 ment). 



(observed). 



(calculated). 



D 2 



(observed). 



volt. 

 0-782 



D 2 



(calculated). 



4000... 



ohms. 

 479-9 



ohms. 



482-0 



volt, 

 0-671 



volt. 

 06704 



volt. 

 0-7836 



6000... 



487-8 



487-3 



0-695 



0-6956 



0-7725 



0-7738 



12000... 



4931 



490-4 



0-722 



0-7227 



0-762 



0-7633 



For this cell D = 0'752 at 16°*5 0., B = 1-0434. 

 Mean value of>=486*75. 



During the experiments, so long as diffusion was prevented, 

 the E.M.F. of the cells remained constant. Even under the 

 most unfavourable circumstances, viz. when the reverse 

 current through 4000 ohms was running through the cell, 

 the E.M.F. only altered about two millivolts. The con- 

 clusion to be drawn from the preceding results is that the 

 cells treated, and consequently all similarly constituted cells, 

 are reversible; for the differences in the values of the E.M.F.'s 

 when calculated and when observed are not greater than 

 might be expected as errors of experiment. 



(5) A few experiments were also carried out with the 

 Clark cell. 



In the foregoing experiments the Clark standard con- 

 sisted of two Clark cells in parallel. These were now 

 separated, and one used as a standard and the other as the 

 experimental cell. The internal resistance of this cell is, of 



