Polarization at a Metallic Anode. 657 



II. 



Solution : '002 n. AgN0 3 in "2 n. HX0 3 . 

 Anode (2) A=l"504 sq. cm. Temp. 22°'5 C. 

 Current of 1*950 x 10~ 3 ampere applied for 10 minutes. 



Y«lc. = ' 



O5871og 10 {l + 14-61( v'i- */*-10)} volt. 



Time from start 



V+CRab 



v 



Diff. 



mins.). 



(obs.). 



(calc). 



103 



0-1890 



0-0704 



0-1186 



223 



•1956 



•0797 



' -1159 



483 



•2046 



•0892 



•1154 



9-67 



•2134 



•0977 



•1157 



10-00 



Current stopped. 



■0984 





10+ 057 



00951 



0-0923 



4- -0028 



„ 125 



0916 



■0895 



+ 24 



.. 257 



•0878 



•0860 



+ 18 



.. 4-40 



•0840 



•0829 



4- 11 



.. 960 



0772 



•0768 



+ 4 



.. 1700 



0714 



•0718 



- 4 



.. 32-0 



0640 



0665 



15 



„ 650 



•0558 



•0580 



22 



There is an agreement to within *003 volt between the 

 observed and calculated values of the polarization during 

 the whole period of recovery observed. This is sufficiently 

 good. It is evident, however, from the regularity of the 

 variation of the differences in the fourth column that the 

 observed polarization dies away somewhat more rapidly than 

 that calculated from the formula. But this effect (which is 

 observable in the experiments throughout) is only to be 

 expected — every error, such as would be produced by con- 

 vection currents, or by a slightly detective insulation of the 

 electrodes A, B, which would allow a slight current to pass 

 between them, would act in the same direction and cause the 

 polarization to die away more rapidly than is indicated by 

 the theory. The variation in the differences is probably not 

 greater than would be accounted for by these sources of 

 error. 



In the two following experiments approximately the same 

 initial polarization i- produced, in the one case by a certain 

 current acting for a given time, and in the second by half 

 the current acting for four times the time. The slower rate 

 of decay, both in theory and practice, of the polarization 

 in the second case is noticeable. Of course, although the 

 same concentration of the silver ions at the surface of the 

 electrode is produced, in the one case twice as many silver 

 ions have been dissolved as in the other, and the concentration 

 gradients, on which the rate of decay depends, are different. 



