656 



Dr. S. E. Milner on the 



During the recovery of the cell, when no current is being- 

 applied, the two columns should of course be identical. 



The most interesting case to which formula (24) applies is 

 that in which a constant polarizing current C is applied for a 

 time t, minutes, and then removed, the cell being left on 

 open circuit to recover. In this case 



8 C = Oat time t = Q, 

 6\0 — — C at time t = t{, 

 and the formula for the polarization becomes 



V='05781og 10 \l + 2 4r C/ 4 



Ac, 



23-80 



1 



for all times up to t = t 1 , and 



V=-0S781og w -[l+^(<VJ-(Vt=ta } 



for all times after t=t lf i. e. during the recovery of the cell. 

 Since the term Qsf t — t x becomes imaginary when t<tj, the 

 second form may be taken to express the polarization at all. 

 times if we exclude imaginary values. The experiments 

 numbered I. to V. were designed to exhibit the dependence 

 of the time-curves of the polarization on the quantities 

 C, t L} and c x . A comparison of I. and II. shows the 

 greater polarization produced, and in particular the much 

 slower rate at which it dies away when the polarizing current 

 is applied for a long time than when it is only applied for a 

 short one. 



I. 



Solution : -002 n. AgN0 3 in '2 n. HN0 3 (i. e. Cl ='002). 

 Anode (1) A= 1-713 sq. cm. Temp. 21°'l C. 

 Current of 1*736 x 10~ 3 ampere applied for 1 minute. 



V calc =-0584 log 10 {1 + ll-63( v7- ^i^Tj} volt. 



Time from start 



V+CRab 



V 



Diff. 



(mins.). 



(obs.). 



(calc). 



0-42 



01554 



0-0544 



+01010 



0-78 



•1594 



•0615 



•0979 



1-00 



Current stopped. 



•0753 





14- 0-92 



0-0464 



00453 



4- -0011 



,. 1-72 



•0410 



•0404 



4- 6 



,. 325 



•0355 



•0352 



4- 3 



„ 8-67 



•0275 



•0272 



4- 3 



„ 1367 



•0231 



•0236 



5 



„ 210 



•0190 



•0206 



16 



„ 28-0 



•0164 



•0187 



- 23 



„ 42-5 



•0127 



•0161 



- 24 



