Polarization at a Metallic Anode. 661 



equation (24) 



S C= 1-695 x 10~ :3 at time *=0, 

 B 1 G= -1-695 „ „ *=1G, 



8,C= 1-695 „ „ £ = 20, 



&c. The solution was as before O002 n. AgN0 3 , in 0*2 n. 

 HN0 3 , area of anode and tube 1'713 sq. cm., temperature 

 20°*O C.j and the calculated polarization becomes 



=0-0582 la&^l + ll-Uii/t—y/t— 10 + y/t-2Q-<yt-Z0 + &c.)} 



at anv time t (real values only to be taken). 



The lower curve (VI) in fig. 2 represents the values cal- 

 culated from this equation plotted with the time. The ©'s 

 are the experimental values of the polarization: the observed 

 potential-differences V + CRab when the current is on have 

 been reduced by the amount CRab = '0904 volt, a value 

 chosen arbitrarily so as to make the two portions of the 

 experimental curve (current on, and current off) join well 

 together. 



In the case to which the upper curve (VII) refers, a 

 current of 1-9-47 x 10~ 3 ampere was applied for 10 minutes ; 

 it was then suddenly reduced to '980 x 10~ 3 ampere (approxi- 

 mately halved), at which value it was maintained constant 

 for the next 10 minutes ; this was then cut off and the cell 

 left insulated for 10 minutes. The whole process was then 

 repeated during the second half hour. The current variations 

 to be introduced into (24) are thus as follows : — 



8„ C= 1-947 x 10- 3 at time t = Q, 

 S 1 C= -0-967 „ „ *=10, 

 g 8 C= -0-980 „ .. t=2D, 

 8,C= 1-947 „ .. *=30, 

 B A G=— 0-967 „ „ *=40, 

 8 § C=-0-980 „ „ *=50. 



The solution being '002 n. AgNO a in '2 n. HN0 3 , A (anode 

 I ]-5(»4 sq. cm., temperature 21°'5 C, the equation fbr the 

 polarization becomes 



Y =0585 log 10 {l + 14-78 \ t —-497 %/t— 10 -'503 »s/t~20 



- \ / — :;t # — --i-HT \ /- [0— -503 V-50;} . (21) 



This is represented by the cnrve (VII). The observed 

 polarizations, represented as before by ©'s, have been deduced 

 where necessary from the observed potential-differences 



