334         Dr.  Gundry  on  the  Asymmetrical  Action  of  an 
actual  concentration  changes  may  be  calculated,  and  so  the 
E.M.F.  o£  asymmetry  reckoned  once  more;  but  this  nearer 
approximation  would  make  no  essential  alteration  and  would 
add  seriously  to  the  complication. 
Following,  now,  the  method  of  Warburg  *,  we  suppose 
i0  sin  mt  the  alternating  current. 
6*o  the   Hg-ion  concentration  in  the  neighbourhood  of 
the  large  electrode  (practically  unaltered), 
c  the  same  in  the  neighbourhood  of  the  small  electrode. 
c  changes,  partly  through  diffusion,  and  partly  through  the 
quantity  of  Hg-ions  brought  in  and  out  of   solution  by  the 
alternating  current. 
Let  q  =  area  of  the  small  electrode, 
and  e  =  the  charge  of  electricity  on  a  grain me-ion. 
For  the  diffusion,  we  have  : 
d*=KB?' (1> 
where  z  is  measured  perpendicular  to  the  small   electrode 
(supposed  a  small  plane),  and  k  is  the  velocity  of  diffusion. 
The  boundary  conditions  are: — 
where  z  =  0,  .     .  ,^  x 
in&mmt  __(dc\  /.n 
V*      ~\W*=o (   } 
and  where  z  =oo  ,  c  =  c0 (3) 
The  solution  is : 
c- 
where 
c0  +  Be~2^  cos  (  mt  —  ~  +  </>  J 
y—     /2k       d>  =  -       B  =  ^°         =        '° 
*_  V    m  '     V      4'  ~  2q€K.sm6       qe  \Um   ' 
Where  z  —  0,  we  have 
c  =  c0  +  Bco$(mt+  ^J (4=) 
The  polarization  is 
110,       c. 
p  = —  loge- 
n       c   c. 
2 
,  c—c0      1  /c  —  c0\-  .    l/c  —  i\ 
im+a??)-»i- 
"Warburg",  foe.  cit. 
