Alternating  Current  on  a  Polarizable  Electrode.       343 
The  arrangement  is  shown  in  fig.  2, 
Fig.  2. 
2>f 
L 
-0    © j 
Z> 
wwvw 
A. 
w 
Kzy^ — -©■ 
M  is  the  alternating  current  machine. 
E,  electro  dynamo  meter. 
AB,  the  solution. 
A,  the  small  electrode. 
B,  the  large  electrode. 
G,  the  galvanometer. 
W,  a  high  resistance. 
R  and  S  are  resistances,  and  e  a  battery,  so  that  an  E.M.F. 
e  could  be  included  in  the  circuit.     R  +  S  was  always 
R+S 
10;000  ohms. 
F,  the  quadrant  electrometer. 
CD  was  a  resistance-box  which  amounted  to  11,000  ohms. 
The  part  CK  could  be  100,  200,  &c.  up  to  1000  ohms  ;  or 
1000,  2000,  &c.  up  to  11,000  ohms.  T  could  in  this  way 
obtain  a  calculable  fraction  of  the  E.M.F.  of  the  machine. 
L  was  a  key,  so  that  the  alternating  current  could  be 
shunted  in  and  out  of  circuit  without  stopping  the  machine. 
All  the  resistances  were  without  self-induction.  With 
higher  frequencies  the  resistance  W  had  a  very  high  value 
(in  most  cases  100,000  ohms),  so  that  the  effective  increase 
of  the  resistance  of  the  galvanometer  and  eleetrodynamometer 
