THE 
LONDON,   EDINBURGH,    and   DUBLIN 
PHILOSOPHICAL     MAGAZINE 
AND 
JOURNAL    OF    SCIENCE. 
[FOURTH    SERIES.] 
FEBRUARY  1872. 
X.  Researches  on  the  Electromotive  Force  in  the  Contact  of  Me- 
tals, and  on  the  Modification  of  that  Force  by  Heat.  By  E. 
Edlund*. 
§1. 
TWO  essentially  different  theories  have  gained  acceptance  in 
the  explanation  of  the  origin  of  the  galvanic  current. 
Volta  himself,  the  creator  of  the  galvanic  pile,  admitted  that  the 
contact  of  heterogeneous  bodies  was  sufficient  of  itself  to  produce 
a  development  of  electricity,  even  if  those  bodies  exercised  no 
chemical  action  on  one  another.  According  to  him,  chemical 
affinity  between  the  bodies  whose  reciprocal  contact  excited  the 
electric  current,  was  of  no  importance,  or  at  least  singularly  sub- 
ordinate, in  an  electromotive  point  of  view.  Volta  based  his 
opinion  chiefly  on  his  fundamental  experiments,  by  which  he 
believed  he  could  demonstrate  that  two  chemically  indifferent 
metals  produce  by  their  reciprocal  contact  a  decomposition  of  the 
electricity — the  one  becoming  electropositive,  and  the  other 
electronegative.  This  is  the  so-called  theory  of  contact,  which, 
without  any  important  modification,  has  hitherto  been  admitted 
as  correct  by  a  great  number  of  scientific  men. 
Nevertheless  weighty  objections  were  early  made  to  the  theory 
of  contact,  by  several  eminent  physicists,  who  endeavoured  to 
demonstrate  that  chemical  affinity  between  the  bodies  whose 
contact  called  forth  electrical  phenomena  was  of  preponderant 
importance  in  the  development  of  electricity.     Among  other 
*  Translated  from  a  separate  impression,  communicated  by  the  Author, 
from  the  Kongl.  Svenska  Vetenskaps-Akademiens  Handlingar,  vol.  ix. 
No.  14. 
Phil.  Mag.  S.  4.  Vol.  43.  No.  284.  Feb.  1872.  G 
