﻿Theory 
  of 
  the 
  Thermoelectric 
  Forces 
  

  

  779 
  

  

  conduction. 
  In 
  the 
  corpuscular 
  theory 
  of 
  the 
  laws 
  of 
  

   thermoelectricity 
  too 
  we 
  do 
  not 
  consider 
  the 
  predominant 
  

   part 
  of 
  the 
  heat 
  conduction, 
  but 
  take 
  into 
  account 
  only 
  the 
  

   small 
  reversible 
  part 
  of 
  the 
  conduction, 
  which 
  depends 
  on 
  

   the 
  variation 
  in 
  the 
  number 
  of 
  free 
  corpuscles 
  in 
  unit 
  volume. 
  

   This 
  variation 
  gives 
  rise 
  to 
  an 
  electric 
  force 
  along 
  an 
  un- 
  

   equally 
  heated 
  bar 
  of 
  metal. 
  All 
  the 
  phenomena 
  connected 
  

   with 
  this 
  force 
  are 
  reversible. 
  According 
  to 
  this 
  theory, 
  a 
  

   current 
  of 
  heat 
  is 
  to 
  a 
  small 
  extent 
  connected 
  with 
  a 
  reversible 
  

   process, 
  able 
  to 
  perform 
  mechanical 
  work. 
  This 
  is, 
  I 
  think, 
  

   the 
  reason 
  for 
  the 
  agreement 
  of 
  the 
  two 
  theories, 
  whose 
  

   assumptions 
  are 
  quite 
  different. 
  The 
  corpuscular 
  theory, 
  

   however, 
  affords 
  a 
  deeper 
  insight 
  into 
  the 
  nature 
  of 
  the 
  

   physical 
  processes, 
  and 
  gives 
  expressions 
  for 
  the 
  electric 
  force 
  

   X 
  and 
  for 
  the 
  electromotive 
  force 
  E, 
  depending 
  on 
  the 
  

   number 
  of 
  free 
  corpuscles. 
  According 
  to 
  the 
  experimental 
  

   law: 
  

  

  g= 
  a 
  „-« 
  i 
  + 
  <l 
  - 
  / 
  3 
  4 
  )(T-273), 
  

  

  Q=T^ 
  =(« 
  a 
  -<)T+ 
  (/3„-/3 
  6 
  )(T-273)T. 
  

  

  If 
  we 
  keep 
  the 
  temperature 
  of 
  a 
  junction 
  between 
  two 
  

   different 
  metals 
  a 
  and 
  b 
  constant 
  at 
  0° 
  C. 
  the 
  Peltier 
  effect 
  

   will 
  be 
  

  

  Q 
  =(* 
  o 
  -a 
  6 
  )273. 
  

  

  If 
  a 
  current 
  of 
  1 
  ampere 
  is 
  flowing 
  from 
  copper 
  to 
  the 
  

   other 
  metal 
  in 
  the 
  following 
  table, 
  the 
  heat 
  developed 
  or 
  

   absorbed 
  in 
  an 
  hour, 
  measured 
  in 
  calories, 
  will 
  have 
  the 
  

   values 
  indicated 
  as 
  follows 
  : 
  — 
  

  

  

  Calculated 
  

  

  from 
  numbers 
  

  

  of 
  Riecke. 
  

  

  Calculated 
  

   from 
  numbers 
  

   of 
  Clemencic. 
  

  

  Observed 
  

   by 
  Jabn 
  * 
  . 
  

  

  Cu-Pt 
  

  

  Cu-Ag 
  

  

  Cu-Fe 
  

  

  Cu-Zn 
  

  

  Cu-Cd 
  

  

  Cu-Ni 
  

  

  +0-292 
  

   -0-183 
  

   -3-762 
  

   -0-207 
  

   -0-306 
  

   +4-37 
  

  

  +0-327 
  

  

  -0-495 
  

  

  -2-64 
  

  

  -0-353 
  

  

  -0-617 
  

  

  +4-68 
  

  

  +0-320 
  

   -0-413 
  

   -3163 
  

   -0 
  585 
  

   -0-616 
  

   +4-362 
  

  

  * 
  Jahn, 
  Wiedemann's 
  Annalen, 
  Bd. 
  xxxiv. 
  p. 
  763 
  (1888). 
  

  

  