﻿tlie 
  Thermoelectromotive 
  Force 
  of 
  Nickel 
  and 
  Iron. 
  183 
  

  

  observations 
  were 
  repeated 
  on 
  the 
  copper-iron 
  junction 
  with 
  

   the 
  bridge- 
  wire 
  shunted. 
  

  

  All 
  temperatures 
  are 
  expressed 
  as 
  air-thermometer 
  tem- 
  

   peratures, 
  correction 
  from 
  the 
  platinum-scale 
  being 
  applied 
  

   graphically 
  by 
  means 
  of 
  a 
  difference-curve. 
  

  

  All 
  E.M.F.'s 
  are 
  given 
  in 
  microvolts. 
  

  

  Discussion 
  of 
  Results, 
  

   The 
  curves 
  for 
  variation 
  of 
  E.M.F. 
  with 
  temperature 
  of 
  

   copper-nickel 
  and 
  copper-iron 
  couples 
  might 
  be 
  roughly 
  

   described 
  as 
  a 
  straight 
  line 
  and 
  a 
  parabola 
  respectively 
  up 
  to 
  

   700° 
  C, 
  but 
  the 
  differences 
  in 
  either 
  case 
  far 
  exceed 
  the 
  

   possible 
  errors 
  of 
  observation 
  (fig. 
  3). 
  In 
  order 
  to 
  exhibit 
  

  

  Fig. 
  3. 
  

  

  

  

  EMT 
  

  

  1500 
  

  

  

  

  

  

  

  

  & 
  

  

  & 
  

  

  

  

  

  

  

  

  

  

  t-^??e^' 
  

  

  

  

  

  

  1000 
  

  

  

  

  

  

  y 
  ~~^Z&^*^' 
  

  

  

  

  

  Oti 
  

  

  

  500 
  

  

  

  

  

  

  x\ 
  b 
  

  

  

  

  

  c 
  

   o 
  

  

  

  

  

  

  

  

  \\ 
  

  

  !L 
  

  

  

  r 
  

  

  r 
  4 
  

  

  

  

  

  at 
  

  

  )0 
  

  

  4< 
  

  

  30 
  

  

  \\\ 
  6 
  1 
  

  

  >0 
  

  

  

  «4H 
  

  

  3 
  

   a 
  

  

  za 
  

  

  

  

  

  

  

  

  

  V 
  

  

  

  

  

  

  

  

  

  

  

  

  \ 
  ■> 
  

  

  

  

  

  

  

  

  

  

  

  

  \ 
  \ 
  

  

  \ 
  

  

  

  

  

  

  

  

  

  

  

  \ 
  

  

  X 
  

  

  

  4 
  

  

  

  

  

  

  

  

  Ni-Cu 
  

  

  fit 
  

  

  is 
  id' 
  seal 
  

  

  'offe-Cu. 
  

  

  

  

  

  

  

  

  

  

  

  

  

  Scale 
  of 
  Temperature. 
  

  

  any 
  peculiar 
  points 
  on 
  a 
  satisfactory 
  scale 
  in 
  either 
  case, 
  

   difference-curves 
  were 
  constructed. 
  For 
  copper-nickel, 
  differ- 
  

   ences 
  from 
  a 
  straight 
  line 
  were 
  plotted 
  from 
  the 
  equation 
  

   Difference 
  = 
  E 
  observed 
  — 
  22£. 
  

  

  