﻿Magnetization 
  on 
  the 
  Resistance 
  of 
  Graphite. 
  175 
  

  

  was 
  then 
  deduced 
  from 
  the 
  temperature 
  curve 
  (,f> 
  = 
  0) 
  fig. 
  3. 
  

   Owing 
  to 
  the 
  difficulty 
  of 
  exactly 
  getting 
  rid 
  of 
  the 
  residual 
  

   field 
  without 
  setting 
  up 
  a 
  field 
  in 
  the 
  opposite 
  direction, 
  and 
  

   on 
  account 
  o£ 
  the 
  small 
  change 
  of 
  resistance 
  with 
  tempe- 
  

   rature, 
  this 
  method 
  of 
  determining 
  the 
  temperature 
  does 
  not 
  

   seem 
  to 
  be 
  capable 
  of 
  great 
  accuracy. 
  The 
  isothermals 
  at 
  

   low 
  and 
  high 
  temperatures 
  were 
  determined 
  for 
  GI. 
  11 
  and 
  

   G 
  I. 
  15. 
  Except 
  for 
  the 
  difference 
  in 
  the 
  magnitude 
  of 
  the 
  

   changes 
  of 
  resistance 
  concerned 
  similar 
  results 
  were 
  found. 
  

   The 
  results 
  obtained 
  with 
  specimen 
  G 
  I. 
  15 
  are 
  shown 
  as 
  

  

  Fig:. 
  4 
  

  

  ZO 
  30 
  90 
  

  

  Isothermals. 
  G 
  I. 
  15. 
  

  

  isothermal 
  curves 
  (fig. 
  4), 
  from 
  which 
  the 
  so-called 
  isopedic 
  

   curves 
  (.0 
  = 
  constant) 
  may 
  easily 
  be 
  deduced. 
  As 
  will 
  be 
  

   seen, 
  the 
  increase 
  of 
  resistance 
  is 
  much 
  greater 
  at 
  low 
  

   temperatures. 
  At 
  the 
  temperature 
  of 
  liquid 
  air 
  the 
  increase 
  

   is 
  9300 
  per 
  cent, 
  for 
  a 
  field 
  of 
  38'8 
  kilogauss, 
  the 
  increase 
  

   at 
  18° 
  0. 
  in 
  the 
  same 
  field 
  being 
  1250 
  per 
  cent. 
  

  

  The 
  isothermal 
  curves 
  for 
  the 
  lower 
  temperatures 
  cannot 
  

   be 
  represented 
  by 
  an 
  equation 
  of 
  the 
  form 
  (1) 
  : 
  at 
  higher 
  

   temperatures 
  this 
  seems 
  to 
  be 
  the 
  case, 
  although 
  more 
  

   accurate 
  measurements 
  appear 
  desirable. 
  I 
  regret 
  that 
  

   owing 
  to 
  external 
  circumstances 
  I 
  was 
  unable 
  to 
  repeat 
  

   the 
  measurements 
  at 
  different 
  temperatures, 
  so 
  that 
  this 
  

   section 
  of 
  the 
  research 
  can 
  hardly 
  be 
  regarded 
  as 
  completed. 
  

   As 
  regards 
  the 
  practical 
  application 
  of 
  the 
  large 
  effect 
  here 
  

  

  