﻿192 
  Mr. 
  E. 
  P. 
  Harrison 
  on 
  the 
  Temperature 
  Variation 
  of 
  

  

  well 
  up 
  to 
  350° 
  C. 
  was 
  calculated 
  passing 
  through 
  + 
  100° 
  and 
  

   -f- 
  300°, 
  and 
  was 
  plotted 
  from 
  the 
  equation 
  

  

  R 
  

  

  Ni 
  : 
  

  

  10288 
  + 
  -00048*- 
  -0000007126* 
  2 
  . 
  

  

  The 
  change 
  of 
  slope 
  in 
  the 
  nickel 
  resistance-curve 
  is 
  not 
  

   sudden 
  but 
  extends 
  over 
  10° 
  or 
  15°. 
  

  

  In 
  the 
  case 
  of 
  iron, 
  the 
  resistance-curve 
  does 
  not 
  change 
  

   its 
  parabolic 
  form 
  till 
  nearly 
  800°, 
  when 
  it 
  becomes 
  linear 
  and 
  

   remains 
  so 
  within 
  the 
  limits 
  of 
  the 
  experiments. 
  

  

  The 
  parabola 
  

  

  R 
  Fe 
  = 
  '3318 
  + 
  -001230* 
  + 
  -Q00002209* 
  2 
  

  

  fitted 
  the 
  iron 
  resistance-curve 
  up 
  to 
  500°. 
  

  

  The 
  shape 
  of 
  the 
  nickel 
  and 
  iron 
  resistance-curves 
  are 
  

   strikingly 
  alike 
  at 
  the 
  temperature 
  of 
  the 
  change 
  in 
  each. 
  

  

  Fig, 
  8. 
  

  

  There 
  was 
  very 
  little 
  oxidation 
  in 
  these 
  high-temperature 
  

   experiments; 
  in 
  most 
  cases 
  the 
  copper 
  leads 
  at 
  their 
  junction 
  

   with 
  the 
  spirals 
  appearing 
  perfectly 
  bright. 
  A 
  reddish 
  

   deposit 
  (apparently 
  of 
  metallic 
  copper) 
  was 
  usually 
  seen 
  on 
  

   the 
  spiral 
  and 
  mica 
  disks. 
  

  

  A 
  further 
  series 
  of 
  measurements 
  was 
  made 
  in 
  hydrogen. 
  

  

  