﻿Temperature 
  Variation 
  of 
  Nickel 
  and 
  Iron. 
  177 
  

  

  Now 
  Kelvin's 
  estimate 
  of 
  the 
  volume 
  of 
  an 
  ordinary 
  mole- 
  

   cule 
  is 
  between 
  3 
  x 
  10~ 
  25 
  and 
  10 
  ~ 
  26 
  c.c. 
  with 
  which 
  the 
  value 
  

   just 
  calculated 
  for 
  Li, 
  the 
  smallest 
  of 
  the 
  ions 
  in 
  Table 
  III., 
  

   is 
  in 
  agreement. 
  The 
  molecular 
  radius 
  of 
  ordinary 
  gases, 
  as 
  

   found 
  by 
  the 
  kinetic 
  theory 
  from 
  measurements 
  of 
  gaseous 
  

   viscosity, 
  is 
  of 
  the 
  order 
  5 
  x 
  10~ 
  8 
  cm., 
  which 
  is 
  about 
  25 
  times 
  

   our 
  value 
  of 
  ai 
  just 
  found 
  for 
  the 
  Li 
  ion. 
  The 
  process 
  of 
  

   calculating 
  the 
  size 
  of 
  a 
  molecule 
  from 
  its 
  observed 
  ionic 
  

   Telocity 
  might 
  prove 
  helpful 
  in 
  the 
  case 
  of 
  large 
  organic 
  ions 
  

   such 
  as 
  physiologists 
  have 
  to 
  deal 
  with, 
  for 
  the 
  molecular 
  

   weight 
  could 
  be 
  estimated 
  from 
  the 
  size 
  when 
  other 
  recognized 
  

   methods 
  of 
  determining 
  it 
  fail. 
  Ostwald's 
  measurements 
  o£ 
  

   the 
  ionic 
  velocities 
  of 
  a 
  large 
  number 
  of 
  organic 
  radicals 
  

   (Wied. 
  Ann. 
  Beibl. 
  xiii.) 
  might 
  supply 
  useful 
  material 
  for 
  a 
  

   preliminary 
  study 
  in 
  making 
  equation 
  (16) 
  available 
  for 
  the 
  

   estimation 
  of 
  very 
  large 
  molecular 
  weights. 
  

   Melbourne, 
  October 
  1901. 
  

  

  XIX. 
  On 
  the 
  Variation 
  with 
  Temperature 
  of 
  the 
  Ther 
  mo- 
  

   electromotive 
  Force, 
  and 
  of 
  the 
  Electric 
  Resistance 
  of 
  Nickel, 
  

   Iron, 
  and 
  Copper, 
  between 
  the 
  Temperatures 
  of 
  — 
  200° 
  and 
  

   + 
  1050°. 
  By 
  E. 
  Philip 
  Harbison, 
  University 
  College, 
  

   London 
  *". 
  

  

  THE 
  main 
  objects 
  of 
  the 
  investigation 
  which 
  forms 
  the 
  

   subject 
  of 
  this 
  paper 
  are 
  as 
  follows 
  : 
  — 
  

   To 
  trace 
  over 
  as 
  wide 
  a 
  range 
  as 
  possible 
  the 
  change 
  with 
  

   temperature 
  of 
  the 
  thermoelectromotive 
  force 
  and 
  the 
  resist- 
  

   ance 
  of 
  Nickel 
  and 
  Iron, 
  using 
  in 
  all 
  experiments 
  the 
  same 
  

   specimens 
  of 
  metal 
  ; 
  to 
  investigate 
  any 
  singularities 
  that 
  may 
  

   be 
  present 
  in 
  the 
  curves 
  representing 
  the 
  change 
  ; 
  and 
  to 
  

   determine 
  whether 
  they 
  occur 
  at 
  the 
  same 
  temperature 
  in 
  

   each 
  of 
  the 
  curves. 
  It 
  was 
  originally 
  intended 
  to 
  investigate 
  

   the 
  magnetic 
  properties 
  of 
  the 
  same 
  specimens, 
  but 
  time 
  has 
  

   not 
  sufficed 
  for 
  this. 
  

  

  Section 
  I. 
  

  

  Thermoelectric 
  Properties. 
  

  

  (1) 
  Results 
  of 
  Previous 
  Observers. 
  

  

  In 
  his 
  researches 
  on 
  thermoelectricity 
  t 
  Tait 
  gives 
  the 
  

   results 
  of 
  some 
  of 
  his 
  measurements 
  for 
  iron 
  which 
  extended 
  

   from 
  0° 
  to 
  the 
  melting-point. 
  The 
  second 
  portion 
  of 
  his 
  iron 
  

  

  * 
  Communicated 
  by 
  the 
  Physical 
  Society 
  : 
  read 
  October 
  25, 
  1901. 
  

   t 
  Proc. 
  Roy. 
  Soc. 
  Edin. 
  December 
  1873; 
  'Nature/ 
  Rede 
  Lecture, 
  

   May 
  1st, 
  1873. 
  

  

  Phil 
  Maa. 
  S. 
  6. 
  Vol. 
  3. 
  No. 
  14. 
  Feb. 
  1902. 
  N 
  

  

  