﻿Resistance 
  of 
  Metals 
  when 
  placed 
  in 
  a 
  Magnetic 
  Field. 
  655 
  

  

  under 
  atmospheric 
  pressure 
  and 
  at 
  0°C, 
  and 
  e 
  the 
  charge 
  on 
  

   an 
  ion, 
  

  

  and 
  therefore 
  - 
  x 
  ,~- 
  = 
  700 
  about 
  : 
  

  

  that 
  is, 
  the 
  pressure 
  exerted 
  by 
  the 
  corpuscles 
  in 
  the 
  case 
  of 
  

   platinum 
  is 
  about 
  700 
  atmospheres. 
  

  

  Again, 
  the 
  charge 
  on 
  a 
  corpuscle 
  is 
  6 
  X 
  10~ 
  lu 
  electrostatic 
  

   units, 
  and 
  this 
  gives 
  

  

  --= 
  1-4 
  x 
  10 
  22 
  . 
  

  

  Richardson 
  * 
  has 
  obtained 
  for 
  n 
  the 
  value 
  1*3 
  x 
  10 
  21 
  at 
  a 
  

   temperature 
  of 
  1542° 
  absolute, 
  from 
  the 
  negative 
  radiation 
  

   of 
  a 
  hot 
  wire. 
  The 
  agreement 
  of 
  this 
  with 
  the 
  above 
  is 
  

   fairlv 
  close 
  considering 
  the 
  difficulties 
  in 
  connexion 
  with 
  the 
  

   experiment, 
  and 
  the 
  wide 
  difference 
  of 
  temperature 
  at 
  which 
  

   the 
  results 
  were 
  obtained. 
  

  

  Since 
  t 
  = 
  - 
  this 
  becomes 
  for 
  platinum 
  8 
  x 
  10~ 
  14 
  , 
  and 
  from 
  

  

  this 
  we 
  obtain 
  for 
  q 
  = 
  -— 
  the 
  value 
  1*8 
  X 
  10 
  35 
  . 
  

  

  1 
  \/c 
  

  

  The 
  results 
  for 
  the 
  other 
  metals 
  are 
  tabulated 
  in 
  the 
  

   following 
  table, 
  those 
  for 
  platinum 
  being 
  also 
  given 
  to 
  make 
  

   the 
  table 
  complete. 
  

  

  Metal. 
  

  

  Platinum 
  ... 
  

  

  Gold 
  

  

  Tin 
  

  

  u 
  . 
  

  

  A. 
  

  

  ne 
  in 
  

   atmos. 
  

  

  99 
  

  

  1-4 
  xKf 
  

   2-2 
  xlO 
  22 
  

  

  21 
  

  

  4-5x10 
  

  

  22 
  

  

  36x10' 
  

  

  22 
  

  

  3-4x10 
  

   5-8 
  XlO 
  21 
  

   2-7 
  XlO 
  21 
  

  

  20 
  

  

  4-3x10 
  

  

  19 
  

   1-08x10 
  

  

  X 
  

   c 
  

  

  —14 
  

  

  8x10 
  

   2-lxlO 
  -13 
  

   1-7 
  xlO" 
  13 
  

   1-7 
  xlO 
  -13 
  

   i.8 
  xlO" 
  13 
  

   3xl0- 
  13 
  

   5-4x10 
  13 
  

   2 
  4xl0" 
  13 
  

   2-35 
  xl0~ 
  13 
  

  

  1-8 
  xlO 
  35 
  

  

  10 
  xio 
  35 
  

  

  26 
  xlO 
  34 
  

   2-lxlO 
  35 
  

   1-9 
  xlO 
  35 
  

   1-9 
  xlO 
  34 
  

   5 
  XlO 
  33 
  

   1-8 
  XlO 
  33 
  

   4-6 
  xlO 
  31 
  

  

  39 
  xlO" 
  7 
  

   1-04 
  xl0~ 
  6 
  

   8-3 
  xlO~ 
  ' 
  

   8-5 
  xlO" 
  7 
  

   8-8x10-7 
  

   l-5xl0~ 
  6 
  

   2-7 
  XlO 
  -6 
  

   1-2x10 
  6 
  

   1-18 
  xlO" 
  6 
  

  

  5-9 
  x 
  10~' 
  

   16 
  xlO" 
  6 
  

   1-3 
  xlO 
  -6 
  

   1-3X10" 
  6 
  

   1-34X10" 
  6 
  

   2-3 
  xlO 
  -6 
  

   4-1 
  X 
  10 
  -6 
  

   1-82 
  XlO 
  -6 
  

   1-79 
  xlO 
  -6 
  

  

  700 
  

   1115 
  

  

  225 
  

   1840 
  

   1730 
  

  

  293 
  

  

  136 
  

  

  21 
  

  

  054 
  

  

  Silver 
  

  

  Copper 
  

  

  Zinc 
  

  

  Cadmium 
  ... 
  

  

  j 
  Mercury 
  

  

  Carbon 
  

  

  In 
  order 
  that 
  the 
  corpuscular 
  pressure 
  may 
  be 
  in 
  equilibrium 
  

   at 
  the 
  surface 
  of 
  the 
  metal, 
  the 
  pressure 
  tending 
  to 
  drive 
  out 
  

  

  * 
  Proc. 
  Camb. 
  Phil. 
  Soc. 
  vol. 
  xi. 
  pt. 
  iv. 
  p. 
  286 
  (1901). 
  

  

  