﻿Properties 
  of 
  Films 
  of 
  Magnetic 
  Metals. 
  855 
  

  

  equation. 
  By 
  measuring 
  E 
  T 
  and 
  x 
  for 
  two 
  films 
  o£ 
  different 
  

   thickness 
  the 
  term 
  containing 
  R 
  2 
  and 
  E 
  R 
  may 
  be 
  eliminated. 
  

   To 
  test 
  this 
  formula 
  a 
  series 
  of 
  very 
  careful 
  observations 
  

   were 
  made 
  on 
  three 
  different 
  films, 
  of 
  which 
  the 
  mean 
  results 
  

   are 
  given 
  in 
  the 
  following 
  table, 
  the 
  "right" 
  vibration 
  being 
  

   given 
  the 
  positive 
  value 
  : 
  — 
  

  

  Table 
  XIII. 
  

   Wave-length, 
  500/*/*. 
  Field-strength, 
  13,600. 
  

  

  Film. 
  

  

  Double 
  

   Botation. 
  

  

  Thickness 
  

   (calc). 
  

  

  Ellipt. 
  x 
  10 
  3 
  . 
  

  

  Jci—7cr, 
  

  

  2 
  

  

  16 
  

   11 
  

   15 
  

  

  '99 
  

   221 
  

  

  2-61 
  

  

  7-5X10" 
  7 
  

   16-6 
  

   19-6 
  

  

  941 
  

  

  161 
  

  

  18-8 
  

  

  9-0 
  xlO 
  3 
  

   8-0 
  s 
  , 
  

   81 
  „ 
  

  

  The 
  above 
  values 
  of 
  

  

  rCl 
  — 
  K 
  r 
  

  

  are 
  calculated 
  by 
  using 
  

  

  2 
  

  

  E 
  E 
  = 
  — 
  2*07 
  x 
  10~ 
  3 
  and 
  R 
  2 
  = 
  '37, 
  as 
  found 
  in 
  the 
  case 
  of 
  

   film 
  15. 
  By 
  eliminating 
  these 
  last 
  two 
  quantities, 
  however, 
  

   films 
  16 
  and 
  11 
  give 
  7'3 
  x 
  10 
  3 
  ; 
  films 
  16 
  and 
  15, 
  7'8 
  x 
  10 
  3 
  ; 
  

   and 
  films 
  11 
  and 
  15, 
  9'1 
  x 
  10 
  3 
  as 
  values 
  for 
  the 
  same 
  expres- 
  

  

  sion. 
  The 
  two 
  methods 
  

  

  results 
  which 
  aoree 
  as 
  well 
  as 
  

  

  the 
  experimental 
  conditions 
  warrant. 
  

  

  11. 
  Light 
  transmitted 
  at 
  Right 
  Angles 
  to 
  the 
  

   Magnetic 
  Field. 
  

  

  To 
  test 
  the 
  possibility 
  of 
  the 
  optical 
  effects 
  in 
  the 
  magnetic 
  

   field 
  being 
  produced 
  by 
  the 
  presence 
  of 
  free 
  ions 
  (as 
  in 
  the 
  

   Hall 
  effect), 
  light 
  plane-polarized 
  at 
  an 
  azimuth 
  of 
  forty-five 
  

   degrees 
  to 
  the 
  field 
  was 
  sent 
  at 
  right 
  angles 
  to 
  the 
  field 
  

   through 
  the 
  film, 
  and 
  tested 
  for 
  the 
  presence 
  of 
  elliptic 
  

   polarization. 
  Film 
  15 
  was 
  used 
  for 
  this 
  test 
  as 
  it 
  gave 
  the 
  

   largest 
  effects 
  in 
  the 
  foregoing 
  experiments. 
  No 
  ellipticity 
  

   could 
  he 
  detected, 
  although 
  about 
  one 
  per 
  cent, 
  of 
  that 
  pro- 
  

   duced 
  on 
  the 
  light 
  transmitted 
  along 
  the 
  lines 
  of 
  force 
  could 
  

   have 
  been 
  seen. 
  

  

  12. 
  Dark 
  Cobalt. 
  

  

  Cobalt 
  films, 
  designated 
  from 
  their 
  appearance 
  by 
  reflected 
  

   light 
  as 
  dark, 
  were 
  obtained 
  in 
  the 
  same 
  manner 
  as 
  the 
  

   corresponding 
  of 
  iron, 
  that 
  is, 
  deposited 
  from 
  the 
  cathode 
  

  

  