﻿THE 
  

   LONDON, 
  EDINBURGH, 
  and 
  DUBLIN 
  

  

  PHILOSOPHICAL 
  MAGAZINE 
  

  

  AND 
  

  

  JOURNAL 
  OF 
  SCIENCE. 
  

  

  [SIXTH 
  SERIES.] 
  

  

  DECEMBER 
  1908. 
  

  

  LXXIII. 
  An 
  Investigation 
  of 
  the 
  Optical 
  Properties 
  of 
  Films 
  

   of 
  Magnetic 
  Metals. 
  By 
  "Clarence 
  A. 
  Siqxxer, 
  Ph.D., 
  

   Professor 
  of 
  Physics, 
  and 
  A. 
  Q. 
  Tool, 
  M.A., 
  Assistant 
  in 
  

   Physics 
  in 
  the 
  University 
  of 
  Nebraska 
  *. 
  

  

  [Plate 
  XXIV.] 
  

  

  THE 
  object 
  of 
  this 
  investigation 
  was 
  to 
  study 
  the 
  magnetic 
  

   rotation 
  and 
  ellipticity 
  produced 
  in 
  plane-polarized 
  light 
  

   by 
  films 
  of 
  magnetic 
  metals, 
  along 
  with 
  other 
  properties 
  

   intimately 
  associated 
  in 
  theory 
  with 
  these 
  — 
  namely, 
  the 
  

   refractive 
  indices 
  and 
  extinction 
  coefficients. 
  

  

  That 
  a 
  thorough 
  investigation 
  of 
  this 
  kind 
  would 
  prove 
  

   fruitful 
  seemed 
  evident 
  from 
  the 
  results 
  obtained 
  in 
  this 
  

   laboratory 
  by 
  W. 
  D. 
  Harris 
  f 
  , 
  who 
  found 
  that 
  iron 
  films, 
  

   obtained 
  by 
  cathode 
  deposit 
  in 
  a 
  glow 
  current, 
  exhibited 
  

   magnetic 
  effects 
  differing 
  with 
  the 
  gas 
  in 
  which 
  they 
  were 
  

   produced. 
  His 
  results 
  also 
  show 
  that 
  the 
  variation 
  in 
  the 
  

   magnetic 
  rotation 
  of 
  these 
  films 
  with 
  the 
  wave-length 
  of 
  light 
  

   is 
  strikingly 
  different 
  from 
  that 
  obtained 
  by 
  Lobach 
  % 
  for 
  

   electrolytic 
  iron. 
  

  

  After 
  improving 
  the 
  optical 
  system 
  used 
  by 
  Harris, 
  we 
  

   have 
  been 
  able 
  to 
  extend 
  observations 
  on 
  these 
  films 
  into 
  the 
  

   region 
  of 
  relatively 
  greater 
  absorption, 
  which 
  this 
  type 
  is 
  

   found 
  to 
  possess. 
  We 
  find 
  there 
  that 
  both 
  magnetic 
  rotation 
  

  

  * 
  Read 
  at 
  the 
  meeting 
  of 
  the 
  American 
  Physical 
  Society, 
  Chicago, 
  

   January 
  1908. 
  Communicated 
  by 
  the 
  Authors. 
  

  

  t 
  W. 
  D. 
  Harris, 
  Phys. 
  Rev. 
  xxiv. 
  p. 
  337 
  (1907). 
  

  

  % 
  W. 
  Lobach, 
  Wied. 
  Ann. 
  xxxix. 
  p. 
  347. 
  

   Phil. 
  Mag. 
  S. 
  6. 
  Vol. 
  16. 
  No. 
  96. 
  Dec. 
  1908. 
  3 
  I 
  

  

  m 
  

  

  