﻿862 
  Optical 
  Properties 
  of 
  Films 
  of 
  Magnetic 
  Metals. 
  

  

  extinction 
  in 
  the 
  magnetic 
  field, 
  and 
  the 
  optical 
  extinction 
  of 
  

   these 
  films 
  are 
  all 
  many 
  times 
  larger 
  than 
  those 
  of 
  the 
  dark 
  

   type. 
  These 
  properties 
  also 
  vary 
  considerably 
  in 
  magnitude 
  

   with 
  different 
  samples. 
  

  

  (d) 
  In 
  the 
  metallic 
  films 
  the 
  shift 
  of 
  the 
  resonance 
  region 
  

   into 
  the 
  ultra-violet, 
  the 
  magnitudes 
  of 
  the 
  magneto-optical 
  

   properties, 
  and 
  the 
  optical 
  extinction 
  are 
  again 
  all 
  greater 
  

   than 
  in 
  the 
  electrolytic 
  

  

  (e) 
  There 
  appears 
  to 
  be 
  a 
  relation 
  between 
  the 
  granular 
  

   structure 
  of 
  these 
  films 
  and 
  their 
  period 
  of 
  resonance. 
  

   Electrolytically 
  deposited 
  metals 
  are 
  known 
  to 
  be 
  granular. 
  

   The 
  dark 
  films 
  are 
  far 
  softer 
  and 
  less 
  tenacious 
  than 
  these. 
  

   It 
  is 
  therefore 
  natural 
  to 
  suppose 
  them 
  to 
  be 
  made 
  up 
  of 
  

   larger 
  structural 
  units. 
  The 
  metallic 
  films, 
  on 
  the 
  other 
  hand, 
  

   produced 
  by 
  cathode 
  sublimation, 
  appear 
  more 
  like 
  the 
  

   fused 
  metal. 
  Their 
  structure 
  should 
  be 
  of 
  smaller 
  units 
  than 
  

   either 
  of 
  the 
  other 
  types 
  : 
  they 
  should 
  therefore 
  possess 
  

   the 
  shortest 
  period 
  of 
  resonance, 
  as 
  the 
  results 
  seem 
  to 
  

   indicate. 
  

  

  ( 
  f 
  ) 
  All 
  films 
  giving 
  magnetic 
  rotation 
  impart 
  also, 
  under 
  

   the 
  same 
  conditions, 
  ellipticity 
  to 
  the 
  transmitted 
  light. 
  In 
  

   some 
  cases 
  an 
  ellipticity 
  was 
  observed 
  in 
  the 
  reflected 
  light. 
  

   Like 
  the 
  magnetic 
  rotation, 
  the 
  ellipticity 
  produced 
  is 
  pro- 
  

   portional 
  to 
  the 
  magnetization 
  of 
  the 
  medium. 
  

  

  Eliminating 
  the 
  ellipticity 
  arising 
  From 
  reflexion, 
  that 
  of 
  

   the 
  transmitted 
  light 
  was 
  found 
  in 
  several 
  cases 
  to 
  be 
  pro- 
  

   portional 
  to 
  the 
  thickness 
  of 
  the 
  film. 
  The 
  exceptions 
  to 
  

   this 
  rule 
  arc 
  considered 
  Lo 
  arise 
  from 
  a 
  difference 
  in 
  structure 
  

   of 
  the 
  films. 
  

  

  No 
  ellipticity 
  was 
  ohserved 
  in 
  cases 
  of 
  light 
  transmitted 
  at 
  

   right 
  angles 
  to 
  the 
  magnetic 
  field. 
  

  

  (</i 
  Films 
  of 
  electrolytic 
  nickel 
  showed 
  marked 
  magneto- 
  

   optical 
  properties, 
  those 
  obtained 
  from 
  the 
  cathode 
  in 
  vacuo 
  

   scarcely 
  a 
  trace. 
  

  

  (/*) 
  The 
  extinction 
  coefficients 
  of 
  both 
  electrolytic 
  and 
  

   metallic 
  films 
  are 
  greatly 
  in 
  excess 
  of 
  those 
  obtained 
  by 
  other 
  

   observers. 
  

  

  (i) 
  Existing 
  theories 
  do 
  not 
  appear 
  to 
  lend 
  themselves 
  to 
  

   explain 
  the 
  results 
  obtained. 
  

  

  The 
  Brace 
  Laboratory 
  of 
  Physics, 
  

   University 
  of 
  Nebraska, 
  Lincoln. 
  

  

  