﻿Minute 
  Metal 
  Particles 
  for 
  Light-waves. 
  407 
  

  

  particles 
  of 
  the 
  metal 
  lying 
  close 
  together. 
  Surrounding 
  

   this 
  was 
  a 
  transparent 
  ring, 
  the 
  particles 
  here 
  being 
  very 
  

   minute 
  and 
  very 
  widely 
  separated. 
  Next 
  came 
  a 
  ring 
  of 
  

   pinkish 
  purple 
  (absorption-band 
  about 
  at 
  the 
  D 
  lines), 
  while 
  

   outside 
  of 
  this 
  came 
  a 
  ring 
  of 
  deep 
  bine 
  (absorption 
  -band 
  in 
  

   the 
  red). 
  The 
  surrounding 
  field 
  was 
  practically 
  colourless, 
  

   being 
  made 
  up 
  of 
  large 
  particles 
  similar 
  to 
  those 
  at 
  the 
  centre 
  

   of 
  the 
  ring 
  (fig. 
  3). 
  In 
  the 
  blue 
  ring 
  the 
  particles 
  were 
  

  

  Fig. 
  8. 
  

  

  ■ 
  ■• 
  •: 
  '--••!# 
  

  

  '— 
  - 
  - 
  £$&>& 
  

  

  distinctly 
  closer 
  together 
  than 
  in 
  the 
  pink 
  one; 
  a 
  circumstance 
  

   which 
  I 
  made 
  sure 
  of 
  by 
  having 
  a 
  number 
  of 
  other 
  observers 
  

   express 
  an 
  opinion 
  on 
  the 
  matter. 
  If 
  now 
  the 
  particles 
  are 
  

   packed 
  closer 
  together 
  in 
  the 
  blue 
  film, 
  we 
  should 
  expect 
  the 
  

   capacity 
  to 
  be 
  increased, 
  the 
  same 
  as 
  by 
  the 
  introduction 
  of 
  

   the 
  medium 
  of 
  high 
  dielectric 
  constant. 
  The 
  period 
  would 
  

   consequently 
  become 
  slower, 
  and 
  the 
  absorption 
  -band 
  would 
  

   lie 
  further 
  along 
  towards 
  the 
  red, 
  which 
  is 
  exactly 
  what 
  was 
  

   observed. 
  In 
  some 
  instances, 
  I 
  have 
  been 
  of 
  the 
  opinion 
  that 
  

   the 
  particles 
  in 
  the 
  blue 
  films 
  are 
  larger 
  than 
  those 
  in 
  the 
  

   pink 
  ones, 
  but 
  of 
  this 
  I 
  am 
  not 
  sure. 
  

  

  Behaviour 
  of 
  the 
  Films 
  with 
  Polarized 
  Light. 
  

  

  One 
  of 
  the 
  first 
  experiments 
  which 
  I 
  tried 
  with 
  the 
  deposits 
  

   which 
  were 
  made 
  up 
  of 
  particles 
  large 
  enough 
  to 
  scatter 
  

   light, 
  was 
  their 
  polarizing 
  power. 
  The 
  angle 
  of 
  complete 
  

   polarization 
  in 
  the 
  case 
  of 
  non-metallic 
  particles 
  is 
  90°, 
  

   as 
  is 
  well-known. 
  J. 
  J. 
  Thomson 
  (Recent 
  Researches) 
  

   has 
  calculated 
  the 
  scattering 
  effect 
  of 
  metallic 
  spheres 
  on 
  

   light-waves, 
  and 
  has 
  found 
  that 
  we 
  should 
  expect 
  complete 
  

   polarization 
  on 
  a 
  line 
  making 
  an 
  angle 
  of 
  120° 
  with 
  the 
  

   direction 
  of 
  the 
  incident 
  light. 
  I 
  am 
  not 
  aware 
  that 
  any 
  

   experiments 
  have 
  been 
  made 
  to 
  test 
  this 
  calculation. 
  The 
  

   results 
  which 
  I 
  obtained 
  gave 
  a 
  value 
  somewhat 
  larger 
  than 
  

   this, 
  the 
  mean 
  being 
  about 
  135°. 
  It 
  is 
  difficult, 
  however, 
  to 
  

   get 
  very 
  accurate 
  results 
  with 
  films 
  deposited 
  on 
  spherical 
  

   surfaces. 
  

  

  Very 
  interesting 
  results 
  were 
  obtained 
  as 
  soon 
  as 
  the 
  

  

  