﻿13S 
  Scientific 
  Intelligence. 
  

  

  ratio 
  of 
  the 
  intensity 
  of 
  the 
  vibrations 
  which 
  are 
  parallel 
  to 
  the 
  

   axis 
  of 
  the 
  original 
  beam 
  to 
  that 
  of 
  the 
  vibrations 
  normal 
  to 
  this 
  

   direction 
  has 
  the 
  values 
  (expressed 
  in 
  per 
  cent), 
  given 
  in 
  the 
  

   parentheses 
  following 
  the 
  name 
  of 
  the 
  substance: 
  pentane 
  (1-2), 
  

   hydrogen 
  (1-7), 
  ether 
  vapor 
  (1-7), 
  chloroform 
  (3-0), 
  ethylene 
  

   (3-0), 
  nitrogen 
  (3-0), 
  argon 
  (3-2), 
  carbon 
  monoxide 
  (3-2), 
  car- 
  

   bon 
  tetrachloride 
  (3-5), 
  air 
  (4-2), 
  benzene 
  (6-0), 
  oxygen 
  (60), 
  

   carbon 
  dioxide 
  (8-0), 
  carbon 
  disulphide 
  (12-0), 
  cyanogen 
  (12-0), 
  

   nitrous 
  oxide 
  (14-0), 
  and 
  helium 
  (420). 
  

  

  The 
  case 
  of 
  helium 
  is 
  remarkable 
  since 
  it 
  polarizes 
  far 
  less 
  

   completely 
  than 
  any 
  other 
  gas 
  studied. 
  The 
  purity 
  of 
  the 
  

   helium 
  may 
  have 
  been 
  decreased 
  to 
  such 
  an 
  extent 
  by 
  the 
  special 
  

   difficulties 
  attendant 
  upon 
  the 
  investigation 
  of 
  its 
  optical 
  proper- 
  

   ties 
  as 
  to 
  lower 
  the 
  ratio 
  of 
  the 
  intensities 
  from 
  50 
  to 
  42 
  per 
  cent. 
  

   Theory 
  indicates 
  that, 
  on 
  the 
  very 
  plausible 
  assumption 
  of 
  ran- 
  

   dom 
  orientation 
  in 
  the 
  primary 
  light, 
  the 
  50 
  per 
  cent 
  ratio 
  is 
  to 
  

   be 
  expected 
  if 
  the 
  vibration 
  in 
  the 
  atom 
  is 
  limited 
  to 
  a 
  direction 
  

   fixed 
  within 
  the 
  atom. 
  Such 
  an 
  atom 
  is 
  the 
  antithesis 
  of 
  the 
  

   "spherical" 
  atom 
  or 
  molecule 
  which 
  would 
  give 
  complete 
  

   polarization 
  of 
  the 
  perpendicular 
  vibrations, 
  that 
  is, 
  zero 
  for 
  the 
  

   ratio. 
  It 
  is 
  thus 
  seen 
  that 
  the 
  behavior 
  of 
  the 
  helium 
  atom 
  at 
  

   least 
  approximates 
  to 
  that 
  of 
  a 
  thin 
  rod 
  or 
  needle. 
  In 
  this 
  con- 
  

   nection 
  Strutt 
  says: 
  "There 
  is 
  reason 
  to 
  regard 
  helium, 
  from 
  

   the 
  part 
  it 
  plays 
  in 
  radioactive 
  phenomena, 
  as 
  being 
  in 
  a 
  special 
  

   sense 
  a 
  fundamental 
  form 
  of 
  matter. 
  It 
  may 
  be 
  that 
  the 
  prop- 
  

   erty 
  here 
  encountered 
  is 
  a 
  direct 
  result 
  of 
  specially 
  simple 
  

   atomic 
  structure." 
  

  

  Within 
  the 
  limits 
  of 
  experimental 
  error, 
  the 
  intensity 
  of 
  scat- 
  

   tering 
  by 
  the 
  different 
  gases 
  tried 
  varies 
  as 
  the 
  square 
  of 
  the 
  

   refractivity. 
  

  

  Saturated 
  vapors, 
  even 
  when 
  very 
  dense, 
  show 
  no 
  increase 
  of 
  

   scattering 
  power 
  above 
  that 
  which 
  the 
  density 
  would 
  lead 
  one 
  to 
  

   expect. 
  If 
  molecular 
  aggregates 
  are 
  formed, 
  they 
  are 
  not 
  num- 
  

   erous 
  enough 
  to 
  admit 
  of 
  detection 
  by 
  the 
  experimental 
  method 
  

   employed. 
  

  

  Liquid 
  ether 
  apparently 
  scatters 
  about 
  seven 
  times 
  less 
  light 
  

   than 
  an 
  equivalent 
  mass 
  of 
  ether 
  vapor. 
  Proc. 
  Roy. 
  Soc, 
  95 
  

   A, 
  155, 
  1918. 
  h. 
  s. 
  u. 
  

  

  8. 
  A 
  Handbook 
  of 
  Physics 
  Measurements; 
  by 
  Ervin 
  S. 
  

   Ferry. 
  Vol. 
  I, 
  pp. 
  ix, 
  251 
  ; 
  vol. 
  II, 
  pp. 
  x, 
  233. 
  New 
  York, 
  1918 
  

   (John 
  Wiley 
  and 
  Sons). 
  — 
  This 
  book 
  was 
  written 
  by 
  the 
  chief 
  

   author 
  in 
  collaboration 
  with 
  O. 
  W. 
  Silvey, 
  G. 
  W. 
  Sherman, 
  and 
  

   D. 
  C. 
  Duncan. 
  "The 
  aim 
  of 
  the 
  present 
  work 
  is 
  to 
  furnish 
  the 
  

   student 
  of 
  pure 
  or 
  applied 
  science 
  with 
  a 
  self-contained 
  manual 
  

   of 
  the 
  theory 
  and 
  manipulation 
  of 
  those 
  measurements 
  in 
  physics 
  

   which 
  bear 
  most 
  directly 
  upon 
  his 
  subsequent 
  work 
  in 
  other 
  

   departments 
  of 
  study 
  and 
  upon 
  his 
  future 
  professional 
  career. 
  ' 
  ' 
  

   Since 
  the 
  book 
  is 
  designed 
  to 
  be 
  commenced 
  during 
  the 
  second 
  

   college 
  year 
  the 
  experiments 
  require, 
  in 
  general, 
  no 
  mathematics 
  

  

  