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  876 
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  LXXIV. 
  On 
  the 
  Electrical 
  Conductivity 
  imparted 
  to 
  Liquid 
  

   Air 
  by 
  Alpha 
  Rays. 
  By 
  Professor 
  J. 
  C. 
  McLennan 
  and 
  

   David 
  A. 
  Keys, 
  University 
  of 
  Toronto 
  *. 
  

  

  [Plate 
  XVIII.] 
  

  

  I. 
  Introduction. 
  

  

  IN 
  the 
  published 
  accounts 
  of 
  their 
  experiments 
  on 
  the 
  

   measurement 
  of 
  the 
  dielectric 
  constants 
  of 
  different 
  

   liquefied 
  gases, 
  a 
  number 
  of 
  investigators 
  including 
  Linde 
  |? 
  

   Dewar 
  and 
  Fleming 
  J, 
  and 
  Hasenohrl 
  §, 
  have 
  drawn 
  atten- 
  

   tion 
  to 
  the 
  high 
  insulating 
  qualities 
  possessed 
  by 
  such 
  

   liquids. 
  In 
  particular, 
  Fleming 
  and 
  Dewar 
  have 
  shown 
  that 
  

   a 
  small 
  condenser 
  when 
  immersed 
  in 
  liquid 
  air 
  and 
  charged 
  

   with 
  a 
  Wimshurst 
  electrical 
  machine 
  held 
  its 
  charge 
  per- 
  

   fectly 
  for 
  a 
  period 
  of 
  some 
  minutes. 
  Quite 
  recently, 
  too, 
  

   Zeeman 
  ||, 
  in 
  studying 
  the 
  Kerr 
  phenomenon 
  in 
  liquid 
  air, 
  

   found 
  when 
  the 
  latter 
  was 
  freed 
  from 
  small 
  ice 
  and 
  carbonic- 
  

   dioxide 
  crystals 
  by 
  filtration, 
  and 
  when 
  precautions 
  were 
  

   taken 
  to 
  prevent 
  the 
  generation 
  of 
  gas-bubbles 
  between 
  the 
  

   electrodes, 
  electric 
  fields 
  as 
  high 
  as 
  90,000 
  volts 
  per 
  cm. 
  and 
  

   even 
  higher 
  ones 
  could 
  be 
  maintained 
  quite 
  readily 
  in 
  the 
  

   liquid. 
  

  

  Fleming 
  and 
  Dewar 
  in 
  the 
  course 
  of 
  their 
  experiments 
  

   made 
  a 
  determination 
  of 
  the 
  dielectric 
  constant 
  of 
  liquefied 
  

   air, 
  and 
  also 
  that 
  of 
  liquid 
  oxygen. 
  The 
  latter 
  they 
  found 
  

   to 
  be 
  1*495. 
  If 
  we 
  assume 
  the 
  density 
  of 
  gaseous 
  oxygen 
  at 
  

   15° 
  C. 
  and 
  760 
  mm. 
  pressure 
  to 
  be 
  0*00134 
  (and 
  its 
  density 
  

   at 
  -182°C. 
  consequently 
  to 
  be 
  0*00424) 
  and 
  its 
  dielectric 
  

   constant 
  at 
  0° 
  C. 
  and 
  760 
  mm. 
  pressure 
  to 
  be 
  1*00059, 
  it 
  

   follows 
  by 
  applying 
  the 
  Olausius-Mosotti 
  relation, 
  — 
  that 
  

   K 
  — 
  1 
  is 
  proportional 
  to 
  the 
  density 
  of 
  the 
  gas, 
  — 
  that 
  the 
  

   dielectric 
  constant 
  of 
  gaseous 
  oxygen 
  at 
  — 
  182°C. 
  and 
  

   760 
  mm. 
  pressure 
  should 
  be 
  approximately 
  1*0018. 
  

  

  Moreover, 
  as 
  the 
  density 
  of 
  liquid 
  oxygen 
  is 
  about 
  1*1375, 
  

   it 
  follows 
  if 
  we 
  assume 
  the 
  Clausius-Mosotti's 
  Law 
  to 
  hold 
  

   continuously 
  in 
  passing 
  from 
  the 
  gaseous 
  to 
  the 
  liquid 
  phase, 
  

   that 
  the 
  dielectric 
  constant 
  of 
  liquid 
  oxygen 
  should 
  be 
  

  

  * 
  Communicated 
  by 
  the 
  Authors. 
  Read 
  before 
  the 
  Royal 
  Society 
  of 
  

   Canada, 
  May 
  26, 
  1913. 
  

  

  t 
  Linde, 
  Wied. 
  Ann. 
  vol. 
  lvi. 
  p. 
  546 
  (1895). 
  

  

  t 
  Dewar 
  and 
  Fleming, 
  Proc. 
  Roy. 
  Soc. 
  London, 
  vol. 
  lx. 
  p. 
  358 
  (1896). 
  

  

  § 
  Hasenohrl. 
  Leiden 
  Comm. 
  No. 
  52, 
  Proc. 
  Amst. 
  Akad. 
  of 
  Set. 
  vol. 
  xi. 
  

   p. 
  211. 
  

  

  || 
  Zeeman, 
  Proc. 
  Amst. 
  Akad. 
  of 
  Set. 
  p. 
  650, 
  Jan. 
  24, 
  1912. 
  

  

  