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  Lord 
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  on 
  the 
  Question 
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  where 
  again 
  on 
  the 
  extreme 
  left 
  the 
  same 
  Kronecker 
  identities 
  

   appear. 
  

  

  Capetown, 
  South 
  Africa, 
  

   3rd 
  February, 
  1902. 
  

  

  XLVI. 
  On 
  the 
  Question 
  of 
  Hydrogen 
  in 
  the 
  Atmosphere. 
  

   By 
  Lord 
  Rayleigh, 
  F.R.S* 
  

  

  IT 
  will 
  be 
  remembered 
  that 
  M. 
  Armand 
  Gautier, 
  as 
  the 
  

   result 
  of 
  very 
  elaborate 
  investigations, 
  was 
  led 
  to 
  the 
  

   conclusion 
  that 
  air, 
  even 
  from 
  the 
  Atlantic, 
  contains 
  by 
  

   volume 
  nearly 
  2 
  parts 
  in 
  10,000 
  of 
  free 
  hydrogen. 
  The 
  

   presence 
  of 
  so 
  much 
  hydrogen, 
  nearly 
  two 
  thirds 
  of 
  the 
  

   carbonic 
  acid 
  which 
  plays 
  such 
  an 
  important 
  part, 
  is 
  of 
  

   interest 
  in 
  connexion 
  with 
  theories 
  pointing 
  to 
  the 
  escape 
  of 
  

   light 
  constituents 
  from 
  the 
  planetary 
  atmospheres. 
  Besides 
  

   the 
  free 
  hydrogen, 
  M. 
  Gautier 
  found 
  in 
  the 
  air 
  of 
  woods 
  and 
  

   towns 
  considerable 
  quantities 
  of 
  hydrocarbons 
  yielding 
  C0 
  2 
  

   when 
  led 
  over 
  hot 
  copper 
  oxide. 
  

  

  Spectroscopic 
  Evidence. 
  

  

  In 
  the 
  Philosophical 
  Magazine 
  for 
  Jan. 
  1901, 
  I 
  described 
  

   some 
  observations 
  upon 
  the 
  spectrum 
  of 
  sparks 
  taken 
  in 
  dried 
  

   air 
  at 
  atmospheric 
  pressure, 
  which 
  seemed 
  " 
  to 
  leave 
  a 
  

   minimum 
  of 
  room 
  for 
  the 
  hydrogen 
  found 
  by 
  M. 
  Gautier." 
  

   Subsequently 
  (April 
  1901) 
  > 
  these 
  experiments 
  were 
  repeated 
  

   with 
  confirmatory 
  results. 
  The 
  spectra, 
  taken 
  from 
  platinum 
  

  

  points, 
  of 
  pure 
  country 
  air 
  and 
  the 
  same 
  to 
  which 
  

   * 
  Communicated 
  by 
  the 
  Author. 
  

  

  of 
  

  

  