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  Miv 
  McClung 
  on 
  the 
  Rate 
  of 
  Recombination 
  of 
  

  

  forth 
  in 
  equation 
  (1), 
  holds 
  true 
  for 
  air 
  under 
  pressures 
  above 
  

   and 
  below 
  an 
  atmosphere. 
  

  

  (2) 
  If 
  it 
  does 
  hold 
  true, 
  to 
  find 
  the 
  relation 
  which 
  the 
  

   quantity 
  a 
  at 
  any 
  given 
  pressure 
  bears 
  to 
  that 
  at 
  any 
  other 
  

   pressure. 
  

  

  (3) 
  To 
  make 
  an 
  absolute 
  determination 
  of 
  a.. 
  

  

  This 
  quantity 
  a. 
  may 
  be 
  called 
  the 
  coefficient 
  of 
  recom- 
  

   bination. 
  

  

  For 
  this 
  purpose 
  the 
  method 
  employed 
  by 
  Professor 
  

   Rutherford 
  in 
  his 
  previous 
  investigation 
  was 
  adopted 
  in 
  

   principle, 
  but 
  with 
  an 
  apparatus 
  differing 
  somewhat 
  in 
  detail. 
  

  

  In 
  order 
  to 
  investigate 
  the 
  law, 
  as 
  given 
  by 
  equation 
  (2), 
  it 
  

   is 
  necessary 
  to 
  be 
  able 
  to 
  measure 
  the 
  maximum 
  number 
  of 
  

   ions 
  in 
  a 
  given 
  volume 
  of 
  the 
  gas 
  when 
  a 
  steady 
  state 
  has 
  

   been 
  reached, 
  and 
  also 
  to 
  measure 
  the 
  number 
  remaining 
  at 
  

   the 
  end 
  of 
  any 
  given 
  interval 
  of 
  time 
  after 
  the 
  rays 
  have 
  

   ceased. 
  For 
  this 
  purpose, 
  then, 
  the 
  following 
  arrangement 
  

   of 
  apparatus 
  was 
  adopted. 
  

  

  Description 
  of 
  Apparatus. 
  

   The 
  complete 
  arrangement 
  of 
  the 
  several 
  parts 
  and 
  con- 
  

   nexions 
  is 
  shown 
  in 
  the 
  diagram 
  (fig. 
  1). 
  

  

  Fig. 
  1. 
  

  

  The 
  bulb 
  used 
  to 
  produce 
  the 
  Rontgen 
  rays 
  was 
  of 
  the 
  

   usual 
  form 
  of 
  automatic 
  focus-tube, 
  with 
  an 
  alternative 
  

  

  