﻿the 
  Ions 
  in 
  Air 
  at 
  Different 
  Temperatures, 
  331 
  

  

  deflexion 
  caused 
  by 
  the 
  charge 
  CiYi. 
  The 
  amount 
  o£ 
  loss 
  

   due 
  to 
  the 
  back-leak 
  then 
  is 
  : 
  

  

  From 
  these 
  determinations 
  we 
  have 
  : 
  

  

  ._(C 
  + 
  COV 
  

   ^~ 
  TiOOe 
  ' 
  

  

  (C 
  + 
  C,)V300« 
  

  

  «=K 
  

  

  T[c.V.-i^^i^.+ 
  (X-p,J 
  

  

  The 
  times 
  t 
  and 
  t' 
  were 
  readily 
  obtained 
  from 
  the 
  

   tracing 
  of 
  a 
  tuning-fork 
  on 
  the 
  surface 
  of 
  a 
  smoked 
  glass 
  

   placed 
  upon 
  the 
  slide. 
  Care 
  is 
  necessary 
  at 
  this 
  point 
  ; 
  

   t 
  must 
  be 
  sufficiently 
  large 
  to 
  allow 
  all 
  the 
  ions 
  to 
  pass 
  to 
  

   the 
  electrodes, 
  and 
  E 
  must 
  be 
  so 
  high 
  that 
  the 
  time 
  

   required 
  for 
  an 
  ion 
  to 
  pass 
  the 
  distance 
  between 
  the 
  electrodes 
  

   permits 
  only 
  a 
  negligible 
  amount 
  of 
  recombination. 
  These 
  

   points 
  are 
  readily 
  tested 
  experimentally 
  by 
  using 
  different 
  

   values 
  for 
  E. 
  It 
  was 
  found 
  that 
  with 
  E 
  = 
  600 
  volts 
  and 
  

   E 
  = 
  1000 
  volts, 
  the 
  same 
  value 
  for 
  a 
  was 
  obtained. 
  This 
  

   test 
  was 
  applied 
  at 
  the 
  temperature 
  of 
  liquid 
  air 
  as 
  well 
  as 
  at 
  

   room-temperature. 
  The 
  value 
  of 
  E 
  used 
  throughout 
  the 
  

   entire 
  work 
  was, 
  however, 
  1000 
  volts. 
  

  

  In 
  order 
  to 
  be 
  certain 
  that 
  the 
  deflexions 
  obtained 
  are 
  due 
  

   to 
  the 
  ions 
  produced 
  by 
  the 
  rays 
  it 
  is 
  necessary 
  to 
  have 
  the 
  

   apparatus 
  so 
  constructed 
  that 
  the 
  radium 
  may 
  be 
  removed 
  

   and 
  the 
  manipulations 
  described 
  above 
  repeated 
  without 
  the 
  

   rays. 
  The 
  inner 
  spherical 
  electrode 
  was 
  therefore 
  constructed 
  

   so 
  as 
  to 
  open 
  to 
  the 
  outside 
  through 
  the 
  tube 
  serving 
  as 
  its 
  

   support. 
  It 
  was 
  found 
  to 
  be 
  possible 
  to 
  get 
  all 
  parts 
  so 
  

   perfect 
  that 
  no 
  motion 
  of 
  the 
  leaf 
  was 
  obtained 
  without 
  the 
  

   rays, 
  and 
  care 
  was 
  taken 
  to 
  have 
  this 
  as 
  the 
  working 
  condition 
  

   throughout 
  the 
  entire 
  work. 
  

  

  The 
  capacity 
  C 
  consisted 
  of 
  two 
  circular 
  plates 
  placed 
  

   2 
  mm. 
  apart. 
  The 
  capacity 
  of 
  this 
  condenser 
  was 
  computed 
  

   according 
  to 
  Kirchhoff's 
  formula 
  (Abhandl. 
  p. 
  113) 
  giving 
  

   700 
  cm. 
  The 
  capacity 
  Ci 
  was 
  obtained 
  from 
  comparison 
  

   with 
  C 
  bv 
  method 
  of 
  mixtures. 
  

  

  