﻿886 
  Prof. 
  McLennan 
  and 
  Mr. 
  Keys 
  on 
  tlie 
  Electrical 
  

  

  inversely 
  as 
  the 
  pressure 
  from 
  one 
  to 
  seventy-five 
  atmospheres, 
  

   and 
  that 
  for 
  the 
  same 
  range 
  of 
  pressures 
  the 
  mobility 
  of 
  the 
  

   negative 
  ion 
  was 
  about 
  1*4 
  times 
  greater 
  than 
  that 
  of 
  the 
  

   positive. 
  Dempsters 
  results, 
  too, 
  show 
  that 
  at 
  100 
  atmo- 
  

   spheres 
  the 
  mobility 
  of 
  the 
  negative 
  ion 
  in 
  air 
  was 
  about 
  

   twice 
  that 
  of 
  the 
  positive 
  ion, 
  but 
  his 
  results 
  indicate 
  that 
  

   while 
  the 
  mobility 
  of 
  the 
  positive 
  ion 
  varied 
  inversely 
  with 
  

   the 
  pressure 
  up 
  to 
  100 
  atmospheres, 
  the 
  mobility 
  of 
  the 
  

   negative 
  ion 
  decreased 
  less 
  rapidly 
  as 
  the 
  pressure 
  was 
  in- 
  

   creased 
  than 
  it 
  should 
  if 
  it 
  followed 
  the 
  inverse 
  pressure 
  law. 
  

  

  With 
  moist 
  carbon 
  dioxide 
  on 
  the 
  other 
  hand, 
  Kovarik 
  

   found 
  that 
  the 
  mobilities 
  of 
  positive 
  and 
  negative 
  ions 
  were 
  

   approximately 
  equal 
  to 
  each 
  other 
  for 
  pressures 
  up 
  to 
  57 
  

   atmospheres, 
  and 
  that 
  the 
  mobilities 
  of 
  both 
  ions 
  decreased 
  

   with 
  increase 
  of 
  pressure 
  much 
  more 
  rapidly 
  than 
  would 
  be 
  

   warranted 
  by 
  supposing 
  the 
  inverse 
  pressure 
  law 
  to 
  hold. 
  

   As 
  the 
  air 
  in 
  the 
  present 
  experiments 
  was 
  obtained 
  from 
  a 
  

   liquid 
  air 
  compressor 
  and 
  no 
  special 
  pains 
  were 
  taken 
  to 
  dry 
  

   it, 
  other 
  than 
  passing 
  it 
  through 
  a 
  chamber 
  filled 
  with 
  

   potassium 
  hydrate, 
  it 
  is 
  possible 
  that 
  the 
  equality 
  in 
  con- 
  

   ductivity 
  indicated 
  by 
  the 
  results 
  irf 
  Table 
  IV. 
  might, 
  in 
  

   small 
  part 
  at 
  least, 
  be 
  traceable 
  to 
  the 
  presence 
  of 
  moisture 
  

   in 
  the 
  air. 
  

  

  It 
  would 
  appear, 
  however, 
  from 
  some 
  work 
  which 
  was 
  

   done 
  later, 
  and 
  which 
  is 
  described 
  in 
  section 
  VI., 
  that 
  the 
  

   equality 
  in 
  the 
  conductivity 
  obtained 
  with 
  positive 
  and 
  

   negative 
  fields 
  in 
  the 
  experiments 
  just 
  described 
  was 
  due 
  in 
  

   great 
  measure 
  to 
  the 
  particular 
  form 
  given 
  to 
  the 
  apparatus 
  

   used 
  in 
  making 
  the 
  measurements. 
  For 
  it 
  was 
  found 
  when 
  

   the 
  apparatus 
  was 
  considerably 
  modified, 
  that 
  results 
  were 
  

   obtained 
  which 
  clearly 
  pointed 
  to 
  the 
  mobility 
  of 
  the 
  

   negative 
  ion 
  produced 
  in 
  air 
  at 
  high 
  pressures 
  by 
  alpha 
  

   rays 
  being 
  considerably 
  greater 
  than 
  that 
  of 
  the 
  positive. 
  

   In 
  taking 
  the 
  readings 
  given 
  in 
  Table 
  IV. 
  the 
  capacity 
  of 
  

   the 
  system 
  was 
  3635 
  e. 
  s. 
  units, 
  and 
  as 
  the 
  capncity 
  of 
  the 
  

   system 
  in 
  the 
  liquid 
  air 
  measurements 
  was 
  only 
  200 
  it 
  would 
  

   follow 
  that 
  the 
  conductivity 
  obtained 
  in 
  the 
  air 
  at 
  101 
  

   atmospheres 
  with 
  the 
  highest 
  fields 
  used 
  was 
  about 
  36 
  times 
  

   that 
  obtained 
  w 
  T 
  ith 
  the 
  same 
  field 
  when 
  the 
  ionization 
  was 
  

   produced 
  in 
  liquid 
  air. 
  This 
  difference 
  was 
  no 
  doubt 
  due 
  to 
  

   the 
  rapid 
  recombination 
  of 
  the 
  ions 
  which 
  must 
  have 
  taken 
  

   place 
  in 
  the 
  liquid 
  air. 
  The 
  layer 
  of 
  ionization 
  in 
  the 
  liquid 
  

   air 
  would 
  be 
  considerably 
  narrower 
  than 
  that 
  in 
  the 
  air 
  at 
  the 
  

   high 
  pressure, 
  and 
  consequently 
  the 
  tendency 
  to 
  recombination 
  

   wouid 
  be 
  very 
  much 
  greater 
  in 
  the 
  case 
  of 
  the 
  former 
  than 
  

   in 
  that 
  of 
  the 
  latter. 
  

  

  