﻿632 
  Prof. 
  E. 
  M. 
  Wellisch 
  on 
  the 
  Distribution 
  of 
  the 
  

  

  brings 
  over 
  to 
  the 
  cathode 
  a 
  larger 
  fraction 
  of 
  ions 
  than 
  of 
  

   positively 
  charged 
  deposit 
  particles 
  ; 
  at 
  a 
  potential 
  of 
  about 
  

   40 
  volts 
  the 
  two 
  carves 
  practically 
  coincide. 
  The 
  difference 
  

   between 
  the 
  two 
  curves 
  can 
  be 
  explained 
  by 
  supposing 
  that 
  

   the 
  negative 
  ions 
  which 
  are 
  produced 
  in 
  the 
  column 
  recom- 
  

   bine 
  with 
  the 
  positively 
  charged 
  active 
  particles 
  with 
  greater 
  

   facility 
  than 
  with 
  the 
  positive 
  ions. 
  

  

  Emanation 
  mixed 
  with 
  Carbon 
  Dioxide, 
  Hydrogen, 
  

   and 
  Ethyl 
  Ether. 
  

  

  7. 
  When 
  the 
  emanation 
  was 
  mixed 
  with 
  dry 
  C0 
  2 
  at 
  various 
  

   pressures, 
  it 
  was 
  found 
  that 
  the 
  maximum 
  value 
  obtained 
  for 
  

   the 
  percentage 
  cathode 
  activity 
  was 
  80' 
  7. 
  In 
  order 
  to 
  obtain 
  

   this 
  value 
  with 
  potentials 
  less 
  than 
  1000 
  volts, 
  the 
  pressure 
  

   had 
  to 
  be 
  less 
  than 
  about 
  150 
  mm. 
  

  

  When 
  the 
  emanation 
  was 
  mixed 
  with 
  dry 
  hydrogen 
  the 
  

   maximum 
  value 
  obtained 
  for 
  the 
  percentage 
  cathode 
  activity 
  

   was 
  89*2, 
  the 
  same 
  as 
  that 
  obtained 
  with 
  air. 
  This 
  value 
  

   could 
  readily 
  be 
  obtained 
  with 
  a 
  potential 
  of 
  160 
  volts 
  and 
  

   with 
  hydrogen 
  at 
  a 
  pressure 
  of 
  1 
  atmosphere, 
  showing 
  that 
  

   there 
  is 
  very 
  little 
  columnar 
  recombination 
  in 
  this 
  gas. 
  

   Hydrogen 
  was 
  found 
  to 
  be 
  particularly 
  sensitive 
  to 
  the 
  pre- 
  

   sence 
  of 
  small 
  traces 
  of 
  water 
  vapour; 
  the 
  effect 
  of 
  the 
  water 
  

   vapour 
  was 
  to 
  increase 
  the 
  potential 
  necessary 
  to 
  obtain 
  the 
  

   same 
  limiting 
  value. 
  

  

  Inasmuch 
  as 
  the 
  presence 
  of 
  minute 
  quantities 
  of 
  water 
  

   vapour 
  resulted 
  in 
  a 
  marked 
  diminution 
  of 
  the 
  amount 
  of 
  

   active 
  deposit 
  which 
  settled 
  on 
  the 
  cathode, 
  it 
  became 
  of 
  

   interest 
  to 
  ascertain 
  the 
  percentage 
  of 
  positively 
  charged 
  

   carriers 
  which 
  would 
  result 
  from 
  mixing 
  the 
  emanation 
  with 
  

   a 
  vapour. 
  For 
  this 
  purpose 
  ethyl 
  ether 
  was 
  chosen 
  ; 
  any 
  

   gas 
  which 
  remained 
  in 
  the 
  vessel 
  was 
  swept 
  out 
  by 
  a 
  stream 
  

   of 
  ether 
  which 
  had 
  previously 
  passed 
  through 
  P 
  2 
  5 
  . 
  The 
  

   following 
  results 
  were 
  obtained 
  : 
  — 
  

  

  Pressure. 
  

  

  Potential. 
  

  

  Percentage 
  cathode 
  

   activity. 
  

  

  mm. 
  

  

  82 
  

  

  85 
  

   128 
  

   235 
  

  

  volts 
  

   160 
  

  

  1070 
  

  

  do. 
  

  

  do. 
  

  

  64 
  

   98 
  

  

  100 
  

   10-8 
  

  

  At 
  the 
  highest 
  pressure 
  there 
  was 
  a 
  large 
  current 
  passing 
  

  

  