﻿760 
  Prof. 
  0. 
  W. 
  Richardson 
  on 
  the 
  Specific 
  

  

  Positive 
  Ionization 
  from 
  Carbon. 
  

  

  Experiments 
  similar 
  to 
  the 
  above 
  were 
  carried 
  out 
  with 
  

   carbon, 
  except 
  that 
  the 
  strip 
  had 
  to 
  be 
  replaced 
  by 
  a 
  filament 
  

   o£ 
  circular 
  section, 
  *0143 
  cm. 
  in 
  diameter. 
  Owing 
  doubtless 
  

   to 
  the 
  strong 
  radial 
  electric 
  field 
  near 
  the 
  cylinder, 
  the 
  

   distribution 
  curve 
  was 
  much 
  broader 
  than 
  with 
  the 
  platinum 
  

   strip, 
  so 
  that 
  the 
  position 
  of 
  the 
  maximum 
  was 
  more 
  difficult 
  

   to 
  determine. 
  The 
  results 
  of 
  the 
  measurements 
  are 
  given 
  in 
  

   the 
  following 
  table 
  : 
  — 
  

  

  z. 
  

  

  H. 
  V. 
  

  

  X. 
  

  

  e/m. 
  

  

  »/H. 
  

  

  37-6 
  

   320 
  

  

  •644 
  

   568 
  

  

  4700 
  

  

  4800 
  

  

  330 
  

   364 
  

  

  1-275 
  

   105 
  

  

  257 
  

   302 
  

  

  Mean: 
  e/m=280, 
  w/H=34-8. 
  

  

  The 
  units 
  are 
  the 
  same 
  as 
  in 
  the 
  previous 
  table. 
  It 
  will 
  

   be 
  observed 
  that 
  the 
  value 
  of 
  elm 
  is 
  the 
  same 
  within 
  the 
  

   limits 
  of 
  experimental 
  error 
  for 
  carbon 
  as 
  for 
  platinum. 
  

  

  Classification 
  of 
  the 
  Ionization 
  dealt 
  with. 
  

  

  The 
  experiments 
  in 
  the 
  positive 
  ionization 
  from 
  hot 
  

   platinum 
  were 
  all 
  made 
  with 
  specimens 
  which 
  had 
  only 
  been 
  

   heated 
  for 
  comparatively 
  short 
  periods. 
  The 
  temperatures 
  

   used 
  were 
  also 
  rather 
  low, 
  the 
  highest 
  being 
  estimated 
  as 
  

   about 
  950°-1000°. 
  When 
  the 
  low 
  pressure 
  (5 
  x 
  10" 
  4 
  mm. 
  

   at 
  most) 
  which 
  prevailed 
  is 
  taken 
  into 
  account 
  it 
  is 
  clear 
  that 
  

   the 
  ionization 
  under 
  investigation 
  is 
  that 
  which 
  has 
  been 
  

   referred 
  to 
  as 
  the 
  initial 
  ionization. 
  Under 
  the 
  conditions 
  of 
  

   the 
  experiments 
  the 
  ionization 
  caused 
  by 
  the 
  gas 
  itself 
  would 
  

   form 
  only 
  a 
  negligible 
  proportion 
  of 
  the 
  whole. 
  

  

  Similar 
  conditions 
  held 
  in 
  the 
  first 
  of 
  the 
  two 
  measure- 
  

   ments 
  with 
  carbon. 
  In 
  the 
  second, 
  however, 
  the 
  temperature 
  

   was 
  considerably 
  higher, 
  and 
  frequent 
  pumping 
  did 
  not 
  

   prevent 
  the 
  pressure 
  from 
  rising 
  to 
  about 
  *01 
  mm. 
  In 
  this 
  

   case 
  a 
  considerable 
  proportion 
  of 
  the 
  ionization 
  may 
  have 
  

   been 
  due 
  to 
  the 
  action 
  of 
  the 
  gas. 
  The 
  agreement 
  between 
  

   the 
  two 
  experiments 
  with 
  carbon 
  would 
  seem 
  to 
  show 
  that 
  

   with 
  the 
  kind 
  of 
  vacua 
  used 
  the 
  positive 
  ions 
  due 
  to 
  the 
  gas 
  

   have 
  about 
  the 
  same 
  value 
  of 
  e/m 
  as 
  those 
  due 
  to 
  the 
  initial 
  

   leak. 
  Both 
  carbon 
  filaments 
  were 
  taken 
  from 
  old 
  lamps 
  

   which 
  had 
  been 
  lying 
  about 
  the 
  laboratory 
  for 
  some 
  time. 
  

  

  