﻿Positive 
  Ions 
  emitted 
  from 
  various 
  Hot 
  Bodies. 
  669 
  

  

  the 
  rate 
  depending 
  chiefly 
  on 
  the 
  temperature 
  o£ 
  the 
  radiator 
  

   and 
  the 
  potential 
  on 
  the 
  upper 
  plate. 
  

  

  It 
  ^Yas 
  found 
  later 
  that 
  the 
  quantity 
  of 
  electricity 
  in 
  this 
  

   effect 
  was 
  not 
  only 
  of 
  the 
  opposite 
  sign 
  to 
  that 
  drawn 
  from 
  

   the 
  radiator, 
  but 
  that 
  it 
  was 
  also 
  equal 
  in 
  amount. 
  Many 
  

   other 
  experiments 
  were 
  undertaken 
  which 
  seemed 
  to 
  lead 
  to 
  

   the 
  unreasonable 
  view 
  that 
  the 
  ions 
  drawn 
  off 
  by 
  the 
  high 
  

   potential 
  acquired 
  additional 
  energy 
  from 
  the 
  high 
  potential 
  

   and 
  held 
  it 
  in 
  a 
  potential 
  form 
  on 
  the 
  upper 
  plate, 
  and 
  when 
  

   the 
  high 
  potential 
  was 
  removed 
  and 
  the 
  radiator 
  was 
  glowing 
  

   this 
  energy 
  became 
  kinetic. 
  

  

  The 
  effect 
  was 
  ultimately 
  fonnd 
  to 
  be 
  due 
  to 
  the 
  presence 
  

   of 
  an 
  insulating 
  layer 
  which 
  had 
  developed 
  on 
  the 
  upper 
  

   disk. 
  The 
  special 
  parts 
  of 
  the 
  apparatus 
  were 
  enclosed 
  in 
  a 
  

   glass 
  tube 
  fitted 
  on 
  to 
  a 
  brass 
  plate. 
  It 
  was 
  made 
  air-tight 
  

   by 
  sealing-wax 
  covered 
  over 
  by 
  soft 
  wax. 
  No 
  doubt 
  after 
  a 
  

   time 
  some 
  of 
  the 
  soft 
  wax 
  condensed 
  on 
  the 
  upper 
  plate, 
  

   forming 
  an 
  insulating 
  layer 
  thereby, 
  thus 
  making 
  a 
  condenser 
  

   vvitb 
  the 
  conducting 
  layer 
  on 
  one 
  side 
  missing. 
  The 
  high 
  

   potential 
  pulled 
  the 
  ions 
  on 
  to 
  this 
  insulating 
  layer 
  and 
  held 
  

   them, 
  and 
  then 
  when 
  the 
  high 
  potential 
  was 
  removed, 
  these 
  

   held 
  the 
  ions 
  on 
  the 
  opposite 
  side 
  of 
  the 
  insulating 
  layer. 
  

   This 
  left 
  a 
  difference 
  of 
  potential 
  between 
  the 
  one 
  side 
  of 
  

   the 
  condenser 
  and 
  the 
  hot 
  radiator. 
  Thus 
  ions 
  of 
  the 
  

   opposite 
  sign 
  were 
  pulled 
  across 
  from 
  the 
  hot 
  body 
  until 
  the 
  

   bound 
  ions 
  on 
  the 
  condenser 
  were 
  neutralized, 
  /. 
  e. 
  until 
  the 
  

   so-called 
  high 
  potential 
  effect 
  had 
  decayed. 
  In 
  one 
  instance 
  

   the 
  quantity 
  of 
  electricity 
  collected 
  on 
  this 
  condenser 
  in 
  this 
  

   way 
  was 
  sufficient 
  to 
  charge 
  up 
  a 
  capacity 
  of 
  "2 
  microfarad 
  

   to 
  a 
  potential 
  of 
  1 
  volt. 
  This 
  required 
  the 
  thickness 
  of 
  

   the 
  insulating 
  layer 
  to 
  be 
  about 
  that 
  of 
  20 
  hydrogen 
  

   molecules. 
  

  

  The 
  capacity 
  of 
  this 
  condenser 
  was 
  measured 
  directly 
  by 
  

   the 
  method 
  of 
  mixtures 
  by 
  bringing 
  up 
  to 
  the 
  surface 
  of 
  the 
  

   upper 
  plate 
  a 
  globule 
  of 
  mercury 
  on 
  the 
  end 
  of 
  a 
  copper 
  

   wire. 
  The 
  mean 
  of 
  several 
  determinations 
  showed 
  the 
  

   capacity 
  to 
  be 
  2\ 
  x 
  10"* 
  E.s.U. 
  per 
  sq. 
  cm. 
  of 
  surface. 
  

  

  To 
  establish 
  that 
  the 
  insulating 
  layer 
  was 
  something 
  

   condensed 
  on 
  the 
  upper 
  plate 
  and 
  not 
  due 
  to 
  an 
  oxide 
  or 
  

   impurity 
  emitted 
  from 
  the 
  platinum 
  itself, 
  several 
  other 
  

   experiments 
  were 
  carried 
  out. 
  Entirely 
  new 
  apparatus 
  

   showed 
  the 
  effect 
  after 
  continued 
  heating. 
  When 
  the 
  upper 
  

   plate 
  was 
  cleaned 
  it 
  would 
  disappear 
  for 
  a 
  time, 
  but 
  would 
  

   always 
  reappear 
  in 
  time, 
  even 
  when 
  the 
  purest 
  resistance 
  

   platinum 
  was 
  used 
  as 
  a 
  thermionic 
  radiator. 
  Also 
  when 
  the 
  

   surrounding 
  atmosphere 
  was 
  hydrogen 
  there 
  was 
  no 
  essential 
  

  

  