﻿1034 
  Mr. 
  F. 
  W. 
  Wheatley 
  on 
  Ionization 
  of 
  

  

  the 
  same 
  for 
  all 
  elements 
  in 
  the 
  same 
  column. 
  The 
  actual 
  

   value 
  found 
  for 
  v\ 
  t 
  — 
  v^ 
  & 
  is 
  1*08 
  x 
  10^, 
  and 
  the 
  calculated 
  

   value 
  is 
  1*07 
  X 
  10 
  s 
  . 
  Whether 
  this 
  relation 
  really 
  holds 
  good 
  

   can 
  only 
  be 
  decided 
  by 
  further 
  experiment. 
  

  

  In 
  conclusion 
  I 
  wish 
  to 
  express 
  my 
  warm 
  thanks 
  to 
  

   Prof. 
  Rutherford 
  for 
  the 
  kind 
  interest 
  which 
  he 
  has 
  taken 
  

   in 
  this 
  work. 
  

  

  Physical 
  Laboratory, 
  

  

  University 
  of 
  Manchester. 
  

  

  XOIY 
  . 
  Ionization 
  of 
  Gases 
  by 
  Collision 
  with 
  Low 
  Electric 
  

   Forces. 
  By 
  F. 
  W. 
  Wheatley, 
  B.A., 
  B.Sc. 
  (Adelaide), 
  

   Lincoln 
  College, 
  Oxford 
  *. 
  

  

  [Plate 
  XXIV.l 
  

  

  "PROFESSOR 
  TOWNSEND 
  in 
  his 
  book 
  'The 
  Theory 
  

   JL 
  of 
  Ionization 
  of 
  Gases 
  by 
  Collision 
  ' 
  has 
  shown 
  that 
  

   the 
  process 
  of 
  ionization 
  by 
  collision 
  between 
  the 
  ions 
  and 
  

   molecules 
  of 
  a 
  gas 
  may 
  be 
  examined 
  by 
  investigating 
  the 
  

   currents 
  between 
  parallel 
  plate 
  electrodes 
  when 
  ultraviolet 
  

   light 
  falls 
  on 
  the 
  negative 
  electrode 
  or 
  when 
  the 
  gas 
  is 
  ionized 
  

   by 
  Rontgen 
  or 
  Becquerel 
  rays. 
  

  

  In 
  the 
  determinations 
  which 
  have 
  already 
  been 
  made, 
  the 
  

   effect 
  of 
  the 
  electrons 
  for 
  values 
  of 
  the 
  ratio 
  X/p 
  larger 
  than 
  

   60 
  has 
  been 
  obtained. 
  

  

  The 
  experiments 
  described 
  in 
  this 
  paper 
  were 
  undertaken 
  

   with 
  a 
  view 
  to 
  finding 
  the 
  effects 
  obtained 
  by 
  collision 
  with 
  

   smaller 
  forces, 
  and 
  for 
  that 
  purpose 
  it 
  is 
  necessary 
  to 
  measure 
  

   the 
  currents 
  between 
  plates 
  at 
  various 
  distances 
  apart 
  to 
  a 
  

   high 
  degree 
  of 
  accuracy. 
  A 
  very 
  constant 
  source 
  of 
  radi- 
  

   ation 
  is 
  therefore 
  required 
  for 
  the 
  experiments, 
  and 
  it 
  would, 
  

   be 
  practically 
  impossible 
  to 
  obtain 
  reliable 
  results 
  either 
  with 
  

   ultraviolet 
  light 
  or 
  with 
  Rontgen 
  rays. 
  

  

  The 
  source 
  of 
  radiation 
  used 
  was 
  polonium. 
  The 
  results 
  

   show 
  that 
  the 
  ionization 
  produced 
  by 
  a 
  rays 
  is 
  identical 
  with 
  

   that 
  produced 
  by 
  Rontgen 
  or 
  Becquerel 
  rays 
  or 
  by 
  ultra- 
  

   violet 
  light, 
  and 
  has 
  this 
  advantage 
  that 
  it 
  produces 
  a 
  

   constant 
  current. 
  

  

  ' 
  The 
  apparatus 
  which 
  was 
  used 
  is 
  shown 
  in 
  the 
  ac- 
  

   companying 
  figure 
  and 
  consisted 
  of 
  two 
  parallel 
  brass 
  plates 
  

   B 
  and 
  C 
  inside 
  an 
  airtight 
  bell-jar 
  A. 
  The 
  bell-jar 
  was 
  

   provided 
  with 
  two 
  outlets 
  D 
  and 
  E. 
  Through 
  D 
  a 
  wire 
  

   passed 
  connecting 
  the 
  lower 
  plate 
  to 
  a 
  source 
  of 
  potential 
  

   Y. 
  The 
  opening 
  E 
  led 
  to 
  a 
  Topler 
  pump, 
  an 
  open 
  mano- 
  

   meter 
  and 
  a 
  MacLeod 
  gauge, 
  and 
  could 
  also 
  be 
  connected 
  

   * 
  Communicated 
  hx 
  Prof. 
  J. 
  S. 
  Townsend, 
  F.Pv.S. 
  

  

  