﻿Conductivity 
  imparted 
  to 
  Liquid 
  Air 
  by 
  Alpha 
  Rays. 
  893 
  

  

  and 
  of 
  preventing 
  the 
  liquid 
  air 
  from 
  becoming 
  contaminated 
  

   with 
  ice-crystals. 
  

  

  In 
  order 
  to 
  ascertain 
  the 
  mobilities 
  of 
  the 
  ions 
  in 
  liquid 
  

   air 
  and 
  over 
  as 
  large 
  a 
  range 
  of 
  pressure 
  as 
  possible, 
  and 
  

   especially 
  to 
  clear 
  up 
  any 
  doubt 
  regarding 
  the 
  results 
  

   obtained 
  in 
  the 
  present 
  experiments 
  on 
  the 
  mobilities 
  at 
  

   116 
  atmospheres, 
  the 
  investigation 
  is 
  being 
  continued 
  with 
  a 
  

   polonium-coated 
  plate 
  of 
  larger 
  area. 
  

  

  VII. 
  On 
  the 
  Existence 
  of 
  a 
  Penetrating 
  Radiation 
  emitted 
  

   by 
  Polonium. 
  

  

  In 
  the 
  earlier 
  portion 
  of 
  the 
  paper 
  when 
  dealing 
  with 
  the 
  

   conductivities 
  represented 
  by 
  the 
  curves 
  shown 
  in 
  figs. 
  2, 
  4, 
  

   and 
  5, 
  it 
  was 
  suggested 
  in 
  explanation 
  of 
  the 
  bend 
  in 
  the 
  

   curves 
  that 
  possibly 
  this 
  effect 
  might 
  be 
  due 
  to 
  a 
  small 
  

   volume 
  ionization 
  in 
  the 
  field 
  due 
  to 
  a 
  penetrating 
  radiation 
  

   from 
  the 
  polonium. 
  That 
  such 
  a 
  volume 
  ionization 
  did 
  

   really 
  exist 
  was 
  shown 
  by 
  means 
  of 
  the 
  apparatus 
  given 
  in 
  

   fig. 
  7 
  before 
  it 
  was 
  put 
  together 
  for 
  the 
  experiments 
  

   described 
  in 
  section 
  VI. 
  

  

  In 
  place 
  of 
  its 
  being 
  constructed 
  as 
  shown 
  in 
  the 
  diagram 
  

   the 
  ebonite 
  plate 
  was 
  not 
  inserted, 
  but 
  in 
  its 
  place 
  a 
  sheet 
  

   of 
  finely 
  meshed 
  gauze 
  was 
  fixed 
  parallel 
  to 
  the 
  two 
  plates 
  

   GH 
  and 
  MN, 
  and 
  about 
  half-way 
  between 
  them. 
  The 
  edges 
  

   of 
  this 
  gauze 
  sheet 
  were 
  turned 
  down 
  and 
  soldered 
  to 
  the 
  

   plate 
  GH. 
  The 
  polonium-coated 
  plate 
  was 
  close 
  to 
  the 
  plate 
  

   GH, 
  and 
  so 
  within 
  the 
  space 
  between 
  it 
  and 
  the 
  gauze. 
  

  

  The 
  apparatus 
  as 
  constructed 
  in 
  this 
  way 
  was 
  placed 
  in 
  

   the 
  steel 
  receiver, 
  which 
  was 
  then 
  filled 
  up 
  with 
  air 
  to 
  over 
  

   100 
  atmospheres. 
  The 
  distance 
  between 
  the 
  gauze 
  and 
  the 
  

   plate 
  PQ 
  was 
  about 
  3*5 
  millimetres, 
  and 
  as 
  the 
  alpha 
  rays 
  

   emitted 
  by 
  the 
  polonium 
  could 
  not 
  have 
  a 
  greater 
  range 
  at 
  

   this 
  high 
  pressure 
  than 
  a 
  fraction 
  of 
  a 
  millimetre, 
  it 
  is 
  clear 
  

   that 
  these 
  rays 
  could 
  not 
  produce 
  any 
  ionization 
  in 
  the 
  space 
  

   between 
  the 
  gauze 
  and 
  the 
  plate 
  MN. 
  On 
  applying 
  a 
  

   potential 
  difference, 
  however, 
  between 
  the 
  gauze 
  and 
  the 
  

   plate 
  MN 
  a 
  well-marked 
  though 
  small 
  current 
  was 
  obtained 
  

   which 
  reached 
  saturation 
  with 
  a 
  field 
  of 
  about 
  20 
  volts 
  ; 
  this 
  

   current 
  was 
  obtained 
  with 
  positive 
  as 
  well 
  as 
  with 
  negative 
  

   fields, 
  and 
  with 
  both 
  fields 
  its 
  maximum 
  intensity 
  was 
  the 
  

   same. 
  This 
  result, 
  combined 
  with 
  the 
  fact 
  that 
  the 
  mobilities 
  

   of 
  the 
  ions 
  are 
  exceedingly 
  small 
  at 
  the 
  high 
  pressure 
  used, 
  

   would 
  seem 
  to 
  show 
  that 
  the 
  current 
  had 
  its 
  origin 
  in 
  

   ionization 
  produced 
  in 
  the 
  space 
  between 
  the 
  gauze 
  and 
  the 
  

   plate 
  MN 
  by 
  a 
  penetrating 
  radiation 
  from 
  the 
  polonium 
  

   rather 
  than 
  in 
  ions 
  diffusing 
  through 
  the 
  gauze 
  into 
  this 
  

   space 
  from 
  the 
  ionized 
  layer 
  close 
  to 
  PQ. 
  The 
  apparatus 
  

  

  