﻿Conductivity 
  imparted 
  to 
  Liquid 
  Air 
  by 
  Alpha 
  Rays. 
  881 
  

  

  rapidly 
  as 
  possible. 
  This 
  was 
  done 
  because 
  even 
  when 
  the 
  

   case 
  was 
  supplied 
  with 
  large 
  quantities 
  o£ 
  P 
  2 
  5 
  and 
  con- 
  

   centrated 
  sulphuric 
  acid, 
  moisture 
  was 
  always 
  deposited 
  on 
  

   the 
  glass 
  and 
  quartz 
  tubes 
  surrounding 
  the 
  wires 
  at 
  a 
  point 
  

   a 
  short 
  distance 
  above 
  the 
  mouth 
  of 
  the 
  Dewar 
  flask, 
  and 
  

   whenever 
  this 
  deposit 
  had 
  gained 
  a 
  considerable 
  thickness 
  it 
  

   was 
  found 
  that 
  small 
  pieces 
  of 
  ice 
  and 
  snow 
  always 
  fell 
  from 
  

   it 
  into 
  the 
  flask 
  and 
  lowered 
  considerably 
  the 
  insulating 
  

   power 
  of 
  the 
  liquid 
  air. 
  

  

  In 
  using 
  the 
  apparatus 
  a 
  set 
  of 
  observations 
  was 
  taken 
  

   immediately 
  after 
  the 
  filtered 
  liquid 
  air 
  was 
  poured 
  into 
  the 
  

   flask 
  with 
  a 
  series 
  of 
  increasing 
  potentials 
  applied 
  to 
  the 
  

   electrode 
  EA. 
  In 
  every 
  case 
  it 
  was 
  found 
  on 
  doing 
  this 
  that 
  

   practically 
  no 
  current 
  passed 
  through 
  the 
  liquid 
  air. 
  A 
  small 
  

   plate 
  of 
  copper 
  about 
  1 
  sq. 
  cm. 
  in 
  area, 
  having 
  on 
  it 
  a 
  deposit 
  

   of 
  polonium 
  which 
  had 
  previously 
  been 
  washed 
  in 
  water 
  and 
  

   dried, 
  was 
  then 
  attached 
  to 
  the 
  face 
  of 
  the 
  electrode 
  B 
  with 
  

   the 
  polonium 
  facing 
  the 
  electrode 
  A. 
  A 
  second 
  series 
  of 
  

   readings 
  was 
  then 
  taken 
  with 
  increasing 
  potentials 
  applied 
  to 
  

   EA. 
  After 
  this 
  the 
  copper 
  plate 
  carrying 
  the 
  polonium 
  

   deposit 
  was 
  quickly 
  removed 
  and 
  a 
  third 
  set 
  of 
  readings 
  

   taken 
  without 
  it. 
  A 
  slight 
  conductivity 
  was 
  generally 
  

   obtained 
  in 
  this 
  third 
  set 
  of 
  readings, 
  but 
  its 
  amount 
  was 
  

   found 
  to 
  depend 
  very 
  largely 
  upon 
  the 
  time 
  which 
  was 
  

   allowed 
  to 
  pass 
  in 
  taking 
  the 
  second 
  and 
  third 
  sets 
  of 
  

   readings. 
  

  

  In 
  the 
  intervals 
  between 
  the 
  first 
  and 
  second 
  sets 
  of 
  readings 
  

   and 
  the 
  second 
  and 
  third 
  sets, 
  care 
  was 
  taken 
  to 
  see 
  that 
  the 
  

   deposit 
  of 
  snow 
  and 
  ice-crystals 
  was 
  removed 
  from 
  the 
  glass 
  

   and 
  quartz 
  tubes 
  surrounding 
  the 
  wires 
  leading 
  to 
  the 
  

   electrodes. 
  These 
  tubes, 
  the 
  leading 
  wires, 
  and 
  the 
  electrodes 
  

   were 
  also 
  thoroughly 
  dried 
  before 
  they 
  were 
  inserted 
  in 
  the 
  

   liquid 
  air 
  for 
  the 
  second 
  as 
  well 
  as 
  for 
  the 
  third 
  sets 
  of 
  

   readings, 
  in 
  order 
  to 
  make 
  certain 
  that 
  no 
  moisture 
  was 
  intro- 
  

   duced 
  with 
  them 
  into 
  the 
  liquid 
  air. 
  All 
  possible 
  care 
  was 
  

   taken 
  to 
  prevent 
  ice-crystals 
  falling 
  from 
  the 
  wires 
  into 
  the 
  

   liquid 
  air 
  during 
  the 
  course 
  of 
  the 
  measurements. 
  But 
  it 
  was 
  

   difficult 
  to 
  make 
  certain 
  that 
  moisture 
  did 
  not 
  deposit 
  from 
  

   the 
  air 
  upon 
  the 
  surface 
  of 
  the 
  liquid 
  air, 
  and 
  the 
  small 
  con- 
  

   ductivity 
  generally 
  observed 
  in 
  the 
  third 
  set 
  of 
  readings 
  was 
  

   taken 
  as 
  an 
  indication 
  that 
  such 
  deposition 
  was 
  not 
  entirely 
  

   prevented. 
  

  

  The 
  readings 
  given 
  in 
  Table 
  II. 
  and 
  the 
  curves 
  representing 
  

  

  them 
  in 
  fig. 
  2 
  (PI. 
  XVIII.) 
  will 
  serve 
  to 
  illustrate 
  the 
  variation 
  

  

  obtained 
  with 
  different 
  voltages 
  in 
  the 
  current 
  through 
  the 
  

  

  presence 
  of 
  the 
  polonium 
  in 
  the 
  liquid 
  air. 
  In 
  this 
  particular 
  

  

  Phil 
  Mag. 
  S. 
  6. 
  Vol. 
  26 
  No. 
  155. 
  Nov. 
  1913. 
  3 
  ~ 
  

  

  