﻿386 
  Mr. 
  H. 
  P. 
  Walmsley 
  on 
  the 
  Distribution 
  of 
  the 
  

  

  We 
  have 
  thus 
  a 
  criterion 
  for 
  the 
  determination 
  of 
  the 
  sign 
  of 
  

   the 
  charges 
  carried. 
  

  

  The 
  wire 
  was 
  exposed 
  as 
  anode 
  to 
  the 
  emanation, 
  then 
  cut 
  

   into 
  sections 
  and 
  its 
  activity 
  measured. 
  This 
  was 
  repeated 
  

   with 
  the 
  wire 
  charged 
  as 
  cathode 
  using 
  the 
  same 
  voltage, 
  

   and 
  the 
  whole 
  repeated 
  over 
  a 
  wide 
  range 
  of 
  potential. 
  The 
  

   results 
  are 
  tabulated 
  and 
  are 
  plotted 
  in 
  fig. 
  4. 
  The 
  accuracy 
  

   of 
  the 
  readings 
  varies 
  with 
  the 
  position 
  of 
  the 
  point 
  on 
  the 
  

   curve. 
  Since 
  each 
  reading 
  is 
  the 
  sum 
  of 
  several 
  measured 
  

   activities, 
  it 
  is 
  difficult 
  to 
  estimate 
  the 
  errors 
  to 
  be 
  expected 
  

   on 
  account 
  of 
  the 
  large 
  variation 
  in 
  activity 
  on 
  separate 
  

   sections. 
  However, 
  the 
  determinations 
  of 
  the 
  cathode 
  activity 
  

   with 
  voltages 
  greater 
  than 
  40 
  varied 
  only 
  about 
  2 
  per 
  cent, 
  

   from 
  one 
  another. 
  Judging 
  from 
  the 
  way 
  in 
  which 
  the 
  

   anode 
  activities 
  vary, 
  it 
  appears 
  as 
  if 
  we 
  had 
  practically 
  

   attained 
  saturation 
  with 
  these 
  voltages. 
  The 
  anode 
  activities 
  

   were 
  much 
  easier 
  to 
  measure, 
  and 
  they 
  at 
  least 
  can 
  be 
  trusted 
  

   to 
  the 
  first 
  significant 
  figure 
  for 
  activities 
  less 
  than 
  ten 
  divi- 
  

   sions 
  per 
  minute, 
  and 
  to 
  a 
  few 
  per 
  cent, 
  for 
  greater 
  activities. 
  

  

  With 
  40 
  volts 
  practically 
  the 
  whole 
  of 
  the 
  activity 
  is 
  col- 
  

   lected 
  on 
  the 
  cathode, 
  but 
  with 
  lower 
  voltages 
  more 
  activity 
  

   is 
  observed 
  on 
  both 
  the 
  anode 
  and 
  the 
  cathode 
  than 
  is 
  to 
  be 
  

   expected 
  if 
  the 
  distribution 
  were 
  due 
  to 
  the 
  electric 
  field 
  

   alone. 
  The 
  ratio 
  of 
  the 
  activity 
  collected 
  with 
  an 
  uncharged 
  

   wire 
  to 
  the 
  activity 
  on 
  the 
  tube 
  should 
  be 
  equal 
  to 
  the 
  ratio 
  

   of 
  the 
  areas 
  of 
  their 
  surfaces, 
  if 
  diffusion 
  alone 
  were 
  operative. 
  

   The 
  latter 
  ratio 
  was 
  0*10, 
  whereas 
  the 
  activity 
  collected 
  by 
  

   the 
  uncharged 
  wire 
  to 
  the 
  maximum 
  cathode 
  activity 
  is 
  0'16. 
  

  

  Fig. 
  4. 
  

  

  '000 
  

  

  5 
  600 
  

  

  400 
  

  

  P00 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  /OlTHOD 
  

  

  r 
  /icw/rr. 
  

  

  

  

  

  

  

  1/ARIAT 
  

  

  ON 
  Of 
  AC 
  

  

  TIVITY 
  W 
  

  

  TH 
  V0LT/> 
  

  

  CE. 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  Aaiod 
  

  

  S 
  ACTIVITY. 
  

  

  

  40 
  

  

  80 
  

  

  100 
  

  

  120 
  

  

  160 
  

  

  l/OLTS. 
  

  

  the 
  

  

  The 
  difference 
  is 
  obviously 
  due 
  to 
  the 
  action 
  of 
  tne 
  air 
  

   current 
  near 
  the 
  aperture 
  0. 
  Since 
  the 
  curve 
  (fig. 
  4) 
  crosses 
  

  

  