﻿756 
  Prof. 
  0. 
  W. 
  Richardson 
  on 
  the 
  Specific 
  

  

  Homogeneity 
  of 
  the 
  Ions. 
  

  

  The 
  type 
  o£ 
  curve 
  obtained 
  by 
  the 
  second 
  method, 
  showing 
  

   the 
  distribution 
  o£ 
  the 
  ions 
  on 
  the 
  plates 
  when 
  H 
  = 
  0, 
  is 
  

   shown 
  by 
  the 
  central 
  curve 
  in 
  fig. 
  4. 
  I£ 
  the 
  ions 
  were 
  not 
  

   homogeneous, 
  if, 
  for 
  instance, 
  they 
  consisted 
  of 
  two 
  groups 
  

   having 
  different 
  values 
  of 
  e/m, 
  then 
  this 
  figure 
  would 
  be 
  

   made 
  up 
  of 
  the 
  superposition 
  of 
  those 
  due 
  to 
  the 
  two 
  groups 
  

   separately. 
  Since 
  the 
  two 
  groups 
  have 
  supposedly 
  different 
  

   values 
  of 
  e/m 
  they 
  would 
  be 
  differently 
  deflected 
  in 
  a 
  

   magnetic 
  field, 
  so 
  that 
  on 
  this 
  hypothesis 
  the 
  effect 
  of 
  the 
  

   magnetic 
  field 
  would 
  be 
  to 
  broaden 
  out 
  the 
  pattern. 
  If 
  

   the 
  magnetic 
  field 
  were 
  great 
  enough 
  the 
  separation 
  should 
  

   be 
  sufficient 
  to 
  give 
  rise 
  to 
  two 
  groups, 
  each 
  similar 
  to 
  the 
  

   first. 
  In 
  the 
  intermediate 
  stages 
  the 
  pattern 
  would 
  develop 
  

   two 
  humps 
  separated 
  by 
  a 
  hollow. 
  

  

  Humps 
  of 
  this 
  character 
  were 
  looked 
  for, 
  and 
  in 
  the 
  

   earlier 
  stages 
  of 
  the 
  investigation 
  readily 
  found. 
  On 
  further 
  

   examination, 
  however, 
  these 
  projections 
  were 
  found 
  to 
  be 
  

   capable 
  of 
  division 
  into 
  two 
  groups 
  : 
  (a) 
  those 
  which 
  were 
  

   permanent, 
  and 
  (b) 
  those 
  which 
  only 
  lasted 
  through 
  two 
  or 
  

   three 
  sets 
  of 
  observations. 
  The 
  first 
  group 
  were 
  not 
  dependent 
  

   on 
  the 
  magnetic 
  field 
  and 
  so 
  obviously 
  arose 
  from 
  lack 
  of 
  

   symmetry 
  in 
  the 
  mechanical 
  arrangements, 
  such 
  as 
  a 
  slight 
  

   bending 
  or 
  twisting 
  of 
  the 
  strip, 
  a 
  point 
  on 
  the 
  metal 
  in 
  its 
  

   neighbourhood, 
  &c. 
  It 
  is 
  probable 
  that 
  the 
  second 
  class 
  

   were 
  of 
  the 
  same 
  character, 
  their 
  temporary 
  nature 
  being- 
  

   determined 
  by 
  the 
  heating 
  of 
  the 
  strip. 
  It 
  is 
  of 
  course 
  

   difficult 
  to 
  prove 
  that 
  they 
  were 
  not 
  due 
  to 
  a 
  short-lived 
  

   emission 
  of 
  ions 
  of 
  another 
  sort, 
  due 
  to 
  impurities 
  or 
  what 
  

   not, 
  but 
  it 
  is 
  a 
  significant 
  fact 
  that 
  the 
  number 
  of 
  effects 
  of 
  

   this 
  kind 
  which 
  were 
  discovered 
  diminished 
  very 
  rapidly 
  

   when 
  great 
  care 
  was 
  taken 
  in 
  setting 
  up 
  the 
  strip 
  and 
  the 
  

   parts 
  adjacent 
  to 
  it. 
  

  

  However 
  this 
  may 
  be 
  it 
  is 
  certain 
  that 
  in 
  the 
  majority 
  of 
  

   cases 
  dealt 
  with 
  the 
  positive 
  ionization 
  from 
  platinum 
  was 
  

   homogeneous 
  to 
  a 
  very 
  high 
  degree. 
  This 
  is 
  well 
  shown 
  

   by 
  the 
  curves 
  in 
  figs. 
  3 
  & 
  4 
  which 
  have 
  been 
  selected 
  as 
  

   typical 
  of 
  the 
  experiments. 
  In 
  fig. 
  4, 
  for 
  which 
  £=•534 
  cm. 
  

   and 
  V 
  = 
  78 
  volts, 
  the 
  left-hand 
  curve 
  represents 
  the 
  distri- 
  

   bution 
  of 
  the 
  ions 
  when 
  H= 
  +4670, 
  the 
  central 
  curve 
  when 
  

   H 
  = 
  0, 
  and 
  the 
  right-hand 
  curve 
  when 
  H=— 
  4670 
  lines 
  per 
  

   square 
  centimetre. 
  It 
  will 
  be 
  seen 
  that 
  on 
  the 
  average 
  the 
  

   curves 
  with 
  a 
  magnetic 
  field 
  have 
  the 
  same 
  width 
  as 
  that 
  with 
  

   H 
  = 
  0, 
  and 
  there 
  is 
  no 
  distinct 
  evidence 
  of 
  separation 
  by 
  the 
  

   magnetic 
  field. 
  The 
  central 
  curve 
  shows 
  on 
  the 
  left 
  a 
  small 
  

   hump 
  of 
  the 
  kind 
  previously 
  alluded 
  to 
  ; 
  these 
  would 
  often 
  

  

  