﻿634 
  Prof. 
  E. 
  M. 
  Wellisch 
  on 
  the 
  Distribution 
  of 
  the 
  

  

  may 
  regain 
  a 
  positive 
  charge, 
  so 
  that 
  if 
  we 
  consider 
  a 
  large 
  

   number 
  of 
  recoil 
  atoms 
  there 
  will 
  at 
  any 
  given 
  moment 
  be 
  

   a 
  certain 
  fraction 
  which 
  carry 
  a 
  positive 
  charge, 
  the 
  re- 
  

   mainder 
  being 
  practically 
  all 
  neutral. 
  The 
  process 
  is 
  in 
  

   many 
  respects 
  similar 
  to 
  that 
  which 
  is 
  known 
  to 
  occur 
  in 
  

   the 
  case 
  of 
  canal 
  rays. 
  During 
  the 
  motion 
  of 
  recoil 
  the 
  

   atom 
  is 
  practically 
  unaffected 
  by 
  any 
  applied 
  electric 
  field, 
  

   so 
  that 
  initially 
  the 
  relative 
  number 
  of 
  uncharged 
  and 
  charged 
  

   recoil 
  atoms 
  is 
  independent 
  of 
  the 
  applied 
  potential. 
  However, 
  

   when 
  the 
  recoil 
  atom 
  has 
  reached 
  the 
  end 
  of 
  its 
  path, 
  if 
  it 
  

   be 
  positively 
  charged 
  it 
  may 
  lose 
  its 
  charge 
  by 
  recombination 
  

   with 
  a 
  negative 
  ion 
  formed 
  in 
  the 
  column 
  ; 
  this 
  recombina- 
  

   tion 
  can 
  be 
  prevented 
  by 
  increasing 
  sufficiently 
  the 
  applied 
  

   potential. 
  Moreover, 
  for 
  small 
  applied 
  potentials 
  a 
  positively 
  

   charged 
  recoil 
  atom 
  may 
  recombine 
  with 
  a 
  negative 
  ion 
  in 
  

   the 
  volume 
  of 
  the 
  gas. 
  

  

  When 
  both 
  columnar 
  and 
  volume 
  recombination 
  are 
  avoided 
  

   by 
  the 
  application 
  of 
  a 
  sufficiently 
  high 
  potential, 
  the 
  distri- 
  

   bution 
  of 
  the 
  active 
  deposit 
  on 
  the 
  electrodes 
  is 
  determined 
  

   entirely 
  by 
  the 
  relative 
  number 
  of 
  charged 
  and 
  uncharged 
  

   carriers 
  resulting 
  from 
  the 
  recoil 
  of 
  the 
  atoms 
  of 
  RaA 
  in 
  the 
  

   gas. 
  Under 
  these 
  circumstances 
  we 
  should 
  expect 
  that 
  the 
  

   distribution 
  would 
  be 
  independent 
  of 
  the 
  pressure 
  of 
  the 
  gas 
  

   because 
  the 
  recoil 
  atom 
  will 
  meet 
  the 
  same 
  number 
  of 
  gas 
  

   molecules 
  before 
  it 
  is 
  brought 
  to 
  relative 
  rest. 
  Of 
  course, 
  if 
  

   the 
  pressure 
  is 
  too 
  low 
  an 
  appreciable 
  number 
  of 
  active 
  

   deposit 
  particles 
  will 
  recoil 
  on 
  to 
  the 
  walls 
  of 
  the 
  vessel, 
  and 
  

   in 
  this 
  manner 
  the 
  cathode 
  deposit 
  will 
  be 
  diminished. 
  

  

  Although 
  nothing 
  has 
  been 
  established 
  in 
  this 
  research 
  

   with 
  regard 
  to 
  the 
  velocity 
  of 
  the 
  recoil 
  atoms 
  when 
  moving 
  

   under 
  the 
  influence 
  of 
  an 
  electric 
  field, 
  nevertheless 
  there 
  is 
  

   distinct 
  evidence 
  that, 
  so 
  far 
  as 
  diffusion 
  and 
  recombination 
  

   are 
  concerned, 
  the 
  recoil 
  atoms 
  behave 
  differently 
  from 
  the 
  

   positive 
  gas 
  ions. 
  It 
  has 
  been 
  shown 
  in 
  Section 
  5 
  that, 
  when 
  

   recombination 
  occurs 
  between 
  negative 
  ions 
  on 
  the 
  one 
  hand 
  

   and 
  positive 
  ions 
  or 
  positive 
  recoil 
  atoms 
  on 
  the 
  other 
  hand, 
  

   a 
  considerably 
  smaller 
  fraction 
  of 
  recoil 
  atoms 
  than 
  of 
  posi- 
  

   tive 
  ions 
  is 
  received 
  by 
  the 
  negative 
  electrode. 
  This 
  is 
  

   especially 
  the 
  case 
  with 
  moist 
  gases, 
  but 
  even 
  in 
  gases 
  which 
  

   had 
  been 
  dried 
  with 
  the 
  utmost 
  care 
  the 
  difference 
  is 
  well 
  

   marked. 
  An 
  examination 
  of 
  the 
  curves 
  of 
  fig. 
  3 
  seems 
  to 
  

   afford 
  further 
  information 
  in 
  this 
  connexion. 
  The 
  curves 
  

   may 
  be 
  regarded 
  as 
  giving 
  the 
  fraction 
  either 
  of 
  positive 
  ions 
  

   or 
  of 
  positively 
  charged 
  recoil 
  atoms 
  that 
  is 
  received 
  at 
  the 
  

   negative 
  electrode 
  for 
  any 
  given 
  potential, 
  volume 
  recom- 
  

   bination 
  being 
  supposed 
  to 
  be 
  entirely 
  absent. 
  It 
  will 
  be 
  

  

  