﻿326 
  E. 
  M. 
  Wellisch 
  — 
  Distribution 
  of 
  the 
  Active 
  Deposit 
  

  

  entirely 
  by 
  the 
  relative 
  number 
  of 
  charged 
  and 
  uncharged 
  car- 
  

   riers 
  resulting 
  from 
  the 
  recoil 
  of 
  the 
  atoms 
  of 
  Ra.A 
  in 
  the 
  gas. 
  

   Under 
  these 
  circumstances 
  we 
  should 
  expect 
  that 
  the 
  distribu- 
  

   tion 
  should 
  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 
  thai, 
  as 
  far 
  as 
  diffusion 
  and 
  recombination 
  are 
  con- 
  

   cerned, 
  the 
  recoil 
  atoms 
  behave 
  differently 
  from 
  the 
  positive 
  

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

   bination 
  occurs 
  between 
  negative 
  ions 
  on 
  the 
  one 
  hand 
  and 
  

   positive 
  ions 
  or 
  positive 
  recoil 
  atoms 
  on 
  the 
  other 
  hand, 
  a 
  con- 
  

   siderably 
  smaller 
  fraction 
  of 
  recoil 
  atoms 
  than 
  of 
  positive 
  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 
  connection. 
  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 
  recombination 
  being 
  supposed 
  

   to 
  be 
  entirely 
  absent. 
  . 
  It 
  will 
  be 
  noticed 
  that 
  these 
  curves 
  cut 
  

   the 
  axis 
  of 
  ordinates 
  at 
  the 
  points 
  marked 
  .7 
  and 
  .4, 
  these 
  

   points 
  representing 
  respectively 
  66 
  per 
  cent 
  of 
  the 
  total 
  num- 
  

   ber 
  of 
  positive 
  ions 
  and 
  38 
  per 
  cent 
  of 
  the 
  total 
  number 
  of 
  

   positively 
  charged 
  deposit 
  particles. 
  This 
  type 
  of 
  curve 
  has 
  

   already 
  been 
  treated 
  by 
  Wellisch 
  and 
  Woodrow* 
  for 
  the 
  case 
  

   of 
  the 
  columnar 
  recombination 
  resulting 
  from 
  a-particle 
  ioniza- 
  

   tion. 
  It 
  was 
  shown 
  by 
  them 
  that 
  the 
  ordinate 
  of 
  the 
  point 
  of 
  

   intersection 
  represents 
  the 
  fraction 
  of 
  the 
  total 
  number 
  of 
  ions 
  

   which 
  escapes 
  from 
  the 
  a-particle 
  column 
  as 
  a 
  result 
  of 
  molec- 
  

   ular 
  agitation 
  and 
  diffusion. 
  Inasmuch 
  as 
  volume 
  recombina- 
  

   tion 
  is 
  absent 
  these 
  ions 
  are 
  brought 
  over 
  to 
  the 
  electrodes 
  by 
  

   a 
  very 
  small 
  electric 
  field. 
  If 
  we 
  draw 
  through 
  the 
  point 
  of 
  

   intersection 
  a 
  straight 
  line 
  parallel 
  to 
  the 
  axis 
  of 
  potential 
  and 
  

   if 
  we 
  refer 
  the 
  curve 
  to 
  this 
  straight 
  line 
  as 
  a 
  new 
  axis 
  of 
  

   potential, 
  then 
  the 
  new 
  ordinates 
  will 
  indicate 
  to 
  what 
  extent 
  

   the 
  electric 
  potential 
  is 
  effective 
  in 
  preventing 
  recombination 
  

   between 
  those 
  ions 
  which 
  still 
  remain 
  in 
  the 
  column 
  after 
  the 
  

   initial 
  diffusion 
  has 
  occurred. 
  If 
  we 
  treat 
  the 
  curves 
  of 
  fig. 
  3 
  

   in 
  a 
  similar 
  manner 
  we 
  see 
  that, 
  whereas 
  in 
  the 
  vessel 
  employed 
  

  

  * 
  Wellisch 
  and 
  Woodrow, 
  this 
  Journal, 
  September, 
  1913. 
  

  

  