﻿Active 
  Deposit 
  of 
  Radium 
  in 
  an 
  Electric. 
  Field. 
  623 
  

  

  absorption 
  experiments, 
  and 
  it 
  is 
  shown 
  why 
  an 
  exponential 
  

   Jaw 
  signifies 
  heterogeneity 
  of 
  the 
  rays. 
  In 
  the 
  case 
  of 
  X 
  rays 
  

   scattering 
  is 
  in 
  most 
  cases 
  so 
  small 
  compared 
  with 
  absorption 
  

   that 
  an 
  exponential 
  law 
  probably 
  signifies 
  homogeneity. 
  

  

  In 
  conclusion, 
  the 
  writer 
  wishes 
  to 
  express 
  his 
  best 
  thanks 
  

   to 
  Prof. 
  Barnes 
  for 
  placing 
  all 
  facilities 
  for 
  this 
  research 
  at 
  

   his 
  disposal. 
  

  

  McGill 
  University, 
  

   Montreal. 
  

  

  LII. 
  The 
  Distribution 
  of 
  the 
  Active 
  Deposit 
  of 
  Radium 
  in 
  

   an 
  Electric 
  Field. 
  — 
  II. 
  By 
  E. 
  M. 
  "Wellisch, 
  Assistant 
  

   Professor 
  of 
  Physics 
  at 
  Yale 
  University* 
  . 
  

  

  Introductory. 
  

  

  1. 
  r 
  j^HE 
  experiments 
  described 
  in 
  the 
  present 
  paper 
  are 
  a 
  

   A 
  continuation 
  of 
  the 
  investigation 
  nmde 
  by 
  Wellisch 
  

   and 
  Bronsonf 
  on 
  the 
  distribution 
  of 
  the 
  active 
  deposit 
  of 
  

   radium 
  in 
  an 
  electric 
  field. 
  In 
  that 
  investigation 
  radium 
  

   emanation 
  mixed 
  with 
  air 
  was 
  introduced 
  into 
  a 
  cylindrical 
  

   condenser, 
  and 
  the 
  relative 
  amounts 
  of 
  active 
  deposit' 
  which 
  

   settled 
  on 
  the 
  central 
  electrode 
  and 
  on 
  the 
  case 
  were 
  deter- 
  

   mined 
  after 
  equilibrium 
  had 
  been 
  established 
  for 
  different 
  

   positive 
  potentials 
  applied 
  to 
  the 
  outer 
  electrode. 
  

  

  It 
  was 
  shown 
  that 
  the 
  part 
  of 
  the 
  active 
  deposit 
  which 
  

   settled 
  on 
  the 
  case 
  (anode) 
  was 
  due 
  to 
  the 
  diffusion 
  of 
  un- 
  

   charged 
  carriers 
  ; 
  no 
  evidence 
  was 
  found 
  of 
  the 
  presence 
  of 
  

   negative 
  carriers 
  in 
  any 
  appreciable 
  amount. 
  It 
  was 
  found 
  

   also 
  that, 
  when 
  the 
  applied 
  potential 
  was 
  not 
  too 
  small, 
  the 
  

   distribution 
  of 
  the 
  active 
  deposit 
  was 
  independent 
  of 
  the 
  

   quantity 
  of 
  emanation 
  employed, 
  and 
  that 
  the 
  fraction 
  of 
  

   the 
  total 
  amount 
  which 
  settled 
  on 
  the 
  cathode 
  in 
  general 
  

   increased 
  with 
  increasing 
  potentials, 
  although 
  under 
  the 
  

   most 
  favourable 
  conditions 
  there 
  was 
  still 
  about 
  10 
  per 
  cent, 
  

   which 
  was 
  deposited 
  on 
  the 
  case. 
  The 
  passage 
  of 
  Rontgen 
  

   rays 
  through 
  the 
  gas 
  during 
  the 
  exposure 
  was 
  found 
  to 
  be 
  

   without 
  effect 
  on 
  the 
  distribution 
  except 
  when 
  the 
  applied 
  

   potential 
  was 
  small, 
  in 
  which 
  case 
  the 
  extra 
  ionization 
  pro- 
  

   duced 
  by 
  the 
  rays 
  caused 
  increased 
  recombination 
  with 
  the 
  

   charged 
  active 
  deposit 
  particles, 
  and 
  in 
  this 
  manner 
  the 
  

   cathode 
  deposit 
  was 
  diminished. 
  Finally, 
  it 
  was 
  found 
  that 
  

   for 
  potentials 
  which 
  were 
  not 
  too 
  small 
  the 
  ratio 
  of 
  the 
  

  

  * 
  Communicated 
  by 
  the 
  Author. 
  

  

  f 
  Wellisch 
  and 
  Bronson, 
  Phil. 
  Mag. 
  [6] 
  xxiii. 
  p. 
  714 
  (1912). 
  

  

  