﻿THE 
  

   LONDON, 
  EDINBURGH, 
  and 
  DUBLIN 
  

  

  PHILOSOPHICAL 
  MAGAZINE 
  

  

  AND 
  

  

  JOURNAL 
  OF 
  SCIENCE 
  

  

  [SIXTH 
  SERIES.] 
  

  

  SEPTEMBER 
  1913. 
  

  

  XXIX. 
  The 
  Distribution 
  of 
  the 
  A 
  ctive 
  Deposit 
  of 
  Actinium 
  

   in 
  Electric 
  Fields. 
  By 
  H. 
  P. 
  Walmsley, 
  M.Sc* 
  

  

  IT 
  is 
  now 
  generally 
  accepted 
  that 
  the 
  active 
  deposits 
  of 
  

   thorium 
  and 
  radium 
  carry 
  positive 
  charges, 
  and 
  are 
  in 
  

   consequence 
  concentrated 
  on 
  the 
  cathode 
  in 
  electric 
  fields. 
  

   Some 
  doubt, 
  however, 
  has 
  arisen 
  in 
  the 
  case 
  of 
  actinium, 
  

   which 
  has 
  exhibited 
  a 
  rather 
  complex 
  behaviour 
  and 
  has 
  

   ;given 
  rise 
  to 
  uncertainties 
  in 
  regard 
  to 
  the 
  origin 
  and 
  sign 
  of 
  

   the 
  charges 
  carried 
  by 
  the 
  atoms 
  of 
  the 
  active 
  deposit. 
  

  

  Amongst 
  the 
  earlier 
  workers 
  on 
  the 
  deposit 
  of 
  actinium, 
  

   Russ 
  f 
  found 
  that 
  under 
  certain 
  circumstances 
  the 
  anode 
  

   activity 
  was 
  nearly 
  half 
  that 
  collected 
  by 
  the 
  cathode, 
  at 
  

   atmospheric 
  pressure, 
  whereas 
  in 
  the 
  case 
  of 
  both 
  radium 
  and 
  

   thorium 
  more 
  than 
  95 
  per 
  cent, 
  of 
  the 
  deposit 
  is 
  collected 
  

   by 
  the 
  cathode. 
  At 
  other 
  pressures 
  he 
  found 
  that 
  great 
  

   variations 
  of 
  the 
  ratio 
  of 
  the 
  two 
  activities 
  occurred. 
  The 
  

   observations 
  led 
  him 
  to 
  conclude 
  that 
  the 
  electrical 
  charge 
  

   of 
  the 
  active 
  deposit 
  particles 
  is 
  mainly 
  determined 
  by 
  the 
  

   •collisions 
  between 
  the 
  atoms 
  and 
  the 
  molecules 
  of 
  the 
  gas 
  

   into 
  which 
  the 
  emanation 
  diffused 
  : 
  in 
  other 
  words, 
  by 
  the 
  

   distance 
  traversed 
  by 
  the 
  atoms 
  before 
  reaching 
  the 
  elec- 
  

   trodes. 
  Kennedy 
  J 
  cjntinued 
  the 
  investigation, 
  endeavouring 
  

   to 
  work 
  with 
  uniform 
  fields, 
  for 
  he 
  had 
  observed 
  that 
  previous 
  

  

  • 
  Communicated 
  by 
  Prof. 
  E. 
  Rutherford, 
  F.R.S. 
  

   t 
  Russ, 
  Phil. 
  Mag. 
  xv. 
  pp. 
  601, 
  737 
  (1908). 
  

   \ 
  Kennedy, 
  Phil. 
  Mag. 
  xviii. 
  p. 
  744 
  (1909). 
  

  

  Fhil. 
  Mag. 
  S. 
  6. 
  Vol. 
  26. 
  No. 
  153. 
  Sept 
  1913. 
  2 
  D 
  

  

  