﻿from 
  Actinium 
  in 
  Unijorm 
  Electric 
  Fields. 
  755 
  

  

  opposite, 
  and 
  diffusion 
  again 
  may 
  be 
  the 
  chief 
  factor 
  in 
  pro- 
  

   ducing 
  the 
  deposit 
  ; 
  or 
  further, 
  if 
  the 
  disintegration 
  recoil 
  

   phenomenon 
  is 
  the 
  determining 
  factor, 
  it 
  is 
  possible 
  that, 
  

   with 
  the 
  plates 
  close 
  together, 
  the 
  deposits 
  are 
  made 
  by 
  

   reason 
  of 
  the 
  velocity 
  of 
  expulsion 
  alone. 
  If 
  this 
  latter 
  be 
  

   the 
  explanation, 
  the 
  sign 
  of 
  the 
  charge 
  carried 
  by 
  the 
  deposit 
  

   particle 
  would 
  not 
  then 
  exert 
  any 
  considerable 
  influence 
  

   except 
  in 
  the 
  most 
  intense 
  fields. 
  

  

  In 
  all 
  the 
  measurements 
  made 
  the 
  cathode 
  deposit 
  was, 
  

   except 
  at 
  the 
  very 
  lowest 
  pressures, 
  considerably 
  in 
  excess 
  of 
  

   that 
  obtained 
  on 
  the 
  positive 
  terminal. 
  This 
  goes 
  to 
  show 
  

   that 
  part 
  at 
  least 
  of 
  the 
  deposit 
  particles 
  carry 
  a 
  positive 
  

   charge 
  and 
  reach 
  the 
  electrode 
  under 
  the 
  influence 
  of 
  the 
  

   field. 
  

  

  The 
  manner 
  in 
  which 
  these 
  particles 
  gain 
  their 
  positive 
  

   charge, 
  however, 
  is 
  not 
  clear. 
  

  

  From 
  experiments 
  by 
  Logeman 
  ^ 
  and 
  others 
  it 
  is 
  known 
  

   that 
  a 
  plate 
  of 
  copper 
  on 
  which 
  polonium 
  is 
  deposited 
  emits 
  

   a 
  copious 
  stream 
  of 
  delta 
  particles. 
  These, 
  it 
  is 
  also 
  known, 
  

   are 
  beta 
  particles 
  of 
  low 
  velocity, 
  which 
  are 
  very 
  probably 
  

   ejected 
  either 
  from 
  the 
  copper 
  or 
  from 
  the 
  polonium 
  or 
  its 
  

   transmutation 
  product 
  under 
  the 
  bombardment 
  of 
  the 
  alpha 
  

   particles. 
  It 
  is 
  possible 
  too 
  that 
  the 
  delta 
  radiation 
  may 
  be 
  

   caused 
  by 
  and 
  accompany 
  the 
  a. 
  particle 
  in 
  its 
  expulsion 
  from 
  

   the 
  parent 
  atom. 
  Such 
  a 
  plate 
  of 
  copper 
  as 
  that 
  mentioned 
  

   above 
  is 
  knowm 
  to 
  acquire 
  a 
  positive 
  charge 
  when 
  placed 
  in 
  a 
  

   very 
  high 
  vacuum, 
  which 
  shows 
  that 
  an 
  excess 
  of 
  negative 
  

   electricity 
  leaves 
  it 
  as 
  a 
  result 
  of 
  the 
  action 
  of 
  the 
  various 
  

   radiations. 
  

  

  It 
  is 
  possible 
  then 
  that 
  some 
  of 
  the 
  deposit 
  particles 
  from 
  

   actinium 
  or 
  other 
  active 
  emanations 
  may 
  gain 
  a 
  positive 
  

   charge 
  under 
  the 
  action 
  of 
  the 
  alpha 
  radiations 
  present 
  in 
  

   much 
  the 
  same 
  way 
  as 
  the 
  copper 
  plate 
  in 
  the 
  polonium 
  

   experiments. 
  This 
  would 
  then 
  account 
  for 
  the 
  positive 
  charge 
  

   on 
  the 
  particles, 
  and 
  consequently 
  for 
  their 
  removal 
  under 
  the 
  

   field 
  to 
  the 
  negative 
  terminal. 
  

  

  On 
  the 
  other 
  hand, 
  some 
  experiments 
  recently 
  made 
  by 
  

   H. 
  W. 
  Schmidt 
  f 
  have 
  brought 
  out 
  a 
  parallelism 
  between 
  the 
  

   amount 
  of 
  active 
  deposit 
  obtained 
  in 
  air 
  under 
  difi'erent 
  

   electric 
  fields 
  and 
  the 
  intensity 
  of 
  the 
  ordinary 
  conduction 
  

   current 
  through 
  the 
  air 
  under 
  the 
  same 
  fields. 
  This 
  would 
  

   seem 
  to 
  show 
  that 
  the 
  charges 
  are 
  acquired 
  by 
  the 
  deposit 
  

   particles 
  as 
  a 
  result 
  of 
  collision 
  with 
  the 
  gaseous 
  ions 
  present 
  

   in 
  the 
  same 
  vessel. 
  

  

  * 
  Logeman, 
  Proc. 
  Roy. 
  Soc. 
  A, 
  Ixxviii. 
  p. 
  212 
  (1907). 
  

   t 
  Phys, 
  Zeit. 
  ix. 
  pp. 
  184-187, 
  March 
  1008. 
  

  

  