﻿Active 
  Deposit 
  of 
  Actinium 
  in 
  Electric 
  Fields. 
  395 
  

  

  of 
  the 
  maximum 
  the 
  activities 
  were 
  measured 
  ten 
  minutes 
  

   after 
  the 
  injection 
  of 
  the 
  emanation 
  into 
  the 
  chamber. 
  

  

  The 
  activities 
  collected 
  by 
  the 
  wire 
  due 
  to 
  diffusion 
  

   alone, 
  though 
  small, 
  were 
  very 
  consistent. 
  The 
  observa- 
  

   tions 
  for 
  time 
  intervals 
  increasing 
  to 
  1*00 
  min. 
  (fig. 
  8) 
  show 
  

  

  Fiff. 
  8. 
  

  

  2-0 
  

  

  KO 
  

  

  0-5 
  

  

  ■75 
  1-0 
  1-5 
  

  

  Time 
  in 
  minutes 
  

  

  3-0 
  

  

  that 
  the 
  amount 
  of 
  deposit 
  diffusing 
  to 
  the 
  side 
  of 
  the 
  vessel' 
  

   decreases 
  exponentially 
  with 
  the 
  time. 
  The 
  observations 
  

   after 
  this 
  period 
  do 
  not 
  agree 
  in 
  this 
  respect, 
  as 
  a 
  constant 
  

   amount 
  of 
  deposit 
  apparently 
  seems 
  to 
  be 
  always 
  collected.. 
  

   This 
  is 
  possibly 
  due 
  to 
  air 
  currents 
  set 
  up 
  when 
  the 
  tube 
  F 
  

   is 
  lowered 
  to 
  make 
  an 
  exposure. 
  The 
  points 
  on 
  the 
  curves 
  

   showing 
  the 
  anode 
  and 
  cathode 
  activities 
  (fig. 
  9, 
  p. 
  396) 
  are 
  

   the 
  means 
  of 
  several 
  exposures 
  in 
  each 
  case. 
  Unfortunately 
  

   the 
  sources 
  of 
  experimental 
  error 
  are 
  extremely 
  numerous 
  

   in 
  this 
  experiment, 
  so 
  that 
  the 
  values 
  given 
  are 
  not 
  of 
  a 
  high 
  

   order 
  of 
  accuracy. 
  After 
  one 
  minute 
  the 
  difference 
  at 
  any 
  

   time 
  interval 
  between 
  the 
  activities 
  collected 
  by 
  the 
  wire 
  

   charged 
  as 
  anode 
  and 
  as 
  cathode, 
  was 
  less 
  than 
  the 
  probable 
  

   errors 
  in 
  the 
  values 
  given, 
  so 
  that 
  we 
  may 
  assume 
  that 
  the 
  

   curves 
  coincide 
  about 
  this 
  time. 
  The 
  curves 
  become 
  ap- 
  

   proximately 
  horizontal 
  after 
  the 
  two 
  minutes 
  interval. 
  The 
  

   value 
  of 
  the 
  constant 
  activity 
  was 
  found 
  to 
  vary 
  from 
  time 
  

   to 
  time. 
  An 
  explanation 
  of 
  this 
  is 
  offered 
  later. 
  Since 
  the 
  

   anode 
  and 
  cathode 
  activities 
  are 
  ultimately 
  equal, 
  the 
  active 
  

   deposit 
  at 
  these 
  times 
  must 
  be 
  uncharged. 
  Hence 
  the 
  curve 
  

   giving 
  the 
  anode 
  activity 
  shows 
  the 
  amount 
  of 
  uncharged 
  

   deposit 
  after 
  any 
  time. 
  The 
  difference 
  between 
  the 
  two 
  

  

  