﻿from 
  Actinium 
  in 
  Uniform 
  Electric 
  Fields. 
  1^1 
  

  

  admission 
  and 
  removal 
  of 
  the 
  different 
  erases 
  used, 
  and 
  throuoli 
  

   its 
  base 
  wires 
  suitably 
  secured 
  were 
  led, 
  for 
  the 
  purpose 
  of 
  

   charging 
  the 
  electrodes. 
  The 
  electrodes, 
  which 
  were 
  circular^ 
  

   were 
  2*5 
  cm. 
  in 
  diameter, 
  and 
  the 
  guard-plates 
  which 
  

   surrounded 
  them 
  were 
  each 
  '5 
  cm. 
  in 
  width. 
  

  

  III. 
  Measurements. 
  

  

  In 
  the 
  various 
  experiments 
  which 
  are 
  to 
  be 
  described 
  

   later, 
  the 
  sample 
  of 
  actinium 
  used 
  was 
  obtained 
  from 
  the 
  

   Chininfabrik, 
  Braunschweig. 
  In 
  making 
  the 
  exposures 
  the 
  

   electrodes 
  w^ere 
  exposed 
  in 
  every 
  case 
  to 
  the 
  action 
  of 
  the 
  

   emanation 
  for 
  two 
  hours 
  before 
  being 
  removed 
  from 
  the 
  ex- 
  

   posing 
  vessel 
  for 
  measurement. 
  The 
  activities 
  of 
  the 
  elec- 
  

   trodes 
  were 
  tested 
  by 
  an 
  ordinary 
  «-ray 
  gold-leaf 
  electroscope, 
  

   and 
  all 
  the 
  values 
  which 
  are 
  quoted 
  in 
  the 
  paper 
  represent 
  

   the 
  activities 
  of 
  the 
  electrodes 
  10 
  minutes 
  after 
  the 
  exposures 
  

   ceased. 
  In 
  making 
  the 
  measurements 
  of 
  the 
  activities 
  of 
  the 
  

   two 
  electrodes, 
  observations 
  were 
  continued 
  for 
  a 
  period 
  of 
  

   forty 
  or 
  fifty 
  minutes. 
  From 
  these 
  observations, 
  of 
  which 
  

   fig. 
  10 
  (PI. 
  XXII.) 
  is 
  illustrative, 
  the 
  rates 
  of 
  decay 
  of 
  the 
  

   deposits 
  on 
  both 
  anode 
  and 
  cathode 
  were 
  found 
  to 
  be 
  the 
  same, 
  

   and 
  to 
  be 
  approximately 
  about 
  39 
  minutes. 
  In 
  making 
  all 
  

   the 
  exposures 
  the 
  electrodes 
  were 
  charged 
  to 
  a 
  potential 
  of 
  

   approximately 
  250 
  volts. 
  

  

  lY. 
  Active 
  Deposits 
  and 
  Distance 
  heticeen 
  the 
  Electrodes. 
  

  

  In 
  commencing 
  the 
  study 
  of 
  the 
  active 
  deposits 
  from 
  

   actinium 
  a 
  set 
  of 
  measurements 
  was 
  made 
  on 
  the 
  active 
  

   deposits 
  obtained 
  on 
  the 
  two 
  electrodes 
  when 
  the 
  salt 
  was 
  

   placed 
  in 
  the 
  vertical 
  tube 
  at 
  a 
  constant 
  distance 
  from 
  the 
  

   cylinder, 
  and 
  the 
  electrodes 
  were 
  gradually 
  separated. 
  In 
  a 
  

   particular 
  set 
  of 
  observations 
  the 
  plates 
  were 
  placed 
  vertically 
  

   1 
  mm. 
  apart, 
  and 
  the 
  salt 
  was 
  brought 
  as 
  close 
  to 
  them 
  as 
  

   the 
  construction 
  of 
  the 
  apparatus 
  would 
  permit. 
  With 
  this 
  

   arrangement 
  the 
  salt, 
  which 
  was 
  always 
  covered 
  with 
  a 
  layer 
  

   of 
  thin 
  filter-paper, 
  was 
  at 
  a 
  distance 
  of 
  11 
  mm. 
  from 
  the 
  

   lov;er 
  edge 
  of 
  the 
  plate 
  electrode. 
  

  

  Observations 
  were 
  made 
  at 
  atmospheric 
  pressure 
  on 
  the 
  

   active 
  deposits 
  obtained 
  on 
  both 
  electrodes 
  for 
  distances 
  1, 
  2, 
  3, 
  

   4, 
  .5, 
  6, 
  and 
  8 
  mm., 
  and 
  the 
  results 
  are 
  all 
  recorded 
  in 
  Table 
  I. 
  

   A 
  curve 
  illustrating 
  them 
  is 
  shown 
  in 
  fig. 
  2 
  (PL 
  XXII.). 
  

   From 
  these 
  results 
  it 
  will 
  be 
  seen 
  that 
  as 
  as 
  the 
  electrodes 
  

   were 
  separated 
  the 
  activity 
  obtained 
  on 
  both 
  plates 
  steadily 
  

   decreased. 
  With 
  distances 
  apart 
  greater 
  than 
  3 
  mm. 
  no 
  

   measurable 
  activity 
  was 
  obtained 
  on 
  the 
  anode, 
  but 
  with 
  the 
  

   greater 
  distances, 
  viz. 
  8 
  mm., 
  the 
  active 
  deposit 
  obtained 
  

  

  3D2 
  

  

  