﻿from 
  Actinium 
  in 
  Uniform 
  Electric 
  Fields, 
  745 
  

  

  active 
  deposit 
  on 
  the 
  negative 
  electrode 
  gradually 
  decreased 
  

   as 
  the 
  pressure 
  was 
  lowered, 
  while 
  that 
  obtained 
  on 
  the 
  

   positive 
  electrode 
  showed 
  a 
  corresponding 
  increase, 
  until 
  

   ultimately 
  at 
  the 
  lowest 
  pressure 
  investigated, 
  the 
  amounts 
  

   of 
  the 
  active 
  deposit 
  obtained 
  on 
  the 
  two 
  electrodes 
  were 
  

   approximately 
  equal. 
  

  

  In 
  a 
  second 
  paper 
  Russ 
  * 
  gives 
  an 
  account 
  of 
  a 
  similar 
  set 
  

   of 
  observations 
  made 
  with 
  the 
  emanation 
  from 
  actinium. 
  In 
  

   these 
  experiments 
  positively 
  and 
  negatively 
  charged 
  elec- 
  

   trodes 
  were 
  again 
  exposed 
  in 
  a 
  vessel 
  filled 
  with 
  air 
  and 
  

   containing 
  a 
  quantity 
  of 
  actinium. 
  In 
  this 
  case 
  as 
  the 
  

   pressure 
  of 
  the 
  air 
  was 
  lowered 
  the 
  amount 
  of 
  the 
  active 
  

   deposit 
  obtained 
  on 
  the 
  negative 
  electrode 
  gradually 
  in- 
  

   creased, 
  passed 
  through 
  a 
  maximum 
  value 
  at 
  a 
  certain 
  

   critical 
  pressure, 
  and 
  ultimately 
  fell 
  away 
  again 
  at 
  the 
  lowest 
  

   pressure 
  investigated. 
  On 
  the 
  other 
  hand, 
  in 
  these 
  experi- 
  

   ments 
  Russ 
  found 
  that 
  the 
  active 
  deposit 
  obtained 
  on 
  the 
  

   positive 
  electrode 
  steadily 
  decreased 
  as 
  the 
  pressure 
  of 
  the 
  

   air 
  was 
  lowered. 
  

  

  In 
  his 
  second 
  paper 
  Russ 
  also 
  describes 
  a 
  series 
  of 
  experi- 
  

   ments 
  in 
  which 
  exposures 
  were 
  made 
  in 
  air 
  when 
  the 
  distance 
  

   between 
  the 
  actinium 
  and 
  the 
  electrodes 
  was 
  gradually 
  in- 
  

   creased. 
  The 
  results 
  which 
  he 
  gives 
  show 
  that 
  with 
  the 
  air 
  

   at 
  760 
  mm. 
  the 
  amount 
  of 
  the 
  deposit 
  obtained 
  on 
  the 
  cathode 
  

   steadily 
  decreased 
  as 
  the 
  salt 
  was 
  placed 
  at 
  distances 
  varying 
  

   from 
  2 
  to 
  50 
  mm. 
  from 
  the 
  electrodes. 
  Under 
  similar 
  cir- 
  

   cumstances 
  the 
  amount 
  obtained 
  on 
  the 
  anode 
  at 
  first 
  increased 
  

   as 
  the 
  salt 
  was 
  removed, 
  and 
  finally, 
  after 
  passing 
  through 
  a 
  

   maximum 
  value, 
  fell 
  away 
  again 
  at 
  the 
  longer 
  distances. 
  

   With 
  the 
  air 
  at 
  2 
  mm. 
  pressure, 
  however, 
  the 
  amount 
  

   obtained 
  on 
  the 
  cathode 
  steadily 
  increased 
  as 
  the 
  distance 
  of 
  

   the 
  salt 
  from 
  the 
  electrode 
  was 
  varied 
  from 
  2 
  to 
  42 
  mm., 
  

   but 
  the 
  active 
  deposit 
  obtained 
  on 
  the 
  anode 
  with 
  the 
  same 
  

   variation 
  of 
  distances 
  gradually 
  decreased. 
  

  

  In 
  discussing 
  his 
  results 
  Russ 
  points 
  out 
  that 
  Debierne 
  

   had 
  found 
  that 
  the 
  amount 
  of 
  emanation 
  obtained 
  at 
  atmo- 
  

   spheric 
  pressure 
  from 
  a 
  uniform 
  layer 
  of 
  actinium 
  fell 
  to 
  

   half 
  value 
  in 
  going 
  '55 
  cm. 
  from 
  the 
  layer, 
  and 
  that 
  con- 
  

   sequently 
  one 
  would 
  expect 
  to 
  find 
  a 
  decrease 
  in 
  the 
  activity 
  

   of 
  the 
  electrodes 
  as 
  the 
  salt 
  was 
  removed, 
  and 
  possibly, 
  too, 
  

   a 
  continuance 
  in 
  the 
  ratio 
  of 
  the 
  activities 
  of 
  the 
  deposits 
  

   obtained 
  on 
  the 
  two 
  exposed 
  terminals. 
  The 
  results 
  given 
  

   by 
  him, 
  however, 
  show 
  that 
  this 
  was 
  far 
  from 
  being 
  the 
  

   case. 
  

  

  * 
  Russ, 
  Phil. 
  Mag. 
  June 
  1908. 
  

   Phil 
  Mag. 
  S. 
  6. 
  Vol. 
  18. 
  No. 
  107. 
  Nov. 
  1909. 
  3 
  D 
  

  

  