﻿754 
  Mr. 
  W. 
  T. 
  Kennedy 
  on 
  the 
  Active 
  Deposit 
  

  

  X. 
  Active 
  Deposits 
  in 
  the 
  Absence 
  of 
  Electric 
  Fields. 
  

  

  In 
  the 
  experiments 
  described 
  up 
  to 
  the 
  present 
  the 
  active 
  

   deposits 
  were 
  all 
  obtained 
  with 
  a 
  potential-difference 
  of 
  

   approximately 
  250 
  volts 
  between 
  the 
  electrodes 
  ; 
  with 
  these 
  

   conditions, 
  however, 
  it 
  was 
  impossible 
  to 
  draw 
  any 
  definite 
  

   conclusion 
  as 
  to 
  the 
  relative 
  quantities 
  of 
  charged 
  and 
  

   uncharged 
  deposit 
  particles 
  involved 
  in 
  any 
  particular 
  

   measurements. 
  With 
  the 
  object 
  of 
  throwing 
  some 
  light 
  on 
  

   this 
  point 
  an 
  additional 
  set 
  of 
  observations 
  was 
  made 
  on 
  the 
  

   deposits 
  obtained 
  in 
  air 
  at 
  different 
  pressures 
  with 
  the 
  elec- 
  

   trodes 
  uncharged, 
  and 
  at 
  a 
  distance 
  of 
  2 
  mm. 
  apart. 
  

  

  The 
  activities 
  obtained 
  on 
  the 
  two 
  electrodes 
  in 
  these 
  expe- 
  

   riments 
  were 
  added 
  together, 
  and 
  the 
  numbers 
  representing 
  

   them 
  are 
  given 
  in 
  Table 
  VIII. 
  For 
  purposes 
  of 
  comparison 
  

   the 
  total 
  activities 
  obtained 
  with 
  air 
  at 
  different 
  pressures 
  under 
  

   a 
  field 
  of 
  250 
  volts 
  are 
  also 
  inserted 
  in 
  the 
  Table, 
  and 
  curves 
  re- 
  

   presenting 
  both 
  sets 
  of 
  values 
  are 
  shown 
  in 
  fig. 
  14 
  (PL 
  XXII.) 
  

  

  Table 
  VIII. 
  

  

  Pressure. 
  

  

  Total 
  Deposit 
  with 
  Field 
  

   of 
  260 
  volts. 
  

  

  Total 
  Deposit. 
  

   No 
  Field. 
  

  

  9 
  mm. 
  

  

  43 
  „ 
  

  

  80 
  „ 
  

  

  127 
  „ 
  

  

  422 
  „ 
  

  

  755 
  „ 
  

  

  46-1 
  

   ()J-0 
  

   653 
  

   50-5 
  

   230 
  

   13-4 
  

  

  21-6 
  

   52-0 
  

   54-4 
  

   50-4 
  

   24-9 
  

   10-8 
  

  

  From 
  an 
  inspection 
  of 
  the 
  two 
  curves 
  it 
  will 
  be 
  seen 
  that 
  the 
  

   total 
  active 
  deposit 
  was 
  practically 
  the 
  same 
  with 
  and 
  without 
  

   the 
  field 
  at 
  all 
  pressures 
  above 
  the 
  critical 
  one. 
  At 
  and 
  

   below 
  this 
  pressure 
  the 
  deposits 
  obtained 
  with 
  the 
  electric 
  

   field 
  applied, 
  as 
  the 
  figure 
  shows, 
  were 
  somewhat 
  in 
  excess. 
  

   From 
  this 
  experiment 
  it 
  would 
  seem 
  that 
  the 
  deposit 
  particles 
  

   in 
  very 
  great 
  measure 
  go 
  to 
  the 
  walls 
  of 
  the 
  vessel 
  in 
  which 
  

   they 
  are 
  produced 
  whether 
  an 
  electric 
  field 
  be 
  applied 
  or 
  not. 
  

  

  The 
  manner 
  in 
  which 
  they 
  are 
  carried 
  there, 
  however, 
  is 
  

   not 
  evident. 
  It 
  is 
  possible 
  that 
  a 
  certain 
  proportion 
  of 
  the 
  

   deposit 
  particles 
  are 
  uncharged, 
  and 
  that 
  these 
  reach 
  the 
  

   walls 
  by 
  ordinary 
  diffusion. 
  

  

  Then 
  again 
  these 
  deposit 
  particles 
  may 
  be 
  electrically 
  

   charged, 
  some 
  of 
  them 
  being 
  of 
  one 
  sign, 
  and 
  some 
  of 
  the 
  

  

  