﻿produced 
  in 
  Gases 
  by 
  Ultra- 
  Violet 
  Light. 
  567 
  

  

  Table 
  XVIII. 
  — 
  Carbonic 
  Acid. 
  Pressure 
  *606 
  mm. 
  

  

  X. 
  

  

  n 
  v 
  

  

  », 
  

  

  n 
  3 
  . 
  

  

  B. 
  ! 
  

  

  ! 
  

  

  262 
  

  

  88 
  

  

  199 
  

  

  462 
  

  

  2-26, 
  232 
  

  

  350 
  

  

  97-5 
  

  

  282 
  

  

  853 
  

  

  2-90, 
  3-03 
  

  

  525 
  

  

  122 
  

  

  518 
  

  

  2270 
  

  

  4-24, 
  4-38 
  

  

  700 
  

  

  157 
  

  

  840 
  

  

  — 
  

  

  5-35 
  — 
  

  

  Table 
  XIX. 
  — 
  Carbonic 
  Acid. 
  Pressure 
  '321 
  mm. 
  

  

  X. 
  

  

  n 
  v 
  

  

  n 
  3 
  . 
  

  

  n 
  5 
  . 
  

  

  E. 
  

  

  262 
  

  

  85 
  

  

  171 
  

  

  355 
  

  

  2-02, 
  2-07 
  

  

  350 
  

  

  95 
  

  

  217 
  

  

  508 
  

  

  2-28, 
  2-33 
  

  

  522 
  

   700 
  

  

  114 
  

  

  300 
  

  

  860 
  

  

  2-63, 
  2-86 
  

   1-76, 
  1-71 
  

  

  n 
  x 
  . 
  

  

  n 
  2 
  . 
  

  

  n 
  z 
  . 
  

  

  126 
  

  

  221 
  

  

  378 
  

  

  1050 
  

  

  152 
  

  

  268 
  

  

  

  1-77 
  — 
  

  

  4. 
  In 
  these 
  experiments 
  the 
  greatest 
  potential-difference 
  

   between 
  the 
  plates 
  was 
  350 
  volts. 
  An 
  appreciable 
  increase 
  

   of 
  conductivity 
  can 
  be 
  obtained 
  with 
  this 
  voltage 
  with 
  gases 
  

   at 
  several 
  centimetres' 
  pressure 
  by 
  having 
  short 
  distances 
  

   between 
  the 
  plates. 
  This 
  can 
  be 
  seen 
  from 
  Tables 
  VI., 
  VII., 
  

   and 
  XIII., 
  the 
  conductivities 
  having 
  been 
  determined 
  with 
  

   the 
  plates 
  at 
  1 
  and 
  2 
  millimetres 
  apart. 
  

  

  The 
  equality 
  of 
  the 
  two 
  ratios 
  — 
  and 
  — 
  (given 
  in 
  the 
  last 
  

  

  column 
  of 
  each 
  table) 
  shows 
  that 
  the 
  conductivity 
  is 
  pro- 
  

   portional 
  to 
  e 
  aXd 
  , 
  d 
  being 
  the 
  distance 
  between 
  the 
  plates, 
  

   and 
  a 
  a 
  constant 
  depending 
  on 
  the 
  force 
  and 
  pressure. 
  

   When 
  the 
  force 
  is 
  constant 
  and 
  the 
  pressure 
  lowered 
  the 
  

   value 
  of 
  a 
  at 
  first 
  increases 
  as 
  the 
  pressure 
  diminishes, 
  then 
  

   reaches 
  a 
  maximum, 
  and 
  afterwards 
  diminishes. 
  It 
  will 
  be 
  

  

  