﻿256 
  

  

  Mr. 
  B. 
  Hodgson 
  on 
  the 
  Conductivity/ 
  of 
  

  

  following 
  results 
  show 
  the 
  increase 
  of 
  conductivity 
  imme- 
  

   diately 
  after 
  insertion 
  of 
  radium. 
  In 
  the 
  cases 
  marked 
  thus 
  * 
  

  

  Fig. 
  4. 
  

  

  A 
  

  

  1- 
  

  

  1 
  

  

  

  ni 
  

  

  S 
  1 
  1 
  1 
  i_J 
  

  

  8 
  

  

  

  

  

  c 
  

  

  

  

  

  

  A 
  

  

  

  

  

  

  

  in 
  Table 
  I. 
  no 
  deflexion 
  was 
  got 
  after 
  some 
  minutes. 
  The 
  

   sensitiveness 
  of 
  the 
  electrometer 
  throughout 
  the 
  experiment* 
  

   was 
  about 
  200 
  scale-divisions 
  per 
  volt, 
  and 
  the 
  capacity 
  of 
  

   the 
  electrometer 
  and 
  connected 
  electrode 
  0*000096 
  micro- 
  

   farad. 
  

  

  The 
  capacity 
  G 
  (fig. 
  1) 
  was 
  0'002454: 
  microfarad. 
  

  

  Table 
  I. 
  

  

  Substance. 
  

  

  Current 
  without 
  

   radium. 
  

  

  Current 
  with 
  

   radium. 
  

  

  Field 
  

   strength. 
  

  

  Heavy 
  paraffin 
  oil... 
  

   » 
  >» 
  >» 
  ••• 
  

  

  Solid 
  paraffin 
  

  

  Ebonite 
  

  

  *0-0 
  X 
  10-13 
  amp. 
  

   0-13 
  „ 
  „ 
  

   ^00 
  ., 
  „ 
  

  

  *oo 
  

  

  1-7 
  X 
  10-12 
  „ 
  

  

  5-1x10-13 
  amp. 
  

  

  1-9 
  „ 
  

   2-2 
  „ 
  

   1-5 
  „ 
  

   2-2x10-12 
  „ 
  

  

  190™" 
  

   cm. 
  

  

  90 
  „ 
  

   260 
  „ 
  

   520 
  „ 
  

   190 
  „ 
  

  

  Vaseline 
  

  

  

  If 
  the 
  radium 
  was 
  removed 
  and 
  the 
  current 
  measured 
  from 
  

   time 
  to 
  time, 
  the 
  E.M.F. 
  being 
  continually 
  applied, 
  it 
  was 
  

   found 
  that 
  the 
  current 
  diminished, 
  and 
  finally 
  reached 
  its- 
  

   initial 
  value 
  (Table 
  II.). 
  

  

  