﻿260 
  

  

  Mr. 
  G. 
  B. 
  Bryan 
  on 
  the 
  Determination 
  of 
  

  

  Aniline 
  was 
  then 
  tested, 
  its 
  conductivity 
  being 
  much 
  higher. 
  

   The 
  amalgamated 
  plates 
  were 
  used. 
  The 
  standard 
  resistance 
  

   was 
  a 
  megohm 
  box 
  ; 
  the 
  battery, 
  five 
  secondary 
  cells. 
  The 
  

   galvanometer 
  was 
  shunted. 
  

  

  A 
  large 
  number 
  of 
  readings 
  were 
  taken 
  with 
  aniline, 
  which 
  

   was 
  distilled 
  several 
  times 
  during 
  the 
  experiments. 
  Its 
  resis- 
  

   tance 
  was 
  found 
  to 
  change 
  considerably 
  with 
  the 
  duration 
  of 
  

   the 
  current, 
  increasing 
  as 
  a 
  rule 
  *. 
  

  

  Thus 
  for 
  a 
  sample 
  of 
  brown 
  aniline 
  : 
  — 
  

  

  Table 
  I. 
  

   E.M.F.= 
  10 
  volts. 
  0=11° 
  C. 
  

  

  d, 
  

  

  ruin. 
  

  

  T, 
  

   minutes. 
  

  

  r, 
  

   oh 
  ins. 
  

  

  •65 
  

   1-28 
  

  

  i 
  

  

  2 
  

   1 
  

  

  5 
  

   20 
  

  

  i 
  

  

  2 
  

   1 
  

  

  5 
  

  

  11,800 
  

   ] 
  4,000 
  

   21,000 
  

   23,800 
  

  

  16,400 
  

   20.800 
  

   34,000 
  

  

  Same 
  aniline 
  distilled. 
  

  

  •65 
  

   1-28 
  

  

  2 
  

  

  4 
  1 
  

  

  ^2 
  

  

  20 
  

   120 
  

  

  i 
  

   1! 
  

  

  120 
  

  

  298,000 
  

   329,000 
  

   400.000 
  

   343,000 
  

  

  542,000 
  

   590,000 
  

   573,000 
  

   623,000 
  

  

  These 
  figures 
  show 
  that 
  the 
  change 
  is 
  very 
  considerable, 
  

   especially 
  in 
  the 
  first 
  few 
  minutes. 
  Two 
  causes 
  were 
  found 
  

   to 
  be 
  producing 
  this 
  change 
  : 
  (1) 
  due 
  to 
  the 
  metal 
  electrodes, 
  

   which 
  were 
  found 
  to 
  produce 
  a 
  slow 
  darkening 
  of 
  the 
  aniline, 
  

   and 
  a 
  slow 
  decrease 
  in 
  the 
  resistance. 
  (2) 
  Due 
  to 
  the 
  passage 
  

   of 
  the 
  current 
  ; 
  this 
  produces 
  an 
  increase 
  of 
  resistance, 
  and 
  

   the 
  rate 
  of 
  this 
  increase 
  depends 
  upon 
  the 
  purity 
  of 
  the 
  aniline. 
  

   Thus 
  before 
  distilling, 
  with 
  a 
  thickness 
  of 
  0*65 
  mm., 
  the 
  

   resistance 
  rose 
  in 
  20 
  minutes 
  from 
  11,800 
  to 
  23,800, 
  i. 
  e. 
  100 
  

   per 
  cent., 
  whilst 
  after 
  distilling, 
  the 
  resistance 
  rose 
  from 
  

   298,000 
  to 
  400,000, 
  i. 
  e. 
  30 
  per 
  cent., 
  in 
  the 
  same 
  time. 
  

  

  After 
  passing 
  the 
  current 
  in 
  one 
  direction 
  for 
  some 
  time, 
  

   * 
  Cf. 
  Warburg, 
  Wied. 
  Ann. 
  liv. 
  1895. 
  

  

  