﻿262 
  Mr. 
  G. 
  B. 
  Bryan 
  on 
  the 
  Determination 
  of 
  

  

  stopping 
  the 
  current, 
  by 
  balancing 
  against 
  a 
  Clark 
  cell. 
  As 
  

   much 
  as 
  0*3 
  volt 
  was 
  found 
  with 
  a 
  thickness 
  of 
  0*628 
  mm., 
  

   which 
  would 
  not 
  account 
  for 
  the 
  large 
  increase 
  in 
  resistance 
  

   during 
  the 
  passage 
  of 
  the 
  current, 
  since 
  the 
  applied 
  E.M.F. 
  

   was 
  10 
  volts. 
  

  

  The 
  polarization, 
  however, 
  fell 
  off 
  very 
  rapidly 
  and 
  might 
  

   have 
  been 
  much 
  greater 
  whilst 
  the 
  current 
  was 
  on. 
  

  

  Hence 
  it 
  would 
  appear 
  that 
  although 
  the 
  conductivity 
  of 
  

   aniline 
  might 
  not 
  vary 
  with 
  the 
  thickness 
  of 
  the 
  layer, 
  it 
  would 
  

   be 
  very 
  difficult 
  to 
  prove 
  it 
  by 
  means 
  of 
  a 
  continuous 
  current. 
  

  

  A 
  large 
  number 
  of 
  readings 
  were 
  taken 
  with 
  different 
  

   thicknesses, 
  and 
  on 
  the 
  whole 
  they 
  appeared 
  to 
  show 
  that 
  

   the 
  conductivity 
  decreased 
  with 
  the 
  thickness. 
  The 
  following- 
  

   are 
  specimens 
  of 
  the 
  results 
  obtained 
  : 
  — 
  

  

  Table 
  IV. 
  

   Distilled 
  Aniline. 
  E.M.F. 
  = 
  10 
  volts. 
  (9=9° 
  (J. 
  

  

  

  T=l 
  i 
  

  

  nin. 
  

  

  d, 
  

   mm. 
  

  

  T=l 
  min. 
  

  

  T 
  = 
  17 
  min. 
  

  

  d, 
  

  

  mm. 
  

  

  r, 
  

  

  ohms. 
  

  

  Sp. 
  R. 
  

  

  c.g.s.xio- 
  15 
  . 
  

  

  Sp.R.XlO" 
  15 
  . 
  

  

  Sp.R.x 
  10-15. 
  

  

  0245 
  

  

  30,300 
  

  

  119 
  

  

  •334 
  

  

  85-1 
  

  

  134 
  

  

  651 
  

  

  89,300 
  

  

  110 
  

  

  •651 
  

  

  84 
  

  

  125 
  

  

  1-29 
  

  

  150,000 
  

  

  94 
  

  

  1-29 
  

  

  81-8 
  

  

  93-3 
  

  

  2-55 
  

  

  232,000 
  

  

  73-4 
  

  

  10-17 
  

  

  41-7 
  

  

  51 
  

  

  5-10 
  

  

  370,000 
  

  

  58-3 
  

  

  

  

  

  764 
  

  

  464,000 
  

  

  49 
  

  

  

  

  

  1017 
  

  

  880,000 
  

  

  466 
  

  

  

  

  

  In 
  these 
  experiments 
  the 
  current-density 
  is 
  much 
  greater 
  

   in 
  the 
  thin 
  layers 
  than 
  in 
  the 
  thick 
  ones. 
  The 
  following 
  are 
  

   some 
  readings 
  in 
  which 
  the 
  current- 
  density 
  was 
  kept 
  constant 
  

   by 
  varying 
  the 
  E.M.F. 
  by 
  means 
  of 
  a 
  liquid 
  rheostat 
  until 
  

   the 
  deflexion 
  of 
  the 
  galvanometer 
  was 
  approximately 
  the 
  same 
  

   in 
  each 
  case. 
  The 
  time 
  taken 
  to 
  do 
  this 
  was 
  about 
  1 
  minute: 
  — 
  

  

  Table 
  V. 
  

  

  d, 
  mm. 
  

  

  Sp. 
  

  

  1 
  

   R. 
  x 
  lO-is. 
  

  

  •334 
  

  

  

  85-6 
  

  

  •651 
  

  

  

  48-1 
  

  

  1-29 
  

  

  

  35 
  

  

  2-55 
  

  

  

  35-8 
  

  

  5-10 
  

  

  

  27-7 
  

  

  7-64 
  

  

  

  25-8 
  

  

  10-17 
  

  

  

  25-2 
  

  

  i 
  

  

  The 
  difference 
  of 
  conductivity 
  between 
  the 
  thick 
  and 
  thin 
  

   layers 
  is 
  here 
  much 
  greater 
  than 
  before. 
  

  

  