﻿Resistance 
  of 
  Mixtures 
  of 
  Xylol 
  and 
  Alcohol. 
  1045 
  

  

  the 
  conductivity 
  of 
  the 
  mixtures 
  is 
  so 
  low 
  that 
  the 
  current 
  

   which 
  can 
  be 
  passed 
  through 
  them 
  by 
  a 
  P.D. 
  comparable 
  

   with 
  the 
  back 
  E.M.F. 
  does 
  not 
  liberate 
  in 
  the 
  time 
  of 
  the 
  

   experiment 
  enough 
  hydrogen 
  to 
  cover 
  the 
  electrode 
  with 
  a 
  

   layer 
  one 
  molecule 
  thick. 
  All 
  the 
  mixtures 
  investigated 
  in 
  

   these 
  experiments 
  have 
  been 
  contained 
  in 
  cells 
  of 
  such 
  a 
  

   form 
  that 
  the 
  total 
  resistance 
  was 
  greater 
  than 
  10 
  8 
  ohm. 
  

   Accordingly 
  a 
  P.D. 
  of 
  1 
  volt, 
  comparable 
  with 
  the 
  expected 
  

   value 
  of 
  the 
  back 
  E.M.F., 
  would 
  only 
  liberate 
  6 
  X 
  10 
  10 
  atoms 
  

   per 
  second 
  ; 
  in 
  order 
  to 
  cover 
  the 
  electrodes 
  (area 
  about 
  1 
  cm. 
  2 
  ) 
  

   with 
  a 
  single 
  layer 
  of 
  these 
  atoms 
  the 
  current 
  would 
  have 
  

   to 
  pass 
  for 
  more 
  than 
  a 
  day. 
  It 
  was 
  found 
  that 
  if 
  distilled 
  

   water 
  were 
  contained 
  in 
  a 
  cell 
  consisting 
  of 
  a 
  metre 
  of 
  the 
  

   finest 
  bore 
  thermometer 
  tubing, 
  so 
  that 
  its 
  total 
  resistance 
  

   was 
  about 
  10 
  9 
  ohms, 
  the 
  current 
  through 
  it 
  appeared 
  to 
  obey 
  

   Ohm's 
  law 
  as 
  perfectly 
  as 
  that 
  through 
  the 
  xylol-alcohol 
  

   mixtures 
  which 
  have 
  been 
  investigated. 
  

  

  Accordingly 
  the 
  only 
  reason 
  which 
  remained 
  for 
  supposing 
  

   that 
  the 
  current 
  in 
  the 
  mixtures 
  was 
  not 
  carried 
  by 
  electrolytic 
  

   ions, 
  and 
  that 
  the 
  mechanism 
  of 
  the 
  conduction 
  was 
  not 
  the 
  

   same 
  as 
  that 
  in 
  all 
  other 
  non-metallic 
  liquids, 
  was 
  the 
  sign 
  

   of 
  the 
  temperature 
  coefficient 
  of 
  the 
  conductivity. 
  The 
  

   anomalous 
  sign, 
  though 
  interesting, 
  did 
  not 
  seem 
  to 
  suggest 
  

   that 
  theoretically 
  important 
  results 
  w 
  r 
  ould 
  be 
  obtained 
  by 
  a 
  

   thorough 
  investigation 
  of 
  the 
  phenomenon, 
  and 
  accordingly 
  

   the 
  experiments 
  were 
  confined 
  to 
  those 
  which 
  would 
  lead 
  to 
  

   results 
  of 
  immediate 
  practical 
  importance. 
  

  

  2. 
  It 
  is 
  desirable 
  to 
  describe 
  in 
  some 
  detail 
  the 
  arrangements 
  

   which 
  were 
  found 
  most 
  suitable 
  for 
  the 
  construction 
  and 
  

   measurement 
  of 
  the 
  resistances. 
  

  

  The 
  mixtures 
  were 
  contained 
  in 
  glass 
  cells 
  with 
  platinum 
  

   electrodes 
  of 
  one 
  of 
  the 
  types 
  shown 
  in 
  fig. 
  1. 
  The 
  cells 
  were 
  

   placed 
  in 
  a 
  thermostat, 
  the 
  water 
  of 
  which, 
  being 
  earthed, 
  

   provided 
  electrostatic 
  shielding. 
  (Such 
  shielding 
  is 
  scarcely 
  

   necessary 
  if 
  the 
  resistance 
  of 
  the 
  cell 
  is 
  less 
  than 
  10 
  9 
  ohms.) 
  

   The 
  coating 
  of 
  sealing-wax 
  is 
  intended 
  to 
  increase 
  the 
  re- 
  

   sistance 
  of 
  the 
  empty 
  cell 
  ; 
  the 
  conductivity 
  of 
  the 
  empty 
  

   cell 
  was 
  always 
  less 
  than 
  10 
  ~ 
  15 
  mho, 
  and 
  could 
  always 
  be 
  

   neglected 
  in 
  comparison 
  with 
  that 
  of 
  the 
  mixture 
  which 
  was 
  

   not 
  less 
  than 
  10 
  ~ 
  12 
  mho. 
  Which 
  form 
  of 
  cell 
  was 
  adopted 
  

   depended 
  simply 
  on 
  the 
  relation 
  between 
  the 
  conductivity 
  of 
  

   the 
  mixture 
  and 
  the 
  magnitude 
  of 
  the 
  resistance 
  desired 
  ; 
  

   otherwise 
  there 
  appeared 
  no 
  advantage 
  in 
  using 
  a 
  cell 
  in 
  

   which 
  the 
  electrodes 
  were 
  near 
  together 
  rather 
  than 
  one 
  in 
  

   which 
  they 
  are 
  far 
  apart 
  The 
  " 
  conductivity 
  constants" 
  of 
  

   the 
  cells 
  were 
  determined 
  in 
  the 
  usual 
  manner 
  bv 
  the 
  use 
  

  

  