﻿1046 
  Dr. 
  Norman 
  Campbell 
  on 
  the 
  Electrical 
  

  

  of 
  standard 
  electrolytes 
  of 
  known 
  conductivity 
  and 
  a 
  

   Kohlrausch 
  bridge. 
  

  

  

  Fig. 
  1. 
  

  

  jf| 
  — 
  ^-Sealing 
  way 
  

  

  •Sealing 
  wax 
  

  

  The 
  resistances 
  of 
  the 
  cells, 
  which 
  in 
  these 
  measurements 
  

   always 
  lay 
  between 
  10 
  12 
  and 
  10 
  8 
  ohm, 
  are 
  most 
  conveniently 
  

   determined 
  by 
  comparison 
  with 
  a 
  known 
  resistance. 
  The 
  

   primary 
  known 
  resistance 
  used 
  was 
  a 
  wire 
  megohm; 
  secondary 
  

   standards 
  were 
  provided 
  by 
  xylol-alcohol 
  resistances 
  which 
  

   have 
  been 
  long 
  in 
  use 
  and 
  were 
  kept 
  constantly 
  in 
  melting 
  ice. 
  

   The 
  secondary 
  standards 
  had 
  been 
  carefully 
  compared 
  with 
  

   each 
  other 
  and, 
  in 
  the 
  case 
  of 
  the 
  lowest, 
  with 
  the 
  wire 
  

   megohm; 
  their 
  resistances 
  were 
  very 
  approximately 
  10 
  11 
  , 
  

   10 
  10 
  , 
  and 
  10 
  9 
  ohms. 
  

  

  When 
  the 
  ratio 
  of 
  the 
  unknown 
  resistance 
  (x) 
  and 
  the 
  

   known 
  (R) 
  is 
  not 
  greater 
  than 
  20, 
  the 
  comparison 
  may 
  be 
  

   conveniently 
  effected 
  by 
  means 
  of 
  an 
  ordinary 
  Wheatstone 
  

   bridge 
  in 
  which 
  the 
  ordinary 
  galvanometer 
  is 
  replaced 
  

   by 
  an 
  electrometer 
  (1500 
  divs. 
  per 
  volt). 
  The 
  scheme 
  of 
  

  

  