﻿and 
  Fluidity 
  of 
  Sodium 
  Chloride 
  Solutions. 
  491 
  

  

  passed 
  down 
  narrow 
  glass 
  tubes 
  , 
  and 
  were 
  sealed 
  through 
  the 
  

   ends 
  to 
  the 
  platinum 
  electrodes 
  which 
  were 
  cup-shaped 
  and 
  

   had 
  been 
  coated 
  with 
  platinum 
  -black. 
  The 
  tubes 
  were 
  kept 
  

   in 
  position 
  by 
  passing 
  through 
  corks 
  which 
  fitted 
  into 
  the 
  

   open 
  ends 
  of 
  the 
  wide 
  tubes. 
  

  

  When 
  all 
  the 
  instruments 
  had 
  been 
  throroughly 
  cleaned, 
  

   and 
  had 
  been 
  fixed 
  in 
  position 
  in 
  the 
  bath, 
  the 
  solution, 
  

   which 
  had 
  been 
  made 
  up 
  by 
  weight 
  according 
  to 
  Bender's 
  

   (Wied. 
  Ann. 
  xxii.) 
  values 
  for 
  the 
  density, 
  was 
  distributed 
  

   among 
  the 
  three 
  instruments 
  in 
  the 
  proper 
  proportions. 
  After 
  

   any 
  excess 
  had 
  been 
  removed, 
  and 
  the 
  dilatometer 
  had 
  been 
  

   weighed 
  and 
  replaced, 
  the 
  experiments 
  on 
  that 
  solution 
  were 
  

   begun 
  at 
  0° 
  and 
  the 
  readings 
  were 
  taken 
  at 
  intervals 
  of 
  

   10° 
  0. 
  up 
  to 
  a 
  degree 
  or 
  two 
  below 
  the 
  boiling-point 
  of 
  w 
  T 
  ater. 
  

   .Everything 
  was 
  then 
  allowed 
  to 
  cool, 
  and 
  final 
  readings 
  

   were 
  taken 
  at 
  the 
  temperture 
  of 
  the 
  room 
  in 
  order 
  to 
  see 
  

   whether 
  there 
  was 
  any 
  appreciable 
  variation 
  in 
  any 
  of 
  the 
  

   quantities 
  observed 
  on 
  account 
  of 
  evaporation. 
  During 
  all 
  

   this 
  time 
  the 
  instruments 
  remained 
  untouched 
  and 
  unaltered 
  

   in 
  position. 
  The 
  electrical 
  resistances 
  were 
  measured 
  by 
  

   a 
  modification 
  of 
  Kohlrausch's 
  method. 
  

  

  The 
  alternating 
  current 
  was 
  derived 
  from 
  a 
  small 
  magneto- 
  

   alternator 
  driven 
  by 
  a 
  water-motor, 
  and 
  a 
  Wheatstone's 
  

   bridge 
  was 
  connected 
  up 
  in 
  the 
  ordinary 
  way. 
  A 
  telephone, 
  

   however, 
  was 
  not 
  used 
  as 
  an 
  indicator, 
  but 
  a 
  reflecting 
  

   D' 
  Arson 
  val 
  galvanometer 
  ; 
  the 
  alternating 
  current 
  in 
  this 
  

   portion 
  of 
  the 
  circuit 
  having 
  been 
  transformed 
  into 
  a 
  direct 
  

   one 
  by 
  passing 
  from 
  the 
  bridge 
  to 
  a 
  commutator 
  attached 
  

   to 
  the 
  axle 
  of 
  the 
  alternator 
  and 
  rotating 
  with 
  it. 
  The 
  gal- 
  

   vanometer 
  connexions 
  were 
  in 
  this 
  way 
  reversed 
  as 
  often 
  as 
  

   the 
  direction 
  of 
  the 
  current 
  from 
  the 
  alternator 
  changed, 
  and 
  

   so 
  the 
  usual 
  deflexion 
  of 
  the 
  galvanometer 
  could 
  be 
  readily 
  

   detected, 
  and 
  the 
  resistances 
  adjusted 
  to 
  give 
  no 
  deflexion. 
  

  

  Owing 
  to 
  the 
  shape 
  of 
  the 
  vessel 
  containing 
  the 
  electrolyte, 
  

   relative 
  measurements 
  of 
  the 
  resistance 
  were 
  obtained. 
  These 
  

   were, 
  however, 
  standardized 
  by 
  using 
  Kohlrausch's 
  recent 
  

   values 
  (Journal 
  of 
  Chemical 
  Society, 
  February 
  1900) 
  for 
  

   the 
  specific 
  molecular 
  conductivity 
  of 
  1*0 
  gramme-molecule 
  

   and 
  of 
  0*5 
  gramme-molecule 
  solutions 
  of 
  sodium 
  chloride 
  at 
  

   18° 
  C. 
  

  

  The 
  strengths 
  of 
  the 
  solutions 
  used 
  were 
  very 
  approximately 
  

   0*1, 
  0*2, 
  0*5, 
  TO, 
  2*0, 
  and 
  4*0 
  gramme-molecule 
  equivalents 
  

   per 
  litre 
  at 
  15° 
  C, 
  the 
  exact 
  strengths 
  at 
  the 
  various 
  tem- 
  

   peratures 
  being 
  determined 
  as 
  the 
  experiments 
  proceeded. 
  

   In 
  the 
  accompanying 
  Table, 
  specimen 
  observations 
  are 
  given, 
  

   with 
  the 
  results 
  deduced 
  from 
  them. 
  

  

  