﻿and 
  Chemical 
  Reactions 
  in 
  Heterogeneous 
  Systems. 
  547 
  

  

  thin 
  ^veil-running 
  tube, 
  1 
  mm. 
  o£ 
  which 
  indicated 
  '01 
  c.c, 
  

   and 
  I 
  read 
  the 
  tube 
  with 
  a 
  lens 
  to 
  about 
  '2 
  mm. 
  or 
  to 
  

   •002 
  c.c, 
  and 
  the 
  excess 
  o£ 
  baryta 
  had 
  to 
  be 
  titrated 
  with 
  

   the 
  more 
  dilute 
  '022 
  normal 
  benzoic 
  acid 
  so 
  that 
  the 
  last 
  

   drop 
  should 
  not 
  affect 
  the 
  result 
  much, 
  and 
  this 
  operation 
  

   had 
  to 
  be 
  repeated 
  twice 
  to 
  further 
  reduce 
  the 
  reading-error. 
  

   As 
  50 
  c.c. 
  of 
  ordinary 
  distilled 
  water 
  contain 
  already 
  an 
  

   amount 
  of 
  COo 
  corresponding 
  to 
  0'3-0*4 
  c.c. 
  of 
  a 
  '022 
  normal 
  

   solution, 
  and 
  at 
  least 
  50 
  c.c. 
  of 
  water 
  are 
  required 
  for 
  washing- 
  

   out 
  the 
  sample 
  bottles 
  and 
  for 
  titration, 
  the 
  COo 
  of 
  the 
  water 
  

   alone 
  is 
  enough 
  to 
  cause 
  an 
  error 
  of 
  10, 
  20, 
  or 
  30 
  per 
  cent. 
  

   in 
  the 
  total 
  difference 
  measured. 
  Therefore 
  the 
  water 
  in 
  the 
  

   wash-bottle 
  had 
  to 
  be 
  freed 
  from 
  CO2 
  by 
  boiling 
  and 
  then 
  

   protected 
  by 
  a 
  tube 
  of 
  soda-lime 
  to 
  prevent 
  its 
  contamination 
  

   with 
  CO2 
  from 
  the 
  air 
  or 
  through 
  our 
  blowing, 
  the 
  total 
  

   amount 
  of 
  wash 
  -water 
  used 
  for 
  each 
  titration 
  had 
  to 
  be 
  kept 
  

   the 
  same 
  in 
  each 
  experiment, 
  and 
  the 
  water 
  itself 
  had 
  to 
  be 
  

   titrated 
  and 
  the 
  samples 
  freed 
  from 
  CO2 
  before 
  titration 
  by 
  

   boiling. 
  As 
  rapid 
  stirring 
  mixes 
  energetically 
  the 
  solution 
  with 
  

   the 
  air 
  containing 
  COo, 
  and 
  the 
  experiment 
  lasts 
  for 
  several 
  

   hours, 
  the 
  water 
  in 
  the 
  beaker 
  had 
  to 
  be 
  protected 
  against 
  

   contamination 
  with 
  CO2, 
  as 
  shown 
  in 
  fig. 
  1 
  (PI. 
  XVIII.). 
  

   The 
  glass 
  cylinder 
  was 
  closed 
  up 
  with 
  a 
  thick 
  ebonite 
  piece 
  and 
  

   sealed 
  up 
  with 
  Crooks' 
  cement 
  between 
  glass 
  and 
  ebonite. 
  

   In 
  the 
  ebonite 
  piece 
  a 
  circle 
  was 
  eccentrically 
  cut 
  out 
  to 
  

   allow 
  the 
  blades 
  of 
  the 
  stirrer 
  mixing 
  the 
  solution 
  to 
  pass 
  

   through 
  it 
  into 
  the 
  beaker. 
  A 
  deep 
  circular 
  groove 
  17 
  mm. 
  

   wide 
  was 
  cut 
  out 
  in 
  the 
  remaining 
  ring, 
  concentric 
  with 
  

   the 
  cut-out 
  circle 
  ; 
  to 
  the 
  stem 
  of 
  the 
  stirrer 
  a 
  circular 
  lid 
  

   with 
  a 
  deep 
  projecting 
  circular 
  rib 
  7 
  mm, 
  thick, 
  cut 
  out 
  of 
  

   one 
  piece 
  of 
  ebonite, 
  was 
  fixed, 
  and 
  the 
  stirrer 
  was 
  fixed 
  so 
  

   that 
  the 
  circular 
  rib 
  entered 
  deep 
  into 
  the 
  groove, 
  leaving 
  

   5 
  mm. 
  free 
  space 
  all 
  round 
  without 
  touching 
  the 
  circular 
  

   ring 
  at 
  the 
  bottom 
  ; 
  this 
  groove 
  was 
  filled 
  with 
  distilled 
  

   water 
  sufficient 
  to 
  form 
  a 
  secure 
  seal 
  with 
  the 
  rotating 
  

   circular 
  rib 
  of 
  the 
  lid 
  of 
  the 
  stirrer, 
  and 
  the 
  stirrer 
  was 
  thus 
  

   always 
  kept 
  in 
  the 
  same 
  position 
  in 
  the 
  beaker. 
  None 
  of 
  

   these 
  very 
  necessary 
  precautions 
  in 
  the 
  titration 
  were 
  taken 
  

   by 
  Nernst 
  and 
  Brunner, 
  Bruner 
  and 
  Tolloczko, 
  and 
  others. 
  

  

  All 
  the 
  above 
  precautions 
  in 
  the 
  preparation 
  of 
  the 
  blocks, 
  

   in 
  the 
  arrangement 
  of 
  constant 
  speeds, 
  in 
  the 
  titration 
  &c., 
  

   I 
  had 
  to 
  take 
  before 
  I 
  was 
  able 
  to 
  get 
  the 
  constants, 
  as 
  I 
  give 
  

   them 
  in 
  this 
  paper, 
  which 
  are 
  considerably 
  worse 
  than 
  those 
  

   supplied 
  by 
  Nernst 
  and 
  Brunner 
  and 
  others. 
  It 
  is 
  true, 
  

   Nernst 
  and 
  Brunner 
  tell 
  us, 
  that 
  " 
  the 
  greater 
  variations 
  ol 
  

   A 
  were 
  omitted 
  if 
  they 
  differed 
  much 
  from 
  the 
  rest," 
  but 
  

  

  