﻿of 
  a 
  Heterogeneous 
  Reaction. 
  455 
  

  

  tively 
  insignificant 
  difference. 
  At 
  the 
  other 
  temperatures 
  this 
  

   procedure 
  has 
  not 
  been 
  followed, 
  but 
  all 
  experiments 
  not 
  evi- 
  

   dently 
  faulty 
  have 
  been 
  included 
  in 
  the 
  table. 
  

  

  While 
  working 
  at 
  55°, 
  the 
  last 
  temperature 
  to 
  be 
  studied, 
  

   the 
  beaker 
  used 
  as 
  reaction 
  vessel 
  was 
  unfortunately 
  broken, 
  

   after 
  only 
  one 
  experiment 
  (No. 
  27) 
  had 
  been 
  made. 
  Although 
  

   a 
  new 
  beaker 
  was 
  procured 
  which 
  had 
  very 
  nearly 
  the 
  same 
  

   dimensions 
  it 
  was 
  found 
  by 
  a 
  series 
  of 
  careful 
  determinations 
  

   at 
  25° 
  that 
  the 
  value 
  of 
  K 
  (corrected) 
  was 
  7'23 
  for 
  the 
  new 
  

   beaker 
  as 
  compared 
  with 
  7"62 
  for 
  the 
  old 
  one. 
  Experiments 
  

   28 
  and 
  29, 
  at 
  55°, 
  were 
  carried 
  out 
  with 
  the 
  new 
  beaker, 
  and 
  

   the 
  observed 
  velocity 
  constants 
  have 
  therefore 
  been 
  multiplied 
  

  

  Fig. 
  l. 
  

  

  0° 
  15° 
  25° 
  35° 
  45° 
  55° 
  65° 
  

  

  TEMPERATURE 
  

  

  throughout 
  by 
  the 
  ratio 
  7*62/7'23 
  to 
  make 
  them 
  comparable 
  

   with 
  the 
  rest 
  of 
  the 
  table. 
  

  

  The 
  value 
  of 
  iTfor 
  0°, 
  3*72, 
  was 
  derived 
  by 
  a 
  short 
  extrapo- 
  

   lation 
  from 
  the 
  observed 
  value 
  for 
  +0'15°, 
  (3*74). 
  

  

  The 
  observed 
  relation 
  between 
  reaction 
  velocity 
  and 
  temper- 
  

   ature 
  is 
  shown 
  graphically 
  in 
  fig. 
  1. 
  

  

  Fhddity. 
  — 
  The 
  above 
  results 
  derive 
  much 
  of 
  their 
  interest 
  

   from 
  their 
  bearing 
  on 
  the 
  diffusion 
  theory 
  of 
  heterogeneous 
  

   reactions, 
  and 
  for 
  this 
  reason 
  the 
  change 
  in 
  the 
  fluidity 
  of 
  the 
  

   solution 
  with 
  the 
  temperature 
  was 
  also 
  measured, 
  on 
  account 
  of 
  

   its 
  possible 
  influence 
  on 
  the 
  thickness 
  of 
  the 
  diffusion 
  layer. 
  

   The 
  solution 
  used 
  was 
  made 
  up 
  to 
  approximate 
  to 
  the 
  compo- 
  

   sition 
  of 
  the 
  reaction 
  liquid 
  near 
  the 
  middle 
  of 
  an 
  average 
  

   experiment 
  of 
  Table 
  IT. 
  It 
  contained, 
  per 
  liter, 
  83*3 
  grm. 
  KI, 
  

   2-8 
  grm. 
  I 
  2 
  , 
  4 
  grm. 
  Cdl 
  2 
  , 
  and 
  Ol 
  mol 
  H 
  2 
  S0 
  4 
  . 
  

  

  Table 
  III 
  gives 
  the 
  values 
  of 
  the 
  density 
  d, 
  the 
  absolute 
  

   viscosity 
  ??, 
  and 
  the 
  fluidity 
  $, 
  for 
  this 
  solution 
  at 
  the 
  different 
  

   temperatures 
  in 
  question, 
  together 
  with 
  the 
  values 
  of 
  the 
  ratio 
  

  

  Am. 
  Jour. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  XLIII, 
  No. 
  258.— 
  June, 
  1917. 
  

   31 
  

  

  