﻿and 
  Chemical 
  Reactions 
  in 
  Heterogeneous 
  Systems. 
  567 
  

  

  a 
  small 
  fraction 
  of 
  a 
  per 
  cent. 
  As 
  the 
  assumption 
  that 
  the 
  

   stirring 
  should 
  produce 
  such 
  a 
  variation 
  in 
  the 
  diffusion- 
  

   layer 
  is 
  not 
  at 
  all 
  probable, 
  this 
  certainly 
  is, 
  in 
  my 
  opinion, 
  

   a 
  proof 
  against 
  the 
  diffusion 
  theory. 
  

  

  2. 
  Up 
  to 
  about 
  3 
  revolutions 
  of 
  the 
  stirrer, 
  the 
  increase 
  

   of 
  A 
  is 
  greater 
  than 
  in 
  direct 
  proportion 
  to 
  the 
  number 
  of 
  

   revolutions, 
  as 
  the 
  same 
  follows 
  from 
  the 
  curve 
  between 
  3^ 
  

   and 
  180 
  revolutions 
  ; 
  the 
  preponderating 
  effect 
  of 
  stirring 
  

   over 
  that 
  of 
  diffusion 
  is 
  seen 
  even 
  at 
  these 
  slow 
  speeds 
  ; 
  the 
  

   speed 
  of 
  solution 
  is 
  here 
  due 
  to 
  stirring 
  and 
  to 
  diffusion, 
  and 
  

   the 
  last 
  cannot 
  yet 
  be 
  neglected. 
  

  

  3. 
  From 
  about 
  3 
  revolutions 
  to 
  about 
  180 
  revolutions 
  the 
  

   value 
  of 
  A 
  is 
  directly 
  proportional 
  to 
  the 
  number 
  of 
  revolu- 
  

   tions 
  of 
  the 
  stirrer 
  (into 
  this 
  region 
  fall 
  the 
  investigations 
  of 
  

   Bruner 
  and 
  Tolloczko 
  under 
  their 
  experimental 
  conditions, 
  

   who 
  found 
  the 
  same 
  result). 
  Thus 
  from 
  about 
  3 
  revolutions 
  

   already 
  the 
  value 
  of 
  transportation 
  due 
  to 
  diffusion 
  no 
  longer 
  

   interferes 
  with 
  the 
  value 
  of 
  speed 
  of 
  solution, 
  as 
  effected 
  by 
  

   stirring 
  only. 
  

  

  4. 
  From 
  about 
  180 
  to 
  about 
  400 
  revolutions, 
  the 
  increase 
  

   in 
  the 
  value 
  of 
  A 
  first 
  gradually 
  becomes 
  smaller, 
  until 
  it 
  

   becomes 
  independent 
  of 
  the 
  number 
  of 
  revolutions 
  of 
  the 
  

   stirrer, 
  i. 
  e. 
  the 
  maximum 
  value 
  for 
  A 
  has 
  been 
  reached. 
  

   Into 
  this 
  region 
  fall 
  the 
  experiments 
  of 
  Lorenz 
  and 
  Siegrist 
  

   under 
  their 
  experimental 
  conditions. 
  

  

  It 
  is, 
  however, 
  evident 
  that 
  the 
  more 
  soluble 
  a 
  substance 
  is,, 
  

   the 
  less 
  will 
  be 
  the 
  number 
  of 
  revolutions 
  requisite 
  to 
  reach 
  

   a 
  constant 
  maximum 
  value 
  of 
  A'. 
  

  

  Nernst 
  and 
  Brunner^s 
  idea 
  that 
  diffusion 
  is 
  the 
  sole 
  factor 
  

   in 
  transportation 
  of 
  benzoic 
  acid 
  from 
  the 
  surface 
  of 
  the 
  

   solid 
  to 
  the 
  rest 
  of 
  the 
  solution 
  is, 
  in 
  my 
  opinion, 
  in 
  no 
  way 
  

   supported 
  by 
  the 
  character 
  of 
  the 
  above 
  results 
  ; 
  quite 
  the 
  

   contrary. 
  One 
  or 
  two 
  revolutions 
  of 
  the 
  stirrer 
  already 
  trans- 
  

   ports 
  considerably 
  more 
  than 
  the 
  whole 
  process 
  of 
  diffusion 
  

   can 
  possibly 
  do 
  alone 
  without 
  stirring 
  ; 
  and 
  I 
  fail 
  to 
  see 
  any 
  

   reasonable 
  support, 
  any 
  reliable 
  proof, 
  that 
  diffusion 
  alone 
  

   should 
  be 
  operative 
  and 
  that 
  as 
  such 
  it 
  should 
  be 
  (owing 
  to 
  

   variation 
  of 
  8) 
  accelerated 
  by 
  stirring 
  to 
  such 
  an 
  enormous 
  

   extent 
  instead 
  of 
  being 
  more 
  or 
  less 
  destroyed 
  by 
  the 
  same, 
  

   owing 
  to 
  the 
  destruction 
  of 
  the 
  drop 
  in 
  concentration 
  near 
  the 
  

   surface 
  of 
  the 
  solid, 
  which 
  is 
  naturally 
  formed 
  when 
  the 
  liquid 
  

   is 
  not 
  stirred 
  at 
  all. 
  Indeed, 
  as 
  already 
  mentioned, 
  there 
  

   is 
  nothing 
  to 
  prevent 
  the 
  stirrer 
  from 
  mixing 
  the 
  liquid 
  up 
  

   to 
  the 
  very 
  solid, 
  and 
  if 
  the 
  liquid 
  can 
  reach 
  the 
  solid 
  during 
  

  

  