﻿560 
  Dr. 
  Meyer 
  Wilderman 
  on 
  Velocity 
  of 
  Molecular 
  

  

  than 
  in 
  water 
  ; 
  B, 
  i£ 
  it 
  existed 
  at 
  all, 
  is 
  evidently 
  much 
  smaller 
  

   than 
  in 
  solution 
  (we 
  look 
  away 
  from 
  the 
  fact 
  that 
  it 
  is 
  incon- 
  

   ceivable 
  that 
  a 
  layer 
  of 
  gas 
  should 
  be 
  formed 
  near 
  the 
  solid 
  

   the 
  molecules 
  of 
  which 
  cannot 
  move 
  into 
  the 
  rest 
  of 
  the 
  

   gaseous 
  space, 
  or 
  that 
  the 
  gas 
  from 
  the 
  total 
  volume 
  should 
  

   not 
  be 
  capable 
  to 
  reach 
  the 
  solid). 
  In 
  view 
  of 
  the 
  above 
  

   equation 
  for 
  solution, 
  the 
  velocity 
  of 
  evaporation 
  ought 
  to 
  go 
  

   on 
  with 
  an 
  infinitely 
  greater 
  speed 
  than 
  velocity 
  of 
  solution. 
  

   We 
  find, 
  however, 
  on 
  the 
  contrary, 
  that 
  the 
  speed 
  of 
  evapo- 
  

   ration 
  of 
  liquids 
  and 
  solids 
  belongs 
  in 
  comparison 
  to 
  the 
  slow 
  

   reactions, 
  as 
  is 
  to 
  be 
  seen 
  already 
  from 
  the 
  fact 
  how 
  difficult 
  

   it 
  is 
  to 
  reach 
  the 
  maximum 
  of 
  vapour-pressure 
  in 
  all 
  the 
  

   researches. 
  

  

  This 
  is 
  a 
  further 
  proof 
  against 
  the 
  diffusion 
  conceptions. 
  

  

  (g) 
  I 
  shall 
  next 
  deal 
  with 
  the 
  variation 
  of 
  the 
  constant 
  A 
  

   with 
  the 
  number 
  of 
  revolutions 
  of 
  the 
  stirrer. 
  There 
  is 
  no 
  

   reason 
  why 
  the 
  ordinary 
  velocity-constant 
  should 
  not 
  change 
  

   with 
  the 
  speed 
  of 
  the 
  stirrer, 
  considering 
  that 
  it 
  does 
  so 
  

   enormously 
  change 
  with 
  the 
  solvent, 
  with 
  the 
  size 
  and 
  

   dimensions 
  of 
  the 
  apparatus 
  and 
  other 
  mechanical 
  conditions, 
  

   but 
  whatever 
  its 
  cause, 
  I 
  will 
  show, 
  however, 
  that 
  this 
  

   variation 
  of 
  the 
  velocity-constant 
  with 
  the 
  number 
  of 
  revo- 
  

   lutions 
  proves, 
  if 
  anything, 
  the 
  imj)rol>al>iUty 
  of 
  the 
  diffusion 
  

   conceptions 
  of 
  Nernst 
  and 
  Brunner. 
  Formerly 
  Tolloczko 
  and 
  

   Bruner 
  found 
  by 
  the 
  very 
  same 
  method 
  which 
  Nernst 
  and 
  

   Brunner 
  use, 
  that 
  the 
  speed 
  of 
  solution 
  of 
  the 
  same 
  benzoic 
  

   acid 
  is 
  directly 
  proportional 
  to 
  the 
  speed 
  of 
  stirring 
  — 
  a 
  rate 
  

   of 
  variation 
  vdiich 
  does 
  not 
  seem 
  probable 
  for 
  the 
  layer 
  S. 
  

   Nernst 
  and 
  Brunner 
  seem 
  to 
  have 
  got 
  at 
  first 
  the 
  same 
  results, 
  

   but 
  they 
  tell 
  us 
  that 
  this 
  was 
  due 
  to 
  some 
  cracks 
  at 
  the 
  rims 
  

   of 
  the 
  acid, 
  and 
  that 
  as 
  soon 
  as 
  these 
  cracks 
  were 
  filled 
  up 
  

   with 
  paraffin 
  the 
  value 
  of 
  A 
  changed 
  as 
  the 
  two-thirds 
  power 
  

   of 
  the 
  speed 
  of 
  the 
  stirrer. 
  It 
  will, 
  however, 
  be 
  seen 
  from 
  the 
  

   details 
  of 
  the 
  method 
  used 
  by 
  Nernst 
  and 
  Brunner 
  (dealt 
  with 
  

   in 
  § 
  2) 
  and 
  from 
  the 
  photographs 
  of 
  the 
  benzoic 
  acid 
  which 
  

   I 
  obtained 
  by 
  their 
  method, 
  that 
  their 
  benzoic 
  acid 
  was 
  never 
  

   free 
  from 
  holes, 
  that 
  the 
  speed 
  of 
  their 
  motor 
  changed 
  too 
  

   considerably 
  for 
  accurate 
  measurements 
  to 
  be 
  carried 
  out 
  in 
  

   this 
  region, 
  and 
  that 
  even 
  their 
  titrations 
  were 
  not 
  arranged 
  

   accurately 
  enough 
  for 
  the 
  very 
  dilute 
  solutions 
  they 
  dealt 
  

   with. 
  With 
  such 
  a 
  method 
  they 
  nevertheless 
  changed 
  the 
  

   variations 
  of 
  speed 
  (see 
  pp. 
  60-61) 
  of 
  their 
  stirrer 
  only 
  from 
  

   144 
  to 
  202 
  and 
  from 
  135 
  to 
  180, 
  i. 
  e. 
  only 
  by 
  25 
  to 
  '30 
  per 
  

   cent., 
  which 
  is 
  not 
  enough 
  to 
  distinguish 
  between 
  the 
  results 
  

   calculated 
  after 
  one 
  equation 
  or 
  the 
  other, 
  even 
  when 
  the 
  

  

  