﻿932 
  Dr. 
  J. 
  W. 
  McBaiii 
  on 
  tie 
  Mechanism 
  of 
  the 
  

   Table 
  XVI. 
  

  

  Eemarks. 
  

  

  Time. 
  

  

  Pressure. 
  

  

  Difference. 
  

  

  Added 
  hydrogen 
  

  

  minute. 
  

  

  2 
  minutes. 
  

  

  9 
  „ 
  

   14 
  „ 
  

   23 
  

   45 
  

  

  4 
  hours. 
  

  

  142-9 
  mm. 
  

   142-5 
  „ 
  

   142-3 
  „ 
  

   1421 
  „ 
  

   141-9 
  „ 
  

   141-9 
  „ 
  

  

  — 
  0-4 
  mm. 
  

   -0-6 
  „ 
  

   -0-8 
  „ 
  

  

  -1-0 
  „ 
  

  

  -1-0 
  „ 
  

  

  

  Further 
  investigation 
  of 
  sorption 
  phenomena 
  at 
  room 
  

   temperature 
  was 
  not 
  undertaken. 
  The 
  question 
  as 
  to 
  

   whether 
  the 
  smalhiess 
  o£ 
  the 
  effect 
  measured 
  here 
  is 
  due 
  

   to 
  the 
  rapidity 
  of 
  diffusion 
  at 
  this 
  temperature 
  or 
  to 
  the 
  

   relative 
  unimportance 
  of 
  the 
  absorption 
  factor 
  was 
  left 
  

   untouched. 
  

  

  Discussion 
  of 
  the 
  Results. 
  

  

  The 
  main 
  thesis 
  of 
  the 
  present 
  paper 
  is 
  the 
  demonstra- 
  

   tion 
  that 
  the 
  so-called 
  adsorption 
  of 
  hydrogen 
  by 
  carbon 
  

   is 
  dual 
  in 
  its 
  nature. 
  The 
  striking 
  fact 
  upon 
  which 
  this 
  

   is 
  based 
  is 
  that 
  hydrogen 
  is 
  temporarily 
  evolved 
  from 
  

   unsaturated 
  carbon, 
  and 
  that 
  such 
  gas 
  is 
  taken 
  up 
  by 
  carbon, 
  

   which 
  is 
  known 
  to 
  be 
  already 
  supersaturated. 
  

  

  It 
  is 
  considered 
  that 
  the 
  experiments 
  disprove 
  the 
  simple 
  

   surface 
  action 
  theory. 
  Their 
  weakness 
  consists 
  in 
  the 
  fact 
  

   that 
  they 
  do 
  not 
  in 
  the 
  same 
  way 
  exclude 
  a 
  clogged 
  diffusion 
  

   hypothesis 
  *. 
  The 
  only 
  refutation 
  of 
  the 
  latter 
  that 
  it 
  seems 
  

   possible 
  to 
  bring 
  forward 
  appears 
  to 
  be, 
  first, 
  that 
  it 
  is 
  

   irreconcilable 
  with 
  the 
  known 
  laws 
  of 
  diffusion, 
  and 
  

   secondly 
  that 
  the 
  fundamental 
  assumption 
  of 
  the 
  clogged 
  

   diffusion 
  hypothesis 
  has 
  admitted 
  of 
  direct 
  experimental 
  

   disproof 
  (page 
  930), 
  for 
  this 
  assumption 
  was 
  that 
  diffusion 
  

   would 
  be 
  more 
  difficult 
  and 
  slower 
  the 
  higher 
  the 
  pressure 
  

   or 
  concentration. 
  

  

  In 
  Davis''s 
  paper 
  f 
  the 
  method 
  adopted 
  for 
  showing 
  

   the 
  co-existence 
  of 
  surface 
  action 
  and 
  solid 
  solution, 
  when 
  

   iodine 
  solutions 
  are 
  exposed 
  to 
  carbon, 
  was 
  as 
  follows 
  : 
  — 
  

   It 
  was 
  first 
  demonstrated 
  that 
  an 
  equilibrium 
  of 
  some 
  type 
  

  

  * 
  See, 
  for 
  example, 
  Zacharias, 
  Zeitschr. 
  physikal. 
  Chem. 
  xxxix. 
  p. 
  468 
  

   (1902) 
  ; 
  Travers, 
  loc. 
  cit. 
  ; 
  compare 
  Zeitschr. 
  physikal. 
  Chem. 
  Ixi. 
  p. 
  241 
  

   (1907). 
  

  

  