﻿Adsorption 
  of 
  Hydrogen 
  l>i/ 
  ( 
  arbon. 
  933 
  

  

  could 
  be 
  attained 
  in 
  a 
  short 
  time 
  ; 
  for 
  the 
  amount 
  of 
  sorption 
  

   after 
  a 
  day 
  was 
  the 
  same 
  when 
  approached 
  from 
  both 
  

   directions 
  (supersaturation 
  and 
  nnsaturation), 
  a 
  phenomenon 
  

   which 
  is 
  characteristic 
  for 
  all 
  equilibria. 
  

  

  This 
  equilibrium 
  point 
  lay, 
  however, 
  appreciably 
  below 
  

   the 
  finul 
  saturation 
  value 
  attained 
  after 
  several 
  weeks. 
  

   Hence 
  the 
  first 
  equilibrium 
  value 
  was 
  referred 
  to 
  surface 
  

   condensation, 
  and 
  the 
  after 
  increase 
  was 
  ascribed 
  to 
  diffusion. 
  

   It 
  should 
  be 
  mentioned 
  that 
  in 
  these 
  experiments 
  with 
  iodine 
  as 
  

   in 
  those 
  with 
  hvdroojen 
  the 
  diffusion 
  effect 
  is 
  areater 
  than 
  ifc 
  at 
  

   first 
  seems 
  ; 
  for 
  it 
  is 
  partlv 
  masked 
  by 
  the 
  necessary 
  simul- 
  

   taneous 
  transfer 
  of 
  some 
  of 
  the 
  surface 
  accumulation 
  into 
  tlie 
  

   interior, 
  as 
  the 
  concentration 
  of 
  the 
  liquid 
  iodine 
  solution 
  falls 
  

   off. 
  

  

  This 
  method 
  was 
  not 
  employed 
  in 
  the 
  experiments 
  with 
  

   hydrogen, 
  for 
  it 
  would 
  demand 
  a 
  thermostat 
  of 
  accurately 
  

   reproducible 
  and 
  sen-;ibly 
  constant 
  temperature, 
  such 
  as 
  

   furnished 
  by 
  liquid 
  oxygen. 
  

  

  The 
  weak 
  point 
  in 
  Davis's 
  proof 
  lay 
  in 
  the 
  fact 
  that 
  

   the 
  after 
  diffusion 
  effect 
  could 
  be 
  ascribed 
  to 
  pores 
  and 
  fine 
  

   cavities 
  in 
  the 
  carbon 
  employed. 
  Consider 
  a 
  tiny 
  cavern 
  in 
  

   the 
  carbon, 
  having 
  a 
  relatively 
  very 
  small 
  entrance. 
  As 
  

   soon 
  as 
  the 
  carbon 
  was 
  wetted, 
  the 
  cavern 
  would 
  probably 
  

   become 
  filled 
  with 
  solution. 
  Practically 
  at 
  once 
  the 
  walls 
  of 
  

   this 
  cavity 
  would 
  become 
  permeated 
  with 
  surface 
  condensa- 
  

   tion 
  of 
  iodine. 
  But 
  the 
  amount 
  of 
  carbon 
  surface 
  which 
  

   would 
  have 
  to 
  be 
  supplied 
  with 
  iodine 
  from 
  the 
  small 
  amount 
  

   of 
  enclosed 
  solution 
  might 
  easilv 
  be 
  relatively 
  much 
  greater 
  

   than 
  the 
  total 
  carbon 
  surface 
  which 
  was 
  supplied 
  from 
  the 
  

   total 
  iodine 
  solution 
  in 
  the 
  vessel. 
  Thus 
  the 
  minute 
  amount 
  

   of 
  solution 
  in 
  the 
  enclosure 
  would 
  become 
  very 
  much 
  weaker 
  

   than 
  the 
  main 
  bulk 
  of 
  the 
  solution. 
  Since 
  the 
  only 
  commu- 
  

   nication 
  with 
  the 
  body 
  of 
  the 
  liquid 
  outside 
  w^ould 
  be 
  through 
  

   the 
  small 
  opening 
  of 
  the 
  pore 
  or 
  cavity 
  it 
  follows 
  that 
  a 
  slow 
  

   diffusion 
  would 
  take 
  place, 
  bul 
  it 
  would 
  be 
  diffusion 
  through 
  

   the 
  liquid 
  enclosed 
  in 
  the 
  pores. 
  

  

  But 
  the 
  whole 
  purpose 
  of 
  the 
  method 
  is 
  to 
  ascribe 
  this 
  after 
  

   difiiision 
  effect 
  to 
  diffusion 
  in 
  t\ie. 
  solid 
  carbon 
  phase. 
  Conse- 
  

   quently 
  the 
  existence 
  of 
  this 
  possible 
  objection 
  must 
  be 
  taken 
  

   into 
  account. 
  It 
  is 
  true 
  that 
  experiments 
  might 
  be 
  carried 
  

   out 
  on 
  finely 
  pulverised 
  carbon, 
  and 
  where 
  the 
  pores 
  were 
  

   excessively 
  small 
  (molecular 
  dimensions) 
  the 
  objection 
  would 
  

   fall 
  to 
  the 
  ground, 
  as 
  diffusion 
  would 
  then 
  become 
  nearly 
  

   instantaneous. 
  

  

  It 
  is, 
  however, 
  satisfactory 
  that 
  such 
  objection 
  cannot 
  be 
  

   Phil 
  May, 
  S. 
  t;. 
  Vol. 
  1«. 
  No. 
  108. 
  Dec, 
  1909, 
  3 
  K 
  

  

  