﻿924 
  Dr. 
  J. 
  W. 
  McBain 
  on 
  the 
  Meclianism 
  of 
  the 
  

  

  /(37-70\3 
  

   have 
  been 
  17'9( 
  ^^ 
  .. 
  i 
  =16*3 
  mm. 
  The 
  maximum 
  pressure 
  

  

  was 
  25*2 
  mm. 
  If 
  the 
  (equilibrium!) 
  formula 
  ^p 
  = 
  kx 
  be 
  

   employed 
  a 
  value 
  is 
  obtained 
  for 
  the 
  ratio 
  of 
  the 
  amount 
  of 
  

   gas 
  on 
  the 
  surface 
  at 
  the 
  end 
  o£ 
  the 
  exponent 
  to 
  that 
  on 
  

  

  the 
  surface 
  at 
  the 
  beginning 
  a 
  / 
  — 
  ^ 
  = 
  86*5 
  per 
  cent, 
  

   approximately. 
  *^ 
  ^^'^ 
  

  

  Hence 
  13*5 
  per 
  cent, 
  of 
  the 
  final 
  sorhed 
  gas 
  is 
  in 
  a 
  state 
  of 
  

   solid 
  solution. 
  13*5 
  per 
  cent, 
  x 
  67'70 
  c.c. 
  (corr.) 
  = 
  9'l 
  c.c. 
  

   (corr.) 
  for 
  2*293 
  g. 
  carbon. 
  That 
  is, 
  the 
  solubility 
  of 
  hydrogen 
  

   in 
  coconut 
  carbon 
  is 
  roughly 
  4*0 
  ex, 
  {corr?) 
  per 
  gram 
  at 
  a 
  

   pi^essure 
  of 
  19 
  mm. 
  and 
  at 
  the 
  temperature 
  of 
  liquid 
  air. 
  

   These 
  values 
  are 
  certainly 
  too 
  small, 
  for 
  the 
  maximum 
  

   pressure 
  is 
  not 
  entirely 
  due 
  to 
  surface-gas, 
  and 
  the 
  minimum 
  

   pressure 
  would 
  have 
  still 
  further 
  decreased 
  with 
  time 
  at 
  a 
  

   truly 
  constant 
  temperature. 
  

  

  Table 
  VI. 
  gives 
  the 
  total 
  amount 
  of 
  gas 
  sorbed 
  by 
  the 
  

   carbon 
  at 
  7 
  and 
  275 
  minutes 
  respectively, 
  as 
  56*70 
  c.c. 
  (corr.) 
  

   and 
  57*02 
  c.c. 
  (corr.). 
  The 
  minimum 
  pressure 
  is 
  15'7 
  mm., 
  

   and 
  after 
  temperature 
  corrections 
  15*5 
  mm., 
  and 
  this 
  cor- 
  

   rected 
  for 
  the 
  new 
  gas 
  taken 
  up 
  becomes 
  15*2 
  mm. 
  The 
  

   ratio 
  between 
  the 
  amounts 
  of 
  surface 
  hydrogen 
  at 
  the 
  end 
  

   and 
  the 
  beginning 
  is 
  therefore 
  93*7 
  percent. 
  Since 
  2*293 
  g. 
  

   carbon 
  was 
  used 
  the 
  dissolved 
  hydrogen 
  is 
  1*6 
  c.c. 
  (corr.) 
  

   per 
  gram 
  under 
  a 
  pressure 
  of 
  15*5 
  mm. 
  If 
  the 
  dissolved 
  

   hydrogen 
  be 
  proportional 
  to 
  the 
  square 
  root 
  of 
  the 
  pressure 
  

   (see 
  later) 
  the 
  value 
  calculated 
  for 
  19 
  mm. 
  from 
  the 
  above 
  

   results 
  amounts 
  to 
  1*8 
  c.c. 
  (corr.). 
  From 
  the 
  conditions 
  of 
  

   the 
  experiments 
  the 
  result 
  obtained 
  from 
  Table 
  VII. 
  must 
  

   be 
  very 
  much 
  nearer 
  the 
  true 
  value. 
  Consequently, 
  it 
  

   appears 
  that 
  the 
  order 
  of 
  magnitude 
  of 
  the 
  solubility 
  of 
  

   hydrogen 
  at 
  19 
  mm. 
  at 
  the 
  temperature 
  of 
  liquid 
  air 
  is 
  

   4 
  c.c. 
  (corr.) 
  per 
  gram 
  of 
  coconut 
  carbon. 
  

  

  Supersaturated 
  Interior. 
  Bare 
  Surface. 
  

  

  It 
  appeared 
  to 
  the 
  author 
  that 
  the 
  best 
  check 
  upon 
  the 
  

   explanation 
  of 
  the 
  qualitative 
  phenomena 
  studied 
  above 
  would 
  

   be 
  to 
  attempt 
  to 
  produce 
  the 
  pressure 
  changes 
  in 
  the 
  inverse 
  

   sense. 
  This 
  is 
  possible 
  if 
  the 
  carbon 
  by 
  long 
  contact 
  is 
  

   allowed 
  to 
  become 
  saturated 
  with 
  hydrogen. 
  Now 
  when 
  

   this 
  carbon 
  is 
  quickly 
  exposed 
  to 
  a 
  much 
  lower 
  pressure 
  the 
  

   surface 
  at 
  once 
  gives 
  up 
  its 
  hydrogen, 
  w^hile 
  the 
  diffusion 
  

   of 
  the 
  dissolved 
  gas 
  requires 
  time. 
  

  

  Thus 
  we 
  have 
  carbon 
  wath 
  empty 
  surface 
  and 
  supersaturated 
  

  

  