﻿Osmosis 
  and 
  Osmotic 
  Pressure. 
  

  

  401 
  

  

  1 
  Exp. 
  

  

  dm. 
  

  

  »■ 
  

  

  T«. 
  

  

  -r. 
  

  

  Q- 
  

  

  7T 
  '. 
  

  

  Oxs. 
  

  

  to. 
  

  

  la 
  ... 
  

  

  10041 
  

  

  1-618 
  

  

  283-6 
  

  

  0-0060 
  

  

  13-68 
  

  

  12-48 
  

  

  161-7 
  

  

  10-3 
  

  

  lb 
  ... 
  

  

  10-247 
  

  

  1-653 
  

  

  282-9 
  

  

  0-0060 
  

  

  13-36 
  

  

  12-15 
  

  

  159-9 
  

  

  

  

  9 
  

  

  5-645 
  

  

  0-8958 
  

  

  282-5 
  

  

  0-0097 
  

  

  24-55 
  

  

  23-17 
  

  

  268-9 
  

  

  9-25 
  

  

  3 
  

  

  3-367 
  

  

  0-5261 
  

  

  280-4 
  

  

  0-0149 
  

  

  41-26 
  

  

  39*85 
  

  

  396-2 
  

  

  7-0 
  

  

  a 
  m 
  = 
  manometer 
  reading 
  corresponding 
  to 
  apparent 
  equilibrium, 
  

   C 
  15 
  = 
  concentration 
  corresponding 
  to 
  15° 
  C. 
  

   T 
  TO 
  =absolute 
  temperature 
  of 
  the 
  air 
  in 
  the 
  manometer. 
  

  

  Experiments 
  by 
  the 
  Second 
  Method. 
  

  

  13. 
  In 
  these 
  experiments 
  the 
  pressure, 
  bj 
  means 
  o£ 
  the 
  

   compressor, 
  was 
  given 
  a 
  certain 
  value 
  and 
  the 
  corresponding- 
  

   velocity 
  X' 
  was 
  observed. 
  The 
  reversion 
  pressure 
  was 
  deter- 
  

   mined 
  by 
  measuring 
  velocities 
  on 
  both 
  sides 
  of 
  the 
  equilibrium 
  

   point. 
  As 
  a 
  liquid 
  for 
  the 
  compressor 
  I 
  used 
  the 
  same 
  solu- 
  

   tion 
  as 
  used 
  in 
  the 
  osmometer. 
  

  

  On 
  account 
  of 
  the 
  osmotic 
  flow 
  or 
  other 
  causes 
  the 
  pressure 
  

   will 
  not 
  keep 
  quite 
  constant, 
  and 
  as 
  it 
  is 
  impossible 
  to 
  get 
  

   the 
  cell 
  arrangement 
  quite 
  stable 
  the 
  change 
  of 
  pressure 
  will 
  

   call 
  forth 
  a 
  small 
  variation 
  of 
  the 
  water-level 
  in 
  the 
  capillary. 
  

  

  In 
  order 
  to 
  find 
  the 
  velocity 
  corresponding 
  to 
  a 
  constant 
  

   pressure 
  we 
  can 
  employ 
  two 
  different 
  methods 
  : 
  — 
  

  

  (1) 
  By 
  means 
  of 
  the 
  compressor 
  we 
  can 
  on 
  an 
  average 
  

   keep 
  a 
  constant 
  pressure, 
  which 
  can 
  be 
  done 
  by 
  keeping 
  the 
  

   mercury 
  column 
  on 
  an 
  average 
  upon 
  a 
  certain 
  mark. 
  We 
  

   can 
  always 
  here 
  arrange 
  matters 
  so 
  that 
  the 
  position 
  of 
  the 
  

   water-level 
  at 
  the 
  beginning 
  and 
  end 
  is 
  read 
  by 
  the 
  same 
  

   pressure. 
  This 
  method 
  wants 
  no 
  corrections, 
  and 
  it 
  is 
  

   especially 
  to 
  be 
  recommended 
  for 
  measurements 
  far 
  from 
  the 
  

   equilibrium 
  point. 
  

  

  (2) 
  Near 
  to 
  the 
  reversion 
  point 
  it 
  will 
  be 
  better 
  to 
  use 
  

   another 
  method, 
  as 
  the 
  variation 
  here 
  is 
  generally 
  very 
  

   small. 
  The 
  positions 
  of 
  the 
  mercury 
  column 
  and 
  water-level 
  

   are 
  observed 
  at 
  the 
  beginning 
  and 
  end 
  of 
  a 
  certain 
  time. 
  

  

  Assume 
  that 
  the 
  readings 
  of 
  mercury 
  column 
  are 
  a 
  1 
  and 
  

   a 
  x 
  -\-k.a 
  x 
  mm. 
  , 
  

  

  Assume 
  that 
  the 
  readings 
  of 
  water-level 
  are 
  b 
  x 
  and 
  b 
  2 
  mm. 
  

   Then 
  we 
  have 
  that 
  the 
  pressure 
  corresponding 
  to 
  a 
  reading 
  

  

  , 
  Aa, 
  -, 
  , 
  , 
  ... 
  b.-,*— 
  fri+eAai 
  

   a 
  x 
  -f 
  -~- 
  corresponds 
  to 
  a 
  velocity 
  — 
  . 
  

  

  t 
  is 
  the 
  time 
  and 
  e 
  is 
  the 
  change 
  of 
  water-level 
  for 
  the 
  

   Phil. 
  Mag. 
  S. 
  6. 
  Vol. 
  16. 
  No. 
  93. 
  Sept. 
  1908. 
  2 
  E 
  

  

  