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  XIX. 
  Researches 
  upon 
  Osmosis 
  and 
  Osmotic 
  Pressure. 
  By 
  

   L. 
  Yegard, 
  Cand. 
  real. 
  (Research 
  Student 
  at 
  the 
  Cavendish 
  

   Laboratory, 
  Cambridge) 
  *. 
  

  

  [Plate 
  VIII.] 
  

  

  Introduction. 
  

  

  1. 
  npHE 
  following 
  paper 
  gives 
  some 
  results 
  obtained 
  from 
  

   JL 
  a 
  series 
  of 
  investigations 
  upon 
  osmotic 
  properties 
  

   Most 
  of 
  the 
  work 
  has 
  been 
  done 
  at 
  the 
  Physical 
  Institute, 
  

   Christiania; 
  but 
  some 
  experiments 
  carried 
  out 
  at 
  the 
  Cavendish 
  

   Laboratory 
  are 
  also 
  included. 
  

  

  These 
  researches 
  have 
  been 
  going 
  on 
  for 
  about 
  two 
  year-, 
  

   as 
  the 
  construction 
  of 
  the 
  cells 
  and 
  first 
  pieces 
  of 
  apparatus 
  

   was 
  done 
  as 
  early 
  as 
  in 
  March 
  1906. 
  The 
  reason 
  why 
  such 
  

   a 
  considerable 
  time 
  has 
  been 
  required 
  to 
  obtain 
  the 
  results 
  is 
  

   due 
  to 
  several 
  circumstances. 
  In 
  the 
  first 
  place 
  the 
  difficulties 
  

   to 
  be 
  dealt 
  with 
  were 
  greater 
  than 
  anticipated, 
  and 
  secondly, 
  

   for 
  most 
  of 
  the 
  time 
  I 
  had 
  only 
  a 
  few 
  hours 
  of 
  the 
  day 
  to 
  

   devote 
  to 
  the 
  work. 
  The 
  greater 
  part 
  of 
  this 
  time 
  has 
  been 
  

   spent 
  in 
  preparing 
  the 
  cells 
  and 
  working 
  out 
  the 
  method, 
  

   and 
  most 
  of 
  the 
  experiments 
  have 
  been 
  made 
  during 
  the 
  past 
  

   autumn 
  and 
  winter. 
  

  

  During 
  the 
  experiments 
  I 
  have 
  had 
  the 
  advantage 
  of 
  

   gathering 
  experience 
  from 
  the 
  works 
  of 
  Morse 
  and 
  Frazer 
  f 
  , 
  

   and 
  later 
  from 
  the 
  work 
  by 
  Berkeley 
  and 
  Hartley 
  ±. 
  

  

  Besides 
  a 
  description 
  of 
  the 
  method 
  used, 
  the 
  paper 
  will 
  

   deal 
  with 
  the 
  following 
  subjects 
  : 
  — 
  

  

  1. 
  A 
  study 
  of 
  the 
  properties 
  of 
  the 
  membrane 
  by 
  its 
  

  

  behaviour 
  for 
  electric 
  currents. 
  

  

  2. 
  General 
  theoretical 
  considerations 
  as 
  to 
  the 
  direct 
  

  

  measurements 
  of 
  osmotic 
  pressure. 
  

  

  3. 
  Measurements 
  of 
  the 
  equilibrium 
  pressure 
  for 
  the 
  cane- 
  

  

  sugar 
  solutions. 
  

  

  4z. 
  Experimental 
  determination 
  of 
  the 
  velocities 
  of 
  osmotic 
  

   flow 
  corresponding 
  to 
  different 
  pressures. 
  (Velocity- 
  

   Curves.) 
  

  

  5. 
  The 
  effect 
  of 
  temperature 
  upon 
  the 
  reversion 
  pressure 
  

  

  (O- 
  

  

  * 
  Communicated 
  by 
  Prof. 
  J. 
  J. 
  Thomson, 
  F.R.S. 
  

  

  t 
  H. 
  N. 
  Morse 
  and 
  J. 
  C. 
  W. 
  Frazer: 
  "The 
  Preparation 
  of 
  Cells 
  for 
  

   Measurements 
  of 
  High. 
  Osni. 
  Press./' 
  Am. 
  Ch. 
  Journ. 
  July 
  1902 
  ; 
  

   ' 
  ; 
  The 
  Osm. 
  Press, 
  and 
  Freezing-points 
  of 
  Solutions 
  of 
  Cane 
  Sugar," 
  Am. 
  

   Ch. 
  Journ. 
  Julv 
  1905. 
  

  

  t 
  Earl 
  of 
  Berkeley 
  and 
  E. 
  G. 
  J. 
  Hartley 
  : 
  " 
  On 
  the 
  Osm. 
  Press, 
  of 
  

   some 
  Concentrated 
  Aqueous 
  Solutions," 
  Phil. 
  Trans, 
  of 
  R. 
  S. 
  London, 
  

   series 
  A, 
  vol. 
  ccvi. 
  pp. 
  481-507. 
  

  

  