﻿Osmosis 
  and 
  Osmotic 
  Pressure. 
  411 
  

  

  Curves 
  observed 
  in 
  the 
  Neighbourhood 
  of 
  the 
  Reversion 
  Point. 
  

  

  19. 
  The 
  velocity 
  curves 
  for 
  the 
  experiments 
  4 
  and 
  5. 
  

   (Figs.* 
  9 
  and 
  10.) 
  

  

  The 
  curve 
  fig. 
  9 
  shows 
  a 
  very 
  well-defined 
  characteristic 
  

   point 
  that 
  lies 
  close 
  up 
  to 
  the 
  reversion 
  point. 
  

  

  In 
  the 
  experiment 
  5 
  no 
  characteristic 
  point 
  is 
  observed. 
  

   From 
  the 
  bend 
  of 
  the 
  curve 
  we 
  have 
  reason 
  to 
  believe 
  that 
  it 
  

   is 
  not 
  far 
  off, 
  as 
  the 
  sudden 
  bending 
  upwards 
  is 
  very 
  cha- 
  

   racteristic 
  of 
  the 
  approach 
  to 
  the 
  point 
  of 
  discontinuity. 
  

  

  Experiment 
  IY. 
  (fig. 
  15). 
  

  

  The 
  experiment 
  is 
  represented 
  by 
  a 
  series 
  of 
  curves 
  in 
  the 
  

   neighbourhood 
  of 
  the 
  equilibrium 
  point, 
  and 
  we 
  notice 
  a 
  

   great 
  variation 
  from 
  day 
  to 
  day. 
  Each 
  curve 
  corresponds 
  to 
  

   a 
  constant 
  temperature 
  and 
  to 
  observations 
  taken 
  in 
  suc- 
  

   cession 
  on 
  the 
  same 
  day. 
  The 
  curves 
  are 
  marked 
  with 
  

   numbers 
  in 
  the 
  same 
  order 
  as 
  they 
  were 
  observed. 
  

  

  Only 
  in 
  the 
  first 
  and 
  last 
  curve 
  the 
  observations 
  are 
  ex- 
  

   tended 
  so 
  far 
  as 
  to 
  give 
  the 
  characteristic 
  point, 
  which 
  in 
  this 
  

   case 
  is 
  very 
  well 
  marked. 
  It 
  appears 
  that 
  also 
  this 
  time 
  we 
  

   have 
  a 
  motion 
  of 
  the 
  characteristic 
  point 
  towards 
  the 
  reversion 
  

   point 
  ; 
  but 
  in 
  this 
  case 
  the 
  motion 
  of 
  the 
  curve 
  is 
  also 
  extended 
  

   to 
  the 
  reversion 
  point, 
  the 
  change 
  in 
  the 
  reversion 
  point 
  is 
  of 
  

   the 
  same 
  order 
  as 
  the 
  change 
  in 
  the 
  curve 
  itself. 
  

  

  On 
  the 
  figure 
  is 
  also 
  drawn 
  the 
  curve 
  (J) 
  representing 
  the 
  

   average 
  velocity 
  of 
  leak. 
  

  

  If 
  the 
  leak 
  had 
  not 
  altered 
  during 
  the 
  experiment 
  this 
  line 
  

   would 
  cut 
  the 
  different 
  curves 
  in 
  points 
  corresponding 
  to 
  the 
  

   pressure 
  (7r 
  '). 
  The 
  curve 
  VII. 
  last 
  observed 
  would 
  then 
  give 
  

   a 
  pressure 
  (vro'j 
  °£ 
  28*8 
  atm., 
  or 
  about 
  the 
  same 
  pressure 
  as 
  

   found 
  at 
  the 
  same 
  temperature 
  in 
  experiment 
  III., 
  where 
  the 
  

   membrane 
  was 
  very 
  perfect 
  and 
  no 
  leak 
  was 
  to 
  be 
  observed. 
  

   At 
  the 
  beginning, 
  however, 
  the 
  leak 
  would 
  have 
  a 
  great 
  in- 
  

   fluence 
  upon 
  7r 
  '. 
  This 
  would 
  mean 
  that 
  if 
  the 
  leak 
  during 
  

   the 
  working 
  up 
  of 
  the 
  membrane 
  had 
  kept 
  constant, 
  it 
  must 
  

   have 
  been 
  changed 
  from 
  one 
  which 
  had 
  a 
  great 
  power 
  of 
  

   influencing 
  the 
  pressure 
  7r 
  ' 
  into 
  a 
  solution 
  leak. 
  Such 
  a 
  

   transformation, 
  however, 
  is 
  very 
  improbable, 
  and 
  we 
  are 
  led 
  

   to 
  the 
  assumption 
  that 
  the 
  increase 
  in 
  the 
  pressure 
  ttq 
  must 
  

   be 
  accompanied 
  by 
  a 
  decrease 
  in 
  the 
  leak. 
  

  

  Conclusions 
  to 
  be 
  derived 
  from 
  the 
  Study 
  of 
  the 
  

   Velocity 
  Curves. 
  

   20. 
  The 
  osmosis 
  is 
  in 
  every 
  case 
  characterized 
  by 
  the 
  

   osmotic 
  velocity, 
  This 
  property 
  forms 
  the 
  sum 
  of 
  effects 
  of 
  

  

  