﻿Osmosis 
  and 
  Osmotic 
  Pressure. 
  

  

  417 
  

  

  /3 
  is 
  the 
  average 
  temperature 
  coefficient 
  of 
  the 
  solution 
  

  

  dir 
  

   between 
  and 
  t. 
  — 
  °- 
  can 
  be 
  found 
  from 
  the 
  curve 
  fig. 
  8. 
  

  

  dC 
  

  

  dir 
  C 
  

  

  For 
  small 
  pressures 
  we 
  can 
  put 
  — 
  ^ 
  — 
  = 
  1. 
  

  

  The 
  observations 
  corresponding 
  to 
  the 
  experiments 
  II. 
  and 
  

   III. 
  are 
  given 
  in 
  the 
  curves 
  figs. 
  13, 
  14. 
  The 
  curves 
  marked 
  

   I. 
  correspond 
  to 
  the 
  highest 
  temperature. 
  As 
  we 
  see 
  the 
  

   velocities 
  measured 
  determine 
  very 
  well-defined 
  curves, 
  so 
  

   that 
  the 
  error 
  in 
  the 
  determination 
  of 
  Air' 
  will 
  not 
  exceed 
  0*02 
  

   atmosphere. 
  The 
  curves 
  drawn 
  as 
  dotted 
  lines 
  correspond 
  

   to 
  the 
  determination 
  on 
  the 
  neighbouring 
  days. 
  

  

  The 
  determination 
  gives 
  the 
  following 
  result 
  : 
  — 
  

  

  Exp. 
  

  

  C. 
  

  

  t. 
  

  

  «•'■ 
  

  

  1 
  

  

  161 
  

  

  320 
  

   320 
  

  

  10-3 
  

   11-3 
  

   11-8 
  

  

  0-00296 
  

  

  00000 
  

  

  00017 
  

  

  IT 
  

  

  Ill 
  

  

  

  We 
  see 
  from 
  II. 
  and 
  III. 
  which 
  correspond 
  to 
  the 
  same 
  

   concentration 
  that 
  the 
  temperature 
  coefficients 
  for 
  ir 
  ' 
  even 
  

   for 
  very 
  good 
  cells 
  is 
  a 
  very 
  variable 
  quantity. 
  Let 
  us 
  con- 
  

   sider 
  these 
  two 
  experiments 
  more 
  closely. 
  

  

  There 
  can 
  be 
  no 
  doubt 
  that 
  the 
  membrane 
  in 
  experiment 
  III. 
  

   was 
  more 
  perfectly 
  semipermeable 
  than 
  in 
  experiment 
  II. 
  This 
  

   is 
  evident 
  from 
  the 
  following 
  facts 
  : 
  — 
  

  

  (1) 
  The 
  maximum 
  electric 
  resistance 
  is 
  greater 
  in 
  experi- 
  

   riment 
  III. 
  

  

  (2) 
  The 
  reversion 
  pressure 
  corresponding 
  to 
  the 
  highest 
  

   temperature 
  is 
  greater 
  in 
  experiment 
  III. 
  

  

  (3) 
  The 
  velocities 
  corresponding 
  to 
  tt^itq 
  are 
  greater 
  in 
  

   experiment 
  III. 
  

  

  This 
  indicates 
  that 
  the 
  temperature 
  coefficient 
  will 
  come 
  

   out 
  greater 
  for 
  a 
  more 
  perfect 
  membrane. 
  If 
  this 
  rule 
  holds 
  

   quite 
  up 
  to 
  perfect 
  semipermeabiiity, 
  we 
  should 
  get 
  for 
  the 
  

   system 
  considered 
  : 
  

  

  © 
  >SOo 
  < 
  8 
  » 
  

  

  Further, 
  we 
  see 
  from 
  the 
  curves 
  that 
  in 
  both 
  cases 
  the 
  

   quantity 
  y^r) 
  will 
  be 
  increased 
  by 
  increase 
  of 
  temperature. 
  

   Phil. 
  Mag. 
  Ser. 
  6. 
  Vol. 
  16. 
  No. 
  93. 
  Sept. 
  1908. 
  2 
  F 
  

  

  