﻿Os 
  

  

  mosis 
  

  

  and 
  Osmotic 
  Pressure. 
  

  

  219 
  

  

  capillaries. 
  One 
  (b) 
  (inner 
  diameter 
  0'49 
  mm.) 
  is 
  open 
  at 
  

   both 
  ends 
  and 
  connects 
  the 
  interior 
  of 
  the 
  cell 
  with 
  the 
  

   air, 
  the 
  other 
  two 
  capillaries 
  go 
  to 
  the 
  compressor 
  and 
  to 
  

   the 
  manometer. 
  In 
  order 
  to 
  give 
  these 
  two 
  capillaries 
  

   a 
  better 
  support 
  the 
  two 
  perforations 
  end 
  in 
  two 
  steel 
  

   tubes. 
  

  

  The 
  glass 
  capillaries 
  are 
  fixed 
  to 
  the 
  tube 
  in 
  the 
  following- 
  

   manner. 
  The 
  tubes 
  used 
  were 
  somewhat 
  conical, 
  and 
  had 
  

   such 
  dimensions 
  that 
  only 
  a 
  certain 
  length 
  could 
  pass 
  the 
  

   tube. 
  The 
  place 
  where 
  it 
  stopped 
  was 
  noticed, 
  and 
  in 
  the 
  

   neighbourhood 
  of 
  it 
  the 
  capillary 
  was 
  heated 
  and 
  covered 
  

   with 
  sealing-wax. 
  Simultaneously 
  the 
  steel 
  tube 
  was 
  heated 
  

   and 
  the 
  capillary 
  pulled 
  through 
  from 
  beneath. 
  

  

  In 
  the 
  course 
  of 
  the 
  experiments 
  the 
  disk 
  B, 
  as 
  well 
  as 
  

   the 
  glass 
  tubes, 
  the 
  compressor, 
  and 
  the 
  manometer 
  could 
  be 
  

   fixed. 
  Only 
  the 
  steel 
  cup 
  A 
  and 
  the 
  cell 
  had 
  to 
  be 
  taken 
  

   down 
  for 
  each 
  trial. 
  

  

  For 
  the 
  fastening 
  of 
  the 
  osmometer 
  three 
  steel 
  rods 
  

   (length 
  31 
  cm., 
  diam. 
  1*0 
  cm.) 
  were 
  fixed 
  to 
  the 
  disk, 
  the 
  

   upper 
  ends 
  of 
  which 
  formed 
  horizontal 
  flanges 
  with 
  screw 
  

   holes, 
  and 
  the 
  other 
  ends 
  serving 
  as 
  set-screws 
  for 
  fixing 
  the 
  

   cup 
  A. 
  

  

  The 
  glass 
  tubes 
  went 
  for 
  sooie 
  distance 
  straight 
  upwards, 
  

   and 
  were 
  thus 
  protected 
  from 
  damage 
  by 
  the 
  three 
  steel 
  

   rods. 
  Further, 
  by 
  this 
  arrangement 
  the 
  osmometer 
  could 
  

   be 
  put 
  into 
  a 
  thermostat 
  so 
  as 
  to 
  secure 
  a 
  constant 
  tempe- 
  

   rature. 
  

  

  

  The 
  Compressor. 
  

  

  3. 
  By 
  means 
  of 
  the 
  compressor 
  the 
  pressure 
  could 
  be 
  

   raised 
  to 
  the 
  height 
  desired. 
  The 
  construction 
  of 
  it 
  is 
  shown 
  

   in 
  fig. 
  2. 
  The 
  apparatus 
  is 
  chiefly 
  made 
  of 
  brass, 
  only 
  the 
  

   screw 
  (/) 
  and 
  the 
  cylindrical 
  piston 
  (g) 
  are 
  made 
  of 
  steel. 
  

   The 
  piston 
  (diam. 
  0'95 
  cm.) 
  passes 
  through 
  a 
  cylindrical 
  

   perforation 
  of 
  exactly 
  the 
  same 
  diameter 
  as 
  the 
  piston. 
  The 
  

   piece 
  (E) 
  ends 
  in 
  a 
  conical 
  tap, 
  that 
  goes 
  down 
  into 
  the 
  

   cup 
  (D). 
  The 
  tightening 
  is 
  brought 
  about 
  in 
  the 
  same 
  

   manner 
  as 
  in 
  the 
  case 
  of 
  the 
  cell 
  ; 
  a 
  piece 
  of 
  rubber 
  tubing 
  

   put 
  on 
  to 
  the 
  end 
  of 
  the 
  brass 
  tube 
  covers 
  the 
  connexion 
  

   with 
  the 
  piston. 
  The 
  pieces 
  (E) 
  and 
  (F) 
  are 
  screwed 
  to 
  the 
  

   cup 
  and 
  tightened 
  by 
  a 
  leather 
  ring. 
  The 
  cup 
  had 
  a 
  perfo- 
  

   ration 
  at 
  the 
  bottom 
  for 
  the 
  glass 
  capillary 
  that 
  led 
  to 
  the 
  

   osmometer, 
  and 
  this 
  tube 
  was 
  fixed 
  with 
  sealing-wax 
  in 
  the 
  

   manner 
  already 
  described. 
  

  

  Phil. 
  Mag. 
  S. 
  6. 
  Vol. 
  16. 
  No. 
  92. 
  Aug. 
  1908. 
  S 
  

  

  