﻿114 
  Van 
  Name 
  and 
  Brown 
  — 
  Freezing 
  Point 
  Lowering. 
  

  

  For 
  most 
  purposes, 
  however, 
  a 
  comparatively 
  rough 
  compen- 
  

   sation 
  is 
  all 
  that 
  is 
  needed. 
  With 
  our 
  apparatus 
  as 
  at 
  first 
  used 
  

   there 
  was 
  a 
  tendency, 
  under 
  ordinary 
  working 
  conditions, 
  for 
  the 
  

   compensation 
  to 
  be 
  incomplete, 
  an 
  unfrozen 
  liquid 
  showing 
  a 
  

   slow 
  rise 
  in 
  temperature. 
  This 
  was 
  corrected 
  in 
  a 
  sufficiently 
  

   effective 
  manner 
  by 
  filing 
  a 
  small 
  notch 
  in 
  the 
  lower 
  edge 
  of 
  

   the 
  inner 
  tube 
  of 
  the 
  cooling 
  device, 
  thus 
  permitting 
  a 
  very 
  

   slight 
  flow 
  of 
  brine 
  at 
  this 
  point 
  even 
  when 
  the 
  ground 
  sur- 
  

   faces 
  were 
  in 
  contact. 
  

  

  We 
  have 
  put 
  the 
  method 
  to 
  a 
  practical 
  test 
  in 
  an 
  extended 
  

   series 
  of 
  determinations 
  of 
  the 
  freezing 
  points 
  of 
  water 
  solu- 
  

   tions. 
  A 
  Beckmann 
  thermometer 
  with 
  a 
  5° 
  scale 
  was 
  used 
  

   throughout 
  so 
  that 
  it 
  was 
  impossible 
  to 
  observe 
  temperature 
  

   differences 
  of 
  less 
  than 
  0*001°, 
  but 
  within 
  the 
  limits 
  of 
  accuracy 
  

   so 
  imposed 
  the 
  results 
  were 
  very 
  concordant 
  and 
  satisfactory. 
  

   A 
  few 
  results 
  obtained 
  with 
  two 
  different 
  solutions 
  prepared 
  

   from 
  a 
  carefully 
  purified 
  sample 
  of 
  cane 
  sugar 
  are 
  given 
  below 
  

   by 
  way 
  of 
  illustration 
  : 
  

  

  Molecular 
  

   Av. 
  lowering 
  

  

  0-233° 
  1'86 
  5 
  

  

  0-480 
  l-92 
  6 
  

  

  The 
  thermometer 
  used 
  had 
  been 
  carefully 
  compared 
  with 
  a 
  

   similar 
  one 
  certified 
  by 
  the 
  IT. 
  S. 
  Bureau 
  of 
  Standards, 
  and 
  the 
  

   observed 
  freezing 
  point 
  lowerings 
  as 
  given 
  in 
  the 
  second 
  col- 
  

   umn 
  of 
  the 
  table 
  have 
  been 
  corrected 
  for 
  the 
  errors 
  of 
  the 
  

   thermometer. 
  Those 
  in 
  the 
  fourth 
  column 
  have 
  been 
  further 
  

   corrected 
  for 
  the 
  undercooling. 
  Considering 
  the 
  lack 
  of 
  sensi- 
  

   tiveness 
  of 
  the 
  thermometer 
  employed, 
  and 
  the 
  fact 
  that 
  it 
  was 
  

   not 
  kept 
  in 
  ice-water 
  when 
  not 
  in 
  use 
  so 
  as 
  to 
  avoid 
  the 
  effect 
  

   of 
  slow 
  volume 
  changes 
  in 
  the 
  glass, 
  the 
  values 
  found 
  for 
  the 
  

   molecular 
  lowering 
  agree 
  about 
  as 
  well 
  as 
  could 
  be 
  expected 
  

   with 
  the 
  best 
  available 
  values 
  for 
  such 
  solutions, 
  as 
  determined 
  

   by 
  Raoult 
  and 
  others. 
  

  

  Gms. 
  sugar 
  

  

  per 
  

   LOOgms. 
  H 
  2 
  

  

  Observed 
  

  

  f.p. 
  

   lowering 
  

  

  Under- 
  

   cooling 
  

  

  Corrected 
  

  

  f.p. 
  

   lowering 
  

  

  4-274 
  

  

  0-239° 
  

  

  1-81° 
  

  

  0-234° 
  

  

  a 
  

  

  0-236 
  

  

  0-94 
  

  

  0-233 
  

  

  (( 
  

  

  0-235 
  

  

  0-67 
  

  

  0-233 
  

  

  8-521 
  

  

  0-487 
  

  

  1-10 
  

  

  0-481 
  

  

  a 
  

  

  0-489 
  

  

  1-48 
  

  

  0-480 
  

  

  a 
  

  

  0-485 
  

  

  0-88 
  

  

  0-480 
  

  

  u 
  

  

  0-488 
  

  

  1-27 
  

  

  0-480 
  

  

  