﻿110 
  Mack 
  and 
  Hnlett 
  — 
  "Water 
  Content 
  of 
  Coal. 
  

  

  by 
  a 
  method 
  which 
  should 
  give 
  a 
  close 
  approximation 
  to 
  the 
  

   true 
  moisture 
  content 
  of 
  these 
  coals. 
  

  

  This 
  work 
  has 
  suggested 
  several 
  ideas 
  on 
  the 
  nature 
  and 
  

   genesis 
  of 
  coal. 
  It 
  is 
  evident 
  that 
  there 
  is 
  practically 
  no 
  

   definite 
  information 
  about 
  the 
  relation 
  of 
  moisture 
  to 
  such 
  sub- 
  

   stances 
  as 
  coal 
  and 
  in 
  fact 
  to 
  all 
  organic 
  and 
  colloidal 
  substances. 
  

  

  Laboratory 
  of 
  Physical 
  Chemistry, 
  

   Princeton 
  University, 
  June, 
  1916. 
  

  

  Art. 
  XI. 
  — 
  An 
  Apparatus 
  for 
  Determining 
  Freezing 
  Point 
  

   Loioering 
  / 
  by 
  K. 
  G. 
  Van 
  Name 
  and 
  W. 
  G. 
  Brown. 
  

  

  [Contributions 
  from 
  the 
  Kent 
  Chemical 
  Laboratory 
  of 
  Yale 
  Univ. 
  — 
  cclxxxvi.] 
  

  

  The 
  apparatus 
  here 
  described 
  and 
  figured 
  operates, 
  like 
  the 
  

   familiar 
  Beckmann 
  method, 
  on 
  the 
  undercooling 
  principle. 
  

   It 
  differs 
  from 
  others 
  of 
  its 
  type 
  both 
  in 
  the 
  manner 
  of 
  effect- 
  

   ing 
  the 
  undercooling, 
  and 
  in 
  the 
  fact 
  that 
  the 
  whole 
  process, 
  

   undercooling, 
  inoculating, 
  freezing, 
  and 
  remelring 
  in 
  prepara- 
  

   tion 
  for 
  a 
  new 
  determination, 
  is 
  carried 
  out 
  in 
  a 
  vacuum 
  walled 
  

   container 
  (Dewar 
  tube). 
  

  

  With 
  any 
  type 
  of 
  freezing 
  point 
  apparatus 
  the 
  need 
  of 
  effec- 
  

   tive 
  heat 
  insulation 
  of 
  the 
  mixture 
  of 
  solid 
  solvent 
  and 
  solution 
  

   during 
  the 
  period 
  of 
  temperature 
  observation 
  is 
  self-evident, 
  

   and 
  the 
  use 
  of 
  a 
  Dewar 
  tube 
  as 
  container 
  is 
  a 
  recognized 
  

   feature 
  of 
  at 
  least 
  one 
  well-known 
  method, 
  that 
  of 
  Richards. 
  

   The 
  convenience 
  and 
  accuracy 
  of 
  the 
  Bichards 
  method 
  are 
  

   unquestioned, 
  but 
  it 
  has 
  the 
  disadvantage 
  shared 
  by 
  others 
  of 
  

   its 
  type, 
  that 
  the 
  concentration 
  of 
  the 
  solution 
  whose 
  freezing 
  

   point 
  is 
  measured 
  cannot 
  be 
  definitely 
  fixed 
  beforehand. 
  For 
  

   this 
  and 
  other 
  reasons 
  methods 
  of 
  the 
  undercooling 
  type 
  are 
  

   in 
  certain 
  cases 
  to 
  be 
  preferred, 
  both 
  for 
  very 
  exact 
  measure- 
  

   ments 
  and 
  for 
  those 
  of 
  lower 
  accuracy, 
  

  

  The 
  form 
  of 
  apparatus 
  which 
  we 
  have 
  used 
  is 
  represented 
  in 
  

   fig. 
  1, 
  which 
  shows 
  all 
  the 
  important 
  parts, 
  but 
  omits 
  the 
  

   mechanism 
  for 
  operating 
  the 
  stirrer, 
  and 
  a 
  few 
  other 
  minor 
  

   details. 
  The 
  Dewar 
  tube, 
  of 
  about 
  one-half 
  liter 
  capacity, 
  is 
  

   surrounded 
  by 
  a 
  projecting 
  jacket 
  of 
  tin, 
  A 
  A, 
  and 
  is 
  closed 
  by 
  

   a 
  cork 
  stopper, 
  B, 
  perforated 
  in 
  four 
  places 
  to 
  admit 
  (1) 
  the 
  

   Beckmann 
  thermometer, 
  (2) 
  the 
  stem 
  of 
  the 
  glass 
  stirrer 
  C, 
  (3) 
  a 
  

   short 
  tube, 
  not 
  shown 
  in 
  the 
  figure, 
  ordinarily 
  kept 
  stoppered, 
  

   .through 
  which 
  inoculation 
  is 
  effected, 
  and 
  (4) 
  the 
  cooling 
  

   device 
  D. 
  This 
  cooling 
  device, 
  consisting 
  of 
  two 
  concentric 
  

  

  