﻿Mack 
  and 
  Hulett 
  — 
  Water 
  Content 
  of 
  Coal. 
  105 
  

  

  the 
  last 
  intervals 
  became 
  no 
  longer 
  measurable. 
  Then 
  other 
  

   isothermals 
  at 
  successively 
  higher 
  temperatures 
  were 
  deter- 
  

   mined, 
  until 
  we 
  reached 
  a 
  condition 
  where 
  there 
  were 
  indica- 
  

   tions 
  of 
  a 
  decomposition 
  of 
  the 
  coal 
  substances. 
  The 
  vapor 
  

   baths 
  were 
  as 
  follows 
  : 
  " 
  95 
  per 
  cent 
  " 
  alcohol 
  for 
  82°, 
  water 
  

   for 
  100°, 
  toluol 
  for 
  111°, 
  xylol 
  for 
  140°, 
  aniline 
  for 
  184°, 
  naph- 
  

   thalene 
  for 
  218°, 
  and 
  thymol 
  for 
  230°. 
  Figs. 
  2, 
  3, 
  and 
  4 
  show 
  

   the 
  time 
  curves 
  for 
  the 
  three 
  coals, 
  New 
  River, 
  Pittsburgh 
  and 
  

   Illinois. 
  It 
  must 
  be 
  noted 
  that 
  the 
  form 
  of 
  the 
  tube 
  in 
  which 
  

   the 
  coal 
  was 
  heated 
  and 
  also 
  the 
  conduction 
  of 
  heat 
  through 
  

   the 
  coal, 
  are 
  factors 
  in 
  determining 
  the 
  slope 
  of 
  the 
  first 
  part 
  

   of 
  each 
  curve. 
  With 
  regard 
  to 
  the 
  form 
  of 
  the 
  apparatus, 
  we 
  

   made 
  blank 
  tests 
  by 
  placing 
  weighed 
  amounts 
  of 
  water 
  in 
  the 
  

   bulb 
  at 
  the 
  bottom, 
  and 
  determining 
  the 
  time 
  required 
  to 
  col- 
  

   lect 
  all 
  the 
  water 
  in 
  the 
  alembic 
  at 
  the 
  top. 
  For 
  example, 
  

   0*1156 
  gm. 
  water 
  was 
  heated 
  at 
  111° 
  and 
  after 
  two 
  minutes 
  

   the 
  amount 
  which 
  had 
  been 
  driven 
  into 
  the 
  upper 
  bulb 
  was 
  

   0*1152 
  gm. 
  Furthermore, 
  the 
  small 
  mass 
  of 
  coal 
  in 
  the 
  bulb 
  

   which 
  is 
  in 
  direct 
  contact 
  with 
  a 
  hot 
  condensing 
  vapor 
  is 
  soon 
  

   brought 
  to 
  the 
  same 
  temperature 
  throughout 
  its 
  entire 
  body. 
  

   Consequently 
  we 
  are 
  justified 
  in 
  looking 
  on 
  these 
  time 
  curves 
  

   as 
  really 
  affording 
  a 
  good 
  idea 
  of 
  the 
  actual 
  rate 
  at 
  which 
  the 
  

   water 
  is 
  given 
  off 
  from 
  the 
  coal 
  at 
  the 
  respective 
  temperatures. 
  

  

  The 
  coals 
  used 
  in 
  our 
  investigation 
  were 
  samples 
  secured 
  by 
  

   engineers 
  of 
  the 
  U. 
  S. 
  Bureau 
  of 
  Mines 
  and 
  analyzed 
  in 
  the 
  

   Bureau 
  of 
  Mines 
  Laboratory. 
  These 
  samples 
  were 
  stored 
  in 
  

   large 
  bottles 
  with 
  paraffined 
  stoppers 
  and 
  kept 
  in 
  a 
  cool 
  room. 
  

   As 
  needed, 
  smaller 
  samples 
  were 
  powdered 
  and 
  kept 
  in 
  small 
  

   rubber-stoppered 
  bottles. 
  The 
  question 
  of 
  loss 
  in 
  sampling 
  

   and 
  powdering 
  was 
  considered 
  and 
  observations 
  made 
  on 
  8-20 
  

   mesh 
  grains, 
  on 
  20-30 
  and 
  on 
  60 
  mesh 
  powder 
  of 
  the 
  same 
  coal 
  

   (fig. 
  5). 
  It 
  was 
  concluded 
  that 
  rapid 
  powdering 
  to 
  20-30 
  

   mesh 
  did 
  not 
  cause 
  a 
  measurable 
  loss 
  of 
  moisture 
  due 
  to 
  expo- 
  

   sure 
  to 
  air 
  or 
  to 
  the 
  dehydrating 
  effect 
  of 
  crushing.* 
  

  

  A 
  second 
  method 
  differing 
  somewhat 
  from 
  the 
  first, 
  was 
  

   used 
  to 
  obtain 
  the 
  time 
  curves, 
  a 
  method 
  which 
  possessed 
  the 
  

   additional 
  advantage 
  that 
  it 
  afforded 
  means 
  by 
  which 
  the 
  gas 
  

   evolved 
  from 
  the 
  coal 
  could 
  be 
  determined 
  along 
  with 
  the 
  

   water. 
  It 
  consisted 
  in 
  heating 
  the 
  coal 
  in 
  the 
  glass 
  bulb 
  

   (fig. 
  6) 
  attached 
  to 
  a 
  capillary 
  glass 
  tube 
  of 
  about 
  *5 
  mm 
  bore 
  by 
  

   the 
  ground 
  glass 
  joint 
  C. 
  The 
  capillary 
  led 
  through 
  a 
  three- 
  

   way 
  stop-cock 
  to 
  a 
  measuring 
  burette 
  having 
  a 
  large 
  bulb 
  at 
  

   its 
  lower 
  end, 
  which 
  was 
  connected 
  to 
  a 
  rubber 
  tube 
  and 
  a 
  

   leveling 
  bulb, 
  both 
  containing 
  mercury, 
  in 
  such 
  a 
  way 
  that 
  by 
  

   lowering 
  and 
  raising 
  the 
  level 
  of 
  the 
  mercury 
  and 
  at 
  the 
  same 
  

   time 
  opening 
  and 
  closing 
  the 
  cock, 
  the 
  air 
  could 
  be 
  driven 
  out 
  

  

  * 
  R. 
  Mauzelius, 
  Sveriges 
  Geol. 
  Undersokning, 
  1907. 
  

  

  Am. 
  Jour. 
  Sci.— 
  Fourth 
  Series, 
  Vol. 
  XLIII, 
  No. 
  254. 
  — 
  February, 
  1917. 
  

  

  8 
  

  

  