﻿Mack 
  and 
  Hulett 
  — 
  Water 
  Content 
  of 
  Coal. 
  93 
  

  

  fore, 
  have 
  been 
  present 
  as 
  such. 
  Later 
  work 
  indicates 
  that, 
  

   even 
  by 
  heating 
  in 
  the 
  manner 
  just 
  described, 
  we 
  did 
  not 
  get 
  

   all 
  the 
  water 
  out. 
  In 
  our 
  deiinition 
  of 
  the 
  water 
  content 
  of 
  

   coal 
  this 
  water 
  must 
  be 
  included, 
  consequently 
  the 
  method 
  of 
  

   drying 
  over 
  phosphorus 
  pentoxide 
  does 
  not 
  give 
  the 
  true 
  

   water 
  content, 
  nor 
  do 
  any 
  of 
  the 
  other 
  methods 
  which 
  have 
  

   been 
  used, 
  so 
  far 
  as 
  we 
  know. 
  

  

  There 
  does 
  not 
  appear 
  to 
  have 
  been 
  any 
  attempt 
  by 
  workers 
  

   in 
  this 
  field 
  to 
  state 
  the 
  problem 
  clearly, 
  that 
  is 
  to 
  consider 
  

   what 
  is 
  the 
  precise 
  significance 
  of 
  the 
  term 
  " 
  the 
  water 
  content 
  

   of 
  coal." 
  In 
  order 
  to 
  get 
  a 
  working 
  definition 
  of 
  the 
  water 
  

   content 
  of 
  coals 
  let 
  us 
  consider 
  the 
  problem 
  from 
  the 
  stand- 
  

   point 
  of 
  the 
  origin 
  of 
  coal. 
  

  

  It 
  has 
  been 
  fairly 
  well 
  established 
  that 
  the 
  starting 
  point 
  of 
  

   coal 
  in 
  the 
  natural 
  process 
  of 
  its 
  making 
  was 
  peat. 
  There 
  is 
  

   considerable 
  evidence 
  which 
  indicates 
  that 
  this 
  peat 
  was 
  

   formed 
  in 
  a 
  manner 
  somewhat 
  analogous 
  to 
  the 
  peat 
  of 
  the 
  

   present 
  age, 
  though 
  on 
  a 
  much 
  vaster 
  scale.* 
  From 
  year 
  to 
  

   year 
  the 
  decaying 
  vegetable 
  matter 
  accumulated 
  at 
  the 
  bottom 
  

   of 
  the 
  swamp, 
  and 
  as 
  it 
  gradually 
  sank 
  below 
  the 
  surface 
  of 
  

   the 
  water, 
  it 
  was 
  protected 
  from 
  the 
  oxygen 
  of 
  the 
  air, 
  and 
  from 
  

   certain 
  ferment 
  organisms 
  which, 
  together 
  with 
  the 
  oxygen, 
  

   were 
  the 
  active 
  agents 
  in 
  the 
  chemical 
  changes 
  that 
  trans- 
  

   formed 
  the 
  vegetable 
  matter 
  to 
  peat. 
  The 
  rate 
  of 
  accumula- 
  

   tion 
  depended 
  on 
  the 
  rate 
  of 
  the 
  vegetable 
  growth, 
  and 
  the 
  

   efficiency 
  of 
  its 
  preservation. 
  As 
  the 
  deposit 
  grew, 
  the 
  deeper 
  

   portions 
  became 
  more 
  dense, 
  and 
  according 
  to 
  a 
  rough 
  esti- 
  

   mate, 
  it 
  .required 
  something 
  like 
  a 
  century 
  to 
  form 
  a 
  thick- 
  

   ness 
  of 
  one 
  foot 
  of 
  such 
  dense 
  peat. 
  

  

  With 
  regard 
  to 
  the 
  changes 
  taking 
  place 
  in 
  the 
  transforma- 
  

   tion 
  of 
  peat 
  to 
  coal 
  our 
  knowledge 
  is 
  still 
  largely 
  speculative. 
  

   One 
  of 
  the 
  most 
  favored 
  ideas 
  at 
  present 
  is 
  that 
  pressure 
  plays 
  

   the 
  most 
  important 
  role 
  in 
  these 
  changes— 
  a 
  pressure 
  due 
  to 
  

   the 
  overlying 
  weight 
  of 
  debris 
  and 
  rock 
  which 
  covered 
  up 
  the 
  

   swamp 
  ; 
  or 
  due 
  to 
  a 
  metamorphic 
  change 
  such 
  as 
  a 
  compres- 
  

   sion 
  in 
  the 
  earth's 
  crust. 
  According 
  to 
  this 
  view, 
  the 
  peat 
  

   subjected 
  to 
  compression 
  gradually 
  became 
  in 
  successive 
  

   stages 
  lignite, 
  sub-bituminous, 
  bituminous 
  and 
  finally 
  anthra- 
  

   cite 
  coal 
  and 
  graphite. 
  Starting 
  with 
  peat 
  and 
  going 
  down 
  

   the 
  series, 
  chemical 
  analyses 
  show 
  that 
  extensive 
  chemical 
  

   changes 
  have 
  taken 
  place,f 
  the 
  net 
  result 
  of 
  which 
  was 
  a 
  pro- 
  

   gressive 
  elimination 
  of 
  volatile 
  matter 
  such 
  as 
  carbon 
  dioxide, 
  

   carbon 
  monoxide, 
  methane 
  and 
  water, 
  and 
  in 
  such 
  relative 
  pro- 
  

  

  * 
  White 
  and 
  Thiessen, 
  The 
  Origin 
  of 
  Coal 
  (page 
  53), 
  Bulletin 
  38, 
  Bureau 
  

   of 
  Mines, 
  1913. 
  

  

  fO. 
  C. 
  Kalston, 
  Graphical 
  Studies 
  of 
  the 
  Ultimate 
  Analysis 
  of 
  Coal. 
  

   Paper 
  presented 
  at 
  Cincinnati 
  meeting 
  of 
  Arner. 
  Chem. 
  Soc, 
  and 
  pub- 
  

   lished 
  as 
  a 
  Bulletin 
  of 
  the 
  Bureau 
  of 
  Mines. 
  

  

  