﻿90 
  Maclc 
  and 
  Hulett 
  — 
  Water 
  Content 
  of 
  Coal. 
  

  

  ferent 
  parts 
  of 
  an 
  ordinary 
  air 
  oven. 
  Furthermore 
  the 
  mois- 
  

   ture 
  ot 
  the 
  air 
  passing 
  through 
  the 
  oven 
  was 
  found 
  to 
  be 
  a 
  

   factor 
  as 
  well 
  as 
  the 
  depth 
  of 
  the 
  coal 
  in 
  the 
  crucible, 
  the 
  dry- 
  

   ing 
  agent 
  used 
  in 
  the 
  desiccator 
  in 
  which 
  the 
  coal 
  and 
  crucible 
  

   were 
  cooled, 
  etc. 
  In 
  short 
  it 
  was 
  found 
  necessary 
  to 
  specify 
  

   numerous 
  empirical 
  details 
  of 
  manipulation, 
  and 
  even 
  when 
  

   these 
  were 
  strictly 
  adhered 
  to, 
  it 
  seemed 
  impossible 
  to 
  obtain 
  

   very 
  satisfactory 
  checks. 
  

  

  Indeed, 
  in 
  this 
  connection 
  Hillebrand 
  and 
  Badger 
  have 
  

   emphasized 
  the 
  fact 
  that 
  loss 
  of 
  moisture 
  is 
  not 
  the 
  only 
  change 
  

   which 
  occurs 
  on 
  heating 
  a 
  sample 
  of 
  coal 
  at 
  105° 
  C. 
  in 
  a 
  drying 
  

   oven. 
  Other 
  factors 
  which 
  may 
  operate 
  to 
  cause 
  a 
  change 
  of 
  

   weight 
  are 
  : 
  the 
  sensitiveness 
  of 
  the 
  powdered 
  coal 
  to 
  the 
  

   atmospheric 
  conditions 
  ; 
  the 
  loss 
  of 
  volatile 
  matter 
  other 
  than 
  

   water 
  ; 
  the 
  taking 
  up 
  of 
  oxygen 
  which 
  may 
  be 
  either 
  oxygen 
  

   added 
  directly 
  to 
  the 
  coal 
  substance, 
  or 
  oxygen 
  combined 
  with 
  

   carbon 
  or 
  with 
  hydrogen, 
  and 
  split 
  off 
  to 
  form 
  respectively 
  

   carbon 
  dioxide 
  and 
  water. 
  Some 
  coals 
  are 
  very 
  easily 
  oxi- 
  

   dized, 
  e. 
  g. 
  Archibald 
  and 
  Lawrence* 
  have 
  showed 
  that 
  the 
  

   error 
  introduced 
  into 
  the 
  value 
  of 
  the 
  moisture 
  determination 
  

   by 
  the 
  effect 
  of 
  oxidation 
  may 
  in 
  extreme 
  cases 
  be 
  very 
  large. 
  

   Moreover 
  it 
  can 
  readily 
  be 
  seen 
  that 
  with 
  different 
  coals 
  the 
  

   modifying 
  factors 
  may 
  assume 
  the 
  most 
  varying 
  values 
  with 
  

   respect 
  to 
  each 
  other, 
  and 
  it 
  is 
  therefore 
  desirable 
  that 
  as 
  many 
  

   as 
  possible 
  of 
  them 
  be 
  eliminated. 
  Yet, 
  in 
  spite 
  of 
  all 
  its 
  

   defects 
  the 
  present 
  method 
  will 
  likely 
  be 
  retained 
  for 
  trade 
  

   purposes 
  in 
  the 
  commercial 
  examination 
  of 
  coals. 
  

  

  The 
  fact 
  remains 
  that 
  there 
  is 
  still 
  a 
  very 
  decided 
  need 
  

   for 
  a 
  method 
  which 
  would 
  give 
  the 
  real 
  moisture 
  content 
  

   of 
  coal 
  and 
  which 
  would 
  serve 
  as 
  a 
  standard 
  of 
  reference. 
  

   This 
  would 
  be 
  of 
  importance 
  in 
  research, 
  especially 
  in 
  con- 
  

   nection 
  with 
  the 
  study 
  of 
  the 
  constitution 
  of 
  coal. 
  

  

  On 
  account 
  of 
  the 
  scientific 
  importance 
  of 
  a 
  definite 
  knowl- 
  

   edge 
  of 
  the 
  moisture 
  content 
  of 
  coal, 
  many 
  methods 
  have 
  been 
  

   proposed, 
  in 
  which 
  anj 
  7 
  effect 
  due 
  to 
  oxygen 
  is 
  excluded, 
  e. 
  g.: 
  

   drying 
  in 
  a 
  vacuum 
  over 
  sulphuric 
  acid 
  or 
  phosphorus 
  pen- 
  

   toxicle 
  for 
  several 
  days, 
  heating 
  the 
  coal 
  sample 
  in 
  a 
  stream 
  of 
  

   dry 
  nitrogen, 
  hydrogen, 
  or 
  carbon 
  dioxide 
  ; 
  treatment 
  of 
  coal 
  

   with 
  calcium 
  carbide 
  and 
  measurement 
  of 
  volume 
  of 
  acetylene 
  

   gas 
  generated 
  ; 
  heating 
  in 
  boiling 
  xylol, 
  toluol, 
  and 
  similar 
  

   liquids 
  with 
  measurement 
  of 
  the 
  volume 
  of 
  water 
  which 
  distils 
  

   over 
  with 
  the 
  oil 
  ; 
  collection 
  of 
  water 
  given 
  off 
  by 
  absorbing 
  it 
  

   in 
  anhydrous 
  calcium 
  chloride 
  or 
  hot 
  lime 
  ; 
  using 
  the 
  reaction 
  

   of 
  water 
  with 
  the 
  Grignard 
  reagents 
  ; 
  and 
  several 
  others. 
  It 
  

   is 
  not 
  necessary 
  to 
  discuss 
  the 
  advantages 
  and 
  disadvantages 
  of 
  

  

  * 
  Determination 
  of 
  Water 
  in 
  Coals, 
  by 
  E. 
  H. 
  Archibald 
  and 
  J. 
  H. 
  Law- 
  

   rence 
  in 
  J. 
  Ind. 
  Eng. 
  Chem., 
  iv, 
  258-62. 
  

  

  