﻿108 
  Mack 
  and 
  Hulett 
  — 
  Water 
  Content 
  of 
  Coal. 
  

  

  of 
  the 
  large 
  bulb 
  and 
  the 
  burette 
  and 
  a 
  vacuum 
  created. 
  The 
  

   mercury, 
  after 
  this, 
  was 
  adjusted 
  to 
  the 
  level 
  L, 
  and 
  the 
  coal 
  

   which 
  had 
  been 
  cooled 
  and 
  evacuated 
  by 
  connection 
  with 
  the 
  

   pump 
  through 
  the 
  three-way 
  cock, 
  was 
  then 
  joined 
  to 
  the 
  

   burette 
  by 
  turning 
  the 
  cock. 
  The 
  gas 
  from 
  the 
  heated 
  coal 
  

   collected 
  in 
  the 
  large 
  bulb 
  and 
  could 
  be 
  measured 
  at 
  any 
  time 
  

   in 
  the 
  burette 
  by 
  closing 
  the 
  cock 
  and 
  raising 
  the 
  leveling 
  bulb. 
  

   The 
  coal 
  bulb 
  was 
  heated 
  in 
  the 
  vapor 
  bath 
  up 
  to 
  the 
  point 
  C, 
  

   and 
  the 
  water 
  from 
  the 
  coal 
  condensed 
  at 
  the 
  opening 
  of 
  the 
  

   capillary 
  tube 
  and 
  was 
  rapidly 
  forced 
  by 
  the 
  slight 
  pressure 
  iu 
  

   the 
  coal 
  bulb 
  to 
  traverse 
  the 
  capillary. 
  The 
  water 
  collected 
  on 
  

   the 
  top 
  of 
  the 
  mercury, 
  but 
  a 
  measurement 
  of 
  the 
  volume 
  of 
  

   the 
  water 
  was 
  not 
  very 
  satisfactory. 
  We 
  obtained 
  the 
  weight 
  

   of 
  the 
  gas 
  by 
  transferring 
  it 
  from 
  the 
  burette 
  by 
  means 
  of 
  the 
  

   mercury 
  into 
  a 
  partially 
  evacuate 
  tube 
  which 
  had 
  been 
  weighed. 
  

   The 
  weight 
  of 
  the 
  gas 
  was 
  subtracted 
  from 
  the 
  total 
  loss 
  from 
  

   the 
  coal 
  bulb 
  to 
  give 
  the 
  weight 
  of 
  water. 
  The 
  determina- 
  

   tions 
  made 
  on 
  the 
  three 
  coals 
  with 
  the 
  alembic 
  method 
  were 
  

   repeated, 
  using 
  the 
  second 
  method, 
  the 
  two 
  sets 
  of 
  results 
  

   agreeing 
  very 
  well, 
  as 
  fig. 
  7, 
  with 
  the 
  results 
  at 
  184°, 
  will 
  show. 
  

   During 
  the 
  first 
  few 
  minutes 
  water 
  was 
  removed 
  more 
  rapidly 
  

   from 
  the 
  coal 
  bulb 
  of 
  the 
  second 
  apparatus 
  than 
  from 
  the 
  first, 
  

   but 
  the 
  fiat 
  portions 
  of 
  the 
  curves 
  are 
  almost 
  identical. 
  

  

  If 
  the 
  final 
  values 
  represented 
  by 
  the 
  flat 
  portions 
  of 
  the 
  

   time 
  curves 
  in 
  figs. 
  2, 
  3, 
  and 
  4, 
  are 
  plotted 
  as 
  ordinates 
  against 
  

   the 
  temperatures 
  to 
  which 
  the 
  coal 
  was 
  heated, 
  as 
  abscissae, 
  the 
  

   curves 
  shown 
  in 
  figs. 
  8, 
  9 
  and 
  10 
  are 
  obtained. 
  The 
  marked 
  

   flattening 
  of 
  the 
  curve 
  at 
  the 
  higher 
  temperatures 
  indicates 
  

   that 
  very 
  little 
  more 
  water 
  could 
  be 
  removed 
  from 
  the 
  coal 
  by 
  

   any 
  further 
  heating, 
  though 
  some 
  water 
  probably 
  still 
  remains 
  

   on 
  the 
  adsorption 
  surfaces 
  even 
  at 
  the 
  highest 
  temperature, 
  

   especially 
  since 
  pressure 
  of 
  the 
  water 
  in 
  the 
  alembic 
  tube 
  is 
  

   appreciable, 
  even 
  when 
  the 
  alembic 
  bulb 
  is 
  cooled. 
  

  

  Below 
  250° 
  very 
  little 
  gas 
  indeed 
  came 
  from 
  the 
  coals 
  used 
  

   and, 
  as 
  we 
  have 
  pointed 
  out, 
  it 
  is 
  probable 
  that 
  a 
  considerable 
  

   portion 
  of 
  this 
  gas 
  was 
  merely 
  adsorbed 
  on 
  the 
  large 
  surfaces 
  

   of 
  the 
  colloidal 
  coal. 
  We 
  were 
  not 
  particularly 
  concerned 
  

   with 
  the 
  gases 
  evolved 
  during 
  the 
  heating 
  of 
  the 
  sample 
  coal, 
  

   except 
  in 
  so 
  far 
  as 
  it 
  enabled 
  us 
  to 
  know 
  whether 
  or 
  not 
  decom- 
  

   position 
  of 
  the 
  coal 
  was 
  taking 
  place. 
  We 
  did 
  however 
  make 
  

   determinations 
  of 
  the 
  amounts 
  of 
  gas 
  liberated 
  in 
  the 
  various 
  

   experiments 
  and 
  the 
  work 
  of 
  Porter 
  and 
  Taylor 
  on 
  these 
  coals 
  

   give 
  us 
  sufficient 
  information 
  on 
  their 
  composition. 
  

  

  Summary. 
  

  

  We 
  have 
  attempted 
  to 
  define 
  the 
  true 
  moisture 
  content 
  of 
  

   coals 
  and 
  have 
  made 
  some 
  determinations 
  on 
  three 
  typical 
  coals, 
  

  

  