WORK    ON    GOAL.  207 
composition  of  the  coal  as  it  was  sampled  under  various  conditions.  Proximate  analyses 
were  made  of  all  of  these  samples  and  one  ultimate  analys  s  for  each  carload  that  was  tested. 
These  analyses  provided  material  for  study  regarding,  first,  the  different  modes  of  sampling, 
and  second,  the  chemical  composition  of  the  coal.  It  is  the  first  instance  in  this  country 
where  a  like  number  of  ultimate  analyses  has  been  made.  In  fact,  it  is  almost  the  only  case 
in  which  such  work  has  been  done,  especially  on  such  a  variety  of  coals,  and  the  resulting 
data  afford  a  most  valuable  basis  for  generalizations  regarding  the  questions  of  coal  compo- 
sition and  origin. 
One  result  of  th's  work  was  a  paper  by  the  writer  on  "The  commercial  value  of  coal-mine 
sampling, "a  in  which  the  data  derived  from  the  analyses  just  mentioned  were  compared 
and  some  very  important  conclusions  were  reached  regarding  the  value  of  coal-mine  sam- 
pling, especially  with  reference  to  the  impurities,  such  as  moisture,  ash,  and  sulphur.  It 
was  found  that  the  moisture  in  the  car  sample  as  it  reached  St.  Louis  in  general  was  about 
the  same  as  that  originally  contained  in  the  coal  of  the  coal  bed,  as  shown  by  the  analyses  of 
the  mine  samples,  which  were  sealed  in  air-tight  galvanized-iron  cans  as  soon  as  collected. 
The  sulphur  and  ash,  however,  were  different,  and  in  the  great  majority  of  cases  were  much 
greater  in  commercial  coal  than  in  the  mine  samples.  This  simply  means  that  in  cutting 
the  mine  samples  more  care  was  exercised  in  excluding  impurities  than  was  done  by  the 
miners  in  the  ordinary  course  of  mining  and  loading  coal. 
The  experience  ga'ned  by  th's  work  seems  to  show  that  it  is  practically  impossible  to  make 
the  two  kinds  of  samples  agree.  Hence  coefficients  of  increase  were  determined  for  the  o0 
samples  that  were  tested.  In  the  case  of  sulphur  the  amount  in  the  car  samples  in  general 
was  found  to  be  1.04  times  the  amount  in  the  mine  samples,  and  consequently  to  obtain  the 
amount  of  sulphur  in  commercial  coal  the  amount  shown  by  the  mine  analysis  should  be 
multiplied  by  the  coefficient  1.04.  Similarly,  the  amount  of  ash  in  the  car  samples  was 
found  to  be  in  general  1.3  times  the  amount  shown  in  the  mine  samples.  Therefore,  to 
obtain  the  amount  of  ash  in  commercial  coal  the  amount  as  shown  by  the  analysis  of  the  mine 
samples  should  be  multiplied  by  1.3.  Heretofore  there  has  been  no  such  determination  of 
the  general  relation  between  impurities  in  mine  samples  and  in  commercial  coal,  and  analy- 
ses made  of  mine  samples  have  generally  been  accepted  as  indicating  the  commercial  value 
of  any  given  coal.  The  results  of  th's  work  show  that  such  a  determination  is  subject  to 
very  grave  errors  and  that  in  general  the  ash  and  sulphur  so  determined  should  be  multiplied 
by  some  such  coefficients  as  those  given  above. 
The  general  conclusions  regarding  the  value  of  mine  sampling  were  expressed  as  follows: 
As  already  stated,  the  rules  and  regulations  adopted  for  mine  sampling  in  this  work  aimed  to  secure 
samples  which  would  correspond  with  the  commercial  product  of  the  mine.  The  results  show  that  this 
was  not  attained,  and,  furthermore,  they  show  that  a,  strong  personal  element  necessarily  comes  in 
where  certain  things  are  left  to  the  judgment  of  the  sa  mpler.  Such  a  system  may  be  fairly  satisfactory 
Where  one  man  does  all  the  sampling,  hut  this  is  seldom  possible.  In  the  light  of  the  results  obtained  in 
this  work  it  seems  to  me  that  some  arbitrary  system  that  will  eliminate  the  personal  equation  entirely 
is  much  better  for  general  work,  and  therefore  I  recommend  the  following  method  of  mine  sampling: 
Proposed  method  of  mine  sampling— \.  Select  a  fresh  face  of  coal,  and  clean  it  of  all  powder  stains  and 
other  impurities. 
2.  Cut  a  channel  perpendicularly  across  the  face  of  the  coal  from  roof  to  floor,  with  the,  exceptions 
noted  in  3,  of  such  a  size  as  to  yield  at  least  5  pounds  of  coal  per  foot  of  thickness  of  coal  bed;  that  is,  5 
pounds  for  a  bed  1  foot  thick,  10  pounds  for  a  bed  2  feet  thick,  20  pounds  for  a  bed  4  feet  thick,  etc. 
3.  All  material  encountered  in  such  a  cut  should  be  included  in  the  sample,  except  partings  or  binders 
of  more  than  0.25  inch  in  thickness  and  except  all  lenses  or  concretions  of  sulphur  or  other  impurities 
greater  than  2  inches  in  maximum  diameter  and  0.5  inch  in  thickness. 
4.  The  sample  may  be  sent  to  the  laboratory  as  it  is  cut,  or  it  may  at  once  be  quartered  down  to  about 
the  size  of  a  q  uart.  If  it  is  quartered  down  it  should  be  pulverized  to  about  three-eighths  of  an  inch,  and 
after  thorough  mixing  it  should  be  divided  into  quarters  and  opposite  quarters  rejected.  The  operation 
of  mixing  and  quartering  should  be  repeated  until  the  desired  size  of  sample  is  obtained.  The  operation 
of  pulverizing  and  quartering  should  be  done  as  rapidly  as  possible,  so  as  to  prevent  a  serious  change  in 
the  moisture  content,  and  then  the  sample  should  be  sealed  in  either  a  glass  jar  or  screw-top  can,  bound 
with  tire  tape,  and  sent  to  the  laboratory  for  analysis. 
5.  The  analysis  of  such  a  sample  will  show  the  grade  of  coal  that  may  be  obtained  by  careful  mining 
and  picking.    In  the  majority  of  cases  the  sulphur  and  ash  in  the  commerical  output  of  the  mine  will 
a  Trans.  Am.  Inst.  Min.  Eng.,  Washington  meeting,  May,  1905. 
Bull.  285-06 14 
