BULL   MOUNTAIN    COAL  FIELD,    MONTANA.  75 
east  of  Roundup  and  at  least  one-half  mile  back  from  the  outcrop  of 
the  coal  bed.  The  sample  of  the  Mammoth  coal,  No.  5799,  which 
ranks  next  to  the  Wildhorse  in  freshness,  was  taken  from  the  bed 
beneath  a  sandstone  cover  and  about  8  feet  horizontally  back  from 
the  outcrop.  The  Dorrity  samples  were  collected  practically  on  the 
outcrop  of  the  coal.  Hence  probably  none  of  the  analyses,  except 
that  of  the  Wildhorse  coal,  represents  the  true  chemical  composition 
and  heating  value  of  the  coals.  It  is  believed  that  fresh  samples  of 
the  other  coal  beds  would  approach  very  closely  and  probably  exceed 
10,000  B.  t.  u.  Indeed,  a  sample  from  the  Mammoth  bed  com- 
parable in  freshness  with  that  of  the  Wildhorse  coal  would,  with  little 
doubt,  reach  11,000  B.  t.  u.  Sample  No.  5797,  which  represents  the 
upper  18  inches  of  the  Mammoth  coal  bed,  has  apparently  suffered 
great  deterioration  from  percolating  waters,  besides  being  cut  by 
many  small  partings.  To  the  latter  fact  may  be  due  a  percentage  of 
ash  double  that  of  the  lower  portion  of  the  bed.  Both  samples  were 
taken  along  the  same  vertical  line  in  the  Mammoth  bed. 
An  examination  of  the  analyses  of  air-dried  samples,  excluding  No. 
5797,  shows  that  these  coals  contain  an  average  of  44  percent  of  fixed 
carbon,  32  per  cent  of  volatile  matter,  9.7  per  cent  of  ash,  and  0.48 
per  cent  of  sulphur.  The  amount  of  sulphur  is  considerably  less  than 
that  of  the  Great  Falls  coals,  which  average  3  per  cent.  The  moisture 
content  is  rather  large,  averaging  about  3  per  cent,  and  this  has  a  dele- 
terious effect  on  the  fuel  value  of  the  coal.  From  the  association  of 
chemical  and  physical  characters,  such  as  the  heating  value,  which 
ranges  between  10,000  and  12,000  B.  t.  u.;  the  disintegration  into 
thin  plates  on  exposure;  the  brownish  streak;  the  lack  of  gray,  leaden 
luster;  the  lack  of  coking  qualities,  etc.,  we  may  safely  conclude 
that  the  coals  of  this  field  should  be  classed  at  least  as  high-grade 
subbituminous. 
When  the  analyses  are  compared  with  those  of  coals  from  Great 
Falls,  Miles  City,  Red  Lodge,  Bear  Creek,  and  the  Bighorn  Basin," 
it  may  be  said  that  the  Bull  Mountain  coals  rank  well.  Few  of  the 
others  have  a  greater  fuel  value  and  many  have  somewhat  less. 
DEVELOPMENT. 
So  far  as  known  no  extensive  mining  has  been  carried  on  during 
the  last  year  in  the  Bull  Mountain  field.  In  the  area  surveyed  nothing 
better  than  three  or  four  dilapidated  coal  pits  was  seen,  except  the 
old  workings  of  the  Northern  Pacific  Railway  at  the  head  of  Railroad 
Creek,  in  sec.  24,  T.  6  N.;  R.  27  E.  During  the  last  season,  however, 
the  projection  of  the  coast  extension  of  the  Chicago,  Milwaukee  and 
St.  Paul  Railway  along  Musselshell  River  has  caused  considerable  pr<  >s- 
pecting  along  that  stream,  which  has  resulted  in  the   establishment 
o  See  papers  on  these  fields  in  this  bulletin, 
