martin.]  PETROLEUM    FIELDS    OF    ALASKA.  375 
greatest  thickness  and  is  entirety  free  from  bands  of  shale  and  other 
impurities,  but,  as  the  above  table  shows,  it  is  the  purest  coal  and  has 
the  highest  heating  power.  Its  composition  shows  it  to  be  semianthra- 
cite  of  somewhat  the  same  composition  as  the  coal  of  the  Bernice  Basin 
(Loyalsoek)  in  Pennsylvania/'  although  it  is  purer  and  has  a  higher 
heating  power  than  that  coal.  It  differs  from  the  anthracite  of  Penn- 
sylvania and  Wales  in  having  more  volatile  matter  in  proportion  to  the 
amount  of  fixed  carbon.  In  the  ratio  of  fixed  carbon  to  volatile  matter 
it  is  nearer  to  the  Bernice  Basin  coal  than  to  any  other  coal  that  reaches 
the  general  market.  In  heating  power  as  well  as  in  the  low  amount 
of  impurities  it  is  almost  identical  with  the  Pocahontas  steam  coal  of 
West  Virginia,  but  excels  this  coal  by  having  a  higher  proportion  of 
fixed  carbon.  There  is  no  other  coal  with  which  it  is  likely  to  come 
into  general  competition  with  which  it  is  to  be  compared,  for  it  is  far 
higher  in  heating  power  and  in  purity  than  any  coal  that  is  mined 
upon  the  Pacific  coast,  either  in  the  United  States,  Canada,  or  Aus- 
tralia. 
The  seams  opened  on  Shepherd  Creek  1  mile  northwest  of  Canoe 
Landing,  and  also  near  the  headwaters  of  Trout  Creek,  are  probably 
representative  of  the  thinner  seams  of  this  region.  These  coals  differ 
from  the  coal  of  the  20-foot  seam  in  having  a  less  amount  of  fixed 
carbon  in  proportion  to  the  volatile  matter  and  in  having  a  higher 
percentage  of  ash  and  sulphur.  The  heating  power  is  consequent^ 
less.  They  resemble  coals  of  the  semibituminous  type  that  enter 
the  market  as  high-grade  steam  coals.  They  correspond  in  texture, 
composition,  and  heating  power  to  the  high-grade  Pocahontas  (West 
Virginia)  and  Georges  Creek  (Maryland)  steam  coals,  and  also  to  some 
of  the  semibituminous  coals  of  Wales. 
The  coke  exposed  in  the  southern  end  of  Carbon  Mountain  is  an 
interesting  deposit,  which  may  prove  to  be  of  considerable  value.  The 
analysis  shows  it  to  be  of  great  purity  and  high  heating  power.  It  will 
be  seen  from  the  section  given  on  page  372  that  it  is  broken  up  by  part- 
ings into  a  number  of  thin  seams  which  vary  considerably  in  thickness 
within  short  distances.  It  may  be  that  some  of  these  will  be  found 
sufficiently  thick  and  persistent  to  be  of  economic  importance.  Part 
of  the  coke  is  dense  and  hard  and  shows  a  well-marked  columnar 
structure.  The  latter  will  break  into  fine  fragments  on  handling,  and 
will  thus  be  at  a  disadvantage  from  the  market  standpoint.  The 
product  should  be  carefully  screened,  when  the  lump  will  make  a  high 
grade  of  domestic  fuel. 
"The  following  is  an  average  of  several  analyses  of  Loyalsoek  coal: 
Per  cent. 
Moisture 1. 49 
Volatile  material 11. 07 
Fixed  carbon 78. 88 
Ash 7. 70 
Sulphur 86 
