252         CONTRIBUTIONS    TO    ECONOMIC   GEOLOGY,    1907,   PART   II. 
In  addition  to  the  results  shown  in  the  table,  a  determination  of 
volatile  matter  by  a  modified  method  was  reported.  This  differs 
from  the  method  adopted  by  the  American  Chemical  Society  for 
obtaining  the  volatile  matter  in  that  the  sample  is  given  four  min- 
utes of  preliminary  heating  over  a  low  flame,  then  seven  minutes 
over  the  full  flame  of  a  Bunsen  burner,  while  in  the  regular  method 
there  is  no  heating  preliminary  to  the  seven  minutes  over  the  full 
Bunsen  flame. a  Sample  No.  5342  in  the  table  gives  a  rather  start- 
ling proximate  analysis  by  the  regular  method,  as  shown  by  com- 
paring it  with  No.  5298,  taken  from  another  bench  of  the  same  bed. 
By  the  modified  method  the  volatile  matter  in  the  two  samples  is 
as  follows: 
No.  5298,  as  received 27.  90 
No.  5298,  air  dried 29.  62 
No.  5342,  as  received 27.  04 
No.  5342,  air  dried 28.  92 
F.  M.  Stanton,  chemist  in  charge,  writes  concerning  sample  No. 
5342: 
The  high  volatile  matter  does  not  indicate  very  much  in  this  kind  of  coal,  and 
I  would  suggest  that  in  any  classification  on  this  coal  the  modified  volatile  results 
be  used.  We  have  found  repeatedly  that  volatile  matter  in  high-moisture  coals 
is  very  unsatisfactory  as  determined  by  the  official  method,  while  the  modified 
method  gives  very  concordant  and  satisfactory  results  on  all  types  of  coal  and  lignite. 
Location,  geologic  'position,  and  sections  of  coal  beds  in  western  part  of  Little  Snake  River 
field,  Wyoming. 
For- 
ma- 
tion. 
Eco- 
nomic 
desig- 
nation. 
Member. 
Labo- 
ratory- 
No. 
Location. 
Section  of  bed. 
Latham,  64  miles  south  of;    SW.  £ 
SW.  i  sec.  23,  T.  19  N.,  R.  93  W. 
Creston,  9  miles  south  of;  Coal 
Bank  Spring;  NE  \  NW  J  sec.  3, 
T.  18  N.,  R.  92  W. 
Ft.  in. 
Shale,  gray 
Coal,  dirty 6 
Shale,  gray. 6 
Coal,  shaly,  gypsif-  7 
erous. 
Shale,  gray 6 
Coal,  shaly 4      2 
Shale,  bituminous..  9 
Coal,  shaly 2      1 
Shale,  brown 
26      6 
Sandstone 
Coal,  dirty,  shaly ...  1 
Shale,  gray 1      6 
Coal,  good 3 
Shale,  gray 2 
Coal,  shaly 5     2 
Shale,  gray 4     8 
Coal,  fair 2    10 
Shale,  bituminous . .  1      4 
Coal,  fair 3      3 
Shale,  gray 9      9 
Coal,  shaly,  gypsif-  8      9 
erous. 
Sandstone 6 
Shale,  gray 10      3 
Coal,  dirty 2 
61      6 
a  For  complete   description  of  the  modified  method   and   general  comparison  of  results  by  the  two 
methods,  see  Bull.  U.  S.  Geol.  Survey  No.  323,  1907,  pp.  36-39. 
