Cl 
HALLS 69, 70, AND 71. 
CARBONS, MINERAL COALS, SOLID AND 
LIQUID BITUMENS. 
At the head of the carbon group are placed the diamond, a 
cry.stallized form of carbon in it.s purest state, and the hard- 
est substance known; and graphite, also a crystallized form of 
carbon, one of the softest minerals, containing generally a 
small amount of impurity. Then follow in order the other carbon 
minerals. 
T/ie Coals : Anthracite, .Semi-anthracite, Semi-L>ituminous, 
Bituminous, Lignite. T3itumens : Solid Bitumen, Liquid Bitumen. 
Some of the leading fossils of the coal measures are shown in 
connection with the coals, although a far greater variety of larger 
and more perfect specimens may be seen in the Division of 
Systematic Geology. 
HALL 69. 
The plate-glass map of the United States, on the floor, shows 
the distribution and extent of the great coal fields. The scale of 
the map is ten miles to one inch. Samples of coal from these dif- 
erent coal areas, representing the chief coal deposits of the United 
States, are to be found arranged under their respective states in 
the wall cases as follows : 
Case 1 — Virginia ; 2, Maryland ; 3, Pennsylvania ; 4-, West 
Virginia ; 3, Ohio, Georgia ; O, Tennessee, Alabama ; 7, Indiana, 
Kentucky ; 8, Illinois ; D, Iowa, Missouri ; 1 O, Iowa, Missouri ; 
11, Texas, Indian Ter. ; 12, Kansas, X. Dakota ; 1 3, Colorado, 
Xew Mexico; 14, Utah, Wyoming; 15, Oregon, >.Iontana ; 
lf>, California, Washington. 
