hayes.1 COAL FIELDS OF THE UNITED STATES. 265 
has passed the anthracite stage and has been partially converted into 
graphite, practically all the volatile compounds having been driven 
off. The Pennsylvania anthracite has fuel ratios varying within 
rather wide limits. In the analyses accompanying Mr. Stoek's paper a 
the maximum is 27 and the minimum 5.11, though most of the samples 
analyzed fall between 9 and 22, the average of 10 analyses being 14.11. 
Within a narrow belt along the eastern margin of the northern 
Appalachian field the coal is relatively hard and high in carbon, form- 
ing an intermediate variety between the true anthracite on the east 
and the true bituminous on the west. The fuel ratios within this belt 
are generally between 3 and 5. 
In the greater part of the Appalachian field the coals have fuel ratios 
ranging from 1 to 3, and as a rule the ratios are higher in the north- 
ern and eastern portions of the field as compared with the southern 
and western portions. There are, however, many exceptions to this 
rule. 
The field presents certain well-marked types of coal which for par- 
ticular purposes are regarded as the standard fuels. Thus the coal of 
the Pittsburg bed, in the Connellsville district, is usually taken as 
the standard with which other coking coals are compared. In the 
same way the Pocahontas coal may be considered a standard steam- 
ing fuel. Small areas occur in this field containing special varieties 
of coal, such as splint, cannel, block, etc. , which are particularly well 
suited for certain purposes — as gas-making, domestic, and locomotive 
fuel. 
The Northern Interior field contains only bituminous coal, which 
forms a fair steaming fuel, though it is inferior to most of the Appa- 
lachian coals. It generally contains a high percentage of ash and 
sulphur. Its fuel ratios vary from about 1.13 to 1.63, the average 
of 8 representative analyses given in Dr. Lane's paper 6 being 1.40. 
Three varieties of coal occur in the Eastern Interior field. By far 
the largest part of the coal mined is soft bituminous, making a good 
steam fuel. In a belt along the eastern margins of the field in Indiana 
is a variety known as block coal, which differs from the ordinary 
bituminous in its physical characteristics rather than in chemical 
composition. It is especially well adapted for domestic fuel. In the 
Kentucky portion of the field are numerous small areas of cannel coal, 
particularly valuable for gas making and domestic purposes. The 
means of the fuel ratios obtained from a large number are as follows: 
For Indiana coals, 1.30; Kentucky, 1.57, and Illinois, 1.71. 
The coal of the Western Interior field is fairly uniform in compo- 
sition, having an average fuel ratio of about 1.30 and forming a fair 
steaming fuel. In the Southwestern field considerable more diversity 
is found, the coal varying from soft bituminous, with a fuel ratio of 
a Twenty-second Ann. Rept. U. S. Ueol. Survey, Pt. Ill, p. 73. &Ibid., p. 81)7. 
