n the other hand, it may result in wider introduction of
briquetting, coking, and other processes, which will tend to improve the
local industry and be conservational in their effect.

Japan will doubtless hold some of the Asiatic coal market gained during
the war.

International coal relations are further discussed in Chapter XVIII.[17]

=Production in the United States.= The main features of the distribution
of coal supplies in the United States are:

(1) Localization of the anthracite production and reserves in a limited
area in the Lawton region of Pennsylvania. Low-grade anthracite coal
also occurs in Rhode Island, North Carolina, Colorado, and Idaho.

(2) Localization of the bituminous production in the eastern and
interior states of Pennsylvania, West Virginia, Ohio, Indiana, Illinois,
and Kentucky. The principal reserves of bituminous coal occur in the
same provinces, but important additional reserves are known in Texas, in
North and South Carolina, and in the Rocky Mountain and Pacific Coast
provinces.

(3) The existence of large tonnages of subbituminous coal in the west,
which have not been mined to any extent.

(4) The existence of large fields of lignite in the Gulf Coast region,
and in the Northern Plains region, which have not been mined.

=Coke.= About one-sixth of the bituminous coal mined in the United
States is made into _coke_, that is, it is subjected to heat in ovens
from which oxygen is excluded in order to drive off the volatile gases
(chiefly hydrocarbons and water) which constitute about 40 per cent of
the weight of the coal. The residual product, the coke, is a light,
porous mass with a considerably higher percentage of fixed carbon than
bituminous coal. In regard to composition, coking accomplishes
artificially somewhat the same result reached by nature in its slow
development of high-grade coals, but the texture of coke is far
different from that of coal. Not all bituminous coals are suitable for
coke manufacture; and such coals are frequently divided into two
classes, known as _coking_ and _non-coking_ coals. Coke is used
principally for smelting purposes. Because of its spongy, porous
texture, it burns more rapidly and intensely than coal.

The gases eliminated in coking are wasted in the old-fashioned "beehive"
ovens, but in modern "by-product" coke ovens these gases by proper
treatment yield valuable coal tar products and ammonia. It is estimated
that the sum of the value of th