MINERAL INDUSTRIES OF THE UNITED STATES COAL PRODUCTS. 9 
Weight for weight coke offers about twice the bulk of coal, and the 
result is a corresponding difference in fuel properties, as anyone who 
has used coke has experienced. Speed or energy of combustion is of 
course proportionate to the area exposed to the attack of fire, and, 
conversely, susceptibility to chilling below combustion temperature, 
or to “ going out,” varies in like manner. Thus the greater bulk of 
coke with its aggregate of cell walls means a correspondingly in- 
creased surface exposure to attack in burning, and under adequate 
conditions a correspondingly more intense fire. Thus, too, on the 
other hand, it means a correspondingly greater liability to become 
chilled and extinguished if neglected. In short, lightness of sub- 
stance giving a flighty tendency toward extremes of behavior are the 
outstanding characteristics of coke as a fuel. 
Where an extreme of clean heat is the aim, coke is the best prac- 
ticable solid fuel obtainable, and hence its adaption as the standard 
for metallurgical use. But susceptibility to control is one of the first 
requisites for a satisfactory general-purpose fuel, and accordingly 
coke has not found favor in that direction. In view of the prejudice 
existing against it, several facts deserve consideration. In the first 
place the whole development of coke quality has been in the direc- 
tion of obtaining the maximum of intensity in combustion under the 
designation of metallurgical coke, a specialization quite at variance 
with the requirements of a general use fuel. Again, the use of any 
particular fuel requires appropriate facilities and understanding, 
and to condemn coke on the basis of its behavior under the treatment 
evolved for coal is comparable to judging the merits of anthracite on 
the basis of its behavior in a wood stove. Finally, the question which 
is slowly and certainly gaining in pressure, is not that of providing 
a fuel competitive with anthracite on equal terms, but one capable of 
practical service in the capacity of a commodity as against anthra- 
cite in the growing capacity of a luxury. A tendency away from 
anthracite is certain to set in, and the only room for choice lies be- 
tween coke and raw bituminous coal. Relative economies are bound 
to be an important factor, if not the deciding one, in the choice. 
Right here the domestic fuel situation in the United States connects 
up with the coal product one in a manner which renders the two in- 
terdependent in their requirements; for if the general purpose use 
of coke fuel is to be economically practicable, it can be rendered so 
only through the support of values derived from that other third of 
bituminous coal mass removed as volatile matters in the course of 
carbonization, and, conversely, an extensive preparation of coal prod- 
ucts necessitates an advantageous coke market. The answer to the 
whole question is to be found in the value of the distillates derivable. 
If this latter can be made to overbalance the cost of preparation, the 
surplus constitutes just so much potentiality for economic advantage 
in favor of coke for the householder. 
