8 BULLETIN 102, PART 1 , UNITED STATES NATIONAL MUSEUM. 
only from the general use of a smokeless fuel. With the passing of 
anthracite, the great natural smokeless fuel, into the realm of life’s 
luxuries, hope must look toward the development of a new smokeless 
fuel dependency artificially from bituminous coal. The relationship 
between the two types as brought out in the historical sketch lends 
plausibility to the idea ; in fact, makes it appear logically to be ex- 
pected, for if nature evolved smokeless anthracite from bituminous 
coal it is natural that man should seek in the same direction for its 
artificial equivalent. As a matter of fact he has not needed the 
inspiration to be found in the example furnished by nature. The 
evolution of a smokeless carbonized fuel is the first stage in the 
burning of bituminous coal. 
Exposed to the temperature of boiling water, some of the volatile 
ingredients in the make-up of bituminous coal begin to break loose 
and escape as gas, and as the temperature increases the process be- 
comes more active, giving rise to flame or smoke. After more or 
less protracted exposure to red heat all of the volatile ingredients 
are freed, leaving a solid residue amounting to approximately two- 
thirds of the original coal weight, which then burns quietly without 
flame or smoke. Extinguishing the fire as soon as the preliminary 
distillation stage is past instead of allowing it to continue through 
the smokeless stage of combustion, the residue will have a chemical 
composition analogous to that of anthracite and from the chart, on 
plate 1, the chemical procedure itself will be seen to be similar to 
that involved in the natural evolution of coal. Physically, however, 
there is an important difference in the two, the importance of which 
will be dwelt upon later. In nature’s laboratory the agencies of 
pressure and time duration were expended with a lavishness beyond 
all hope of human approximation, resulting in the dense stony char- 
acteristics of anthracite, whereas in the artificial product the escaping 
gas in the pasty body of the distilling coal develops cellular structure 
exactly comparable to the familiar instance of bread making. 
This coherent spongy mass representing the nonvolatile residue 
left over from the distillation of the volatile ingredients in bitumi- 
nous coal is known as coke. Coke then is the artificial expression 
for the results attained by nature in the form of anthracite, but with 
important differences arising from the fact that whereas the latter 
is the outcome from a geologic vastness of time and pressure operat- 
ing in conjunction with heat, the former comes as the direct response 
to heat alone. Around coke centers not only the opportunity for 
relieving the domestic fuel situation, but every manner of coal- 
product supply as well, so a special degree of interest attaches to its 
character and adaptability, the more especially since coke is not alto- 
gether unfamiliar as a household commodity and has been to a 
considerable degree misjudged as to its possibilities of value. 
