tates are not affected seriously during storage from the standpoint of
weight and heating value, the latter loss averaging about 3-1/2 per cent
for the first year of storage. They found that the losses due to
disintegration and to spontaneous ignition were of greater importance.
Their conclusions agree with those deduced from the other experiments,
viz., that the storing of a larger size coal than that which is to be
used, will overcome to a certain extent the objection to disintegration,
and that the larger sizes, besides being advantageous in respect to
disintegration, are less liable to spontaneous ignition. Storage under
water will, of course, entirely prevent any fire loss and, to a great
extent, will stop disintegration and reduce the calorific losses to a
minimum.

To minimize the danger of spontaneous ignition in storing coal, the
piles should be thoroughly ventilated.

Pulverized Fuels--Considerable experimental work has been done with
pulverized coal, utilizing either coal dust or pulverizing such coal as
is too small to be burned in other ways. If satisfactorily fed to the
furnace, it would appear to have several advantages. The dust burned in
suspension would be more completely consumed than is the case with the
solid coals, the production of smoke would be minimized, and the process
would admit of an adjustment of the air supply to a point very close to
the amount theoretically required. This is due to the fact that in
burning there is an intimate mixture of the air and fuel. The principal
objections have been in the inability to introduce the pulverized fuel
into the furnace uniformly, the difficulty of reducing the fuel to the
same degree of fineness, liability of explosion in the furnace due to
improper mixture with the air, and the decreased capacity and efficiency
resulting from the difficulty of keeping tube surfaces clean.

Pressed Fuels--In this class are those composed of the dust of some
suitable combustible, pressed and cemented together by a substance
possessing binding and in most cases inflammable properties. Such fuels,
known as briquettes, are extensively used in foreign countries and
consist of carbon or soft coal, too small to be burned in the ordinary
way, mixed usually with pitch or coal tar. Much experimenting has been
done in this country in briquetting fuels, the government having taken
an active interest in the question, but as yet this class of fuel has
not come into common use as