ould render the making of readings difficult. To
obtain accuracy of readings, they should be made through a telescope or
eyeglass.

A spring and screw device for revolving the agitator.

A lever L, by the movement of which the agitator is revolved.

A pressure gauge M, for noting the amount of oxygen admitted to the
bomb. Between 20 and 25 atmospheres are ordinarily employed.

An oxygen tank O.

A battery or batteries P, the current from which heats the fuse wire
used to ignite the fuel.

This or a similar calorimeter is used in the determination of the heat
of combustion of solid or liquid fuels. Whatever the fuel to be tested,
too much importance cannot be given to the securing of an average
sample. Where coal is to be tested, tests should be made from a portion
of the dried and pulverized laboratory sample, the methods of obtaining
which have been described. In considering the methods of calorimeter
determination, the remarks applied to coal are equally applicable to any
solid fuel, and such changes in methods as are necessary for liquid
fuels will be self-evident from the same description.

Approximately one gram of the pulverized dried coal sample should be
placed directly in the pan of the calorimeter. There is some danger in
the using of a pulverized sample from the fact that some of it may be
blown out of the pan when oxygen is admitted. This may be at least
partially overcome by forming about two grams into a briquette by the
use of a cylinder equipped with a plunger and a screw press. Such a
briquette should be broken and approximately one gram used. If a
pulverized sample is used, care should be taken to admit oxygen slowly
to prevent blowing the coal out of the pan. The weight of the sample is
limited to approximately one gram since the calorimeter is proportioned
for the combustion of about this weight when under an oxygen pressure of
about 25 atmospheres.

A piece of fine iron wire is connected to the lower end of the plunger
to form a fuse for igniting the sample. The weight of iron wire used is
determined, and if after combustion a portion has not been burned, the
weight of such portion is determined. In placing the sample in the pan,
and in adjusting the fuse, the top of the calorimeter is removed. It is
then replaced and carefully screwed into place on the bomb by means of a
long handled wrench furnished for the purpose.

The bomb is then placed in the calorimeter, which has been filled with