boiler pressure the temperature would be 388 degrees Fahrenheit.

11. Q. What is carbon?

A. Carbon forms the greatest part of all kinds of coal; the higher the
per cent. of carbon, the higher the grade of coal.

12. Q. What is the composition of bituminous coal?

A. It is composed of carbon about 75 per cent. and many gaseous
substances, as is shown by its burning with a large flame and much
smoke. Anthracite, on the contrary, is nearly pure carbon and burns with
a small flame.

13. Q. What is combustion?

A. Combustion or burning is a chemical process, it is the action of fire
on inflammable substances and is the union of the oxygen in the air with
the carbon in the fuel; this is called rapid combustion. Slow combustion
is the decaying of wood or iron by the elements.

14. Q. Is air necessary for combustion?

A. Yes.

15. Q. About how many cubic feet of air is necessary for the combustion
of a pound of coal in a locomotive fire-box?

A. About 300 cubic feet of air must pass through the grates and fire
for complete combustion of one pound of coal.