FUEL AND SMOKE.

[Footnote: Second of two lectures delivered at the Royal Institution,
London, on 17th April, 1886. Continued from SUPPLEMENT, No. 585, p. 9340.]

By Prof. OLIVER LODGE.

LECTURE II.


The points to which I specially called your attention in the first lecture,
and which it is necessary to recapitulate to-day, are these: (1) That coal
is distilled, or burned partly into gas, before it can be burned. (2) That
the gas, so given off, if mixed with carbonic acid, cannot be expected to
burn properly or completely. (3) That to burn the gas, a sufficient supply
of air must be introduced at a temperature not low enough to cool the gases
below their igniting point. (4) That in stoking a fire, a small amount
should be added at a time because of the heat required to warm and distill
the fresh coal. (5) That fresh coal should be put in front of or at the
bottom of a fire, so that the gas may be thoroughly heated by the
incandescent mass above and thus, if there be sufficient air, have a chance
of burning. A fire may be inverted, so that the draught proceeds through it
downward. This is the arrangement in several stoves, and in them, of
course, fresh coal is put at the top.

Two simple principles are at the root of all fire management: (1) Coal gas
must be at a certain temperature before it can burn; and (2) it must have a
sufficient supply of air. Very simple, very obvious, but also extremely
important, and frequently altogether ignored. In a common open fire they
are both ignored. Coal is put on the top of a glowing mass of charcoal, and