nother method to dye the mixed silk and wool and cotton dresses black,
four dresses_.--Bring boiler to the boil, put in 3 or 4 oz. aniline black,
either the deep black or the blue black or a mixture of the two, add 1/4 gill
hydrochloric acid or sulphuric acid, or 3 oz. oxalic acid, shut off steam,
enter, and handle for half an hour, lift, rinse through water, dye the
cotton in the manner previously described.--_Dyer_.

* * * * *

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
the gas distilled off is for a longtime much too cold for ignition, and
when it does catch fire it is too mixed with carbonic acid to burn
completely or steadily. In order to satisfy the first condition better, and
keep the gases at a higher temperature, Dr. Pridgin Teale arranges a
sloping fire-clay slab above his fire. On this the gases play, and its
temperature helps them to ignite. It also acts as a radiator,