light more closely resembles sunlight in composition or "colour." It is
more nearly a pure "white" light than is any other flame or incandescent
body in general use for illuminating purposes. The nature or composition
of the light of the acetylene flame will be dealt with more exhaustively
later, and compared with that afforded by other illuminants; but,
speaking generally, it may be said that the self-luminous acetylene light
is superior in tint, to all other artificial lights, for which reason it
is invaluable for colour-judging and shade-matching. In the second
place, when the gas issues from a suitable self-luminous burner under
proper pressure, the acetylene flame is perfectly steady; and in this
respect it in preferable to most types of electric light, to all self-
luminous coal-gas flames and candles, and to many varieties of oil-lamp.
In steadiness and freedom from flicker it is fully equal to incandescent
coal-gas light, but it in distinctly superior to the latter by virtue of
its complete freedom from noise. The incandescent acetylene flame emits a
slight roaring, but usually not more than that coming from an
atmospheric coal-gas burner. With the exception of the electric arc,
self-luminous acetylene yields a flame of unsurpassed intensity, and yet
its light is agreeably soft. In the third place, where electricity is
absent, a brilliancy of illumination which can readily be obtained from
self-luminous acetylene can otherwise only be procured by the employment
of the incandescent system applied either to coal-gas or to oil; and
there are numerous situations, such as factories, workshops, and the
like, where the vibration of the machinery or the prevalence of dust
renders the use of mantles troublesome if not impossible. Anticipating
what will be said later, in cases like these, the cost of lighting by
self-luminous acetylene may fairly be compared with self-luminous coal-
gas or oil only; although in other positions the economy of the Welsbach
mantle must be borne in mind.