One tip only of this description evidently
produces a long, jet-like flame, or a "rat-tail," in which the latent
illuminating power of the acetylene is not developed economically. In
practice, therefore, two of these tips are employed in unison, one of the
commonest methods of holding them being shown at B. From each tip issues
a stream of acetylene mixed with air, and to some extent also surrounded
by a jacket of air; and at a certain point, which forms the apex of an
isosceles right-angled triangle having its other angles at the orifices
of the tips, the gas streams impinge, yielding a flat flame, at right-
angles, as mentioned before, to the plane of the triangle. If the two
tips are three-quarters of an inch apart, and if the angle of impingement
is exactly 90 deg., the distance of each tip from the base of the flame
proper will be a trifle over half an inch; and although each stream of
gas does take fire and burn somewhat before meeting its neighbour,
comparatively little heat is generated near the body of the steatite.
Nevertheless, sufficient heat is occasionally communicated to the metal
stems of these burners to cause warping, followed by a want of alignment
in the gas streams, and this produces distortion of the flame, and
possibly smoking.
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