negative flames.

A peculiar result is that the end of a negative flame returns to its own
conductor, and that, according to the intensity of the electricity, and
also depending on the width of the burner, this turning back of the
flame is either intermittent or constant. Most noticeable are these
results:

When the flame rises from a circular burner, or when burning round a
metallic cylinder, in the latter case it returns to the metallic surface
according to the intensity of electricity in an arc or angle, while the
point of the flame divides into two branches, which separately perform
more or less equal movements. If a body connected to the earth by a
conducting wire is held opposite the flame at some distance, the flame
will in all cases bend toward it; as the body is brought closer,
the flame, if negative, will be repulsed, and, if positive, will be
attracted, at least the upper luminous part of the flame, while the
lower dark body of flame is also repulsed.

This phenomenon explains why a positive flame will burn through wire
gauze, while a negative flame remains below the gauze. The positive
flame becoming pointed explains the fact that this will drive a small
fan wheel, while a negative flame will only just move it.

All these results are most prominently obtained with a pure gas flame, a
stearine, wax, or tallow candle, very indifferently with a spirit flame,
and least from a Bunsen flame rich in oxygen. They may not only be
obtained with flames electrified direct, but also when placed under the
influence of a long "Holtz" machine.