Turpentine smoke
acts very well, and can be tried on a larger scale; a room filled with
turpentine smoke, so dense that a gas-light is invisible inside it,
begins to clear in a minute or two after the machine begins to turn,
and in a quarter of an hour one can go in and find the walls thickly
covered with stringy blacks, notably on the gas-pipes and everything
most easily charged by induction. Next fill a bell-jar full of steam,
and electrify, paying attention to insulation of the supply point in
this case. In a few seconds the air looks clear, and turning on a beam
of light we see the globules of water dancing about, no longer fine
and impalpable, but separately visible and rapidly falling. Finally,
make a London fog by burning turpentine and sulphur, adding a little
sulphuric acid, either directly as vapor or indirectly by a trace of
nitric oxide, and then blowing in steam. Electrify, and it soon
becomes clear, although it lakes a little longer than before; and on
removing the bell-jar we find that even the smell of SO2 has
disappeared, and only a little vapor of turpentine remains.
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