ate amount of smoke but a great deal of ashes, small
and frequent lightning flashes were observed in the twilight darting
through the smoke, which was dark in colour. In 1850 the eruption was
more vigorous, the smoke more abundant, and the ashes scarce, but the
flashes were very rare. In 1855, 1858, and 1868, with a scanty supply of
ashes and at intervals, no flashes were observed, and the electricity
remained constantly positive. But having regard to the facts of
antecedent eruptions, one sees that the flashes are always derived, from
the midst of smoke accompanied with ashes and lapilli, which separate
like rain from the rolling volumes of smoke, in the midst of which they
were ejected.

But how can we account for the positive electricity of the smoke, and
the negative electricity of the falling ashes? Without denying the
probability that a part of the positive electricity depends upon the
elevation of the smoke, as in the case of every other conductor we raise
aloft, or with a jet of water sent from a vessel by compressed air, I
think that the greater part of the electricity proceeds from the rapid
condensation of vapours, which are changed from the gaseous condition
into dense clouds; for even when the smoke issues tranquilly and does
not rise, because carried away horizontally by the wind, it gives signs
of positive electricity. From all my studies of atmospheric electricity,
and from some experiments made specially, it follows that the
condensation of vapours is the origin of this development of positive
electricity.

The negative electricity of the falling ashes certainly arises from the
fact itself of their fall; for if we place a metallic vessel full of
ashes upon an elevated and well-situated terrace, while the atmospheric
electricity is positive, and cause the ashes from the vessel to fall
gradually into an insulated metallic cup, communicating with
Bohnenberger's electroscope placed at three or four metres distance from
the vessel, the electroscope will manifest negative electricity. If the
upper vessel be insulated, and the ashes permitted to fall upon the
ground, we shall obtain, from the vessel, positive electricity. The
intensity of these electric manifestations depends (other things being
equal) upon that predominant at the moment in the air; so that if the
experiment be made while negative electricity prevails, the falling
ashes will manifest positive electricity, the upper vessel then showing
negati