th that supports at one end a scale pan and weights,
and, at the other, a corked porous vessel that carries a glass tube,
c, which dips into a vessel containing either water or methylic
alcohol. Three or four gas jets, one of which is shown at E, are
arranged around the porous vessel, as close as possible, but in such a
way as not to touch it during the oscillation of the beam. These gas
jets communicate with a gasometer tilled with hydrogen, the bell of
which is so charged as to furnish a jet of sufficient strength.
Experience will indicate the best place to give the gas jets, but, in
general, it is well to locate them at near the center of the porous
vessel when the beam is horizontal.

[Illustration]

It is now easy to see how the device operates. When the hydrogen comes
in presence of the porous vessel it becomes diffused therein, and the
pressure exerted in the interior then produces an ascent. When the
bottom of the porous vessel gets above the jets, the internal
diffusion ceases and the hydrogen becomes diffused externally, the
internal pressure diminishes, and the vessel descends. The vessel then
comes opposite the jets of hydrogen and the same motion occurs again,
and soon indefinitely. The work produced by this motor, which has
purely a scientific interest, is very feeble, and much below that
assigned to it by theory. In order to obtain a maximum, it would be
necessary to completely surround the porous vessel each time with
hydrogen, and afterward remove the jets to facilitate the access of
air. All the mechanical arrangements employed for obtaining such a
result have failed, because the friction introduced by the maneuvering
parts also introduces a resistance greater than the motor can
overcome. There is therefore a waste of energy due to the continuous
flow of hydrogen; but the apparatus, for all that, constitutes none
the less an original and interesting device.--_La Nature._

* * * * *

SOME RELATIONS OF HEAT TO VOLTAIC AND THERMO-ELECTRIC ACTION OF METALS
IN ELECTROLYTES.[1]

[Footnote 1: Read before the Royal Society, Nov., 1883.]

By G. GORE, F.R.S., LL.D.

The experiments described in this paper throw considerable light upon
the real cause of the voltaic current. The results of them are
contained in twenty tables; and by comparing them with each other, and
also by means of additional experiments, the following general
conclusions and chief facts were o