onducting, either by a tinfoil coating or
otherwise, and the external electrode is connected to a terminal of
the coil.

The arrangement diagrammatically indicated in Fig. 24 was found to be
an inferior one when it was desired to render incandescent a filament
or button supported in the centre of the globe, but it was convenient
when the object was to excite phosphorescence.

In many experiments in which bodies of a different kind were mounted
in the bulb as, for instance, indicated in Fig. 23, some observations
of interest were made.

It was found, among other things, that in such cases, no matter where
the bombardment began, just as soon as a high temperature was reached
there was generally one of the bodies which seemed to take most of the
bombardment upon itself, the other, or others, being thereby relieved.
This quality appeared to depend principally on the point of fusion,
and on the facility with which the body was "evaporated," or,
generally speaking, disintegrated--meaning by the latter term not only
the throwing off of atoms, but likewise of larger lumps. The
observation made was in accordance with generally accepted notions. In
a highly exhausted bulb electricity is carried off from the electrode
by independent carriers, which are partly the atoms, or molecules, of
the residual atmosphere, and partly the atoms, molecules, or lumps
thrown off from the electrode. If the electrode is composed of bodies
of different character, and if one of these is more easily
disintegrated than the others, most of the electricity supplied is
carried off from that body, which is then brought to a higher
temperature than the others, and this the more, as upon an increase of
the temperature the body is still more easily disintegrated.

It seems to me quite probable that a similar process takes place in
the bulb even with a homogeneous electrode, and I think it to be the
principal cause of the disintegration. There is bound to be some
irregularity, even if the surface is highly polished, which, of
course, is impossible with most of the refractory bodies employed as
electrodes. Assume that a point of the electrode gets hotter,
instantly most of the discharge passes through that point, and a
minute patch is probably fused and evaporated. It is now possible that
in consequence of the violent disintegration the spot attacked sinks
in temperature, or that a counter force is created, as in an arc; at
any rate, the local tearing off