at one distance, and
repel at another. This may be observed by approaching to each other
two electric atmospheres round insulated cork-balls; or by pressing
globules of mercury, which roll on the surface, till they unite with
it; or by pressing the drops of water,' which stand on a cabbage leaf,
till they unite with it, and hence light is reflected from the surface
of a mirror without touching it.

Thus the peculiar attractions and repulsions of the particles of
bodies, and the general ones of the masses of matter, perpetually
oppose and counteract each other; whence if the power of attraction
should cease to act, all matter would be dissipated by the power of
repulsion into boundless space; and if heat, or the power of
repulsion, should cease to act, the whole world would become one solid
mass, condensed into a point.

II. _Preliminary Propositions._

The following propositions concerning Electricity and Galvanism will
either be proved by direct experiments, or will be rendered probable
by their tending to explain or connect the variety of electric facts,
to which they will be applied.

1. There are two kinds of electric ether, which exist either
separately or in combination. That which is accumulated on the surface
of smooth glass, when it is rubbed with a cushion, is here termed
vitreous ether; and that which is accumulated on the surface of resin
or sealing-wax, when it is rubbed with a cushion, is here termed
resinous ether; and a combination of them, as in their usual state,
may be termed neutral electric ethers.

2. Atmospheres of vitreous or of resinous or of neutral electricity
surround all separate bodies, are attracted by them, and permeate
those, which are called conductors, as metallic and aqueous and
carbonic ones; but will not permeate those, which are termed
nonconductors, as air, glass, silk, resin, sulphur.

3. The particles of vitreous electric ether strongly repel each other
as they surround other bodies; but strongly attract the particles of
resinous electric ether: in similar manner the particles of the
resinous ether powerfully repel each other, and as powerfully attract
those of the vitreous ether. Hence in their separate state they appear
to occupy much greater space, as they, gravitate round insulated
bodies, and are then only cognizable by our senses or experiments.
They rush violently together through conducting substances, and then
probably possess much less space in this their com