frosty day, become so electric
as frequently to give a perceptible spark to one's finger from their
ears without friction.

A fourth method of separating the two ethers would seem to be by the
decomposition of metallic bodies, as in the experiment with Volta's
Galvanic pile; which is said by Mr. Davy to act so much more
powerfully, when an acid is added to the water used in the experiment;
as will be spoken of below.

From experiments made by M. Saussure on the electricity of evaporated
water from hot metallic vessels, and from those of china and glass, he
found when the vessel was calcined or made rusty by the evaporating
water, that the electricity of it was positive (or vitreous), and that
from china or glass was negative (or resinous), Encyclop. Britan. Art.
Elect. No. 206, which seems also to show, that vitreous electric ether
was given out or produced by the corrosion of metals, and resinous
ether from the evaporation of water.

VII. _The spark from the conductor, and of electric light._

When either the vitreous or resinous electric ether is accumulated on
an insulated conductor, and an uninsulated conductor, as the finger of
an attendant, is applied nearly in contact with it, what happens? The
attractive and repulsive powers of the accumulated electric ether pass
through the nonconducting plate of air, and if it be of the vitreous
kind, it attracts the resinous electric ether of the finger towards
it, and repels the vitreous electric ether of the finger from it.

Hence there exists for an instant a charged plate of air between the
finger and the prime conductor, with an accumulation of vitreous ether
on one side of it, and of resinous ether on the other side of it; and
lastly these two kinds of electric ethers suddenly unite by their
powerful attraction of each other, explode, and give out heat and
light, and rupture the plate of nonconducting air, which separated
them.

The rupture or disjunction of the plate of air is known by the sound
of the spark, as of thunder; which shows that a vacuum of air was
previously produced by the explosion of the electric fluids, and a
vibration of the air in consequence of the sudden joining again of the
sides of the vacuum.

The light which attends electric sparks and shocks, is not accounted
for by the Theory of Dr. Franklin. I suspect that it is owing to the
combination of the two electric ethers, from which as from all
chemical explosions both light and heat are