ls in the contrary direction.

[A] If a metallic vessel three or four inches deep, containing oil of
turpentine, be insulated and electrified, and a rod with a ball (an
inch or more in diameter) at the end have the ball immersed in the
fluid whilst the end is held in the hand, the mechanical force
generated when the ball is moved to and from the sides of the vessel
will soon be evident to the experimenter.

1623. Travelling particles of the air can effect chemical changes just as
well as the contact of a fixed platina electrode, or that of a combining
electrode, or the ions of a decomposing electrolyte (453. 471.); and in the
experiment formerly described, where eight places of decomposition were
rendered active by one current (469.), and where charged particles of air
in motion were the only electrical means of connecting these parts of the
current, it seems to me that the action of the particles of the electrolyte
and of the air were essentially the same. A particle of air was rendered
positive; it travelled in a certain determinate direction, and coming to an
electrolyte, communicated its powers; an equal amount of positive force was
accordingly acquired by another particle (the hydrogen), and the latter, so
charged, travelled as the former did, and in the same direction, until it
came to another particle, and transferred its power and motion, making that
other particle active. Now, though the particle of air travelled over a
visible and occasionally a large space, whilst the particle of the
electrolyte moved over an exceedingly small one; though the air particle
might be oxygen, nitrogen, or hydrogen, receiving its charge from force of
high intensity, whilst the electrolytic particle of hydrogen had a natural
aptness to receive the positive condition with extreme facility; though the
air particle might be charged with very little electricity at a very high
intensity by one process, whilst the hydrogen particle might be charged
with much electricity at a very low intensity by another process; these are
not differences of kind, as relates to the final discharging action of
these particles, but only of degree; not essential differences which make
things unlike, but such differences as give to things, similar in their
nature, that great variety which fits them for their office in the system
of the universe.

1624. So when a particle of air, or of dust in it, electrified at a
negative point, moves on through