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WOODWARD'S DIFFUSION MOTOR.
The energy produced by the phenomena of diffusion is exhibited in
lecture courses by placing a bell glass filled with hydrogen over a
porous vessel at whose base is fixed a glass tube that dips into
water. The hydrogen, in diffusing, enters the porous vessel, increases
the internal pressure, and a number of bubbles escapes from the tube.
On withdrawing the bell glass of hydrogen, the latter becomes diffused
externally, a lower pressure occurs in the porous vessel, and the
level of the water rises.
The arrangement devised by Mr. C.J. Woodward, and recently presented
to the Physical Society of London, is an adaptation of this experiment
to the production of an oscillating motion by alternations in the
internal and external diffusion of the hydrogen.
The apparatus, represented herewith, consists of a scale beam about
three feet in length 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.
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