ion emit a gross or vapourous or aeriform effluvium produce
no effect; for either such effluvia are alien to the humour (the uniter of
all things), or being very like common air are blended with the air and
intermingle with the air, wherefore they produce no effect in the air, and
do not cause motions different from those so universal and common in
nature. In like manner * bodies strive to be united and move on the surface
of water, just [Illustration] as the rod C, which is put a little way under
water. It is plain that the rod E F, which floats on the water by reason of
the cork H, and only has its wet end F above the surface of the water, is
attracted by the rod C, if the rod C is wet a little above the surface of
the water; they are suddenly united, just as a drop adjoining a drop is
attracted. So a wet thing on the surface of water seeks union with a wet
thing, since the surface of the water is raised on both; and they
immediately flow together, just like drops or bubbles. But they are in much
greater proximity than electricks, and are united by their clammy natures.
If, however, the whole rod be dry * above the water, it no longer attracts,
but drives away the stick E F. The same is seen in those bubbles also which
are made on {58} water. For we see one drive towards another, and the
quicker the nearer they are. Solids are impelled towards solids by the
medium of liquid: for example, touch the end of a versorium with the end of
a rod on which a drop of water is projecting; as soon as the versorium
touches the top of the droplet, immediately it is joined * strongly by a
swift motion to the body of the rod. So concreted humid things attract when
a little resolved into air (the effluvia in the intermediate space tending
to produce unity); for water has on wet bodies, or on bodies wet with
abundant moisture on the top of water, the force of an effluvium. Clear air
is a convenient medium for an electrical effluvium excited from concreted
humour. Wet bodies projecting above the surface of water (if they are near)
run together so that they may unite; for the surface of the water is raised
around wet substances. But a dry thing is not impelled to a wet one, nor a
wet to a dry, but seems to run away. For if all is dry above the water, the
surface of the water close to it does not rise, but shuns it, the wave
sinking around a dry thing. So neither does a wet thing move towards the
dry rim of a vessel; but it seeks [Illustration