pitch, the softer kinds of resin,
camphor, galbanum, ammoniack[133], storax, asafoetida, benzoin, asphaltum,
especially in rather warm weather) towards them small bodies are not borne;
for without rubbing most electricks do not * emit their peculiar and native
exhalation and effluvium. The resin turpentine when liquid does not
attract; for it cannot be rubbed; but if it has hardened into a mastick it
does attract. But now at length we must understand why small bodies turn
towards those substances which have drawn their origin from water; by what
force and with what hands (so to speak) electricks seize upon kindred
natures. In all bodies in the world two causes or principles have been laid
down, from which the bodies themselves were produced, matter and form[134].
Electrical motions become strong from matter, but magnetick from form
chiefly; and they differ widely from one another and turn out unlike, since
the one is ennobled by numerous virtues and is prepotent; the other is
ignoble and of less potency, and {53} mostly restrained, as it were, within
certain barriers; and therefore that force must at times be aroused by
attrition or friction, until it is at a dull heat and gives off an
effluvium and a polish is induced on the body. For spent air, either blown
out of the mouth or given* off from moister air, chokes the virtue. If
indeed either a sheet of paper or a piece of linen be interposed, there
will be no movement. But a loadstone, without friction or heat, whether dry
or suffused with moisture, as well in air as in water, invites magneticks,
even with the most solid bodies interposed, even planks of wood or pretty
thick slabs of stone or sheets of metal. A loadstone appeals to magneticks*
only; towards electricks all things move. A loadstone[135] raises great
weights; so that if there is a loadstone weighing two ounces and strong, it
attracts half an ounce or a whole ounce. An electrical substance only
attracts very small weights; as, for instance, a piece of amber of three
ounces weight, when rubbed, scarce raises a fourth part of a grain of
barley. But this attraction of amber and of electrical substances must be
further investigated; and since there is this particular affection of
matter, it may be asked why is amber rubbed, and what affection is produced
by the rubbing, and what causes arise which make it lay hold on everything?
As a result of friction it grows slightly warm and becomes smooth; two
results which