Corollary.
Gravity is the general Endeavour and Tendency of Bodies towards the Center of the Earth; this is overcome by the Magnet with Regard to Iron, and by Electricity with Regard to light Substances both in its Attraction and Repulsion; but I have never been able to discern that vortical Motion, by which this Effect was said to be brought about by the late Dr. Desaguliers and others, having no other Conception of its Manner of acting than as Rays from a Center, which indeed is confirmed by several Experiments. One of which, very easy to be tried, is, that if a single downy Seed of Cotton Grass is dropped from a Man's Hand, and in its Fall comes within the Attraction of the rubbed Tube; the Down of this Seed, which before seemed to stick together, separates, and forms Rays round the Center of the Seed: Or if you fasten many of these Seeds with Mucilage of Gum Arabic, round a Bit of Stick, the Down of them when electrified, which otherwise hangs from the Stick, is raised up, and forms a circular Appearance round the Stick. As these light Bodies are directed in their Motions, only by the Force impressed upon them, and as their Appearance is constantly radiatim, such Appearance by no Means squares with our Idea of a Vortex. Some have imagined a Polarity also, when they have observed one end of an excited Glass Tube repel light Substances, and the other attract them. But this Deception, arising from the whole Length of the Tube not being excited, but only such Part of it as has been rubbed; so that as much of the Tube as is held in the Hand, remains in an unexcited State, and permits light Substances to lie still thereon, though forcibly repell'd at the other End. This attractive Power of Electricity acts not only upon Non-electrics, as Leaf-Gold, Silver, Thread, and such like, but also upon originally Electrics, as Silk, dry Feathers, little Pieces of Glass and Resin; it attracts all Bodies, that are not of the same Standard of Electricity, (if I may be allowed the Expression) as the excited Body from which it proceeds. I have found no Body however dense, whose Pores are not pervious to Electricity by a proper Management, not even Gold itself.