How the attraction of electrics is performed, he acknowledges is not easily determined; though, he says, “that it is performed by effluviums is plain, and granted by most; for electrics will not commonly attract, except they grow hot and perspirable. For if they be foul and obnubilated, it hinders their effluxion; nor if they be covered, though but with linen or sarsenet, or if a body be interposed, for that intercepts the _effluvium_. If also a powerful and broad electric of wax or _anime_ be held over fine powder, the atoms or small particles will ascend most numerously unto it; and if the electric be held unto the light, it may be observed that many thereof will fly, and be as it were discharged from the electric to the distance sometime of two or three inches. Which motion is performed by the breath of the _effluvium_ issuing with agility; for as the electric cooleth, the projection of the atoms ceaseth.” Sir Francis Bacon in his “Physiological Remains,” has inserted a catalogue of bodies attractive and not attractive; but he differs in nothing worth mentioning from his predecessors. Mr. Boyle, who so eminently distinguished himself in the latter part of the seventeenth century, was led by the study of chemistry, to give some attention to electricity. He enlarged the catalogue of electrics; and noticed some circumstances relating to electrical attraction, which had escaped former philosophers. The electrical properties of bodies he found were increased by wiping and warming them, before they were rubbed. Bodies of all kinds, he observed, were indiscriminately attracted; and this attraction he supposed took place in vacuo as well as in the open air. Hitherto the attraction of electrics was the single phenomenon noticed by philosophers. Gilbert, even when remarking on the characteristic differences between magnetism and electricity, observes, that in magnetism there is both attraction and repulsion, but in electricity only the latter, and not the former.[5] Boyle made an approach to the discovery of this fact of electrical repulsion, by remarking that light bodies, as feathers &c. would cling to his fingers and other substances, after they had been attracted by electrics.