Page:A history of the theories of aether and electricity. Whittacker E.T. (1910).pdf/67

 drop.' In order to account for the attraction between oppositely charged bodies, in one of which there is an excess of electricity as compared with ordinary matter, and in the other an excess of ordinary matter as compared with electricity, he assumed that "though the particles of electrical matter do repel each other, they are strongly attracted by all other matter", so that "common matter is as a kind of spunge to the electrical fluid."

These repellent and attractive powers he assigned only to the actual (vitreous) electric fluid; and when later on the mutual repulsion of resinously electrified bodies became known to him, it caused him considerable perplexity. As we shall sec, the difficulty was eventually removed by Aepinus.

In spite of his belief in the power of electricity to act at a distance, Franklin did not abandon the doctrine of effluvia. "The form of the electrical atmosphere," he says, "is that of the body it surrounds. This shape may be rendered visible in a still air, by raising a smoke from dry rosin dropt into a hot teaspoon, under the electrified body, which will be attracted, and spread itself equally on all sides, covering and concealing the body, And this form it takes, because it is attracted by all parts of the surface of the body, though it cannot enter the substance already replete. Without this attraction, it would not remain round the body, but dissipate in the air." HC observed, however, that electrical effluvia do not seem to affect, or be affected by, the air; since it is possible to breathe freely in the neighbourhood of electrified bodies; and moreover a current of dry air does not destroy electric attractions and repulsions.

Regarding the suspected identity of electricity with the matter of heat, as to which Nollet had taken the affirmative position, Franklin expressed no opinion. "Common fire," he