(7.) When artificial or natural accumulations of these separate ethers are in a very small quantity or intensity, they pass slowly and with difficulty from one body to another, and require the best conductors for this purpose. Whence many of the phenomena of the Torpedo, the Gymnotus, and of Galvanism. (8.) The electric ethers may be separately accumulated, by the contact of conductors with non-conductors—by vicinity of the two ethers—by heat—and by decomposition. (9.) When these two ethers unite suddenly and with explosion, a liberation of light and heat takes place, as in all chemical explosions. Accordingly it is said that a _smell_ is perceptible from electric sparks, and even a _taste_, which must be supposed to arise from new combinations or decompositions.” The theory founded on the principles above stated is supposed, by those who adopt it, to solve many difficulties which can scarcely be accounted for on the theory of Franklin. Dr. Gibbes also adopts a chemical theory of electricity. He supposes that oxygen gas is produced by the union of _positive electricity_ with water; and hydrogen gas by the union of _negative electricity_ with water: and that water, uniting in different proportions with the two electricities, is the ponderable part of all the elastic fluids. He asserts that by the _positive electricity_ metals are oxydated, and blue vegetable colours reddened; and also that the acidifying effect of electric commotions in the atmosphere, on weak fermented liquors, is unquestionable.—On the other hand, according to this writer, by _negative electricity_ the vegetable blue is restored, and the oxydated metal revived. These circumstances, among others, led Dr. Gibbes to conclude that when hydrogen gas is produced by the affusion of water on red-hot metal, and the metal is at the same time oxydated, a decomposition of _fire_ rather than of _water_ has taken place; that the hot metal has parted with negative electricity, which, uniting with a small proportion of the water, has formed hydrogen gas; that a greater proportion of the water has united with the positive electricity, and entered, as oxygen gas, into combination with the metal. When the two gases are inflamed together, the spark attracts to itself, in due proportions, the two electricities contained in the two gases, which unite with explosion, and produce fire. The water with which they were before combined is of course deposited. The reason why inflammable substances burn in oxygen gas, and not in hydrogen, Dr. Gibbes supposes to be, that negative electricity greatly prevails in all inflammable substances. Neither of the gases can be inflamed separately, because fire depends on the union of the two electricities; and such union cannot be effected unless both are present in due proportion.