Dr. Gibbes supposes that the further illustration of the effects of the two electricities, as chemical agents, will set aside some of the leading doctrines of the Lavoisierian theory, and afford an easy solution of certain phenomena which that theory cannot explain. _Æpinus’ Theory of Electricity._ Mr. Æpinus, of the imperial academy of Petersburgh, has attempted to class the phenomena of electricity and magnetism in a mathematical method. In the course of his works he gives some views of the subject which are new and highly ingenious, and as some good judges suppose, calculated to surmount many difficulties, and to answer many questions, which occur in considering the Franklinian theory. The leading principles of his plan are comprehended in the following propositions. 1. Its particles repel each other, with a force decreasing as the squares of the distances increase. 2. Its particles attract the particles of some ingredients in all other bodies, with a force decreasing according to the same law, with an increase of distance; and that this attraction is mutual. 3. The electric fluid is dispersed in the pores of other bodies, and moves with various degrees of facility through the pores of different kinds of matter. In those bodies which we call non-electrics, such as water or metals, it moves without any perceivable obstruction; but in glass, resin, and all bodies called electrics, it moves with very great difficulty, or is altogether immoveable. 4. The phenomena of electricity are of two kinds: 1. Such as arise from the actual motion of the fluid, from a body containing more, to one containing less of it. 2. Such as do not immediately arise from this transference, but are instances of its attraction and repulsion.— These principles are applied at great length, and with a pleasing degree of precision, by the ingenious theorist, to the Leyden phial, and to the various phenomena of electric attraction and repulsion. It will be readily seen that Æpinus adopts, in substance, the theory of Franklin, of which, in some particulars, he presents new and more satisfactory views than the American philosopher. In the sixty first volume of the Philosophical Transactions, there is a dissertation by the Hon. Mr. Cavendish on this subject, which he considers as an extension and more accurate application of Æpinus’s theory. CHAP. III. _The Franklinian Theory of Electricity._ We are now to give Dr. Franklin’s theory of plus and minus, or positive and negative electricity, and adduce facts, to shew how far this theory will go to explain the different phenomena.