and France, making the acquaintance of the most distinguished men of science in those countries. Volta's first scientific paper, on the Attractive Force of the Electric Fire (De Vi attractiva Ignis electrici), which was addressed in 1769 to P. Beccaria, is described by M. Biot as giving only an imperfect explanation of electric phenomena, and as illustrating the characteristic trait of his mind, which led him rather to sure deductions from facts which he could experimentally follow out than to the formation of sound general theories. That part of the paper in which he showed the application of his theory to the generation of electricity is mentioned by Prof. Arthur Schuster as being of historical importance, because in it can be traced the germ of many future discoveries. He supposed that all bodies in the natural state contain electricity in such proportions that they are in electrical equilibrium, and that this was shown in the experimental results obtained by rubbing one metal with another. But when bodies are brought into close contact, as in friction, he considered that the attractions of electricity and matter might alter, according to Boscovich's theory that attraction and repulsion alternate at short distances, and that a new equilibrium would establish itself. He expressed a belief that a disturbance of electrical equilibrium takes place during the progress of chemical action, in which the particles of matter change their position; attributed the want of proof of the fact to experimental difficulties; and hoped that he would succeed in obtaining evidence of it; and he thought that atmospheric electricity might be accounted for in accordance with these views.
In his second paper he attempted to explain electrical insulation by the supposition of a repulsion between the insulating matter and electricity. His experiments, made in 1775, on the insulating property which wood acquires when impregnated with oil, led to the construction of the electrophorus, an apparatus which acts as a permanent and inexhaustible source whence electricity can be drawn at will. A letter of Volta's to Priestley is preserved, dated June 10, 1775, announcing the construction of this instrument, and asking the English chemist, as the historian of electricity, how far the discovery was new. Volta's experiments on the electrostatic capacity of conductors, described in a letter to De Saussure in 1778, were in advance of anything that had been published up to that time, although Cavendish had already experimented on the subject; but Cavendish's results were not published for a long time afterward. Volta's ingenious efforts, pursued continuously, to improve the electrophorus, led up to the discovery of the electric condenser, the description of which, and the account of its applications to the study of electrical phenomena, were published in the Philosophical Transactions