Having, first, so far freed the instrument, from the small quantity of electricity collected, by wiping it, that none was indicated by a very sensible electrometer of linen-yarn, suspended from the wooden part of its handle; I placed it within a few inches of a glass stand, upon which I had laid a plate of zinc, supporting a frog recently killed, and with its sciatic nerves within the abdomen laid bare. A bar of zinc formed the communication between the frog and the metal plate of the electropherus. Contractions were then excited in the frog, by placing one end of a bent silver wire, insulated in sealing wax, upon the nerves of the frog, and the other end upon the bar of zinc. After strong contractions had, in this way, been kept up for about half a minute, I carefully removed the bar of zinc, by means of a stick of wax, that there might be no possibility of the electricity escaping, if any should have been collected. The metal plate was then raised from the varnished surface. The electrometer attached to its handle was very slightly affected; but a fine thread, presented to the plate, was perceptibly attracted by it. I had a strong suspicion, that the electricity, thus collected, had been excited solely by the friction of the frog’s legs during contraction, against the insulated plate of zinc upon which it lay; and I soon found that my conjecture was just; for an equal quantity of electricity was obtained from another frog similarly disposed, when contractions were excited in it, by merely mechanical irritation. The result was the same when these frogs were laid successively upon the metal plate of the electropherus itself, and excited, the one in M. Galvani’s method, the other by mechanical irritation only. These experiments were very frequently repeated, but the quantity of electricity collected was always greater where the contractions, or, in other words, the friction had been most considerable, and did not, in any instance, appear to depend on the means employed to excite the contractions. What still further proves, that the electricity, in this way collected, had no dependence whatever, for its production, upon the application of the metals to the frog, but had been merely the portion of electricity, naturally possessed by the frog, in common with other conducting substances, is, that when the electricity, which was collected from its first contractions, had been drawn off from the plate, no more could afterwards be collected, although the contractions, excited by the metals, still continued as vigorous as ever.