II. As it had been proved by a great many experiments, that common electricity could be obtained from non-conducting bodies in the most perfect vacuum possible to be formed by means of an air pump, experiments were undertaken in order to ascertain whether the same phænomenon was common also to animal electricity, and with this view attempts were made to excite the latter in vacuo[7]. Muscati indeed had deprived animals of life in vacuo, and afterwards found them susceptible of Galvanism in the open air; but he made no attempt to determine whether the animal electricity could be manifested in vacuo. I employed for my experiments a glass vessel; Plate IV. fig. 6., furnished with a metallic rod, which could be, raised up or pushed down at pleasure. To the extremity of the rod, within the receiver, was affixed at right angles a metallic wire, from one end of which an armed frog was suspended by the muscles, and from the other a small metallic chain a little longer than the frog, a plate of silver being placed below both the frog and the chain. When as perfect a vacuum as possible had been obtained, the metallic rod was pushed down, so that the small chain and the spinal marrow of the suspended frog were made to touch the silver plate, and by these means the latter formed an arc in the exhausted receiver. In this experiment, the power of Galvanism was found to be the same as in the open air, so that as often as the rod was pushed down contractions were excited in the frog. By this method it was easy to ascertain what repeated contact could produce by forming new arcs: for though the small chain and the extremity of the spinal marrow touched the silver plate; yet, when removed from that position ever so little, by moving the rod new contractions took place, which could not have been expected unless new contact on moving the rod had produced as it were new arcs. This kind of apparatus seemed the most convenient for performing in vacuo all those experiments which Galvani had performed in the open air. III. But it was as yet difficult to determine, whether the contractions which took place were stronger in rarefied than in common air; for the difference between the electricity was so small, that it was impossible to say which was the more powerful. I therefore resolved to clear up this point by other experiments. For this purpose, having cut in two a prepared frog, I placed in vacuo one part of it, by means of the above apparatus, and after a short period drew it out, and compared it with the half which had not been subjected to the action of a vacuum. On applying an arc, the one exhibited strong and the other faint contractions; from which it appeared that the vacuum had occasioned some loss of the animal electricity; as the muscular and nervous parts subjected to experiment belonged to the same frog, this evidently showed that the whole difference arose from the action of the vacuum.