[9] Josephi Gardini de Electrici Ignis Natura Dissertatio, Regiæ Scientiarum Academiæ Mantuanæ exhibita, Mantuæ 1792, p. 100.
[10] This may be accomplished in a much more simple manner, without the aid of a magnet, by connecting a wire with the lower part of the nerves, and applying the wire to the muscles by turning the rod round.
[11] Précis historique et expérimental des Phénomènes électriques, par M. Sigaud de la Fond, Paris 1781, sect. i. art. 4.
[12] Aloysii Galvani de Viribus Electricitatis in Motu musculari Commentarius, Mutinæ iterum editus, p. 29.
[13] M. Valli Cinquième et Huitième Lettre sur l’Electricité Animale, dans Observations sur la Physique, par M. l’Abbé Rozier, tom. xlii. Paris, 1792.
[14] Recherches sur la Distribution de Fluide Electrique entre plusieurs Corps Conducteurs, et la Détermination de la Densité Electrique dans les différens Parties de la Surface de ces Corps. Mem. de l’Acad. Royale des Sciences, An. 1788.
CONCLUSION.
I publish my experiments respecting muscular contractions produced by one metal with the greater confidence, as they were repeated different ways by the celebrated Humboldt, who has adopted my opinion. In his work on Galvanism, under the head which he entitles “Answer to the Objections made by Volta to the Experiments of Aldini,” he says, “J. Aldini of Bologna invented a very ingenious apparatus, by means of which he was enabled to refute the supposition of Professor Volta. For this purpose he had recourse to mercury: every thing relating to his experiments is very well represented in the plate which accompanies his memoir. Volta, in reply to these experiments, observes, that they can impose only on those who have not thoroughly examined them. He denies the facts related by Aldini, and persists in his opinion that the phænomena of Galvanism may all be referred to the laws of heterogeneity. In regard to the experiments made with mercury, he says that there is a great difference between the surface of this metal and the interior of its mass; because the surface becomes oxidated by the contact of the atmospheric air; that consequently, in the experiment of Aldini, the conducting arc is not really but apparently homogeneous, the organs being immersed to different depths in the metal: besides, that the mercury in these experiments produces a
shock; and that, as this shock is not the same at both extremities of the arc, the result is an unequal development of electricity. Volta, therefore, opposes to the phænomena described by Aldini nothing but hypothesis. We might reply in the same manner; but as it is much better in philosophical disputes to have recourse to experiments, I undertook some researches for the purpose of removing all doubt in regard to this subject.