[8] In the description of a new air-pump of his invention, where he shows that electricity cannot pass through a vacuum, he adds: “There can be little doubt, from the above experiment, of the non-conducting power of a perfect vacuum; and this fact is still more strongly confirmed by the phænomena, which appear upon the admission of a very minute particle of air into the inside of the gauge. In this case, the whole becomes immediately luminous upon the slightest application of electricity; and a charge takes place, which continues to grow more and more powerful, in proportion as fresh air is admitted, till the density of the conducting medium arrives at its maximum. _An Essay on Electricity, explaining the Theory and Practice of that useful Science._ Third edit. London, 1787. [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.