change was made by the contact of one of these metals with the liquid matter 

 always found on the parts of the animal body ; and that the immediate cause 

 of the convulsions was not, as supposed by Galvani, due to animal electricity, 

 nor, as assumed by Volta, to a current of electricity emanating from the sur- 

 face of contact of the two metals, but to the decomposition of the fluid upon 

 the animal substance, and the transition of oxygen from a state of combination 

 with it to combination with the metal. The electricity produced in the experi- 

 ments Fabroni ascribed entirely to the chemical changes, it being then known 

 that chemical processes were generally attended with sensible signs of elec- 

 tricity. He maintained that the convulsions were chiefly due to the chemical 

 changes, and not to the electricity incidental to them, which, if it operated at 

 all, he considered to do so in a secondary way. 



The necessary limits of this notice will not allow of a further analysis of the 

 researches of this philosopher ; but if his original papers be referred to, it will 

 be seen that he is entitled to the credit of having first distinctly demonstrated 

 the chemical origin of Voltaic electricity. 



In the year 1800, the attention of the scientific world was withdrawn from 

 the controversy respecting the origin of Galvanic electricity, and all trther 

 matters of minor importance, and engrossed by one of those vast discoveries 

 which constitute an epoch in the progress of knowledge, and give a new di- 

 rection to the sciences. On the 20th of March, 1800, Volta addressed a letter 

 to Sir Joseph Banks, then president of the Royal Society, in which he an- 

 nounced to him the discovery of the VOLTAIC PILE, one of the most powerful 

 instruments for the investigation of the laws of nature, as exhibited in the mu- 

 tual relations of the constituent parts of matter, which ever did honor to the 

 science of any age, or any nation. 



In order to complete the experimental analysis of the effects of Galvanic 

 electricity, Volta felt the necessity of collecting it in much greater quantities 

 than could be obtained in the processes which had then been adopted. Ac- 

 cording to his theory, when two plates of metal, zinc and copper for example, 

 were brought into contact, two currents of electric fluid originated at their 

 common surface, and moved from that point in opposite directions. The posi- 

 tive fluid passed along the zinc, and the negative along the copper. If the 

 extremities of the two metals most remote from their mutual contact were con- 

 nected by an arc of conducting matter, these contrary currents would flow 

 along this arc, the positive fluid moving from the zinc toward the copper, and 

 the negative from the copper toward the zinc ; but the intensity of these cur- 

 rents was supposed to be so feeble that no ordinary electroscope, whatever 

 might be its sensibility, would be affected by it. In order to bring into opera- 

 tion in this question those instruments which had been applied to common 

 electricity, he therefore sought some expedient by which he could combine, 

 and, as it were, superpose two or more currents, and thus multiply the intensity, 

 until it should attain such an augmentation as to produce effects analogous to 

 those which had been obtained by ordinary electricity. 



With this object, he conceived the idea of placing alternately, one over the 

 other, disks of different metals, such as zinc and copper. Let us suppose the 

 lowest disk to be copper, having a disk of zinc upon it. On this disk of zinc 

 let a second copper disk be placed, and over that a second disk of zinc, and so 

 on. According to Volta's theory, currents of electricity would be established 

 at each surface of contact of the two metals, the positive current running along 

 the zinc, and the negative along the copper. With the arrangement above 

 described, there would proceed from the first surface a negative downward, and 

 a positive upward current ; from the second a positive downward, and a nega- 

 tive upward current ; from the third a negative downward, and a positive up- 



