GALVANISM. 



a man of a very respectable character, and 

 there fell into a state of languor and al- 

 most imbecility. The republican gover- 

 nors, probably ashamed of their conduct 

 towards such a man, passed a decree for 

 his restoration to his professional chair 

 and its emoluments ; but it then was too 

 late. He died on November 5, 1798, at 

 the age of sixty, amid the tears of his 

 friends, and the public regret. 



GALVANISM, this surprising branch 

 of philosophy has been denominated gal- 

 vanism, from Galvani, an Italian professor, 

 whose experiments led to its discovery. 



In 1789, some time before he made the 

 most important discovery, he was by ac- 

 cident led to the fact, of electricity hav- 

 ing the property of exciting contractions 

 in the muscles of animals. Stimulated by 

 the then prevailing idea of electricity 

 being a principal inherent in animals, 

 which, acting upon the muscular suscep- 

 tibility, was the immediate cause of mus- 

 lar motion, he was induced to persevere 

 in the inquiry, during the prosecution of 

 which he brought to light other facts, 

 which laid the foundation of this valuable 

 scientific acquisition. 



After having observed that common 

 electricity, even that of lightning, pro- 

 duced vivid convulsions in the limbs of 

 recently killed animals,he ascertained that 

 metallic substances, by mere contact, un- 

 der particular circumstances, excited si- 

 milar commotions. 



He found that it was essential, that the 

 forces of metals employed should be of 

 different kinds. He applied one piece of 

 metal to the nerve of the part, and the 

 other to the muscle, and afterwards con- 

 nected the metals, either by bringing 

 them together, or by connecting them by 

 an arch of a metallic substance ; every 

 time this connection was formed, the con- 

 vulsions took place. The diversity in the 

 metals employed in these experiments 

 appeared, in the very early stages of this 

 inquiry, to be connected with their re- 

 spective degrees of oxydability, the one 

 being possessed of that property in a 

 great degree, and the other little liable 

 to the change. Hence zinc, and silver, 

 or gold, was found to produce the great- 

 est muscular contractions. 



The experiments of Galvani were con- 

 firmed by many able philosophers, by 

 whom they were repeated. Those who 

 particularly distinguished themselves by 

 their labours on this subject were, Valli, 

 Volia, Drs. Monro and Fowler. 



Galvani had theorised upon the pheno- 

 mena, which he had observed to a consir 

 derable extent. He conceived, that the 



convulsions were produced by a disturb-^ 

 ance of the electricity inherent in ani- 

 mals, which was identical with the ner- 

 vous fluid, and that the metallic substan- 

 ces employed had not any other effect, 

 than that of transmitting the electricity 

 from the nerve to the muscles producing 

 the contractions in question. 



Simon Volta, with much labour and in- 

 genuity, successfully opposed the hypo- 

 thesis of Galvani. He had recourse to 

 those valuable experiments made by Ben- 

 net, by which to explain the phenomena 

 observed by Galvani. Bennet had some 

 time before observed, when plates of dif- 

 ferent metals were brought in contact, 

 that one of the metals transmitted a por- 

 tion of its electricity to the other, each 

 of which, when separated, being at the 

 same time insulated, evinced signs of 

 contrary states of electricity. When the 

 plates, for instance, were one of copper 

 and the other zinc, the former, while the 

 two were in contact, gave a portion of its 

 electricity to the latter. Hence, when 

 they were separated, and thus presented 

 to the electrometer, the copper exhibited 

 signs of negative electricity, and the zinc 

 that of positive. 



On this ground it was that Volta object- 

 ed to the hypothesis of Galvani, and esta- 

 blished the more plausible idea, that the 

 electricity was furnished by the disturb- 

 ance of that fluid, arising from the con- 

 tact of the different metals, and that the 

 convulsions were excited by the stimulat- 

 ing effect of that active agent. It was in 

 the investigation of this experiment, that 

 this truly ingenious philosopher was led 

 to the discovery of the pile, which,from its 

 inventor, has been called the Voltaic pile. 

 This apparatus consisted, in combining 

 the effects of a number of pairs of the dif- 

 ferent metals, and by that means constitut- 

 ing a battery in galvanism, similar in effect 

 to the Leyden phial in common electricity. 



As silver and zinc had been found in 

 the minor experiments to produce the 

 greatest effect, these metals were employ- 

 ed by Volta in the construction of*his bat- 

 tery. The silver plates generally consisted 

 of coins ; and the zinc plates were of the 

 same size, being frequently cast in moulds 

 made with the silver. The same number 

 of pieces of cloth, pasteboard, or leather, 

 of the same size, and steeped in solution 

 of common salt, were also provided. The 

 above substances were formed into a pile, 

 in the following order : zinc, silver, wet 

 cloth ; zinc, silver, wet cloth ; and so on, 

 in the same order, till the pile became 

 sufficiently high. If it were to be elevat- 

 ed to any considerable height, it was usual 



