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72 Galvanism, Jrom Galvani to O/it/i. 



Scarcely more than a year after the death of Galvani, the 

 new science suddenly regained ' the eager attention of philo- 

 sophers. This renewal of interest was due to the discovery by 

 Volta, in the early spring of 1800, of a means of greatly increasing 

 the intensity of the effects. Hitherto all attempts to magnify 

 the action by enlarging or multiplying the apparatus had ended 

 in failure. If a long chain of different metals was used instead 

 of only two, the convulsions of the frog were no more violent. 

 But Volta now showed* that if any number of couples, each 

 consisting of a zinc disk and a copper disk in contact, were taken, 

 and if each couple was separated from the next by a disk of moist- 

 ened pasteboard (so that the order was copper, zinc, pasteboard, 

 copper, zinc, pasteboard, &c.), the effect of the pile thus formed 

 was much greater than that of any galvanic apparatus previously 

 introduced. When the highest and lowest disks were simul- 

 taneously touched by the fingers, a distinct shock was felt ; and 

 this could be repeated again and again, the pile apparently 

 possessing within itself an indefinite power of recuperation. It 

 thus resembled a Leyden jar endowed with a power of automati- 

 cally re-establishing its state of tension after each explosion; 

 with, in fact, " an inexhaustible charge, a perpetual action or 

 impulsion on the electric fluid." 



Volta unhesitatingly pronounced the phenomena of the pile 

 to be in their nature electrical. The circumstances of Galvani's 

 original discovery had prepared the minds of philosophers for 

 this belief, which was powerfully supported by the similarity of 

 the physiological effects of the pile to those of the Leyden jar, 

 and by the observation that the galvanic influence was conducted 

 only by those bodies e.g. the metals which were already 

 known to be good conductors of static electricity. But Volta 

 now supplied a still more convincing proof. Taking a disk of 

 copper and one of zinc, 'he held each by an insulating handle 

 and applied them to each other for an instant. After the disks 

 had been separated, they were brought into contact with a deli- 



* I'hil. Trans., 1800, p. 403. 



