CHAPTEE III. 



GALVANISM, FROM GALVANI TO OHM. 



UNTIL the last decade of the eighteenth century, electricians 

 were occupied solely with statical electricity. Their attention 

 was then turned in a different direction. 



In a work entitled Recherches sur Vorigine des sentiments 

 agreables et cUsagr cables, which was published* in 1752, 

 Johann Georg Sulzer (b. 1720, d. 1779) had mentioned that, if 

 two pieces of metal, the one of lead and the other of silver, be 

 joined together in such a manner that their edges touch, and if 

 they be placed on the tongue, a taste is perceived " similar to 

 that of vitriol of iron," although neither of these metals applied 

 separately gives any trace of such a taste. " It is not probable," 

 he says, " that this contact of the two metals causes a solution 

 of either of them, liberating particles which might affect the 

 tongue : and we must therefore conclude that the contact sets 

 up a vibration in their particles, which, by affecting the nerves 

 of the tongue, produces the taste in question." 



This observation was not suspected to have any connexion 

 with electrical phenomena, and it played no part in the incep- 

 tion of the next discovery, which indeed was suggested by a 

 mere accident. 



Luigi Galvani, born at Bologna in 1737, occupied from 1775 

 onwards a chair of Anatomy in his native city. For many years 

 before the event which made him famous he had been studying 

 the susceptibility of -the nerves to irritation ; and, having been <- 

 formerly a pupil of Beccaria, he was also interested in electrical 

 experiments. One day in the latter part of the year 1780 he ' 

 had, as he tells us,f " dissected and prepared a frog, and laid it 

 on a table, on which, at some distance from the frog, was an 

 electric machine. It happened by chance that one of my 



* Mem. de 1'Acad. de Berlin, 1752, p. 356. 



t Aloysii Galvani, De Viribus E 'lee trie itatis in Motu Mnsculari : Commentarii 

 Bononiensi, vii (1791), p. 363. 



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