GALVANISM. 



CHAPTER I. 

 Origin of Galvanism. 



(1.) THE term GALVANISM " is em- 

 ployed to designate a peculiar form of 

 electric agency, elicited under particular 

 circumstances, and capable of produc- 

 ing certain effects on bodies, not usually 

 resulting from the ordinary modes of 

 excitation. The first notice that we 

 find of any phenomenon referable to this 

 branch of electricity, occurs in a meta- 

 physical work, published in 1767, and 

 entitled, The General Theory of Plea- 

 swes, by a German writer of the name 

 of Sulzer, who observed, that by apply- 

 ing two metals, one above, and the other 

 below the tongue, and then bringing 

 them into contact, a peculiar taste was 

 perceived. He ascribed this sensation 

 to some vibratory motion, excited by 

 the contact of the metals, and commu- 

 nicated to the nerves of the tongue. 

 Content with this loose and fanciful 

 explanation, Sulzer appears to have 

 pursued the inquiry no farther ; and the 

 curious fact he had announced remained 

 for many years unnoticed, until the at- 

 tention of the philosophic world was 

 drawn to the subject, by the discovery 

 of Galvani. Important discoveries in 

 science seem often to arise from ac- 

 cident ; but, on closer examination, it is 

 found that they always imply the exer* 

 cise of profound thought. As the fer- 

 tility of the soil is essential to the germi- 

 nation and growth of the seed which 

 the wind may have scattered on its sur- 

 face, so it is principally from the quali- 

 ties of mind in the observer that an 

 observation derives its value, and may 

 be made eventually to expand into an 

 important branch of science. This has 

 been remarkably exemplified in the ori- 

 gin of galvanism. Its founder, Gal- 

 vani, was professor of anatomy at 

 Bologna, and had early distinguished 

 himself by his attainments and his zeal 

 in his profession, and especially by the 

 ardour with which he cultivated com- 

 parative anatomy. It happened, in the 



year 1790, that his wife, being con- 

 sumptive, was advised to take, as a 

 nutritive article of diet, some soup made 

 of the flesh of frogs. Several of these 

 animals, recently skinned for that pur- 

 pose, were lying on a table in the labo- 

 ratory, close to an electrical machine, 

 with which a pupil of the professor was 

 amusing himself in trying experiments. 

 While the machine was in action, he 

 chanced to touch the bare nerve of the 

 leg of one of the frogs with the blade of 

 the knife that he held in his hand ; when 

 suddenly the whole limb was thrown 

 into violent convulsions. Galvani was 

 not present when this occurred, but re- 

 ceived the account from his lady, who 

 had witnessed, and had been struck 

 with the singularity of the appearance. 

 He lost no time in repeating the expe- 

 riment, in examining minutely all the 

 circumstances connected with it, and in 

 determining those on which its success 

 depended. He ascertained that the con- 

 vulsions took place only at the moment 

 when a spark was drawn from the prime 

 conductor, and the knife was at the same 

 time in contact with the nerve of the 

 frog. He next found that other metallic 

 bodies might be substituted for the 

 knife ; and very justly inferred that they 

 owed this property of exciting mus- 

 cular contractions to their being good 

 conductors of electricity. 



(2.) Far from being satisfied with 

 having arrived at this conclusion, it only 

 served to stimulate him to the further 

 investigation of this curious subject; 

 and his perseverance was at length re- 

 warded by the discovery, that similar 

 convulsions might be produced in a frog, 

 independently of the electrical machine, 

 by forming a chain of conducting sub- 

 stances between the outside of the mus- 

 cles of the leg, and the crural nerve. 

 Galvani had previously entertained the 

 idea that the contractions of the muscles 

 of animals were in some way dependent 

 on electricity ; and as these new expe- 

 riments appeared strongly to favour 

 this hypothesis, he with great ingenuity 

 applied it to explain them. He com- 



