HISTORY OF GALVANISM. 301 



\lepend upon the fenfibilify of oar nerves (o fmall quantities of 

 the electric fluid. Bennet difcovered by means of his electro- Bennet's early 

 meter, that zinc, when feparate from other metals, always is .'^"J ° f c c 

 in the minus ftate, and filver in the plus ftate ; when therefore zinc (1789.) 

 they are brought nearly together, a fmall plate of air is charged 

 like a Ley den phial ; when the metals are brought into con- 

 tact this is difcharged. 



In the Phil. Tranf. for the year 1795, is a Paper by Dr. Dr. Wells, 

 Wells on the t abject of gatvanifm. He propofes for confide- J^JJJjf. 

 ration the three following enquiries; Do the contractions ob-ments thatani- 

 ferved by Galvani depend upon any property peculiar to the"™' 5 are afte &- 

 livingbody? What are the conditions necelfary for the ex-means of humi- 

 citement of the influence? Is it electrical? With refpect to dit '/i that the 



.1-^ n . . r r 1 -lrti ft ate °* t' 15 me * 



the nrft queltion, he luppoles that animals act only on account ta i b ; s nnt a j_ 

 of their moifture. With refpect to the fecond, he found thatt eied b y contact; 

 one metal and charcoal excited the contractions as readily as phenomena^re 

 two metals; in this he corrects the miftake of Fowler noticed electrical. 

 above. He however found that all charcoal will not act as a 

 conductor of the influence, in which opinion Volta agrees 

 with him. Wells does not agree in the hypotheuY adopted 

 by Volta and others, that the contact of the metals produces 

 an alteration in the difpofition of the electric fluid, for he very 

 properly a(ks, why mould not the natural moifture of the animal 

 afford a communication between the two metals before they 

 are connected by any other conductor ? He farther difcovered, 

 that. contractions could be excited by one metal only when it 

 had been rubbed upon another metal, or even upon the hand. 

 Charcoal may by the fame means be made to produce the fame 

 effect ; he proved by a variety of experiments that the fric- 

 tion does not in thefe cafes communicate electricity to the 

 metal or the charcoal; we may conjecture that an incipient . 



oxidation, or feme other chemical change was produced upon 

 the fur face of thefe fubftances. With refpect to the third 

 queftion, Wells is decidedly of opinion, that the phenomena 

 are electrical ; the influence being conducted by all conductors 

 of electricity, and by them alone. 



Keiides the works here mentioned a number of communi- Various other 

 cations appeared in the different fcientific journals of Italy, F a ?j rs, D HuQa " 

 France, and Germany, and feveral diftinct treatifes were Monro, the In • 



publiflied on the fubjeft of animal electricity. Humbolt par- J itute of c 



J '■ • , , France, &c. 



tieularly 



