ON 



GALVANISM. 171 



the pofition he advanced. This I may be permitted to obferve, 

 without the imputation of detradion from thofe whofe labours 

 and talents demand my refpedl. 

 I am. Sir, 



Your very obedient fervant. 

 City Road, J. C. HORNBLOWER. 



June Jl, ISO-k 



VII. 



FaSis and Ohfervations tending to elucidate the Theory of GaU 

 vaniftn. By A Correspondent. 



JL HE pile of Volta has difclofed many new properties which General effedls 

 were not known to belong to the two powers of the electric ^"j ^ ^?^^ 

 fluid, for by its operation, two fets of chemical phenomena 

 are produced, differing etTentialiy from each other, thereby de- 

 termining the real or potitive nature of each power. It has 

 introduced eledricily as a chemical agent, and has fliewn us 

 that it a6ls as fuch in its two-fold charafler very generally 

 throughout nature. Eledricity has hitherto been confidered 

 moftly as an adventitious power excited upon the furfaces of 

 bodies, it is now known to attach itfelf to, and to enter into 

 combination with various fubftances. 



If the fpinal marrow of a frog be coated with tin foil, and 

 the mufcles of the lower extremities be laid bare, if the frog, 

 thus prepared be drawn through water, at the bottom of which 

 there is a piece of iilver, when the tin foil touches the filver, 

 the limbs of the frog are thrown into ftrong convulfions. If 

 the tin foil be kept fteadily at the firft place Of contadi, the 

 convullions foon ceafe; but if it be removed to the fmalleft 

 diftance from where it firfi: touched the filver, and is again in 

 contact with it, the convulfi.ons are renewed with their origi- 

 nal violence. The fame thing happens when the filver is con- 

 nected with the mufcles by means of a metal, though that 

 metal touch the mufcle in a point, as when the water adis as 

 the conducting arch. 



Thefe experiments fliew that there is a power in each affign- 

 able particle of the metal which excites the a6tion of the muf- 

 cles, and that nothing but t!ie contad of the metals feeras ne- 

 cellary for the production of the effect. 



It 



