Chemical EffeEls of Galvanic Exper'imenis. 1.8 1 



I had fecn in the mufeum at Cortona, Etrufcan infcriptions engraved upon pure lead, 

 which are ftill in perfe£t prefervation, though of the moft remote antiquity; and on the 

 contrary, I had found with furprize in the gallery of Florence, medals of lead of the dif- 

 ferent pontiffs, in which tin, and perhaps arfenic had been mixed, to render them more 

 beautiful and folicf, were jntirely reduced to a white powder, or changed into oxide, not- 

 vithftanding they had been wrapped in paper, and kept in drawers. 



I had likewife obferved, that the alloy made ufe of in foldering the plates of copper 

 which cover the moveable roof of the Obfervatory at Florence, was fpeedily changed, and 

 converted manifeftly into a white oxide at its extreme contact: with that metal. 



Laftly, I had learned in England, that the iron nails formerly ufed in attaching the cop- 

 per to the bottoms of fliips, corroded this lad metal fo much by their contaft, that the 

 holes foon became dilated, fo as to exceed the fize of the head of the nail itfelf. 



Thefe fafts appeared to me to be amply fufficient to fliew, that the metals exercife a 

 mutual aflionin this cafe, and that the caufe of the phenomena produced by their union, 

 or contaft, was to be attributed to this aftion. 



It is known, that the metals are in general fufceptible of conibining together by mutual 

 folution. We may therefore form a notion, that their tendency to mutual combination 

 begins as foon as the particles arc brought into contaft. It is only by virtue of the im- 

 menfe fuperiority of their force of cohefion, that, they are prevented from mutual penetra- 

 tion and folution in the cold. Fire is neceffary to difunite and give mobility to their par- 

 ticles. We fee this happen in amalgams which are formed without heat ; and it is known, 

 that in the manufaflure of tinned plates, the tin penetrates the iron without this lad metal 

 being liquified. It is, probably, the fame force of cohefion which fometimes prevents the 

 oxidable metals from attrafting oxigen with fpeed. If a rapid movement tends to difag- 

 gregate the particles of mercury in the midft of water, nothing more is required to enable 

 it to affume the principle of oxidation in a very fhort time, by attra£ting it from the fluid. 

 Thefe fafts, as well as many others of the fame nature, no lefs common than well known, 

 ought to have proved to philofophers, that the metals by exercifing their mutual attractive 

 force, muft by the fame energy diminifli their refpe£livc powers of aggregation ; that 

 though neither of them feparately may be able feparately to attraft oxigen from the at- 

 mofphere, or from water, they may acquire that power by fimple mechanical touch, as 

 they pafs to new combinations. We might therefore fufpecft, that fome, at leaft, of the 

 effeifts produced on the bodies of animals, by the application of metallic coatings to the 

 nerves and the mufcles, maybe attributed to a chemical operation; to the tranfition of 

 oxigen into a combination ; to the formation of a new compound ; or to the developement 

 of a foluble or fapid tafte, which is fo perceptibly manifefted on the organ of that fenfation. 



Galvani, Aldini, Volta, and other philofophers equally fkilful, who have fo fuccefsfully 

 dire<fled their attention to this kind of refearcli, not reflefting that the chemical adtion 

 exerts itfelf with the fwiftnefs of lightning, and, furpiized at the fuddennefs with which 

 the two different metals exert their effedls on the animal fibre, were of opinion, that it 



Vol. IV.— June 1800. R could 



