tit Falls and Obfervatiom to elucidate the Quejlion 



could only be attributed to the ekftric fluid. The tranfmiffion of galvanifm to a diftance, 

 and by a circuit, favored their notion, which was generally received, notwithftanding the 

 very ftrong objeftions which might, in fome cafes at leafl, be oppofed to their fyftem. In 

 faft, fome figns of eleftricity have been obferved on the feparation of two metals, which 

 had been before placed in contaft ; but it is very well known, that even fcveral chemical 

 operations are conflantly attended with a change of equilibrium in the eleftric fluid, and 

 confequently by perceptible marks of ele£lricity. Thus it is that flaflies of lightning are 

 feen in the great volcanic fufions or eruptions ; and this alfo is one of the cafes in which 

 philofophers have taken that for the caufe of thefe fires, which is merely one of their 

 eiFe£ts. The figns of ele£tricity may be produced by melting a fmall quantity of fulphur, 

 or of chocolate, or even by boiling or evaporating water ; but afTuredly thefe are fufions, 

 and are not caufed by the eledtricity. I do not pretend to exclude all ele£lrical influence 

 from the prodigious efFefts of galvanifm. I propofe merely to prove, that this principle is 

 not concerned in the phenomena of Sultzei, and that various other fimilar fails are de- 

 rived from the fame fource. 



The metals having a mutual affinity, their particles mufl; mutually attraft each other 

 when they are brought into contaft. We cannot eftimate the magnitude of this force ; 

 but I think it is fufficient to weaken the force of their aggregation, fo as to difpofe them 

 to engage in new combinations, and to yield more readily to the adion of the weakeft 

 folvents. 



I had obferved in repeating the experiment of Sultzer, that if I wiped my tongue as 

 accurately as poffible, the fenfation excited by the approach of the two metals in contaft 

 was diminifhed, fo as to be hardly diftinguiflied. The faliva, or fome other moifture, 

 mud therefore be of fome importance in this phenomenon. But to afcertain the truth of 

 my fuppofition, I placed in dificrent goblets filled with water, 



1. Separate pieces of metal; for example, in the one gold ; in another filver ; in a third 

 copper; and in others tin, lead, &c. 



2. In other fimilar goblets I put the fame metals as before, but two pieces in each 

 goblet, one of which metals was more, and the other lefs oxidable. They were feparatcd 

 from contaft by a fmall flip of glafs. 



3. Laftly, I placed in other goblets metals of different kinds, but two in each, and in 

 immediate contaft. The two firft fetts exhibited no perceptible change, but in the laft 

 the moft oxidable metal was vifibly loaded with oxide, a few moments after having been in 

 contafl: with a different metal. This oxide gradually incrcafed, fo as to hang beyond the 

 lower metal, uniting with it in a mafs, and flowing in a cafcadc along the whole of the 

 fides. This phenomenon commences, though infenfibly, at the very inftant of conta£l ; 

 but I left the metals of this experiment for a confiderable time, to fee what would happen. 

 I examined them at the end of a month, and found that the two metals had contra£led fo 

 confiderable an adhefion, that in order to detach a piece of b'rafs about two centimeters 

 broad from a plate of tin, a force of no lefs than two kilogrammes was neceffary. 



I afterward? 



