^)$ LAW OF GALVANISM IN BURNING THE METAL*. 



Reafonlngon A plate of eight inches diameter expofes a furface four times 



h^ ^'^ll* e greater than a plate of four inches, and fuppoling the quanti- 



throw our dec- ties of electricity given out, to be in proportion to the furface 



tncity move expofed to the chemical a6lion of the fluid'^, the intenfity of (or 

 rapidly. , . ... 



rapidity of evolution from) ea<I;h plate of an eight inch trough 



may be eftimated as four times greater than the intenfity of 

 eledricity from the four inch plates; but the power of ignition 

 is fixteen times greater. 



Upon thefe remarkable circumftances I fliall venture to fub- 

 mit to you a few conjedlures. 

 The eledlridtjr y\ fimple galvanic combination refembles in its properties a 

 the parts under L^yden phial, that fide of the metallic plate which undergoes 

 the proccfs of the greateft change refembles the pofitive fide of the jar, and 

 •xi ation, the other fide, the negative, there being no other difference 



between electricity and galvanifm, than the mode in which 

 they are produced. EleClricity which appears from the exci- 

 ts^tion of glafs, is occafioned by a temporary change in the 

 f capacity of the glafs for electricity, while under the rubbing 



aClion, being momentarily increafed; while galvanifm is in 

 fome refpeds the reverfe, being occafioned by the diminifiied 

 capacity of good conducting bodies, when expofed to certain 

 chemical changes. Thus metals which are excellent conduc- 

 tors, when oxydated become non-conduclors. While thej 

 undergo this change a portion of the combined ele6tricity is 

 evolved, and confequently in the part thus changing pofitive' 

 figns will be evinced. 

 — aiftdthusby The eleCtricity exifling in an unchanged metal being per- 

 aaf.n ^^oduces ^^^'^ quiefcent, is fubjed, when difturbed, to thofe laws to 

 a ne^jative ftate which all material fubftances are amenable ; namely of mov- 



oa the. unoxided j^g in the direClion where it meets with the leaft refiftance. 

 furface* 



As the diredlion of the eleClricity is from the fubfiance of the 



metal towards the furface undergoing the chemical change, it 

 muft follow that the other fide of the metallic plate which is 

 defended from the a<5tion of the fluid will evince negative figns, 

 while the fide a6led upon pofitive, nearly upon the fame prin- 

 ciples as thofe of the eleCtraphams. 

 The difchargeis In effeCling a difcharge of the galvanic battery, the circuit 

 by a fucceflion j^^Q [jg completed between the zinc and copper ends of the 

 pairs of plates battery. The two plates nearefl the points of contact are firll 

 concluded ; thus the two next, and fo on in fuccetfive parts, 

 each plate at equal difiances from the points of contadl j and 

 4 the 



