7d'$ 0» GALVAJiIISM AMD ELECTltlClTY. 



Obfervations on All fubfiances wliich are condn6lors. of ele6lricity, if they 

 galvainfm, &c yntiergjo any change as to their conducing power, fo as to 

 become diminiflied as conduftors, always in the change lofe a 

 portioa of ti>eir natural eledricity, T^ms metals which are 

 the bed condiidors, when oxidat<^d, become non-condu6lors 

 irt this change, the coftibined electricity is loft. 



If a plate of zinc is ufiiverfaJly immeifed in a fluid which 

 will produce ciiemical changes upon it, no galvanic plienome- 

 non will be produced becaufe the metal in every alfignable 

 point, being equally a6ted on, the contrary ftates of cleQricity 

 cannot then be produced. 



If only one fide be afted on.everyaffignabie point on that fide 

 undergoing a chemical change, by which it isdifpofed to part 

 with its combined eledricity, there will be a general tendency* 

 of the eledricity in the fubftance of the metal towards the fur- 

 face aded on ; the fame as if in a vetfel filled with water, a 

 fmall aperture be formed, there will be a general tendency or 

 current of the water towards the aperture, fo of eledricity. 



Dr. Wollafton has proved by very ingenious experiments, 

 that when two difiimilar metals are placed in a fluid which will 

 ad upon one of the metals and not upon the other, when the 

 two metals are put into contad in the fame fluid, that thus che* 

 mical changes are effeded on both ; thus that gold and filver 

 thus arranged, will be aded on. by the nitric acid. — When two 

 metals are placed in a fluid which will ad upon either of them 

 feparately, if the two metals are preferved in a ftate of fepa- 

 ration while in the fame fluid, chemical changes will only be 

 effeded upon one. Thus zinc and copper placed in nitrous 

 acid and water, only the zinc will be aded on. 



Thefe principles point out the neceflity in our galvanic 

 troughs to have our cells perfedly infulated, and that there be 

 no communication between the refpedive plates. 



Mr. T. has by miftake obferved that tJie fenfation is in pro- 

 portion to the furface aded on; the experiments of the French 

 philofophers proved that the adion of galvanifm on animal 

 fubftances is in the ratio x)f the number of plates employed, 

 and not the fur faces expofed. 



In all my experiments in town with my own eledrlc battery 

 I never fucceeded.in giving the flighted charge with my gal- 

 vanic apparatus; In forae coaverfation 1 had with you, Mr. 

 I^itor, you conjedured that an extenfive feries of fmall jars 



>vould 



