Expermetii] on the Chemicat ProduBlon and Agency of EUclr'wliy. 339 



diameter, each furniflied with a Aiding eleftrometcr, to regulate the ftrength of the fpark 

 received from them. 



Experiment /K, Having a wire of fine filver -y j^o of an inch in diameter, I coated the 

 middle of it for two or three inches, with fealing wax, and by cutting through in the mid- 

 dle of the wax, expofed a fe£tion of the wire. The two coated extremities of the wire 

 thus divided, were immerfedin a folution of fulphate of copper, placed in an eledtric cir- 

 cuit between the two eonduftors ; and fparks, taken at-rV of an inch diftance, were pafled 

 by means of them through the folution. After lOO turns of the machine, the wire which 

 communicated with (what is called) the negative condudlor, had a precipitate formed on 

 its furfacc, which, upon being burniflied, was evidently copper; but the oppofitc wire 

 had no fuch coating. 



Upon reverfing the direfltion of the current of eleftricity, the order of the phenomena 

 was of courfe reverfed ; the copper being fliortJy re-diflblved by affiftance of the oxidating 

 power of pofitive ele£tricity, and a fimiiar precipitate formed on the oppofite wire. 



Experiment 5. A fimiiar experiment made with gold wires t4o of an inch diameter, ill 

 a folution of corrofivc fublimate, had the fame fuccefs. 



The chemical agency, therefore, of common eleftricity, is thus proved to be the fame 

 with the power excited by chemical means ; but, fince a difi^erence has been obferved ia 

 the comparative facility with which the pile of Volta decompofes water, and produces 

 other elFefts of oxidation and de-oxidation of bodies expofed to its aftion, I have been at 

 fome pains to remove this difficulty, and can at lead produce a very clofe imitation of the 

 galvanic phenomena, by common eledtricity. 



It has been thought neceffary to employ powerful machines, and large Leyden jars, for 

 the decompofition of water ; but when I confidered that the decompofition mud depend on 

 duly proportioning the ftrength of the charge of ele£tricity to the quantity of water, and 

 that. the quantity expofed to its adtion at the furface of communication depends on the ex- 

 tent of that furface, I hoped that, by reducing the furface of communication, the decom- 

 pofition of water might be effcdied by fmaller machines, and with lefs povfrerful excitation) 

 than have hitherto been ufed for that purpofe ; and, in this hope, I Jiave not been dif- 

 appointed. 



Experiment 6. Having procured a fmall wire of fine gold, and given it as fine a point 

 as I could, I inferted it into a capillary glafs tube ; and after heating the tube, fo as to 

 make it adhere to the point and cover it in every part, I gradually ground it down, tiU> 

 with a pocket lens, I could difcern that the point of the gold was expofed. 



The fuccefs of this method exceeding ray expectations, I coated feveral wires in the 

 fame manner, and found, that when fparks from the conductors before-mentioned were 

 made to pafs through water, by means of a point fo guarded, a fpark paffing to the diftance 

 of •!• of an inch would decompofe water, when the point expofed did not exceed -j-^-g of an 

 inch in diameter. With another point, which I eftimated at t t'oo a fucceflion of fparks 

 xs of an inch in length, afforded a current of fmall bubbles of air. 



X X 2 [ have 



