ON* THE GALVANIC PHENOMENA. 137 



cat phenomena much more diftinctly marked, I generally em- repeatedly ap- 



ploy a fecond condenfer, mounted upon the electrometer it- P lie ? to / noth e* 

 r w . i • i » it r , condenfer. 



fait, and proceed in the following manner : — I apply the plates 



.of copper and of zinc to each other, and feparate them feveral 



times, at each reparation bringing one of thefe infulated plates 



into contact with the upper difc of the condenfer, and the 



other, alio infulated, with the lower difc, which is attached 



to the electrometer. When this contact has been repeated 



ten, twelve, or twenty times, the difc .of the above-mentioned 



condenfer being railed, the electrometer fupports the inferior 



difc alone, which eleVates itfelf to 10, 12, 15, 20 degrees, 



&c. &c. 



It might be imagined that, independent of the action of the The application 

 condenfer, the extent of contact between the two different ofthe flat fur ; 

 metals greatly contributes, as fuch, to raife the electricity to an( j CO ppet does 

 the degree which we have feen, and that we mould obtain not increafe 

 a much inferior degree, if they touched each other only by a L^!^* 1 ** 

 few points. But I prove the contrary ; that is to fay, that in 

 the one cafe, as well as in the other, the electric tenfion rifes, 

 during the contact, to the fame point, which is about a fix- 

 tieth part of a degree of my electrometers of thin ftraws, 

 when the metals are zinc and copper, and a little more when 

 they are zinc and filver ; which tenfion requiring a quantity 

 of electric fluid in the plate which performs the office of con- 

 denfer, proportionally larger, accordingly as it condenfes 60, 

 150, 200 times, it is evident why we obtain l x 1-*, 2 degrees, 

 &c. &c. 



In order to prove that tliQ contact of two metals of little Metals of other 

 extent, and which even fubfiits only at fome points, difplac.es . forms brou S ht 

 the electric fluid in fuch a manner as to raife the tenfion in f m °ller or mi/ 

 thefe metals to the fame degree ; I join a fmall plate of cop- nute furfaces. 

 per with another of zinc, either fimilar or dillimilar with re- 

 fpect to figure and fize, applying them to each other at a few 

 points only, or at more points, or even foldering them toge- 

 ther end to end. See Plate VIU. fig. .'3. 



Holding the piece z of zinc with two fingers, or in any Manipulation. 

 other manner, I make the other, c, of copper, communicate A fi . n S le couple 

 with the fuperior difc of the condenfer, whilft the inferior difc which is' held in 

 communicates, as it ought, with the ground. A moment af- f h e hand, and 

 terwards, raiiing this upper difc into the air, and holding it -,i; ed t0 t h e con- 

 ciliated, it gives me by the electrometer from 2 to 3 degrees denfer, produces 



of 



