24-2 On Copper-zinc and Platina-zinc Voltaic Pairs. 



let V be the actual current, k the current measured by the 

 balance, we have the equation 



k = k< - y k'\ 



from which is deduced fJ = - (1 V \-khy}. For my 



*y 



balance I have found, by a series of observations, y 

 0-00004228 (Bulletin Sc. de VAcad. Sc. torn. v. p. 375.)- 



The following table contains the experiments made with 

 the voltaic combinations in question. The first column con- 

 tains the resistances, L, of the helices which serve as conjunc- 

 tive wire, and which had been found by other experiments ; 

 the two other columns contain the forces of the effective 

 currents, or of the currents measured in grammes, and cor- 

 rected according to the formula above indicated. 



Let A, A' be the electro- motive forces, X, A/ the resistances 

 of the pair itself, we shall have, according to Ohm's formula, 

 the four following equations : 



A A' 



= 380 .,.,. = 395 



X+23-1 

 A 



97 



X'+23-l 

 A' 



= 135, 



X+ 135-3 X' + 135-3 



whence A = 14-610, X = 15-35, A' = 23000, X' = 35 ; or 

 taking X as the unit of surface, which is here 36 square inches, 



X' = 35x2 ' 5 = 2-4-. Let 5 be the total surface of a pile, 



z the number of pairs, C the force of the current, L any re- 



^ z As 



sistance, we have C = 2 T . * rom this equation we 



Z A/-)- JL< S 



find, that the maximum of force is obtained, if the pile be 



arranged so that = L, i. e. that the total resistance of the 



s 



pile shall be equal to the resistance of the conductor, what- 

 ever its nature may be, this resistance being one which is in- 

 terposed in the circuit, and not belonging to the pile. As for 



