506 OHM ON THE GALVANIC CIRCUIT. 



am [n — m)' 

 when X designates the value of x, for which z = ^. Since in 

 this case the value of ;: constantly changes to the same amount 

 on Hke differences of the abscissa, the abscissa X; which belongs 

 to its mean value ?, as it was at all places of the changeable 

 portion previous to the commencement of the chemical decom- 

 position, must be referred to the middle of this portion. If, 

 therefore, z' and z", as above, represent the values of z, which 

 correspond to the commencement and end of the variable por- 

 tion, and / the actual length of this portion, it follows, from our 

 last equation, that 



~" — ? — -1. 1 ^^ 



a CO [n — m) 

 and 



S — 2 



a w [n—m) 

 and from these two equations results 



^ ' ^ 'am 



or, if we put, instead of — , by which here nothing further is 



expressed than the unchangeable reduced length of the chemi- 

 cally variable portion, the letter A, the following : 



(ra-m) (;:"-;;') = X 2.] 

 If we place this value of {n — m) (~ " — z') in the equation found 

 in § 38, 



g, _ g _ ^{n-m) {z"-z') 



and at the same time substitute for 2 its value S' + ^ w a, we 

 obtain 



S' = S - ^ (S' + ^J/ w a), 



an equation, the form of which is extremely well suited to indi- 

 cate in general the nature of the change of the current pro- 

 duced by the chemical alteration, and the expressions of which] 

 coincide exceedingly well with the numerous experiments 11 

 have made on the fluctuation of the force in the hydro-circuit,^ 

 and of which only a small part have been published*. 



* Schwiiig^ev's JahrOuc/i, 182J, Parti and 1S2(J, Part 2. 



