On Galvanic Polarization in Liquids free from Gas. 145 

 u , f <J>'(a>)-« .1 



in which the three functions <f>, yjr l} yjr 2 are arbitrary. But in 

 any particular case of motion, p, p, and v must follow some given 

 law, i. e. must be expressible at a given time by definite functions 

 of x ; from which circumstance, as I have elsewhere shown, the 

 forms of $, t/tj, ^ can be determined ; and, being so determined, 

 the last three equations will represent the motion throughout the 

 entire period of its continuance. And there can be no relations 

 between^, p s v, x, t in the case of motion under consideration 

 other than those above given ; for if there were such, it would 

 follow that definite values of the pressure, density, and velocity 

 at a given time admit of those quantities having alternative, and 

 therefore ambiguous, values during the subsequent motion; 

 which is impossible. 



6 New Square, Lincoln's Inn, 

 January 17, 1874. 



XVIII. On Galvanic Polarization in Liquids free from Gas. 

 By Dr. Helmholtz*. 



I TAKE leave to communicate to the Academy the results of 

 a series of experiments which I have made upon the gal- 

 vanic polarization of platinum. The experiments mostly required 

 a very long time; and I therefore crave pardon if I am obliged 

 to leave unanswered for the present a number of further ques- 

 tions which at the same time obtrude themselves. 



It is known that when a Daniell's zinc-copper element is 

 closed by a water-decomposition cell with platinum electrodes, a 

 current arises of quickly diminishing force, which, in the usual 

 way of arranging the experiment, becomes indeed after a short 

 time very feeble, but does not entirely cease even after a very 

 long time. We will call this the polarizing current. If we 

 afterwards separate the decomposition cell from the Darnell's 

 element, and connect its platinum plates with the voltameter, 

 we obtain another (the depolarizing) current, which in the cell 

 is opposite in direction to the polarizing current, and is likewise 



* Translated from the Monatsbericht der koniglicli preussischen Aka~ 

 demie der Wissenschaften, 1873, pp. 587-597. 



Phil. Mag. S. 4, Vol. 47. No. 310. Feb. 1874. 7, 



