EEVISIONS OF THE THEORY OF ELECTKOLYSIS. 153 



and the resulting moleonlar cleavages and re-formations were due to 

 the attraction and repulsion between the electric charges, or their 

 polarity. His conception was crude and imperfect compared with 

 the corresponding concejots of the present time. But it showed at 

 least that the phenomena of electrolysis take place by a conceivable 

 process. If it did not satisfy all intellectual demands, it quieted 

 clamor and bridged the gulf between the known and the inexplicable. 

 It was indeed a gleam of light that has never been efi'aced ; and we 

 owe an everlasting debt of gratitude to the farmer philosopher of 

 Lithuania. 



Grotthus gave a vivid picture of the chief phenomenon of elec- 

 trolysis, the appearance of the separated constituents at the electrodes 

 only. The knowledge of his time scarcely reached be^yond this one 

 fact. It was not long, hoAvever, before new observations were made, 

 which could with difficulty be fitted into his picture. 



The essential fact which the theory of Grotthus Avas incompetent 

 to answer satisfactorily was that the smallest electromotive force 

 may produce a current through an electrolyte, and the strength of 

 this current follows Ohm's law. 



Grotthus assumes that the application of an electromotive force 

 to the electrodes gives rise to a polarized condition of the molecules, 

 and that at the instant of the separation of the hydrogen and oxygen, 

 for example, a separation of their natural charge of electricit}^ takes 

 place, either through contact or friction; so that one part becomes 

 electropositive and the other electronegative. This perhaps means 

 that the normal condition of an electrolyte is one of equilibrium 

 with rigidly combined molecules. Grotthus did not appear to con- 

 ceive of the cleavage of a polarized molecule until current passed. 



From the time of Grotthus there was a long pause of fift}^ years in 

 the theory of electrolysis, for no important step was taken until 

 Clausius, in 1857, published his profound modification of the Grotthus 

 theory. Clausius's study of the kinetic theory of heat prepared him 

 to apply similar principles to the interpretation of electrolj^tic phe- 

 nomena. He leaves no doubt about his meaning; his conceptions 

 are always clear and clearly expressed. I will let him speak for 

 himself : " 



Let there be a liquid, consisting wholly or in part of electrolytic molecules; 

 and let it be assumed that these molecules are arranged in the natural condi- 

 tion of the liquid in any definite manner in which they persist, so long as no 

 foreign force acts on them, while the individual molecules oscillate perhaps 

 about their positions of equilibrium, but are unable to get quite away from 

 them. Further, let an attraction be assumed between two part-molecules, as 

 there must be in every possible arrangement, and let two part-molecules be 



aAnnal. d. Physik, vol. 101, 1857. 



