334 Conducting Power of Solid and Liquid Bodies. 



author and referred to heterogeneity of the circuit. He does not 

 appear to decide on the actual existence of such a force. In con- 

 sidering the chemical force the term polarization of the electrodes 

 is used throughout in a manner seeming to imply that the polari- 

 zation is an absolute obstacle to the decomposition and the passage 

 of the current, so that the latter meets with greater resistance to 

 transit than it would with electrodes that were perfectly neutral 

 in their relations to the elements set free and evolved them at 

 once as gas without attracting a particle of them to their surface, 

 the electrolyte itself being supposed also to have no attraction or 

 solvent power for the gaseous elements. Whether this be the 

 author's view does not seem certain, but to us it appears that 

 in proportion as the electrodes become perfectly coated with the 

 films of oxygen and hydrogen evolved by a passing current, 

 water being the electrolyte, the more nearly will the forces 

 encountered by the current approach identity with those which 

 with the neutral electrodes just mentioned, it would have to en- 

 counter from the first instant of its passage. In this latter case 

 the oxygen and hydrogen from the first instant of decomposition 

 will be set free in the absence of any body for which they have 

 any sort of attraction, and it is only in such case that their sepa- 

 ration by the current is opposed by the whole force of their 

 affinity for each other. But if the electrodes or the fluid or both 

 have an attraction for the oxygen and hydrogen to be separated, 

 such attraction facilitates the separation and diminishes the elec- 

 tro-motive force required to effect it, and it is not till after the 

 electrodes have become completely coated and the adjacent films 

 of fluid saturated with the oxygen and hydrogen respectively, 

 that we approach that state of the forces that is presented by 

 neutral electrodes and in Avhich each element is set free. 



If it be objected that the attractions for the oxygen and hydro- 

 gen are equal at each electrode and ought to balance each other, 

 it may be replied, that they act with reference to the alternative 

 whether they shall be satisfied not at all or shall be satisfied in 

 the only way in which they can be, that is, by giving the oxygen 

 to the positive electrode and the hydrogen to the negative. This 

 alternative, it will be seen, has reference to the case in which the 

 electromotive force is just insufficient of itself to produce the 

 decomposition and is supposed to do so by aid of the attractive 

 forces in question. 



If this view be correct, it seems probable that the amount oi 

 electromotive force necessary to carry on the decomposition after 

 the polarization is established and the elements are all evolved as 

 gases, is precisely that which is competent to the separation of 

 these elements with electrodes having no action on them, unless 

 it be a merely catalytic action, so that the elements assume the 

 gaseous form in contact with them with the same readiness as in 



