in Liquids free from Gas. 11/ 



only by a force of equal or greater equivalent of work, so as to 

 make the attracted particle freely movable in the liquid. 



But if the electromotive force of the Darnell's element pro- 

 duces in our case no visible decomposition of water, it yet pro- 

 duces polarization of the electrodes ; and this is itself an equi- 

 valent of work ; for the polarized plates are afterwards, when 

 separated from the polarized galvanic element, able for a certain 

 time to generate independently an electric current, therefore to 

 develop heat in the conducting wire, or, with a suitable ar- 

 rangement, to perform respectively all other forms of work which 

 galvanic currents can perform. In the state of polarization we 

 have evidently to do w T ith a changed arrangement of the ponder- 

 able atoms and the electricities in the decomposition-cell and on 

 its electrodes, on the particular nature of which we have no need 

 here to make any more special assumptions or suppositions, as 

 long as the question is only the consideration of the work- 

 values. The state of polarization is to be regarded as a new 

 state of equilibrium, to which the source of decomposition, under 

 the influence of the electrizing of the electrodes, tends, and 

 which, when the electricity accumulated in the electrodes can 

 discharge itself, tends back again to the state of electrically neu- 

 tral equilibrium. But since for the production of a changed 

 equilibrium in a limited system of bodies (such as is the decom- 

 position-cell) only a finite amount of work is ever necessary, the 

 production of polarization must always give only a current of 

 finite duration, or one whose intensity asymptotically approaches 

 to zero, and the polarizing current could on the whole make only 

 as much electricity flow in the one direction as the depolarizing 

 in the opposite. 



So far as this is the case (and my experiments show that in 

 gas-free liquids and with gas-free electrodes such a condition 

 can be very nearly attained) the decomposition-cell acts as a con- 

 denser of very great capacity. In fact, if (according to the usual 

 mode of representation) negatively charged oxygen be supposed 

 in the vicinity of one electrode, and positively charged hydrogen 

 near the other, but so that an interchange of electricities be- 

 tween the electrodes and the said constituents of water is not 

 possible, the corresponding quantity of the opposite electricity 

 may accumulate on the electrode itself; and each electrode 

 would then, with the liquid, form a condenser with vanishingly 

 small thickness of the insulating layer and, just on this account, 

 of enormous capacity. This analogy has recently been empha- 

 sized by Messrs. Varley* and Maxwell f. 



* Proc. Roy. Soc. Jan. 12, 1871. 



t A Treatise on Electricity and Magnetism (Oxford, 1873), vol. i. 

 p. 322. 



L2 



