Electricity in Electrolytes. 107 



the potential of the free electricity upon the electricity flowing 

 through the partition. 



Within a porous partition the effects of this work^ as trans- 

 ferred to the material masses, are in some respects different from 

 those in a continuous liquid mass. A portion, and in most cases 

 by far the greater portion of the work, will be employed in over- 

 coming, in the ordinary manner, the resistance to conduction in 

 decompositions and recombinations of molecules, and in opposite 

 motions of the partial molecules. This portion of the work 

 within the partition will be completely converted into heat. 

 Another portion of the work will, on the other hand, be em- 

 ployed in moving the whole liquid, and in reference to this 

 latter portion, a twofold deportment may manifest itself. 



We must distinguish between the cases when the liquid, in 

 passing through the partition, has, and has not to overcome a 

 counter-pressure, which latter may be considered as a hydro- 

 static pressure. If the liquid encounters no counter-pressure, 

 then there is only the friction within the partition to be over- 

 come, and the portion of the work employed in doing so will 

 also be completely converted into heat. When a counter- 

 pressure exists, however, sufficiently great to impede, but not to 

 prevent the translation of the liquid, then the work employed in 

 forcing the liquid forwards is itself smaller because there is less 

 liquid moved; and of this smaller quantity of work, only a part 

 is converted into heat, the other being consumed in overcoming 

 the hydrostatic pressure, or, as we may express it, annulled by 

 the negative work of the hydrostatic counter-pressure. Lastly, 

 when the counter-pressure is so great, that the force driving the 

 liquid through the partition is thereby held in equilibrium, when, 

 consequently, no translation of the liquid occurs, then that por- 

 tion of the work devoted to the same is also zero. 



These different cases may be thus comprised. In the two 

 limiting cases, where no counter-pressure exists, and where the 

 latter is so great that no translation takes place, the whole work 

 done by the electric force is converted into heat ; on the contrary, 

 in the intermedi;ite cases a portion of this work is employed in 

 overcoming the hydrostatic counter-pressure. 



14. Tlie magnitude of the work employed in forcing the liquid 

 through the partition, and that part of the same spent in over- 

 coming the counter-pressure, may be easily determined. If we 

 rejjresent by weights to the unit of surface tlie force whicli 

 drives the liquid through the jjartition, and which may also be 

 conceived to be replaced by a hydrostatic pressure, we shall obtain 

 the work done by the driving force in a given time, by sinqjly 

 multiplying the above weight by the volume of liquid driven 

 through the partition iu that time. In the same manner wc 



