Passage of Electricity through Liquids. 279 



litmus, then I noticed on the electrodes, but not in the interior 

 of the liquid or in the opening of the mica plate, a change of the 

 chemical condition — though, of course, numberless bubbles of 

 oxygen and hydrogen gas were developed on the anode and 

 cathode. 



In vessels in which water was poured over a concentrated so- 

 lution of the above-mentioned salt, on passing the current a 

 change was observed at the boundary of the water and the solu- 

 tion of salt, as Faraday* also had already found a separation of 

 hydrate of magnesia at the boundary of water and a solution of 

 sulphate of magnesia when the current was passed. 



§64. 



The equations in § 55 contain so many unknown magnitudes 

 that it is for the most part extremely difficult to determine the 

 latter more accurately. Only in a few particularly simple cases 

 can any thing be said about the magnitudes C and e. 



The simplest case is that of a salt fused by heat. We may 

 then neglect the summation and the index r, and equations (21), 

 (23), (24), and (16) give 



e: 



= - 



-e', 





m 

 a 



= 



h 





\-- 



=P 



.e(CH- 



■c'h 



\-- 



=P 



■•> 



+ C'), 



or 



= 2. 



This relation must hold as long and as accurately as Faraday^s 

 law holds, therefore for every liquefied salt which is decomposed 

 by means of the electrical current at any given temperature. 

 The quantity of electricity 2 is measured by the same unit as the 

 current-intensity i; and that quantity of electricity has been put 

 = 2 which decomposes one equivalent of an electrolyte through 

 which it passes. Hence we have this proposition : — 



If any salt in a liquefied condition is decomposed by the elec- 

 trical current, then there is a quantity of free electricity + 2 on 

 the complex atom which forms the one partial molecule, and a 

 quantity of free electricity —2 upon the complex atom which 

 forms the other partial molecule. 



The quantity of electricity +2 or —2 is just as great as that 

 positive or negative quantity of electricity which must flow 

 through the liquid conductor in one or the other direction in 

 order to decompose this one equivalent of salt. 



* Experimental Researches, vol. i. p. 495. 



