k 



HELMHOLTZ ON THE CONSERVATION OF FORCE. 143 



wire is proportional to the quantity -^. He however denotes 



by S the surface of the coating of the jars. With similarly con- 

 structed jars, however, this must be proportional to the capacity 

 of discharge. Vorsselmann de Heer* and Knochenhauerf have 

 also deduced from their respective experiments, that the develop- 

 ment of heat with equal charges of the same battery remains the 

 same, however the connecting wire may be altered. The latter has 

 proved the same law to exist in branches of the connecting wire. 



With regard to the quantity — , we as yet possess no experi- 

 mental data. 



It is easy to explain this law if we assume that the discharge 

 of a battery is not a simple motion of the electricity in one di- 

 rection, but a backward and forward motion between the coat- 

 ings, in oscillations which become continually smaller until the 

 entire vis viva is destroyed by the sum of the resistances. The 

 notion that the current of discharge consists of alternately op- 

 posed currents is favoured by the alternately opposed magnetic 

 actions of the same ; and secondly, by the phaenomena observed 

 by Wollaston while attempting to decompose water by electric 

 shocks, that both descriptions of gases are exhibited at both 

 electrodes. This assumption also explains, why in these experi- 

 ments the electrodes must possess the smallest surface possible. 



Galvanism. — With regard to galvanic phaenomena, we have to 

 distinguish two classes of conductors : — 1. Those which conduct 

 in the manner of metals, and follow the law of the tension series. 

 2. Those which do not follow this law\ To the latter belong all 

 compound liquids, which undergo during conduction a decom- 

 position proportional to the quantity of electricity conducted. 



We can classify the experimental facts in accordance with 

 the above, 1, into such as take place between conductors of the 

 first class only — the charging with different electricities of dif- 

 ferent metals which are in contact ; and 2, those between con- 

 ductors of both classes, the electric tensions in open, and 

 the electric currents in closed circuits. By any combination 

 whatever of conductors of the first class electric currents can 



* Pogg. Ann. vol. xlviii. p. 292, and the remark of Riess, ibid. p. 320. 

 t Pogg. Atin. vol. Ixii. p. 364 ; Ixiv. p. 64. 



