164< Prof. Schoenbein's Discussion q/M. Fechner's 



4. Water containing for 100 parts 5—20 parts of com- 

 mon nitric acid did not disturb the needle at all ; 25 parts 

 produced a rather long continuing deviation of about 50° in 

 favour of the water current; '30 parts had the same effect, 

 though the difference of currents was a little smaller. If in 

 the latter experiment the two systems of pairs were made to 

 change their cells, so that the set of pairs having previously 

 been in water were placed in the acid-cells, and vice versd^ 

 a current equilibrium was obtained. In most of the fore- 

 mentioned cases, where the needle remained at rest, the pairs 

 of the water-cells could have their place supplied by platina 

 wires, without thereby disturbing the equilibrium ; and even if 

 a deviation of the needle took place (immediately after having 

 effected such a change), it was always very insignificant, and 

 the equilibrium of currents was speedily re-established. 



From the results of the experiments described, it appears 

 that only in a few instances the chemical difference of the ex- 

 citing fluids contained in the two systems of cells determines 

 a difference of currents produced by the two sets of pairs, and 

 that the general rule is the production of current equilibrium. 



Now, if I have correctly understood Fechner's statements, 

 they imply the assertion, that on using water in one system 

 and an acid liquid in the other system of cells as exciting 

 fluids, and everything else being equal in the arrangement, 

 the equilibrium which takes place in the first instance is al- 

 ways by degrees disturbed in favour of the water current. 

 If such were the case, the fact, as it seems to me, would be 

 entirely contradictory to the theory of Volta ; for according 

 to the views of this philosopher the current produced by the 

 one set of pairs must be equal to that which is excited by 

 the other set, and the addition of acid to one system of cells 

 has no other effect than to increase the conducting power of 

 the whole arrangement. I have already remarked, that in 

 the circumstances mentioned current equilibrium is the rule, 

 the contrary an exception to it, and that even if a difference 

 of currents occurs, it is generally so insignificant as to be 

 made only perceptible by the means of a most delicate gal- 

 vanometer. We may therefore consider the facts to be in 

 perfect accordance with the theory of Volta. But does not 

 the current equilibrium in question disagree with that theory 

 which makes the production of current electricity dependent 

 upon chemical action, and the quantity of the former upon 

 the extent of the latter? I think it does not, and hope to be 

 able to prove the correctness of my assertion by what I am 

 about to say. 



On the first view of the case, it seems, indeed, as if the fact 



