162 Prof. Schoenbein's Discussion ofM. Fechner's 



Ten pairs of zinc and copper, in every respect as equal to 

 one another as possible, were arranged into a " couronne des 

 tasses," so that half of the said pairs produced a current op- 

 posite in its direction to that which was originated by the 

 other half. The exciting fluid used was common water. Such 

 an arrangement being connected with the galvanometer, can, 

 according to either of the two principal theories of galvanism, 

 have no effect upon the needle, provided everything in the 

 two systems of cells be equal. Fechner, after having ob- 

 tained current equiUbrium in the manner described, put mu- 

 riatic acid into one of the above-mentioned systems, and found 

 that in these circumstances the previous equilibrium was in 

 the first instance maintained, but that by degrees the current 

 of the water-cells got the ascendency over that of the acid 

 system. Fechner thinks these results to be quite irrecon- 

 cilable to Faraday's theoretical views on galvanism, and is 

 inclined to consider his experiment as an " experimentMrn 

 crucis" against the very first principle of the chemical theory 

 of the voltaic phaenomena. Before judging of the validity of 

 Fechner's conclusions, I must not omit to give an account of 

 some of the results which I lately obtained from a great many 

 experiments made upon the subject under discussion. 



1. Ten equal pairs consisting of zinc and copper were ar- 

 ranged in the manner before mentioned, and the vessels hold- 

 ing the former charged with common water. On closing the 

 circuit by the means of a most delicate galvanometer (pro- 

 vided with 2000 coils), the needle deviated a little, but after 

 a very short time it returned to zero. Current equilibrium 

 being thus obtained, it was disturbed again by breaking and 

 re-establishing the circuit through the means of any pair of 

 either system. The deviation of the needle amounted to 

 about 20°, and was always such as to indicate the superiority 

 of that current which was produced by the set of pairs left 

 untouched. The equilibrium, however, was also in this case 

 very soon re-established after the closing of the circuit. 



2. Equilibrium taking place in the arrangement just de- 

 scribed, 1 added ^^^ of common sulphuric acid to the water of 

 one set of the cells. On closing the circuit by means of the 

 galvanometer, the needle of the instrument was made to de- 

 viate about 180° in such a direction as to show the ascend- 

 ency of the current excited by the acidulated water. Leaving 

 the circuit closed for a few minutes, the needle however took 

 up its usual position. Opening and closing the arrangement 

 again by the means of any pair of plates belonging to the cells 

 charged with the acid fluid, or doing the same by the means 

 of the platina ends of the galvanometer-wire, had not the least 



