Retardation produced by interposed Plates. 345 



position equal to the full amount of the force of mutual attrac- 

 tion between its oxygen and hydrogen, has that force coun- 

 teracted in part, and therefore diminished by the attraction of 

 the hydrogen at the cathode for the oxygen of the nitric acid 

 which surrounds it, and with which it ultimately combines 

 instead of being rendered in its free and independent state. 



1022. When a little nitric acid was put into the exciting 

 cells, then again the circumstances favouring the transmission 

 of the current were strengthened, for the intensity of the cur- 

 rent itself was increased by the addition (906.). When there- 

 fore a little nitric acid was added to both the exciting and the 

 retarding cells, the current of electricity passed with very con- 

 siderable freedom. 



1023. When dilute muriatic acid was used, it produced 

 and transmitted a current more easily than pure dilute sul- 

 phuric acid, but could not compete with nitric acid. As 

 muriatic acid appears to decompose more freely than water 

 (765.), and as the affinity of zinc for chlorine is very power- 

 ful, it might be expected to produce a current more intense 

 than that from the use of dilute sulphuric acid; and also to 

 transmit it more freely by undergoing decomposition at a 

 lower intensity (912.). 



1024-. In relation to the effect of these interpositions, it is 

 necessary to state that they do not appear to be at all de- 

 pendent upon the size of the electrodes, or their distance from 

 each other in the acid, except that when a current can pass^ 

 changes in these facilitate or retard its passage. For on re- 

 peating the experiment with one intervening and one pair of 

 exciting plates (1011.), fig. 20, and in place of the interposed 

 plate P using sometimes a mere wire, and sometimes very large 

 plates (1008.), and also changing the terminal exciting plates 

 Z and P, so that they were sometimes wires only and at others 

 of great size, still the results were the same as those already 

 obtained. 



1025. In illustration of the effect of distance, an experi- 

 ment like that described with two exciting pairs and one in- 

 tervening plate (1012.), fig. 21, was arranged so that the di- 

 stance between the plates in the third cell could be increased 

 to six or eight inches, or diminished to the thickness of a 

 piece of intervening bibulous paper. Still the result was the 

 same in both cases, the effect being no greater, sensibly, when 

 the plates were merely separated by the paper, than when a 

 great way apart; so that the principal opposition to the cur- 

 rent does not depend upon the quantity of intervening elec- 

 trolytic conductor, but on the relation of its elements to the 



Third Series, Vol. 6. No. 35. May 1835. 2 Y 



