QUANTITY OF ELECTRICITY NOT INCREASED WITH NUMBER OP PLATES. 455 



other, it will rather assist it. This is simply the case of two voltaic pairs of metals 

 arranged so as to form one circuit. In such arrangements the activity of the whole 

 is known to be increased, and when ten, or a hundred, or any larger number of such 

 alternations are placed in conformable association with each other, the power of the 

 whole becomes proportionably exalted, and we obtain that magnificent instrument of 

 philosophic research, the voltaic battery. 



990. But it is evident from the principles of definite action already laid down, that 

 the quantity of electricity in the current cannot be increased with the increase of the 

 quantity of metal oxidized and dissolved at each new place of chemical action. A 

 single pair of zinc and platina plates throws as much electricity into the form of a 

 current, by the oxidation of 32'5 grains of the zinc (868.) as would be given by the 

 same alteration of a thousand times that quantity, or nearly five pounds of metal 

 oxidized at the surface of the zinc plates of a thousand pairs placed in regular bat- 

 tery order. For it is evident, that the electricity which passes across the acid from 

 the zinc to the platina in the first cell, and which has been associated with, or even 

 originated by, the decomposition of a definite portion of water in that cell, cannot 

 pass from the zinc to the platina across the acid in the second cell, without the de- 

 composition of the same quantity of water there, and the oxidation of the same quan- 

 tity of zinc by it (924. 949.). The same result recurs in every other cell ; the electro- 

 chemical equivalent of water must be decomposed in each, before the current can 

 pass through it ; for the quantity of electricity passed, and the quantity of electrolyte 

 decomposed, must be the equivalents of each other. The action in each cell, there- 

 fore, is not to increase the quantity set in motion in any one cell, but to aid in urging 

 forward that quantity, the passing of which is consistent with the oxidation of its own 

 zinc ; and in this way it exalts that peculiar property of the current which we endea- 

 vour to express by the term intensity, without increasing the quantity beyond that 

 which is proportionate to the quantity of zinc oxidized in any single cell of the series. 



991. To prove this, I arranged ten pairs of amalgamated zinc and platina plates 

 with dilute sulphuric acid in the form of a battery. On completing the circuit, all 

 the pairs acted and evolved gas at the surfaces of the platina. This was collected 

 and found to be alike in quantity for each plate ; and the quantity of hydrogen 

 evolved at any one platina plate was in the same proportion to the quantity of metal 

 dissolved from any one zinc plate, as was given in the experiment with a single pair 

 (864. &c.). It was therefore certain, that, just as much electricity and no more had 

 passed through the series of ten pair of plates as had passed through, or would have 

 been put into motion by, any single pair, notwithstanding that ten times the quantity 

 of zinc had been consumed. 



992. This truth has been proved also long ago in another way, by the action of the 

 evolved current on a magnetic needle ; the deflecting power of one pair of plates 

 in a battery being equal to the deflecting power of the whole, provided the wires 

 used be sufficiently large to carry the current of the single pair freely ; but the cause 



3 N 2 



