Decomposition of Water by the Galvanic Battery. 81 



passing from one end of the battery to the other but through the 

 interposed plates and fluid. In each plate there should be a small 

 hole near the bottom, that the cells may always remain nearly 

 filled with the fluid. The fluid should never rise above the 

 upper edge of the electrodes, otherwise a great part of the gal- 

 vanic cm-rent would be transmitted by it from one terminal plate 

 to the other without passing through the interposed plates or 

 fluid. The number of cells formed by the interposed plates 

 should be about one- fourth of the number of cells in the battery. 

 Thus for a battery of 12 cast-iron cells, there should be 3 cells 

 or 2 plates between the two terminal plates. For a battery of 

 100 cast-iron cells in series, there may be 25 decomposing cells 

 or 24 interposed plates. A battery of 100 cells has twenty-five 

 times the intensity of a battery of 4 cells, therefore the current 

 from it will overcome twenty-five times as much resistance as 

 the current from 4 cells, ancl will pass through 25 decomposing 

 cells successively as freely as a current from a battery of 4 cells 

 will pass through a single decomposing cell. If the current 

 from a battery of a hundred well insulated cells be sent through 

 25 decomposing cells, and afterwards through the coil of a gal- 

 vanometer, which coil is made of thick copper wire, it will be 

 found that the deflection of the needle will be equal to that 

 which will be produced by a current from a battery of 4 cells 

 passing through one decomposing cell and through the coil of 

 the same galvanometer. Hence there is as much of the mixed 

 gases produced in each of the 25 decomposing cells as in the 

 single cell through which the current from the battery of 4 cells 

 passed, that is, twenty-five times as much of the mixed gases 

 as is produced by a batteiy of four cells. Hence the fidl decom- 

 posing power of a battery of a hundred cells is exerted ; and 

 because the intensity of the current is reduced to that of a bat- 

 teiy of four cells, the power of the battery is not exhausted more 

 rapidly than if it consisted of four cells in series. If the current 

 of a battery of a hundred cells in one series were sent through 

 the electrodes as they are commonly arranged, the power of the 

 battery would be exhausted about twice as soon as if the current 

 passed through the electrodes arranged for batteries of high in- 

 tensity, and the twelfth part of the full decomposing power of the 

 battery would not be effective. To those who wish to show with 

 the same battery the deflagrating power of the voltaic current, 

 the coke light, and the decomposition of water, and the lime 

 light, an arrangement of the electrodes similar to that which has 

 been just described will be useful, because a battery arranged for 

 intensity will answer for all these effects. But when a battery is 

 put up for the sole purpose of decomposing water, it is better to 

 arrange the cells in such a way that the intensity may not exceed 



