Decomposition of Water by the Galvanic Battery. 91 



the ratio of the quantity of water decomposed to the quantity of 

 electricity passing through it is diminished ; and consequently 

 that Mr. Faraday's law of definite electro-chemical decomposition 

 does not hold for powerful currents, which differ much in their 

 intensity. In my last experiments I perceived a defect in the 

 magnetic needle employed, and therefore do not feel myself 

 warranted in drawing a positive conclusion. Besides, I am sure 

 that my experiments were not made with as much accuracy as 

 Mr. Faraday's were; but they incline me to believe that the 

 decomposing power of strong currents decreases when their in- 

 tensity increases. I am inclined to believe that there is a certain 

 intensity above and below which there is a loss of decomposing 

 power; and that, in a cast-iron battery, it is the intensity of 

 4 cells in one series. I am inclined to think that, when the in- 

 tensity is greater than that, some of the electricity passes through 

 water without meeting the resistance or reaction necessary for 

 decomposition ; and that the greater the intensity the greater 

 the quantity which passes without the required resistance. The 

 current from a battery of 12 cast-iron cells does not meet with 

 much resistance in passing through a solution of carbonate of 

 soda. For when the current was sent, without passing through 

 the fluid, through the coil of the tangent galvanometer, it pro- 

 duced a deflection of 69° ; and when sent first through the fluid 

 and then through the coil, the needle was deflected to 68°. 

 When a current was sent from 60 cells, first through the fluid 

 and then through a pair of coke points, the deflection was the 

 same as when it passed through the coke points without passing 

 through the fluid. Hence a current from a battery of 60 cells 

 appears to meet with as little resistance in passing through a 

 fluid as in passing through a wire. Hence a current of very high 

 intensity experiences little or no resistance or reaction from the 

 fluid, and therefore can produce little effect on it. 



In comparing the deflection of the needle produced by a cur- 

 rent from 6 cells through a solution of carbonate of soda with 

 the deflection produced by the current from the same battery 

 sent directly through the coil of the galvanometer, it occurred 

 to me that if 12 cells were arranged in two rows, and the two 

 end zinc plates connected as one, and the two iron cells con- 

 nected so as to act as a single cell, the current from these two 

 rows would, after passing thi'ough a fluid, produce a greater 

 deflection of the needle than they would, if, whilst they acted in 

 one series, the current were sent directly through the coil of the 

 galvanometer. Subsequent experiments proved that my con- 

 jecture was well founded. When 12 cells were arranged in two 

 rows of six each, and the current from both was sent through a 

 Bolutiou of carbonate of soda and then through the coil, a dc- 



H2 



