Mr. Grove on the Gas Voltaic Battery. 275 



hydrogen was found to be absorbed in the ratio of rather less 

 than 0*1 cubic inch in twenty-four hours. 



On some occasions I found the rise of liquid in the hydro- 

 gen cell to be unequal in different tubes of the battery, and 

 this I found more particularly the case in the battery fig. 4; 

 it was some time before I discovered the cause of this. I will 

 not enumerate my different conjectures, but state that which 

 proved to be the correct one. As, in using the two forms of 

 batteries (figs. 1 and 4), the chief difference consisted in the 

 introduction of the finger, it occurred to me that my assist- 

 ant's hands, which were employed in various manipulations, 

 might, in placing the tubes in the cells of fig. 4, introduce into 

 the electrolyte small portions of foreign matter, particularly 

 metals, and that thus a local action might be occasioned; this 

 view was strengthened by my frequently observing copper de- 

 posited upon some of the immersed portions of the platinum, 

 and where this happened an excess of hydrogen was generally 

 found to have been absorbed : to examine the accuracy of this 

 view I caused 



Experiment 2. — Four cells to be charged with a solution of 

 sulphate of copper, and connected in closed circuit; after 

 twenty-four hours' work, the liquid in the oxygen and hydro- 

 gen tubes had risen equally in three of the pairs, but in the 

 fourth the liquid in the hydrogen tube had risen rather more 

 than twice as high as in any of the others, and the whole of 

 the platinum in this tube, from the water-mark downwards, 

 was covered with metallic copper ; it was thus evident that a 

 slight precipitation having commenced on this platinum from 

 some local circumstance which offered less resistance in this 

 cell than in the others, a separate local current had been 

 established, the hydrogen and the copper acting as a voltaic 

 circuit, fresh copper had been constantly deoxidated at the 

 expense of the hydrogen : the phaenomenon is perfectly analo- 

 gous to that observable in an ordinary sulphate of copper bat- 

 tery, when a slight portion of copper is deposited upon the 

 zinc, and a local current is established by which the zinc is 

 worn into a hole without contributing to the general current. 



I have been thus particular in order to explain points in 

 the action of this battery which might seem exceptions to the 

 law of definite electrolysis, or what perhaps we should here 

 call electro-synthesis ; as a general result, the equivalent action 

 of the battery was very beautiful; with fifty cells in action 

 there was but a trifling difference in the rise of liquid in all 

 the cells, and the rise of gas in the voltameter appeared so di- 

 rectly proportional, that an observer unacquainted with the 

 rationale of a voltaic battery, would have said the gases from 



T2 



