276 



Mr. Grove on the Gas Voltaic Battery. 



the exterior cells of the battery were conveyed through the 

 solid wires and evolved in the voltameter; and had this been 

 the first voltaic battery ever invented, this probably would 

 have been the theory of its action. 



In my original paper, I considered the points of voltaic 

 action to be those where the liquid, gas, and platinum met; 

 and it was to increase the number of these points that I em- 

 ployed platinized or spongy platinum ; indeed, from what I 

 have since observed, I have much doubt whether I should 

 have obtained any success had I used smooth platinum. The 

 local action detailed in the last experiment, however, made 

 me anxious to ascertain whether the principal points of action 

 were those which I had originally believed, or whether the 

 gases entered into solution first, and were then electro-syn- 

 thetically combined by the immersed portion of the platinum ; 

 whether, for instance, the efficient parts of the plates were the 

 parts p q, p' q' (fig. 4), or q r, q' r 1 . To ascertain this the fol- 

 lowing experiment was made : — 



Experiment 3. — A battery of five cells 

 was constructed, in which the platinum 

 reached only to half the height of the 

 tubes (fig. 10). This was charged with 

 oxygen and hydrogen, so that the liquid 

 just covered the extremities of the 

 platinum. In this case we have only 

 the immersed portions of the platinum, 

 q r, q' 7 J , and can examine the action of 

 the gases which enter into solution, and 

 are unaffected by the platinum until in 

 solution. This battery so charged gave 

 a very trifling action indeed ; it would 

 not decompose iodide of potassium, and 

 but slightly affected a highly sensitive 

 galvanometer ; but when a little gas was 

 added, so as to expose the platinum to 

 the gaseous atmosphere, a considerable 

 current was developed, and a single pair decomposed 

 iodide. 



If, again, a battery of this description (fig. 10) be charged 

 so that the water-mark is below the upper edge of the plati- 

 num, and the ends are connected in closed circuit, the liquid 

 rises in both tubes until that in the hydrogen tube has reached 

 the top of the platinum, and then there is no further rise. 

 This experiment decides the question as to what is to be con- 

 sidered the working portion of the battery, but it does not 

 positively decide whether solution and electrolysis are con- 



the 



