262 EXPERIMENTAL INVESTIGATIONS. 



to that observable in an ordinary sulphate of copper battery, 

 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 directly proportional, that an observer unacquainted with 

 the rationale of a voltaic battery would have said the gases 

 from 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 

 employed platinised 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- 

 Fig. 10. synthetically combined by the immersed por- 

 tion of the platinum ; whether, for instance, 

 the efficient parts of the plates were the parts 

 / ^, p f q' (fig- 4), or q r, q' r f . To ascertain 

 this the following 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 (see 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 por- 

 tions of the platinum, q r, q' r', and can examine the action 



