Mr. Grove on the Gas Voltaic Battery. 277 



temporaneous or successive, as it may be said that even what 

 I have termed the exposed parts of the platinum are covered 

 with a film of liquid. I should myself hesitate for the present 

 to express a decided opinion on this point; my first impres- 

 sion was, that there would be, as it were, three sets of points 

 in contact, but I have not been able to devise an experiment 

 definitively to settle this point*. 



I aimed next at further establishing the analogies of this 

 battery with the ordinary voltaic battery, i. e. regarding the 

 hydrogen tube as analogous to the plate of zinc or other oxi- 

 dable metal at the anode ; I wished to see how far this rela- 

 tion was borne out. It was beautifully shown in 



Experiment 4. — Where a single pair was charged with 

 oxygen and hydrogen, and a second with hydrogen in one 

 tube, the other being filled with dilute sulphuric acid; when 

 the hydrogen of the second was metallically connected with 



Fig. 11. 



the oxygen of the first, and the liquid of the second with the 

 hydrogen of the first, as in fig. 11, bubbles of gas rose from 

 the platinum, which proved, as I anticipated, to be hydrogen. 

 In short, though it required four pairs to decompose water 

 with immersed platinum electrodes, yet the platinum in the 

 atmosphere of hydrogen being analogous to an oxidable anode, 

 one pair was with this assistance sufficient to decompose water, 

 just as one pair of an ordinary battery will decompose water 

 with an anode of copper. 



* I have sometimes remarked when mixed oxygen and hydrogen have 

 been collected in one tube of the gas battery over distilled water, the ad- 

 dition of a little sulphuric acid causes the gases rapidly to disappear. 



