264 



EXPERIMENTAL INVESTIGATIONS. 



Fig. ii. 



with immersed platinum electrodes, yet the platinum in the 

 atmosphere of hydrogen being analogous to an oxidable 



anode, one pair was, with this as- 

 sistance, sufficient to decompose 

 water, just as one pair of an 

 ordinary battery will decompose 

 water with an anode of copper. 



The nitric acid battery, an 

 account of which I originally 

 published in 1839, having shown 

 me the value of highly oxy- 

 genated acids and peroxides as 

 voltaic excitants,* I determined, 

 with a view of farther extending the analogy of the gaseous 

 and metallic voltaic batteries, to try the nitric acid as an elec- 

 trolyte with the gas battery. Therefore, in 



Experiment 5, I charged a battery with hydrogen and 

 nitric acid in alternate cells, the nitric acid being only diluted 

 sufficiently to prevent injury to the wooden parts of the 

 battery. With this arrangement I found that three cells 

 were capable of decomposing water ; and thus here, also, the 

 analogy held good, the gaseous hydrogen deoxidating the 

 nitric acid in this arrangement, by nascent hydrogen as in the 

 metallic battery. 



I now endeavoured to produce the converse effects, viz. 

 to form a battery in which oxygen should be the gaseous 

 element, and be absorbed by an electrolyte having an affinity 

 for it. To this end, in 



Experiment 6, I caused a battery of ten cells to be 

 charged, the one set of tubes with oxygen and the alternate 

 tubes with solution of protosulphate of iron. This battery 

 decomposed iodide of potassium, but was not able to decom- 

 pose water. The tubes which contained the solution of proto- 

 sulphate represented the hydrogen tubes of the ordinary gas 

 battery. The voltaic action caused by oxygen and protoxide 

 of iron was, however, but temporary.f After a few hours it 



* See Phil. Mag., May and Oct. 1839, pp. 389, 290. 



f In Experiment 26 it will be seen that a continuous current is obtained from 

 oxygen and a liquid (solution of ammonia) ; oxygen likewise gives a current with 

 solution of cyanogen, and probably with many organic compounds. 



