HISTORY OF GALVANISM. 33 



but in a reverse order ; the hydrogen now pro- 

 ceeding from the wire connected with the zinc 

 end of the pile, and the oxygen from the silver 

 or copper wire. 



These experiments, which at the time when New com, 

 they were performed seemed most extraordinary, 

 and almost inexplicable, were succeeded by others 

 equally curious, in which Sir H. Davy produced 

 the galvanic effect, by a new combination of 

 substances. He found that charcoal was capable 

 of conducting the influence and of decomposing 

 water, the copper end giving out hydrogen, hold- 

 ing a little carbon in solution ; the zinc end did 

 not produce any considerable quantity of gas, as 

 the carbonic acid which was produced was ab- 

 sorbed by the water in which the charcoal was 

 immersed. He formed a pile of zinc and charcoal, piieof one 

 which acted with considerable energy ; and he metal * 

 afterwards discovered that a pile may be con- 

 structed of only one metal, with different fluids 

 applied to its two surface?, one of them capable 

 of oxidating the metal, the other of preventing 

 the effect of oxidation, the two fluids being se- 

 parated from each other by water. The series 

 which he employed was metal, diluted nitric acid, 

 water, sulphuret of potash, and then again metal. 

 In a subsequent train of experiments, he proceeded 

 still farther, and composed a pile without any pj] e O f 

 metal, but consisting solely of pieces of charcoal, c ^^ 

 having their opposite surfaces exposed to the ac- metal - 



D 



