244 TEE POPULAR SCIENCE MONTHLY, 



state of things very favorable to the hope that Faraday's fundamental 

 conceptions may in the immediate future receive general assent. His 

 theory, indeed, is the only existing one which is at the same time in 

 perfect harmony with the facts observed, and which at least does not 

 lead into any contradiction against the general axioms of dynamics. 



It is not at all necessary to accept any definite opinion about the 

 ultimate nature of the agent which we call electricity. 



Faraday himself avoided as much as he could giving any afiirma- 

 tive assertion regarding this problem, although he did not conceal his 

 disinclination to believe in the existence of two opposite electric fluids. 



For our own discussion of the electro-chemical phenomena, to 

 which we shall turn now, I beg permission to use the language of the 

 old dualistic theory, because we shall have to speak principally on re- 

 lations of quantity. 



I now turn to the second fundamental problem aimed at by Fara- 

 day, the connection between electric and chemical force. Already, 

 before Faraday went to work, an elaborate electro-chemical theory 

 had been established by the renowned Swedish chemist, Berzelius, 

 which formed the connecting link of the great work of his life, the 

 systematization of the chemical knowledge of his time. His starting- 

 point was the series into which Volta had arranged the metals accord- 

 ing to the electric tension which they exhibit after contact with each 

 other. A fundamental point w^hich Faraday's experiment contradicted 

 wats the supposition that the quantity of electricity collected in each 

 atom was dependent on their mutual electro-chemical differences, 

 which he considered as the cause of their apparently greater chemical 

 affinity. But, although the fundamental conceptions of Berzelius's 

 theory have been forsaken, chemists have not ceased to speak of posi- 

 tive and negative constituents of a compound body. Nobody can 

 overlook that such a contrast of qualities, as was expressed in Berze- 

 lius's theory, really exists, well developed at the extremities, less evi- 

 dent in the middle terms of the series, playing an important part in all 

 chemical actions, although often subordinated to other influences. 



When Faraday began to study the phenomena of decomposition by 

 the galvanic current, which of course were considered by Berzelius as 

 one of the firmest supports of his theory, he put a very simple ques- 

 tion ; the first question, indeed, which every chemist speculating about 

 electrolysis ought to have answered. He asked. What is the quantity 

 of electrolytic decomposition if the same quantity of electricity is 

 sent through several electrolytic cells ? By this investigation he dis- 

 covered that most important law, generally known under his name, 

 but called by him the law of definite electrolytic action. 



Faraday concluded from his experiments that a definite quantity 

 of electricity can not pass a voltametric cell containing acidulated 

 water between electrodes of platinum without setting free at the nega- 

 tive electrode a corresponding definite amount of hydrogen, and at the 



