LECTURE V.] HISTORY OF CHEMISTRY. 73 



from that which it naturally possesses ; that is, by bringing it 

 artificially into a state similar to the other, so it may be in- 

 creased by exalting its natural energy. Thus, whilst zinc, one 

 of the most oxidable of the metals, is incapable of combining 

 with oxygen when negatively electrified in the circuit, even by 

 a feeble power ; silver, one of the least oxidable, easily unites 

 to it when positively electrified ; and the same thing might be 

 said of other metals." 



He observes in another place that if there were no cohesion, 

 the chemical attraction would necessarily be proportional to the 

 electrical forces. Both are, in his view, effects of the same 

 power, which, if it extends to the mass of a substance, gives 

 rise to electricity, while, if it excites the smallest particles, it 

 produces affinity. 16 By the action of the electric current, the 

 electricity which was liberated from the atoms upon their com- 

 bination, is restored to them again, and decomposition is there- 

 by effected. In this action the positive substance goes to the 

 negative pole and vice versa. 



It must be admitted that these views start from a simple 

 and a clear idea, and that by the application of this idea they 

 explain the observed facts in a way that is easily understood. 

 They therefore fulfil the conditions which are required in a 

 scientific hypothesis, and secure that their founder, Davy, shall 

 always be regarded as an investigator of undoubted originality. 

 Davy's fame spread very rapidly, and, when he succeeded, a 

 year afterwards, in isolating the alkali metals, it appeared as if 

 he had, for the first time, pointed out the proper line of ad- 

 vance in chemistry. It is true that Davy's theory was illumi- 

 nated by but short glimpses of sunshine, for ten years later we 

 find that it is abandoned. It was certain to fall as soon as the 

 contact with one another of heterogeneous substances was no 

 longer regarded as a source of the excitation of electricity ; and 

 the affirmative view with respect to this matter was soon vigor- 

 ously contested. Ritter, in particular, strove to show 17 that 



16 Davy, Elements of Chemical Philosophy, 165. 17 Ritter, Elek- 

 trisches System, 49 ; see also Gehlert's Physikalisches Worterbuch. 4, 795. 



