228 On some Chemical Agencies of Electricity. 



X. On some general Illustrations and Applications of the 

 foregoing Facts and Principles, and Conclusion. ' 



The general ideas advanced in the preceding pages are 

 evidently directly in contradiction to the opinion advanced by 

 Fabroni, and which, in the early stage of the investigation, 

 appeared extremclv probable, namely, that chemical changes 

 are tlie priniary causes of the phaenoniena of Galvanism. 



Before the experiments of M. VoUa on the electricity ex- 

 cited by the mere contact of metals were published, I had 

 to a certam extent adopted this opinion ; but the new facts 

 immediately proved that another power must necessarily be 

 concerned ; for it was not possible to refer the electricity 

 exhibited by the apposition of metallic surfaces to any che- 

 mical alterations, particularly as the effect is more distinct 

 in a dry atmosphere, in which even the most oxidable metals 

 do not change, than in a moist one, in which many metals 

 undergo chemical alteration. 



Other facts likewise soon occurred demonstrative of the 

 same thing. In the Voltaic combination of diluted nitrous 

 acid, zinc and copper, as is well known, the side of the 

 zinc exposed to the acid is positive. But in combinations of 

 zinc, water and diluted nitric acid, the surface exposed to 

 the acid is negative; though if the chemical action of the 

 acid on the zinc had been the caus^ of the effect, it ought to 

 he the same in both cases. 



In mere cases of chemical change likewise electricity is 

 never exhibited. Iron burnt in oxygen >ias, properly con- 

 nected with a condensing electrometer, gives no charge to it 

 during the prqcess. Nitre and charcoal deflagrated in com- 

 iiuuiication with the same iiistrument do not by iheir agen- 

 cies in the slightest degree affect the gold leaves. Solid pure 

 potash and sulphuric acid made to combine in an insulated 

 platina crucible produce no electrical appearances, A solid 

 amalgam of bismuth and a solid amalgam of lead become 

 fluid when mixed together : the experiment, I find, is con- 

 nected with a diminution of temperature, but with no .exhi- 

 bition of electrical eflects. A thin plate of zinc, after being 



placed 



