200 INDUCTIVE AFFINITY. 



The solution of the zinc in hydrochloric acid which deve- 

 lopes these powers, acting at a distance, is not itself impeded, 

 but on the contrary, is promoted by exerting such an influence. 

 For placed alone in the acid, that metal scarcely dissolves at 

 all, if pure and uncontaminated with other metals, or if its 

 surface has been silvered with mercury, but it dissolves with 

 rapidity when a copper plate is associated with it in the same 

 jar, in the manner described. Hence the decomposing power 

 which appears between A and B, cannot be viewed as actually 

 a portion of that which causes the solution of the zinc in the 

 hydrochloric acid, for that force has suifered no diminution in 

 its own proper sphere of action. 



This combination of metals and fluids is known as the simple 

 voltaic circle. 



To explain the phenomena of the voltaic circle, the exis- 

 tence of a substantial principle, the electric fluid, has been 

 assumed, of such a nature that it is readily communicable to 

 matter, and capable of circulating through the voltaic arrange- 

 ment, carrying with it peculiar attractive and repulsive forces 

 which occasion the decompositions observed. A vehicle was thus 

 created for the chemical affinity which is found to circulate. But 

 it is generally allowed that this form of the electrical hypothesis 

 has not received support from observations of a recent date, 

 particularly from the great discoveries of Mr. Faraday, which 

 have completely altered the aspect of this department of 

 science, and suggest a very different interpretation of the phe- 

 nomena. All electrical phenomena whatever are found to 

 involve the presence of matter, or there is no evidence of the 

 independent existence of electricity apart from matter, so that 

 these phenomena may really be exhibitions of the inherent pro- 

 perties of matter. The idea of anything like a circulation of 

 electricity through the voltaic circle appears to be abandoned. 

 Electrical induction, by which certain forces are propagated to 

 a distance, is found to be always an action of contiguous par- 

 ticles upon each other, in which it is unnecessary to suppose 

 that anything passes from particle to particle, or is taken from 

 one particle and added to another. The change which a par- 

 ticle undergoes, takes place within itself, and it is looked upon 

 as a temporary development of different powers in different 

 points of the same particle. The doctrine of polarity has thus come 

 to be introduced into the discussion of electrical phenomena .* 



* For Mr. Faraday's more recent views, the Eleventh and subsequent series of 



