280 DR. FARADAY'S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XIV.) 



the effects observed in solid helices where wires are coiled over wires to the amount 

 of five or six or more layers in succession, no diminution of effect on the outer ones 

 being occasioned by those within. 



^. 22. Note on electrical excitation. 



1737. That the different modes in which electrical excitement takes place will some 

 day or other be reduced under one common law can hardly be doubted, though for 

 the present we are bound to admit distinctions. It will be a great point gained when 

 these distinctions are, not removed but, understood. 



1738. The strict relation of the electrical and chemical powers renders the chemi- 

 cal mode of excitement the most instructive of all, and the case of two isolated com- 

 bining particles is probably the simplest that we possess. Here however the action 

 is local, and we still want such a test of electricity as shall apply to it, to cases of 

 current electricity, and also to those of static induction. Whenever by virtue of the 

 previously combined condition of some of the acting particles (923.) we are enabled, 

 as in the voltaic pile, to expand or convert the local action into a current, then chemical 

 action can be traced through its variations to the production of all the phenomena of 

 tension and the static state, these being in every respect the same as if the electric 

 forces producing them had been developed by friction. 



1739. It was Berzelius, I believe, who first spoke of the aptness of certain particles 

 to assume opposite states when in presence of each other (959.). Hypothetically we 

 may suppose these states to increase in intensity by increased approximation, or by 

 heat, &c. until at a certain point combination occurs, accompanied by such an arrange- 

 ment of the forces of the two particles between themselves as is equivalent to a dis- 

 charge, producing at the same time a particle which is throughout a conductor (17OO.). 



1740. This aptness to assume an excited electrical state (which is probably polar 

 in those forming non-conducting matter) appears to be a primary fact, and to par- 

 take of the nature of induction (1162.), for the particles do not seem capable of re- 

 taining their particular state independently of each other (1177') or of matter in the 

 opposite state. What appears to be definite about the particles of matter is their 

 assumption of a particular state, as the positive or negative, in relation to each other, 

 and not of either one or other indifferently ; and also the acquirement of force up to 

 a certain amount. 



1741. It is easily conceivable that the same force which causes local action between 

 two free particles shall produce current force if one of the particles is previously in 

 combination, forming part of an electrolyte (923. 1738.). Thus a particle of zinc, and 

 one of oxygen, when in presence of each other, exert their inductive forces (1740.), and 

 these at last rise up to the point of combination. If the oxygen be previously in union 

 with hydrogen, it is held so combined by an analogous exertion and arrangement of 

 the forces ; and as the forces of the oxygen and hydrogen are for the time of combi- 

 nation mutually engaged and related, so when the superior relation of the forces be- 



