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



tinuous current unless combination take place, so as to allow other particles to act 

 successively in the same manner, and not even then unless one set of the particles be 

 present as an element of an electrolyte (923. 963.) ; i. e. mere quiescent contact 

 alone without chemical action does not in such cases produce a current. 



1746. Still it seems very possible that such a relation may produce a high charge, 

 and thus give rise to excitement by friction. When two bodies are rubbed together 

 to produce electricity in the usual way, one at least must be an insulator. During 

 the act of rubbing, the particles of opposite kinds must be brought more or less 

 closely together, the few whicli are most favourably circumstanced being in such 

 close contact as to be short only of that which is consequent upon chemical combi- 

 nation. At such moments they may acquire by their mutual induction (1740.) and 

 partial discharge to each other very exalted opposite states, and when, the moment 

 after, they are by the progress of the rub removed from each other's vicinity, they 

 will retain this state if both bodies be insulators, and exhibit them upon their com- 

 plete separation. 



1747. AH the circumstances attending friction seem to me to favour such a view. 

 The irregularities of form and pressure will cause that the particles of the two rubbing 

 surfaces will be at very variable distances, only a few at once being in that very close 

 relation which is probably necessary for the development of the forces ; further, those 

 which are nearest at one time will be further removed at another, and others will be- 

 come the nearest, and so by continuing the friction many will in succession be ex- 

 cited. Finally, the lateral direction of the separation in rubbing seems to me the 

 best fitted to bring many pairs of particles, first of all into that close vicinity ne- 

 cessary for their assuming the opposite states by relation to each other, and then to 

 remove them from each other's influence whilst they retain that state. 



1748. It would be easy, on the same view, to explain hypothetically, how, if one of 

 the rubbing bodies be a conductor, as the amalgam of an electrical machine, the state 

 or the other when it comes from under the friction is (as a mass) exalted ; but it 

 would be folly to go far into such speculation before that already advanced has been 

 backed or corrected by fit experimental evidence. I do not wish it to be supposed 

 that I think all excitement by friction is of this kind ; on the contrary, certain expe- 

 riments lead me to believe that in many cases, and perhaps in all, effects of a thermo- 

 electric nature conduce to the ultimate end ; and there are very probably other causes 

 of electric disturbance influential at the same time, which we have not as yet distin- 

 guished. 



Royal Institution, 

 June, 1838. 



