368 Proceedings of the 



diately produced. By trying the different metals in succession in 

 this manner, a table is formed, in which each metal is negative as 

 regards those which follow it. This order is precisely the same as 

 that which is obtained for thermo-electric effects, in the closed circles 

 composed of two of the same metals, when the temperature of one of 

 the junctions is raised. It is demonstrated that the kind of electricity 

 acquired by each plate is independent of the greater or less degree 

 of friction which each of them undergoes ; and, consequently, that 

 the effect cannot be produced by the greater or less degree of heat 

 produced by the friction upon each of the surfaces. Since the 

 electric effects of friction are similar to those obtained by raising 

 the temperature of one of the points of junction of two plates, it 

 would appear that the heat produced by the friction is the cause of 

 the phenomenon ; while, on the other hand, it may be asked, does 

 not the friction, by augmenting the power of attraction of the two 

 bodies, heighten the electric effects which result from the action 

 of this power, or does it not produce a particular concussion in 

 the molecules of each body, the difference of which produces these 

 effects? But if two plates be struck against each other without fric- 

 tion, no electric effect is produced ; the two disengaged electricities 

 recombine upon the surface of contact, and there is no current. Yet 

 in this experiment there is a much greater concussion of the mole- 

 cules of the two surfaces, and a much greater liberation of heat than 

 in the slight friction of the plates against each other. We must, 

 therefore, admit that if the displacement of the molecules disengages 

 simultaneously heat and electricity, these two effects are independent 

 of each other ; it is even probable that the body which is the most 

 heated, or the parts of which are the most displaced, is that which 

 assumes the negative electricity. M. Becquerel then demonstrates 

 that there ought not to be any electricity rendered free by the vibra- 

 tion of metallic cords, although there are electrical phenomena from 

 molecule to molecule ; and afterwards proceeds to examine the 

 modifications produced in the phenomena by the reduction of one of 

 the metals into filings, and by variations made in the temperature. 

 When the filings of a metal are thrown upon a plate of the same metal, 

 the latter acquires an excess of positive electricity, and the filings an 

 excess of negative electricity. Generally, filings of metal have a 

 tendency to negative electricity ; but the filings of a positive metal 

 will, notwithstanding this tendency, be positive with relation to me- 

 tals of a more negative tendency. The author proves, by a variety 

 of experiments, that these effects are produced, not by a difference 

 in the action exercised on the metals by the air and water contained 

 in them, nor by the heat which is disengaged, but by a difference in 

 the mode of aggregation of the molecules of the surfaces, and conse- 

 quently of their faculties of vibration. 



The influence of the molecular state on this phenomenon may be 

 still more strongly illustrated by means of an apparatus giving a 

 rapid rotatory movement to the plate on which the filings are thrown. 



