Mr. R. Phillips on Frictional Electricity. 39 



The particles of a substance, on approximating each other, 

 may possibly effect a mutual discharge, as in chemical action, 

 and cohere in consequence. As an example, suppose steam to 



change to ice. A line of particles of steam, + f- h — , 



on approaching another similar set of particles, may discharge 



and together become ______ _• n adding two 



chains, one on each side of the former two, the molecules may 

 take the form — • — 



+ • + + • + +•+ 



+•+ +•+ +•+ 

 the electric force of the two added lines passing through the 

 intervening particles. Other modes of superposition can be 

 imaged ; and if the hypothesis is true, it would seem that some 

 others must indeed exist to account for the varieties of crystalline 

 form. 



Now, since combination generates heat, and decomposition 

 consumes heat, the same, according to this theory, must take 

 place with cohesion ; and thus may be so far explained the loss 

 of heat produced by evaporation, and its reproduction by con- 

 densation*. 



This hypothesis will also at once apply to the production of 

 heat by the friction of solids, at least in some cases. For all the 

 force expended in tearing the two rubbing surfaces is, at the first 

 separation of the particles, represented by the electricity deve- 

 loped : now if the particles thus separated, or the surfaces to 

 which they are attached, did not during the process of rubbing 

 discharge to each other, clearly all the force expended in friction 

 should appear as electricity. But from the nature of the rubbing 

 process, it is impossible not to suppose that much of the electri- 

 cities produced do neutralize each other ; which thereby, as in 

 the case of chemical combination, produces for the electricity its 

 equivalent of heat. 



An attempt was made by Wollaston to apply Davy's electro- 

 chemical theory to the electricity of friction. This view, as 

 expounded by Faraday, consists in supposing that " during the 

 act of rubbing, the particles of opposite kinds must be brought 

 more or less closely together, the few which are most favourably 

 circumstanced being in such close contact as to be short only of 

 that which is consequent upon chemical combination. At such 

 moments they may acquire, by their mutual induction and par- 

 tial discharge to each other, very exalted opposite states; and 

 when, the moment after, they are by the progress of the rub 



* Phil. Mag., S.4. vol. ii. p. (i. 



