Otf SOME CHEMICAL AGENCIES OF ELECTRICIT V. £(J 



General illus- 

 trations and 

 application;, 



body independent of chemical change, and is to be referred to General illus- 



.. . v , - m trations and 



a diflerent law*. 



I mentioned the glass plates of Beccaria as affording a 

 parallel to the case of combination in consequence of the 

 diflerent electrical states of bodies. In Guyton de Morveau's 

 experiments on cohesion, the diflerent metals are said to have 

 adhered to mercury with a force proportional to their che- 

 mical affinities. But the other metals have different electrical 

 energies, or different degrees of the same electrical energy 

 with regard to this body; and in all cases of contact of mer- 

 cury with another metal, upon a large surface, they ought to 

 adhere in consequence of the difference of their electrical 

 states, and that with a force proportional to the exaltation of 

 those states. Iron, which M. Guyton found slightly adhesive, 

 I find exhibits little positive electricity after being laid upon 

 a surface of mercury, and then separated. Tin, zinc, and 

 copper, which adhere much more strongly, communicate 

 higher charges to the condensing electrometer: I have had 

 no instrument sufficiently exact to measure the differences: 

 but it would seem, that the adhesion from the difference of 

 electrical states must have operated in these experimentsf, 

 which being proportional to the electrical energies are, on the 



* The cHarigs of the capacities of bodies in consequence of the alter- 

 ation in their volumes, or states of existence by heat, is a continually 

 operating source of electrical effects : and as I have hinted, page 47, it 

 often interferes with the results of experiments on the electrical energies 

 of bodies as exhibited by contact. It is likewise probably one of the 

 sources of the capricious remits of experiments of friction, in which the 

 same body, according as its texture is altered, or its temperature changed, 

 assumes different states with regard to another body. Friction may be 

 considered as a succession of contacts, and the natural energies of bodies 

 would probably be accurately exhibited by it, if the unequal excitation of 

 heat or its unequal communication to the different surfaces did not inter- 

 fere by altering unequally their electrical capacities. Of the elements of 

 flint glass, silex is slightly negative with regard to the metals, the soda is 

 positive j and in contacts of glass with metals I find it exhibits the excess 

 of the energy of the alkali: the case, as is well known, is the same in 

 fiiction, the amalgam of the common machine is essential to its powerfu/ 

 excitation. 



f Amalgamation undoubtedly most have interfered; but the genera} 

 result .seems to have been distinct. 



hvpothes's 



