chemical Agencies of Electricity. gi 
I mentioned the glass plates of Beccaria as affording a 
parallel to die case of combination in consequence of the dif- 
ferent electrical states of bodies. In Guyton de Morveau’s 
experiments on cohesion, the different 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 experiments,* 
which being proportional to the electrical energies are, on 
the hypothesis before stated, proportional to the chemical 
affinities. How far cohesion in general may be influenced 
or occasioned by this effect of the difference of the electrical 
energies of bodies is a curious question for investigation. 
Many applications of the general facts and principles to 
regard to the metals, the soda is positive ; and in contacts of glass with metals I find 
it exhibits the excess of the energy of the alkali : the ease, as is well known, is the 
same in friction, the amalgam of the common machine is essential to its powerful 
excitation. 
* Amalgamation undoubtedly must have interfered; but the genreal result seems 
to have been distinct. 
H 2 
