i88i.J The Source of Electric Energy. 463 
vibrations, it has a normal heat and an abnormal eleCtric 
vibration, whose pitch is either above or below that of the 
heat, according as the charge is positive or negative. Thus 
there is a surface layer of electrically charged molecules, 
aCting inductively in both directions, inward and outward. 
Its outward inductions are effective ; its inward are in- 
effective, except in the case of an irregularly shaped body, in 
which the induCtive effedt, through the body, on equal areas 
of the surface, differs in vigour. 
The principle considered in the above argument is un- 
doubtedly a universal principle of Nature, and one which 
arises from the necessary relations of the molecular condi- 
tion of matter. EleCtric disturbance is not necessary to its 
aCtion. Any discordance in the motive relations of mole- 
cules is sufficient to produce its effects. Every molecule 
disturbs the motive conditions of every other not actually 
homogeneous with it. There is a constant resistance to 
heterogeneity, and a constant effort to produce homogeneity, 
in the motive conditions of the molecules of all substances. 
But this effort is partly balanced by a counter effort in each 
substance to retain its normal molecular condition. Thus 
between the effort to produce conformity and the effort to 
resist change there is a constant struggle. The latter is 
usually the stronger when the bodies are separated ; but 
when they are brought into contact the former may often 
prevail, even if there is no difference in their motive vigours, 
if we may judge by the apparent results of contadl elec- 
tricity, When there is a difference in vigour, whether this 
results from heat, from friction, or from chemical change, 
the effort to produce conformity usually, perhaps always, 
overcomes, with the production of the various electrical 
phenomena. Every molecule whose vibratory relations are 
disturbed causes a similar disturbance, gradually decreasing 
with distance, in the vibratory relations of surrounding 
molecules. Every molecule having a different vibratory 
period from that of any other seeks to produce conformity 
to its own condition in this other, and the disturbance may 
become measurable if they be in contact. Wherever the 
vibratory energy of the one exceeds that of the other, the 
disturbance is followed by a flow of energy, if resistance to 
this flow be not too declared. The principle is that every 
molecule strives to preserve its normal motive conditions, 
and if these be disturbed to restore them, either inwardly or 
by the aid of a like disturbance of the motive conditions of 
neighbouring molecules, and an outward neutralisation of 
the disturbed vibratory energy. These molecules, in their 
