190 Mr. G. J. Knox on the Dh'ection and Propagation 
produced by heat depends, whether upon a peculiar arrange- 
ment of the crystalline parts of the metal, or of their compound 
elementary particles, we are as yet perfectly ignorant. 
That the same general law of the contact of metals and of 
fluids applies equally (although in an inferior degree, owing 
to their want of conducting power) to the contact of the gases, 
may be shown by the experiment of Dr. Faraday (Sixth Se- 
ries) of the union of hydrogen and oxygen by a plate of pla- 
tinum ; the electrical force, which circulates by the interposed 
platinum plate, facilitating the union of the two gases*. 
To return to the source of the voltaic force in the battery. 
Zinc, when placed in contact with a dry acid, has been found 
to become positively electrified. When the zinc plate has 
been immersed in the acid solution, being positive, it attracts 
oxygen, by union with which its electrical state is disguised, 
while the hydrogen, set free in a highly positive electrical 
state, reacts upon the oxide of zinc, rendering it negative by 
induction. The platinum wire connecting the positive solu- 
tion with the negative zinc plate, reduces all for the moment 
to a state of equilibrium, so that the electricity becomes dis- 
guised, not transferred bodily from the platinum to the zinc \ 
which state of equilibrium is no sooner restored than it is de- 
stroyed, the zinc regaining its positive state, and the oxide 
being removed by the acid. 
If we consider then what takes place, we shall perceive that 
the zinc plate undergoes alternate states of induction and equi- 
librium, as do likewise the particles of the solution between 
the zinc and platinum plates, and, in fine, the platinum plate 
itself, and that as the number of alternations of zinc and plati- 
num increases, the electrical energy of the zinc plate increases, 
as does also the rapidity of its oxidation and, deoxidation^ and 
as a consequence the rapidity of change of induction and equi- 
librium upon nxhich the mtensity of the current depends. 
The decomposition of the electrolyte may be considered to 
be the effect produced by two forces acting upon its particles ; 
the attraction of the polesf of the battery (whether they be 
* Aqueous solutions of different gases, when brought into contact, have 
been found to produce electrical currents. 
t In place of poles^ I should more properly have said electrodes, their 
bounding surfaces. It follows, as a consequence of the theory, that the 
particles of oxygen in contact with the electrodes should be attracted by, 
and set free from, those electrodes upon each alternation of the states of 
induction and equilibrium ; and that, when the induced state has not suf- 
ficient energy to overcome the affinities already engaged, the current of 
electricity passes without producing electrolyzation. For a different ex- 
planation, vid. Dr. Faraday’s Series of Researches, 493, 494, 495,534, 535, 
536,537, 807. 
