tially neutralize each other in their action
upon the selenium. Lastly, the current flows through not only the surface
layer, which is acted upon by the light, but also the portion which is
underneath, and not affected thereby, and which therefore detracts from
the actual effect of the light upon the selenium at the surface.

My form of cell is a radical departure from all previous methods of
employing selenium, in all of these respects. In the first place, I form
the selenium in very thin plates, and polarize them, so that the
opposite faces have different electrical states or properties. This I do
by melting it upon a plate of metal with which it will form a chemical
combination, sufficient, at least, to cause the selenium to adhere and
make a good electrical connection with it. The other surface of the
selenium is not so united or combined, but is left in a free state, and a
conductor is subsequently applied over it by simple contact or pressure.

During the process of melting and crystallizing, the selenium is
compressed between the metal plate upon which it is melted and another
plate of steel or other substance with which it will not combine. Thus by
the simultaneous application and action of heat, pressure, chemical
affinity, and crystallization, it is formed into a sheet of granular
selenium, uniformly polarized throughout, and having its two surfaces in
opposite phases as regards its molecular arrangement. The non-adherent
plate being removed after the cell has become cool, I then cover that
surface with a _transparent conductor of electricity_, which may be a
thin film of gold leaf. Platinum, silver, or other suitable material may
also be employed. The whole surface of the selenium is therefore covered
with a good electrical conductor, yet is practically bare to the light,
which passes through the conductor to the selenium underneath.[5] My
standard size of cell has about two by two and a half inches of surface,
with a thickness of 1/1000 to 5/1000 inch of selenium. But the cells can,
of course, be made of any size or form. A great advantage of this
arrangement consists in the fact that it enables me to apply the current
and the light to the selenium in the same plane or general direction,
instead of transversely to each other as heretofore done, so that I can
cause the two influences to either coincide in direction and action, or
to act upon opposite faces of the selenium and oppose each other,
according to t