IMPROVEMENTS IN APPARATUS FOR THE PRODUCTION OF LIGHT BY ELECTRICITY
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by Thomas Francis Scott at the Office of
the Commissioners of Patents on the 2nd March 1878.
THOMAS FRANCIS SCOTT, of Birmingham, in the County of Warwick, Photo-
grapher. "IMPROVEMENTS IN APPARATUS FOR THE PRODUCTION OF LIGHT BY
ELECTRICITY."
My Invention consists, first, in the following improvements in the manufacture
of rods, sticks, blocks and discs, and hollow cylinders of carbon to be used in the
production of light by electricity.
I take finely powdered gas retort carbon, or well burned coke or other carbon
possessing good electrical conducting power, and I thoroughly incorporate the
said finely powdered carbon with thin flour paste or thin starch paste so as to
produce a plastic mass, having a consistency suitable for moulding by dies and
pressure.
When discs or blocks are to be made from the said plastic mass, it may be
treated by pressure and dies of the kind ordinarily employed for shaping plastic
materials.
When sticks or rods are to be made, they may either be made in the same way,
or they may be made by forcing the plastic mass through a hole in a draw plate,
or they may be made, when cylindrical in figure, by rolling portions of the plastic
mass on a flat surface, or by the action of grooved rolls.
In making hollow cylinders, I force the plastic mass through a hole in which a
plug or bulb mandril is supported concentrically. The hollow cylinders produced
are received upon a wooden or other cylinder on which they are supported until
they have hardened sufficiently to preserve their figure. After the fashioning of
the rods, sticks, blocks, discs, or bollow cylinders they are allowed to harden by
exposure to the air; they are next further hardened in a stove or heated chamber,
and are finally strongly heated in a kiln or muffle so as to decompose the flour or
starch and leave the articles composed of nearly pure carbon.
Where it is wished that the articles should contain clay or other mineral material,
the said clay or material is finely powdered and thoroughly mixed with the

page_text: powdered carbon before the admixture of the latter with the flour or starch paste.
The articles thus produced may be coated with copper, applied as copper bronze or
deposited by electricity, or may be coated with plumbago, the said coatings having
for their object to make the articles better conductors of electricity.
My Invention consists, secondly, in manufacturing flexible bands, ribbons, or
cords of carbon (or mixtures consisting essentially of carbon) to be used as herein-
after described in the production of light by electricity. I take the carbon or
carbon mixture and incorporate therewith fibres of asbestos or fibres of hempor
other mineral or organic fibres, together with adhesive matter, as herein-before
explained. By rolling or otherwise, I form the mixture into long bands, strips, or
ribbons, and dry them heat.
When the fibres are mineral, the heat applied may be sufficiently high to decompose
the flour or starch paste, but when organic fibres are employed the heat must not
be so high as to decompose the said fibres. The conducting power of these bands
may be increased in the manner herein-before described with reference to rods,
sticks, and blocks.
:
My Invention consists, thirdly, in making sticks, blocks, or pieces of carbon
moulded from the plastic mixture, berein first described, of such a figure that when
fixed close together upon a flexible band they shall, when the band is passed over a
pulley, engage or interlock with one another. This I effect by making one edge of
the stick or block overhang, and its opposite edge chamfered or inclined; or by
making one side of the figure of a convex flute and the other side of the figure of a
concave flute. By these arrangements there is no break in the continuity of the
electric light, when, by the motion of the travelling band, the point of ignition
passes from one pair of rods or pieces to another.
My Invention consists, fourthly, in preventing or diminishing the rapid waste by
combustion of carbons employed in producing light by electricity. This I effect by
delivering a stream of finely divided carbon or carbonaceous matter upon the
ignited carbons, whereby the solid carbon of the sticks, rods, discs, or bands is
preserved to a large extent from combustion, and consequently lasts much longer
than carbon not so protected.
My Invention consists, lastly, in the following methods of using the flexible
carbon bands, ribbons, or cords, or the rods or blocks fixed on a travelling flexible
band, and the hollow cylinders herein-before described.
Where flexible bands are employed, I mount two metallic rollers on axes, by
preference, slightly inclined to one another. Over these rollers the bands are slowly
passed by giving a slow rotation to the rollers. The electricity passes from the
rollers to the carbons and across the space between their nearest points. By the
slow renewal of the carbon in the path of the current, great steadiness and uniformity
are obtained in the light produced.
The
The flexible bands may either be endless bands or bands unconnected at their
ends. The bands may be used several times, the portions which have passed out of
use being made to approach each other before they are again brought into use.
hollow carbon cylinders described are used by being mounted on rollers with their
axes slightly inclined to one another. The electricity passes between the parts
of the edges of the two hollow carbon cylinders which approach nearest each
other, these points being slowly changed by the rotation of the hollow cylinders.