IMPROVEMENTS IN LIGHTING BY ELECTRICITY
Year: 1878

page_text: LETTERS PATENT to Edward Griffith Brewer, of the Firm of Brewer and
Jensen, of 33, Chancery Lane, in the County of Middlesex, Patent Agents,
A
for the Invention of "IMPROVEMENTS IN LIGHTING BY ELECTRICITY."
communication from abroad by Thomas Alva Edison, of Menlo Park, in the
State of New Jersey. United States of America.
Sealed the 21st January 1879, and dated the 7th November 1878.
PROVISIONAL SPECIFICATION left by the said Edward Griffith Brewer at
the Office of the Commissioners of Patents on the 7th November 1878.
EDWARD GRIFFITH BREWER, of the Firm of Brewer and Jensen, of 33, Chancery
Lane, in the County of Middlesex, Patent Agents. "IMPROVEMENTS IN LIGHTING
BY ELECTRICITY.' (A communication from abroad by Thomas Alva Edison, of
Menlo Park, in the State of New Jersey, United States of America.)
According to this Invention the light giving material is. employed in the form of
cylinders or prisms consisting of finely divided metals, such as platinum, iridium,
ruthinium, or other material having a high melting point, mixed with nonconductors
such as inagnesium or zircon oxides that are with difficulty melted. These are
mixed and compressed into the proper form for the light, and rendered luminous
and incandescent by the passage of the electric current.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edward Griffith Brewer in the Great Seal Patent Office on the 7th
May 1879.
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EDWARD GRIFFITH BREWER, of the Firm of Brewer and Jensen, of 33, Chancery
Lane, in the County of Middlesex, Patent Agent. IMPROVEMENTS IN LIGHTING
BY ELECTRICITY." A communication from abroad by Thomas Alva Edison, of
Menlo Park, in the State of New Jersey, United States of America.
The light giving device or candle is in the form of a solid, such as a cylinder or
prism. In the Drawing a form of candle is shown that is convenient for use in the
present Invention.
Fig. 1 is a section of the candle showing also the circuit connections.
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2 is an enlarged section of the candle detached; and
3 is a perspective view of the candle portion x, which is a slightly tapering
hollow cylinder, and split vertically except at the upper end; this ensures uniform
and complete incandescence as the electric current passes up one side and down the
other.
The base is by preference enlarged, as shown, in order that the electric conductors
may be easily connected therewith, and in Fig. 1 a thermal circuit regulator is
shown similar to that in Letters Patent No. 4226, granted October 23rd 1878, in
Great Britain, to the said Thomas Alva Edison.
The electric current enters at n¹, passes by the wire k to the candle x, up one
side and down the other, there being clamps to connect the wires to the base of the
split candle, thence by the circuit regulator n, spring L, and clamp to the other wire
of the circuit.
If the current is excessive the regulator n becomes heated, and expands so as to
bring L into contact with the adjusting screw m, and short circuit the current and
lessen its action in the light.
The special feature of this Invention relates to the candle itself.
Metals or oxides of metals are made use of that produce in a comparatively large
candle sufficient resistance to render the whole candle incandescent.
Finely divided metal or particles of metal having a high melting point are
caused to adhere by earthy materials, such as magnesium or zircon oxides, or
magnetic oxide of iron or other substances that are with difficulty fused. The
oxides of metals may be obtained by chemical precipitation or otherwise, and the
candle is moulded in either a moist or dry condition by pressure.
The fine particles of metal may be platinum, iridium, ruthinum, or other metal
that can only be melted at a very high temperature. The earthy materials should
be such as are infusible, such as oxide of magnesia or zirconium, lime, silicum, boron,
or other suitable material.
In cases where these oxides or earthy materials are mixed with the fine metallic.
particles such particles are thoroughly and uniformly mixed into the mass before
it is moulded, and hence such particles are kept separate by the earthy material,
and cannot fuse or run together, and the metallic oxides themselves are electric
conductors to a greater or less extent, and hence may in some instances be used
without the particles of metal. In all cases the substances are moulded and pressed
into shape under powerful pressure, and if the particles do not adhere together
sufficiently sugar, tar, silica, or similar material may be used in moulding the candles
to shape, and these substances may be volatilized by the heat.
The metallic particles are rendered highly incandescent, and the earthy materials
or oxides also are rendered luminous by the passage of the electric current.
In some instances the rods or prisms of oxides are saturated with a salt of metal
difficult of fusion, and this salt is reduced to the metallic state by heat, and the
metal permeates the entire body in very minute particles, and these particles are
I

page_text: not liable to be melted and run together in consequence of the intervening oxide or
earthy matter.
This Invention is not limited to any particular form in which the candle may be
moulded or otherwise shaped, but it relates to the materials employed in such
candles, whereby the mass is adapted to the passage of an electric current, and it is
rendered highly luminous or incandescent by such current.
Having now described the nature of the said Invention and in what manner the
same is to be performed, I declare that,--
What is claimed as the Invention of the said Thomas Alva Edison, and to be
secured by Letters Patent is,―
A candle or light giving body for electric lights, in which particles of metal or
metallic oxide are moulded into a mass that is adapted to the passage of the electric
current and rendered luminous by the same, substantially as set forth.
In witness whereof, J, the said Edward Griffith Brewer, have hereunto set
my hand and seal, this Sixth day of May, in the year of our Lord One
thousand eight hundred and seventy-nine.
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