Improvements in Incandescent Electric Lamps.
Year: 1899

page_text: Date of Application, 4th Nov., 1899-Accepted, 30th Dec., 1899
COMPLETE SPECIFICATION.
Improvements in Incandescent Electric Lamps.
--
We, THE BRITISH THOMSON-HOUSTON COMPANY LIMITED, of 83, Cannon Street,
in the City of London, Electrical Engineers, do hereby declare the nature of
our said invention (which has been communicated to us from abroad by :--
Charles P. Steinmetz, residing at Schonectady, in the County of Schenectady,
State of New York, United States of America, Electrical Engineer,) and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement.—
This invention relates to illuminating conductors for electric lamps. Its
object is to provide a conductor whose incandescing surface shall be of pyro-
olectrolytic material, that is, a substance which is a non-conductor at ordinary
temperatures, but becomes a conductor at very high temperatures, and which shall
not require, to raise it to such temperatures that it will become a conductor,
auxiliary starting apparatus which must be rendered inoperative when the pyro-
electrolyte attains conductivity
To this end, the invention consists in ananging in heat-conducting relation
with respect to the pyro-electrolytic substance, an electrical conductor suficiently
efiactory to remain stable under the high temperature obtained, and of such
resistance that when a culent 18 passed there-though, there will be sufficient
heat generated to gradually 1aise the electrolyte to the temperature at which it
becomes a conductor.
Fig. 1 is an elevation of a lamp provided with a conductor made in accordance
with the present invention, and Fig 218 a section through such a conductor A,
as indicated in Fig. 1, and composed of the refiactory conductor B and the prio-
electrolyte C. X is a transparent protective casing, in which the conductor is
sealed in any suitable manner, as indicated at Y Z is a hole in the casing for
the admission of atmospheric aur, but the conductor as made according to this
invention may be used in a vacuum lamp, and in this case the casing is exhausted
and not perforated. Any conductor may be used which is stable at very high
temperature and has sufficient resistance to generate heat to raise the pуio-
electrolyte by connection to the high temperatures at which it attains con-
ductivity. We prefer the carbids which are stable at such temperatures, and
such substances can be readily embodied with the pyro-electrolyte by various
processes
A convenient method is to cover an ordinary carbon filament with the pyio-
electrolyte, and then pass an electric current through the filament 01 heat it
in any other way to cause the deaned chemical reaction, which is a combination
with the carbon of the metal base of the pyro-electrolyte, thus changing the
filament from its unstable condition into a carbid which can endure the high
temperatures: for example, if calcium oxide is the prio-electrolyte, the carbon
filament becomes a calcium carbid core within the enveloping electrolyte
Another method consists in mixing lime with the material from which the
carbon filament is made, then carbonizing the mixture in the usual manner in

page_text: which the carbon filament is treated, and finally causing a chemical combination
of the carbonized mixture by the passage of an electric current, or in any other
suitable manner. This resulting filament is then covered with lime or other
pyro-electrolyte If the chemical reaction 18 to be caused by passing an electric
current through the conductor, this step in the manufacture need not be taken
until the fist use of the lamp, the conductor being made and sealed in the latter
without fist causing the reaction
The invention may be applied in various ways with slight immaterial modifica-
tions, such, for example, as if it were desned to have a more extended luminous
surface than that of a filament, and the conductor were made in varied forms, as
large flat or curved surfaces.
Having now particularly described and ascertained the nature of our said
invention (as communicated to us from abroad) and in what manner the same is
to be performed, we declare that what we claim 18.
1-An illuminating conductor which consists of a refractory conducting sup
poit with a py1o-electrolyte thereon
2-An illuminating conductor which consists of a refractory conducting
support which is the carbid of the metal base of a py1o-electrolyte on said
support
An illuminating conductor for electic lamps, which consists of a refractory
conducting core enveloped by a py1o-electrolyte
-An illuminating conductor for electric lamps, which has an illuminating
sui face consisting of calcium oxid forming an envelope for a core of calcium
carbid.
5 The method of making an illuminating conductor for electric lamps, which
consists in binging into intimate physical relation, a pyro-electrolyte and a
conductor containing a carbon, and then causing the carbon to unite chemically
with the base of the pyro-electrolyte.
-The method of making an illuminating conductor for electric lamps,
which consists in binging into intimate physical relation, a pro-electrolyte and
a conductor containing carbon, and then causing an electic current to flow
through the conductor.
Dated this Fourth day of November. 1899
THE BRITISH THOMSON-HOUSTON CO LTD.
ALFRED CLEMENTS.
Assistant Secretary
A R. MONKS,
Duector