Improvements in Incandescent Electric Lamps.
Year: 1899

page_text: Improvements in Incandescent Electric Lamps.
I, CHARLES LUDWIG RUDOLF ERNEST MENGES, of Balistraat, The Hague, in
the Kingdom of Holland, Electrical Engineer, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particu-
larly described and ascertained in and by the following statement:-
Hitherto incandescent filaments for electric lamps have generally been com-
posed of materials having metallic conductivity; at first metal filaments, and
subsequently carbon filaments being used. More recently, however, such fila-
ments have been made of a material not having metallic conductivity, that is
to say of insulating material; such material consisting more especially of the
oxides of earths and being employed, either as a coating round a conductive core,
or after being heated to a high temperature so as to render them conductive.
This invention relates to filaments or conductors for incandescent electric
lamps, composed of an intimate mixture of a substance having metallic con-
ductivity with a substance not having metallic conductivity. The conductive
substance may be a metal or carbon or a carbide or the like having suitable
conductivity. The non-conductive substance or insulator may be an oxide of
an alkaline earth or an earthy oxide, or nitrure of boron (boron-nitrogen) or
like substance capable of sustaining very high temperatures; and is hereinafter
referred to as the oxide."
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The mixing of the conductive substance and the "oxide" may be effected by
mechanical means but as the mixture must be exceedingly intimate it is gener-
ally preferable to make use of physical or chemical agency; for example, by
employing liquid compositions (in solution or in a molten condition) which are
mixed and from which the incandescence substance which will be used to form
the filament is obtained by precipitation, calcination, or otherwise. Or one of
the said substances, that is to say either the conductive substance or "the oxide,"
may be used in the form of powder and mixed with the other of the substances
while the latter is in a liquid condition, to produce a paste which is then formed
into a filament by pressing it into moulds or through a draw-plate. If for
example "the oxide" is employed together with a solution of a salt of iridium,
a simple calcination will be sufficient to obtain the metal in the mixture.
Another method is to add to the mixture a third substance such as carbon,
which acts as a reducing agent.

page_text: In the employment of carbon in the reduction action the said carbon must be
in a finely divided condition and may conveniently be obtained by the use of a
liquid composition (tar or syrup of sugar), which is added to the substances
and calcined in the absence of air. If the temperature is sufficiently raised
during this calcining for the carbon to become an electric conductor, an electric
current can be used to finish the reaction, whereby the metal or the metallic
carbide is obtained in the mixture.
In this manner, according to my invention, filaments or conductors may be
produced which are composed of an intimate mixture of an "oxide
with a
substance having metallic conductivity, such for example, as titanium, vanadium,
uranium, or with the carbides of these metals, or with a mixture of the metal
and its carbide.
The process is as follows;
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"The oxide" is mixed with the solution of, say, a titanium compound.
According to the oxide" employed either titanic oxide (titanic acid) is immedi-
ately obtained in the mixture; or it is precipitated therein by any of the well
known means. Of this mixture a paste is made with syrup of sugar or tar and
carbon in a finely divided condition. This paste is then formed into filaments
of the shape required for the conductors, by pressing it into moulds or through
a draw plate. These filaments or pieces are then gradually heated in the absence
of air to a sufficiently high temperature to make the carbon therein an electric
conductor, and then mounted upon the platinum wires of an electric circuit and
heated by an electric current in vacuo or in a suitable gas until reduction of the
titanic acid to metallic titanium or to titanium carbide, takes place.
In the foregoing examples the "oxide" is supposed to be present from the
beginning of the operation. This however is not necessary. The titanic acid
for instance, may be employed with a solution of a salt (nitrate of magnesium
for example) which, by calcination, produces the desired oxide."
Suitable mixtures may also be obtained by employing gelatinous precipitates
such as hydroxides.
$5
The composition of the conductor formed as aforesaid may be altered either
throughout the entire incandescent body or locally for instance, near the point
of its connection with the platinum wires, by soaking the said conductor in a
liquid compound which contains one of the substances of the mixture, which
substance is then precipitated by heat or other suitable means.
It is obvious that, if in order to obtain a certain reaction, an ingredient has
to be introduced which must not exist in the final product, such ingredient is
to be eliminated by lixiviation or otherwise, unless it is certain that the same
will be eliminated by volatilization or decomposition during the subsequent
treatment.
The incandescent body may also be composed of a mixture of more than two
substances, that is to say not only one "oxide" and one conductive substance,
but several of either or both.
The production of light by these filaments, is possibly due only to the high
temperature sustained by the substances specified and produced by the electric
current having to pass the high resistance offered by the various substances of
the mixture. However it is thought that possibly the discontinuity of the in-
candescent body, either directly or indirectly, through the effect of successive
decomposition and recomposition, produces a discontinuity in its electric con-
ditions in such a manner as to furnish, at least partially, a direct transformation
of the electric energy into light.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is-
1. The manufacture of incandescent conductors composed of an intimate mix-
tura of motola or metallin oonbides with "vidos" by mixing taontbon hamil

page_text: compound of the metal, carbon and "the oxide," forming such mixture into the
shape of the incandescent conductor, baking it till the carbon becomes electric-
ally conductive, and then heating it by an electric current till the metal or the
metallic carbide is reduced from the compound.
2. An incandescent conductor for an electric lamp containing an intimate
mixture of metallic titanium, or titanium carbide, or metallic vanadium, or
vanadium carbide, or metallic uranium, or uranium carbide, with "the oxides."
1900
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.
ced this word day
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.