Electrical Resistances and Heating Bodies composed of Metallic Oxides.
Year: 1899

page_text: Date of Application, 8th Aug., 1899-Accepted, 11th Nov., 1899
[Communicated from abroad by ALLGEMEINE ELEKTRICITATS GESELLSCHAFT, of 22,
Schiffbauerdamm, Berlin, Germany.]
Electrical Resistances and Heating Bodies composed of Metallic
Oxides.
I, VICTOR ISIDORE FEENY, of 60, Queen Victoria Street, in the City and County
of London, Consulting Engineer and Chartered Patent Agent, do hereby declare
the nature of this invention and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement:-
The resistances and heating bodies employed in electro-technical matters are
composed generally of metals or their alloys and in consequence of their relatively
low melting temperature are not heated much beyond red-heat. For certain
purposes, such, for example, as the exciting of the illuminating bodies of "Nernst "
lamps, heating bodies are requisite, capable of supporting as high a temperature
as possible, in order, on the one hand, to effect a quick preliminary heating of
the Nernst" body and, on the other, in consequence of the relatively high
temperature necessary to obtain a certain emission of light during the period
of excitation.
$6
Experiments made with this object have led to the discovery that certain
metallic oxides, especially those of the heavy metals after undergoing suitable
preparation, but without the addition of metallic conductors, will act as relatively
good conductors even at the ordinary temperature, so that with a sufficient supply
of current, they become white-hot, in consequence of their extraordinarily high
evaporating temperature, in which condition they also emit light.
Such metal oxides are for example, oxide of iron, oxide of copper, oxide of
chromium, oxide of uranium, oxide of manganese, oxide of nickel, oxide of cobalt,
oxide of titanium, oxide of zinc, oxide of tungsten, oxide of molybdenum, etc. If
a plastic substance be formed of the pulverised oxides or of a mixture of the
same, with the assistance of a binding medium such as water, or a solution of
gum, etc., and small sticks or tubes be made thereof, such bodies act precisely
like non-conductors of electricity; on the other hand, they will act as fairly
good conductors even at an ordinary temperature, if subjected to an incandescence
process, whereby they contract or draw together" very much. That is to say,
these bodies are contracted to a compact mass under the action of fire or heat.
It is desirable beforehand to add to the plastic substance some material that will
strongly "draw-together" such as porcelain earth, magnesia, etc. In the case
of porcelain, for instance, this contraction, shrinking or drawing together"
occurs in such a decided manner that the specific weight of that substance is
greater after than before, and powerful tension prevails between the various
particles of the material. Small sticks or tubes of this kind strongly contracted
or drawn together" are then furnished at their ends with current-conductors
of metals not readily fusible, such as platinum or nickel. In this form, they
can be used as resistances as well as light-emitting heating bodies, but in the
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page_text: latter case require a reducer or rheostat as, at a high temperature, they have a
negative temperature coefficient.
Having now particularly described and ascertained the nature of my said
invention, and. in what manner the same is to be performed, I declare that what
I claim is:-
(1). Electrical resistances and heating bodies consisting of materials strongly
contracted by an incandescence process, and in any preferred form, being metal
oxides such as oxide of iron, oxide of manganese, oxide of nickel, oxide of cobalt,
oxide of chromium, oxide of zinc, oxide of titanium, and allied oxides, or mixtures
of the same, substantially as described.
(2). In the resistances and heating bodies indicated in Claim 1, an addition
of strongly contracting or "drawing-together" material such as porcelain earth;
magnesia, etc., for the purpose of augmenting the contracting effect or area,
as described.
(3). In heating bodies according to Claim 1, the arrangement of a reducer or
rheostat for the purpose of counterbalancing or compensating the negative
temperature-coefficient of the heating body, substantially as described.
WASED
For the Applicant,
GEDGE & FEENY,
Chartered Patent Agents, 60, Queen Victoria Street, London, E.C.