Improvements in the Manufacture of Filaments or Incandescing Media for Electric Lamps.
Year: 1894

page_text: Date of Application, 2nd Aug.. 1894
Complete Specification Left, 30:h Apr., 1895-Accepted, 2nd Sept., 1895
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Filaments or Incandescing
Media for Electric Lamps.
I, RUDOLF LANGHANS, of 12 B, Elisabeth Strasse, Berlin, in the Empire of
Germany, Electrical Engineer, do hereby declare the nature of this invention to
be as follows:-
:-
This invention has for its object to produce improved filaments, or incandescing
media, for use in electric lamps, the said filaments, or incandescing media, consisting
of carbon and silicon, or of carbon aud boron, or of carbon, silicon, and boron,
they being in each instance chemically combined, and being produced in the manner
hereinafter described. I take a carbo-hydrate which, on treatment with a suitable
solvent, will form a plastic mass, such for example as sugar (CHO) or a
vegetable gum (CHO) or a cellulose (CHO) and I dissolve it, or form it into
a plastic mass, by means of a solvent such as water, an acid, or an alkali, or a
metallic salt, according to the nature of the carbo-hydrate selected and I intimately
mix therewith finely powdered pure silicon, or boron, or both silicon, and boron, so
as to form a homogeneous mass. The boron, or silicon, may be in a crystalline
amorphous, or graphitic condition.
The proportion of silicon, or boron, or of silicon and boron, to the solution of
the carbo-hydrate is determined approximately by the atomic weights of the silicon,
or boron, or both, and the carbo-hydrate selected, for instance for a carbo-hydrate
represented by the formula CHO, I add to each 11 grammes of carbo-hydrate,
gramme of
pure powdered silicon, or the equivalent of boron, or of both
together. An exact approximation to the combining atomic weights of the
constituents is not necessary. The mixing should be so complete as to ensure that
the particles of the metal, or metals, are in intimate contact with the particles of
the carbo-hydrate.
The mass thus produced is shaped, by any suitable means, into the desired
thread-like form, or filaments, which may be effected in any suitable way, for
example, by squirting or pressing the mass through an aperture (of the size of the
filaments to be produced), into a liquid of the alcoholic group, such as alcohol, or
glycerine, and then passing the produced filaments into, and through, water to
further free them from acid. The alcoholic liquid aud the water may be in the
same vessel as their different specific gravities will keep them separate. Or I may
spread the mass upon a table, or slab, so as to form a sheet and coagulate it with a
liquid of the alcoholic group, and wash it with water, and then cut the said sheet
into the desired filaments.
The filaments thus formed are then dried until all the absorbed water is
evaporated therefrom, and then the said filaments are gradually heated whilst
atmospheric air is excluded, the temperature, and the time of heating, being such
that a chemical combination between the carbon and the silicon, or boron, or both
silicon and boron takes place and a carbide of silicon, or a carbide of boron, or
a carbide of both silicon and boron is produced. A temperature of about
2000 degrees Celsius is usually sufficient.
To attain this result it is necessary that the access to the filament of not only
oxygen but also of nitrogen during the process of heating shall be prevented.
In the process of carbonizing in making carbon filaments it only necessary to
exclude oxygen and the filaments have therefore being packed during carbonization

page_text: in graphite, or powdered carbon, which excludes cxygen but through which nitrogen
passes. The presence of nitrogen has no injurious effect upon carbon filaments,
but, as it does injuriously affect a mechanical mixture of the character to which
this invention relates, owing to the affinity for nitrogen of the metal, or metals,
employed, it becomes necessary to employ in the packing, a material which, at the
temperature of carbonization, has a greater affinity for nitrogen than has the
metal, (or mixture of metals), employed in making the combination according to
this invention, and which is moreover inert as regards the said metal, or metals.
I have found that if rutile (titanic acid) be employed in the packing the desired
result is obtained the access of nitrogen to the filaments being prevented thereby.
I prefer to surround the filaments with finely powdered rutile, and then to surround
this again with a mixture of powdered carbon, or of powdered carbon and rutile.
If desired, after the filaments have been treated as described, they may be
flashed," or incandesced, by an electric current, whilst surrounded by a vapour
of silicon, boron, or carbon, or vapours of any two, or all, of these to the exclusion
of oxygen and nitrogen.
66
Dated this 2nd day of August 1894.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Filaments or Incandescing
Media for Electric Lamps.
I, RUDOLF LANGHANS, of 12 B, Elizabeth Strasse, Berlin, in the Empire of
Germany, Electrical Engineer, 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:-
This invention has for its object the production of improved filaments, or incan-
descing media, for use in electric lamps, the said filan:ents, or incandescing media,
consisting of carbon and silicon, or of carbon and boron, or of carbon, silicon and
boron; they being in each instance chemically combined, and being produced in
the manner hereinafter described.
In carrying out my invention, I take a carbohydrate, such for example as
sugar (CHO) or a vegetable gum or cellulose (CHO) which, on treatment
with a suitable solvent, will form a plastic mass, and I dissolve it, or form it into a
plastic mass, by means of a solvent, such as water, an acid, an alkali or a metallic
salt, according to the nature of the carbohydrate selected; and I intimately mix
therewith finely powdered pure silicon, or boron, or both silicon and boron, so as to
form a homogeneous mass. The boron or silicon may be in a crystalline, amorphous
or graphitic condition.
The proportion of silicon or boron, or of silicou and boron, to the solution of
the carbo-hydrate is determined approximately by the atomic weights of the silicon
or boron, or both, and the carbo-hydrate selected. For instance, for a carbo-
hydrate represented by the formula C¿HO, I add to each 11 grammes of carbo-
hydrate gramme of pure powdered silicon, or the equivalent of boron, or of
both together. An exact approximation to the combining atomic weights of the
coustituents is not necessary. The mixing should be so complete as to insure the
particles of the metal or metals being in intimate contact with the particles of
the carbo-hydrate.
The mass thus produced is shaped, into the desired filamentous or thread-like
form in any suitable manner, as for example, by squirting or pressing the mass
through an aperture (of the size of the filaments to be produced), into a liquid of
the alcoholic group, such as alcohol or glycerine, and then passing the resulting

page_text: filament into and through water, to further free it from acid.
The alcoholic liquid
and the water may be contained in the same vessel, as their different specific
gravities will keep them separate. Or I may spread the mass upon a table or
slab, so as to form a sheet, and coagulate it with a liquid of the alcoholic group.
wash it with water, and then cut the sheet into strips or filaments.
The filaments thus formed are then dried until all the absorbed water is evaporated
therefrom. They are then gradually heated whilst atmospheric air is excluded,
the temperature and the duration of the beating being such that a chemical com-
bination between the carbon and the silicon or boron, between the carbon and the
silicon and boron takes place, a carbide of silicon, or a carbide of boron, or a
carbide of silicon and boron resulting. A temperature of about 2,000 degrees
Celsius is usually sufficient.
To attain the desired result, it is necessary to prevent the access not only of
oxygen, but also of nitrogen to the filament, during the process of heating.
In making carbon filaments, it is only necessary during the process of carbonizing
to exclude oxygen. The filaments have accordingly been packed during carboniza-
tion in graphite or powdered carbon, which excludes oxygen, but through which
nitrogen passes. The presence of nitrogen has no injurious effect upon carbon
filaments, but, as it does injuriously affect a mechanical mixture of the character to
which this invention relates, owing to the affinity for nitrogen of the metal or
metals employed, it becomes necessary to employ in the packing a material which,
at the temperature of carbonization, has a greater affinity for nitrogen than
pertains to the metal or mixture of metals employed in making the combination
according to this invention, and which is, moreover, inert as regards the said metal
or metals. I have found that by employing rutile (titanic acid) in the packing,
the desired result is obtained; the access of nitrogen to the filaments being thereby
prevented. I prefer to surround the filaments with finely powdered rutile, and
then to surround this again with a mixture of powdered carbon, or of powdered
carbon and rutile.
After the filaments have been treated as described, they may, if desired, be
" Hashed "
or incandesced by an electric current whilst surrounded by a vapour of
silicon, boron or carbon, or vapours of any two or all of these, to the exclusion of
oxygen and nitrogen.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I claim :-
1. The manufacture of filaments or incandescing media for electric lamps by
mixing a solution of a carbo-hydrate with finely divided silicon or boron, or with
silicon and boron, forming filaments therefrom, and then subjecting the filaments
thus formed to a temperature such as described; the filaments being embedded in,
or surrounded by, material which prevents the access of both oxygen and nitrogen
to the said filaments.
2. The use, in the manufacture of filaments for incandescent lamps, of rutile as
packing during the process of baking in order to protect the filaments from access
of nitrogen.
3. The use, in the manufacture of filaments for incandescent lamps, of both
rutile and powdered carbon, either separately or mixed together, as packing during
the process of baking.
4. As a new article of manufacture, a filament or incandescing medium for
electric lamps, such as is produced by the means hereinbefore described.
Dated the 19th day of April 1895.
For the Applicant,
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Chartered Patent Agent.