Improvements in Incandescence Bodies for Electric Glow Lamps.
Year: 1890

page_text: Date of Application, 10th July, 1890
Complete Specification Left, 3rd Apr., 1891-Accepted, 9th May, 1891
DRAWIN
[Communicated from abroad by the firm of SIEMENS AND HALSKE, of 94, Mark-
grafen Strasse, Berlin, in the Empire of Germany, Electrical Engineers.]
Improvements in Incandescence Bodies for Electric Glow Lamps.
We, SIEMENS BROS. & Co. LIMITED of No. 12 Queen Annes Gate, West-
minster in the County of Middlesex, do hereby declare the nature of this invention
to be as follows:-
:-
This invention relates to improvements in the production of incandescence bodies
for electric glow lamps whereby the filaments (especially carbon filaments) are
coated with a solid covering of a material that will not melt at the temperature of
incandescence and that will prevent the carbon filament from disintegration. The
materials which are more particularly suited for this purpose are silicon-nitride,
and boron-nitride, which bodies are stable at the highest temperatures, do not lose
any nitrogen and do not take up oxygen, so that an incandescence body coated
therewith can, under certain circumstances, also be made to operate in the presence
of air.
The process for the preparation of these compounds may consist of any of those
known in chemistry; preferably, the carbon filaments are heated to incandescence in.
an atmosphere of volatile or vaporisable inorganic or organic silicon or boron com-
pounds and aminonia, or of volatile nitrogen compounds free from oxygen. The
carbon filaments can also be saturated with easily reducible compounds poor in
oxygen,and double salts (haloid ammonia double salts) and be then gradually raised
to incandescence in the presence of aminonia or of volatile nitrogen compounds.
The preparation of the said compounds can however also be effected by heating
the carbon filaments to incandescence in an atmosphere of the required volatile.
metalloids, such as chlorides bromides, iodides, oxychlorides, or hydrochloric com-
pounds, in the presence of hydrogen, whereby the metalloids are deposited, after
which they are made to combine at a white heat with nitrogen.
Dated this 10th day of July 1890
ABEL & IMRAY,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Incandescence Bodies for Electric Glow Lamps.
We, SIEMENS BROS. & Co. LIMITED of No. 12 Queen Annes Gate, West-
minster in the County of Middlesex 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 relates to improvements in the production of incandescence bodies
for electric glow lamps whereby the filaments (especially carbon filaments) are
coated with a solid covering of a material that will not melt at a temperature of
incandescence and that will prevent the carbon filament from disintegration. The
materials which are more particularly suited for this purpose are silicon-nitride, and
boron-nitride, which bodies are stable at the highest temperatures, do not lose any
nitrogen and do not take up oxygen, so that an incandescence body coated there-
with can, under certain circumstances, also be made to operate in the presence
of air.
The process for the preparation of these compounds may consist of any of those
known in chemistry, preferably; the carbon filaments are heated to incandescence

page_text: in an atmosphere of volatile or vaporisable inorganic or organic silicon or boron
compounds and ainmonia, or of volatile nitrogen compounds free from oxygen.
The carbon filaments can also be saturated with easily reducible silicon or boron
compounds poor in oxygen, and double salts (haloid ammonia double salts) and be
then gradually raised to incandescence in the presence of ammonia or of volatile
nitrogen compounds.
The preparation of the said compounds can however also be effected by heating
the carbon filaments to incandescence in an atmosphere of the required volatile
metalloids, such as chlorides, bronides, iodides, oxychlorides, or. hydrochloric com-
pounds, in the presence of hydrogen, whereby the metalloids are deposited, after
which they are made to combine at a white heat with nitrogen.
Having thus described the nature of this invention and in what manner the same
is to be performed, we claim.
1. An incandescence body for electric glow lamps consisting of a carbon or other
suitable filament coated with a refractory layer of silicon-nitride or boron nitride
produced by heating the filament in an atmosphere consisting of volatile silicon or
boron compounds and of a gaseous nitrogen compound, free from oxygen such as
ammonia or by first soaking the filament in a solution of silicon or boron compounds
and then heating the same to a high degree in a reducing atmosphere "containing
nitrogen, substantially as described.
2. An incandescence body for electric glow lamps consisting of a carbon or other
suitable filament coated with a refractory layer of silicon-nitride or boron nitride
produced by first heating the filament to incandescence in an atinosphere of volatile
silicon or boron compounds for effecting a deposit of these substances, and then
heating them to a high degree in an atmosphere of gaseous nitrogen compounds
poor in oxygen, in order to produce the said nitrogen compounds.
1100
ABEL & IMRAY,
Agents for the Applicants.