Improvements in the Manufacture of Incandescent Bodies for Incandescent Gas Lighting.
Year: 1893

page_text: This Print is in accordance with the Original Specification as it stands after Amend-
ment (under Section 18 of the Patents, &c. Act, 1883) as allowed by the
decision of the Chief Examiner of the 29th day of July 1898.
Date of Application, 22nd Nov., 1893-Accepted, 23rd Dec., 1893
COMI LETE DIECIFICATION (AMENDED).
Improvements in the Manufacture of Incandescent Bodies for
Incandescent Gas Lighting.
I, RUDOLF LANGHANS, of 15, Hedemann Strasse, Berlin, Germany, 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:
In order to manufacture incandescent bodies for incandescent gas lighting, it
is usual to utilise fabrics of knitted cotton and other yarn which are impregnated
with saline solutions of suitable earthy metals, and leave, after having been dried
and having had their organic base or foundation consumed, a skeleton of oxides
of the salts used. This skeleton of oxides had the great defect that it had very
little toughness and crumbled to pieces as soon as shaken or touched. This inven-
tion has for its object to remedy such defects, and is entirely successful.
I use for the manufacture of the incandescent body instead of a cotton fabric, a
tissue or plaiting of very fine platinum wires which is covered or coated by
electrolysis with the oxid-hydrates, oxalates or other almost insoluble compounds
of the ordinary metals; this being effected by connecting the platinum tissue with
the negative pole of a source of electricity, and immersing the same in a saline
solution, or a mixture of saline solutions of the suitable earthy metals, until a
sufficiently thick layer of the oxid-hydrates, oxalates or other insoluble com-
pounds, is deposited upon the metallic foundation or base. It is necessary to add
ammoniacal salts to the salts of the earthy metals, as this facilitates and modifies
the separation of the oxid-hydrates occurring as a secondary effect with the
separation of the radical ammonium. Salts of potassium and sodium have given
results which are far from satisfactory on account of the separated oxid-hydrates
of the earthy metals containing inseparable potassic and sodic hydrates.
The platinic plait or tissue being provided with a sufficiently thick covering or
coating of oxid-hydrate, oxalate or other almost insoluble compound of the
earthy metals, is slowly dried and then heated until all the water and acid is
expelled and nothing remains on the platinum wires but the pure oxides, either
alone or in combination. When the metallic tissue or plaiting, prepared in the
manner above set forth, is rendered incandescent, the same can withstand the
effects of shocks or shaking or of rough handling, and can be even altered in shape
without impairing its utility when in use. The incandescence of the tissue thus
prepared appears, on account of the co-action of the layer of oxides and of the
metallic foundation, much less green than before, but on the contrary much more
yellowish white.
Should the emissive power of the incandescent tissue be impaired after long
usage, the oxides used can be dissolved in the electrolytic bath. wherein the tissue

page_text: is used as positive pole, under the action of an electric current, the reversal of
which will cause the renewed deposit of the oxides on the metallic tissue in
utilisable form. According to another mode of manufacture of this metallic tissue
for the purposes of being made incandescent, I use instead of plain metallic wires,
wires around which cotton wool or silk is wound, and which are subsequently
treated electrolytically in the manner above set forth. This is done for the purpose
of obtaining a certain amount of porosity for the layer of oxides, which porosity
is favorable to the effect of incandescence as no homogeneous deposit takes place
where the organic fibres are; while, as soon as the threads are consumed, there
are formed in their places small hollow spaces. It must be further mentioned that
a fabric may be made where the yarn is covered with platinum wound thereon.
The platinum winding is so arranged that the yarn core remains visible; this
platinum fabric being electrolytically covered in the manner above set forth with
the oxid-hydrates, oxalates or other almost insoluble compounds of the earthy
metals.
There remains now to describe a process which consists in making the fabric of
tubular platinum twisted together and enclosing a core of yarn. For this purpose,
fine platinum wire is rolled flat, and is drawn at the same time with a yarn core
through a wire plate, being afterwards twisted around a platinum tube, so as to
form a tube. According to a modification in the manufacture of this thread, I
form beforehand, with the aid of a pair of rollers, the flat rolled platinum wire;
in this case, the yarn core should be visible through the slit of the platinum tube.
The platinum fabric thus manufactured is covered, by electrolysis and in suitable
saline solutions of earthy. metals, with the oxid-hydrates oxalates or other almost
insoluble compounds of earthy metals.
Besides the above described processes, I manufacture fabrics for similar purposes
in the manner hereinafter set forth. A fifth process consists in using a plaiting of
compound wires made either by rolling, drawing or by galvanic means, and the
central wire or core of which is made of metals which fuze with difficulty, such as
nickel, for example, while the outer envelope or sheath consists of platinum, or
of a metal belonging to the platinum group, or of an alloy of gold and platinum.
The treatment of this metallic fabric by electrolysis is similar to that above
described for metal only.
A sixth process consists in making a plaiting of oxidizable metals, such as very
fine aluminium wire for instance, which can be electrolytically covered with the
hydrates, oxalates or other almost insoluble compounds of the earthy metals; this
fabric being subsequently immersed in a concentrated aqueous solution of peroxide
of hydrogen and left therein until the aluminium metal below is converted into
a fixed hydrate of aluminium, which takes place after a lapse of about 3 to 4 days.
The conversion of the aluminium into fixed hydrate of aluminium by means of
peroxide of hydrogen takes place without any deformation or any injurious effect
on the mould while the three times diluted hydrate is formed. The fabric is then
removed from the peroxide of hydrogen bath (H202) and dried, first in the air,
then in the heat and finally in a hot air bath, until incandescence is produced;
thus prepared, the fabric can be used directly as an incandescent body.
Instead of aluminium, I may use rich aluminium alloys.
According to a seventh process, I use non-metallic foundations. In order to pre-
pare fabrics, such as aluminates for instance, in conjunction with carbonized
organic textile fibres, as a good conductor of electricity and in the form of plaits,
I proceed as follows:-A fabric or plait of organic textile fibres, such as cotton
yarn for instance, is first thoroughly freed from grease and then impregnated with
a mixture of concentrated solutions of an aluminium salt, and of a magnesium
salt in the form of sulphate for instance, to which about 10% of boric acid is added
and dissolved. Instead of the sulphate, I may also use a chloride with the addition
of a calcium salt, and the fabric may after having been impregnated with the
aluminate compound, be further saturated with liquor silicum.
The impregnated fabric is dried in the air until it remains a little moist, and is

page_text: then drawn on a mould or mandril made of fireproof material, such as gas graphite
or chamotte being subsequently thoroughly dried and finally heated to a tempera-
ture of 150° C. The mould with the fabric is now placed in a fireproof crucible,
which is filled with graphite dust, and the crucible, being tightly closed, is
gradually heated with its contents to a white heat; this causes on the one hand the
organic foundation to be carbonized while retaining its structure; while on the
other hand, the mineral salts laid therein and thereon are decomposed and leave
the oxides; these oxides are united together into aluminates and form highly
fireproof and fixed bodies; by adding liquor silicum, there are also formed fire-
proof silicates. When the crucible is cold, the mould with the carbonized fabric
is removed therefrom and is cleaned with a brush dipped in adhesive graphite dust.
The carbonized fabric is subsequently covered by electrolysis with the hydrates,
Oxalates or other almost insoluble incandescible metallic earths, the carbon of the
organic foundation being further used for the current.
To increase the electric affinity of the fabric thus produced, the carbonized fabric
may be covered. before receiving its electrolytic coating of earthy metals, with a
very good conductor of electricity, such as a layer of sulphide or phosphide of
silver, by immersing it in an alcoholic solution of nitrate of silver, subsequently
drying it and subjecting it to the action of sulphurretted hydrogen, or of phos-
phuretted hydrogen, gas. The fabric may moreover be rendered a still better con-
ductor of electricity by means of a silver deposit obtained according to the known
silverizing process.
After having been subsequently electrolytically covered with the metallic earths,
the fabric is carefully dried, and gradually and carefully heated in a hot air bath
until incandescence is obtained. Thus treated, the fabric can be successfully used
as a body or material capable of being rendered incandescent.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:-
-
1. Bodies or material capable of producing incandescence for incandescent gas
lighting prepared in such a manner that a fabric of plain platinum wires, or of
yarn on which platinum wire is wound, or of tubular platinum wire containing
a yarn core, is electrolytically coated with one of the oxid-hydrates, oxalates or
other almost insoluble compounds of suitable earthy metals, and is dried and heated
for the purpose of converting the deposit into an oxide, or an oxide compound.
2. Bodies or material capable of producing incandescence for incandescent gas
lighting manufactured in such a manner that a fabric of compound wires pre-
pared by means of rollers. wire plates, or galvanic deposits, in which fabric, the
wire core, or central wire is made of metals, which fuze with difficulty, or of their
alloys, while its outer envelope or sheath is made of platinum, or of a metal belong-
ing to the platinum group, or of alloys, a little gold for instance, this fabric being
electrolytically covered with a deposit of one of the oxid-hydrates, oxalates or
other almost insoluble compounds of suitable earthy metals which deposit is con-
verted into an oxide, or an oxide compound, by drying and heating.
3. Bodies capable of producing incandescence for incandescent gas lighting
made of compound wires upon which yarn is wound, and which are electrolytically
covered with a deposit of an oxid-hydrate, oxalate or other almost insoluble com-
pound of suitable earthy metals converted, by drying and heating, into an oxide
or an oxide compound.
4. Bodies capable of producing incandescence for incandescent gas lighting con-
sisting of wires made of aluminium, or of alloys rich in aluminium which are
electrolytically covered with a deposit of an oxid-hydrate, oxalate or other almost
insoluble compound of suitable earthy metals, which deposit, after the subsequent
conversion, by means of an aqueous solution of peroxide of hydrogen H2O, of the
aluminium or of its alloys into a fixed hydrate, is converted, by drying and heating,
into an oxide or an oxide compound,

page_text: 5. Bodies capable of producing incandescence for incandescent gas lighting which
are made in such a manner that a fabric of organic textile fibres is impregnated
with mixed solutions of aluminium and magnesium salts with the addition of
boric acid, or liquor silicum is dried upon a mandril, and rendered incandescent
during the exclusion of air, the organic fibres being converted into carbon, and the
inlaid salts into an aluminate or silicate framework or skeleton; while the fabrics,
being, on account of their carbonaceous structures, good conductors of electricity,
are electrolytically covered with a deposit of an oxid-hydrate, oxalate or other almost
insoluble compound of suitable earthy metals, which deposit is converted, by drying
and heating, into an oxide or an oxide compound.
Dated this 22nd day of November 1893
H. GARDNER,
Patent Agent, 166, Fleet Street, London,
Agent for the said Rudolf Langhans.