Year: 1885

page_text: I ALEXANDER BERNSTEIN, of N° 9, Commercial Road, Pimlico, in the county of
Middlesex, Electrician do hereby declare the nature of this invention to be as
follows:-
My invention relates to an improved method of manufacturing carbon filaments
for incandescent lamps and has for its object the production of filaments which
will withstand the action of the current much longer than those in use at the
present time.
At present carbon filaments are made by carbonizing an organic substance which
has the form of a fibre, through the effect of heat in a suitable furnace under
absence of air. But the filaments so obtained are not of the required hardness
and durability and it has become customary to improve them by means of a process
called "flashing." This process consists in heating the original filament by the
passage of a current while the filament is immersed in hydro-carbon liquid or
The finished filament may then be considered as consisting of two materials,
one a soft carbon in the inside and the other a very dense and hard carbon on the
outside.
gas.
The defect of this structure consists in the fact, that the whole filament is
destroyed as soon as the soft carbon in the interior is deteriorated by the effect of
the current.
My improved process or method of manufacturing carbon filaments for incan-
descent lamps, consists in making a carbon filament entirely out of hard and dense
carbon which is obtained by the decomposition of a liquid or gaseous carbon com-
pound and without any filament to deposit on. In order to accomplish this I use
a vessel containing a carbon compound which is decomposable by heat and which
compound may be in the form of a liquid or vapour.
On the bottom of the vessel
I place a conductor, say a piece of copper, which is connected with the negative
pole of a suitable current generator. Then I suspend a wire which is connected
with the positive pole of the generator in such a way, that it may be made to
touch the copper and can be gradually and slowly withdrawn from it by suitable
mechanism. As soon as the wire is withdrawn from the copper an arc is formed

page_text: between them and as the greatest beat is at the end of the wire which forms the
positive pole, a deposit of carbon takes place at the end of the wire. The deposit
so formed shortens the arc, but if the wire is withdrawn at the same rate, at which
the deposit is formed, the result will be that a filament is gradually formed at the
end of the wire, which filament consists entirely of a hard and dense carbon.
The filament may be of any length and the thickness of it can be varied by the
varying speed given to the motion of the wire.
Alternating currents can be used instead of continuous ones and in this case a
filament is formed at both poles.

page_text: Lamps.
I ALEXANDER BERNSTEIN, of N° 9° Commercial Road, Pimlico, in the county of
Middlesex, Electrician, 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 :-
.
My invention relates to an improved method of manufacturing carbon filaments
for incandescent lamps and has for its object the production of filaments which will
withstand the action of the current much longer than those in use at the present
time.
Carbon filaments are made at present by carbonizing an organic substance, which
has the form of a fibre, through the effect of heat in a suitable furnace from
which air is excluded. But the filaments so obtained are not of the required hard-
ness and durability and it has become customary to improve them by means of a
process called "flashing." This process consists in heating the original filament by
the passage of a current, while the filament is immersed in a hydro-carbon liquid
or gas.
The finished filament may then be considered as consisting of two materials,
namely a very hard and dense carbon on the outside and a softer carbon on the
inside.
The defect of this structure consists in the fact that the whole filament is
destroyed as soon as the soft interior carbon becomes deteriorated through the
effect of the current.
My improved process or method of manufacturing carbon filaments for incan-
descent lamps consists in making a filament or carbon thread entirely of hard and
dense carbon, which is obtained by the decomposition of a liquid or gaseous carbon
compound without any filament to deposit on.
In order to accomplish this I proceed as follows:-
In the interior of a vessel containing a carbon compound preferably a hydro-
carbon, I place a piece of copper or other conductor which is connected to one pole
of the current generator. Then I suspend a small wire, which may afterwards
serve as one of the leading-in wires of the lamp, in such a way that it can be
made to touch the piece of copper and afterwards gradually be withdrawn from it.
This wire forms the other terminal of the current generator.
The motion of the wire may be produced by hand, by electrical mechanism or by
a mechanical device such as clock work. As soon as the wire is withdrawn from
the piece of copper an arc is formed between them and the end of the wire becomes
intensely hot. Dissociation of the surrounding hydro-carbon now takes place and
a deposit of hard carbon is formed on the end of the wire. The deposit so formed
shortens the arc, but if the wire is withdrawn at the same rate at which the
deposit takes place the result will be that a filament is gradually formed on the end
of the wire which filament consists entirely of hard and dense carbon such as
cannot be obtained by any other process.
The filament may be made of any length or form according to the motion of the
wire and the thickness of it will correspond with the strength of the current and
the speed of motion which is given to the wire.

page_text: Alternating currents can be used instead of continuous ones and in this case a
filament is formed at both poles.
In order to enable the invention to be fully understood I will proceed to describe
the same by reference to the accompanying drawing in which figure 1 shews the
apparatus in which continuous currents are used; figure 2 shews the apparatus for
use with alternating currents.
In both figures A is a frame which carries a guide piece B for a toothed rod C
to the lower end of which a wire D can be attached. This wire forms one electrode;
G, is a metal piece which is insulated from the frame A and serves as the other
electrode; J and K, are terminals to which the conducting wires are attached.
The toothed rod C gears into the pinion E and the latter can be turned by means
of the crank F.
V is a vessel containing a hydro-carbon or other suitable carbon compound. In
figure 2, L, is another toothed rod which also gears with the pinion E and moves
in a direction opposite to the toothed rod C. The piece G is attached to the
toothed rod L, by means of an insulating piece and it carries the wire H.
The operation is as follows:
The toothed rod C, is lowered until the circuit is closed and the wire D, is then
slowly withdrawn. An arc is formed and the formation of the filament takes place
as above described either on the end of the wire D in figure 1, or on the ends of the
wires D and H, in figure 2. The wires or pieces D and H may be of any material
such as metal or carbon.
As the motion produced by hand is hardly steady enough for this purpose it is
advisable to use a mechanical device such as clock-work for operating the toothed
rod C; or an electrical device similar to those used in arc lights may be employed.
In cases where the carbon compound employed is in a gaseous state, the vessel V
must be closed and the rod C, tigure 1 or the rods C and G, figure 2 work through
stuffing boxes.
The filament which is formed in this way may be afterwards increased in thick-
ness by the ordinary process of "flashing."
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. The process of forming a filament for incandescent electric lamps by the
decomposition of carbon compounds by means of the electric are substantially as
herein before described.
2. The formation of a filament for incandescent electric lamps by placing two
electrodes between which an arc is established within a vessel containing a carbon
compound such as a hydro-carbon and moving the said electrodes apart from each
other (or one of the said electrodes apart from the other) at the same rate of
speed as deposition of the carbon takes place on them as herein before described.
3. The manufacture and use of the improved carbons for incandescent lamps
herein before described.