Year: 1886

page_text: 1, WILLIAM MAXWELL, of 34 Claybrook Road, Fulham, in the County of Middlesex,
Engineer, do hereby declare the nature of this invention to be as follows:-
My invention relates to a furnace heated by electricity, arranged in such a manner
that substances can be treated in it under special conditions as to the quality and
pressure of the atmosphere surrounding them, and the amount and character of the
heat imparted to them, while they can be kept under observation during the
treatment.
For this purpose, pass insulated through the base or sides of a closed vessel two
electrical conducting wires or rods which, within the vessel, terminate in holders
clamping a refractory conductor that extends between them. The conducting wires
or rods should be large and the holders should be massive so that they offer little
resistance to an electric current sufficiently powerful to heat the refractory conductor,
when required, to a very high temperature. Also, in order that the quality and
pressure of the atmosphere within the vessel may be varied and maintained different
from that without, the holes for the conducting wires or rods are made with stuffing
boxes, packed with asbestos or the like, and the vessel is provided with an inflow and
an outflow pipe by which various gases or vapours can be caused to pass into or
through the vessel, one or both of these pipes being connected to a pump or other
apparatus by which the pressure of the fluid can be varied. For many purposes,
when the pressure within the vessel is not intended much to exceed that of the atmo-
sphere, the vessel may consist of a glass dome fitted on a metallic base through which
the conducting wires or rods pass. When the vessel is altogether of metal I provide
in suitable places sight holes fitted with glass or tale, through which I can observe
what takes place in the interior. The vessel also may be made with double walls
through which hot fluid may be made to circulate so as to heat to a certain extent the
atmosphere within. When very high temperatures are employed, and especially when

page_text: this is done under a glass dome, I prefer to place within the vessel à hood or screen of
refractory material wholly or partially surrounding the heated conductor at some
distance from it so as not to interfere with the objects undergoing treatment.
The conductor which connects the two holders is of refractory material capable of
being heated to a high temperature by the passage of an electrical current through
it. Generally, carbon in some of its various forms, is most suitable for this purpose.
The objects to be treated are placed on or in or near the heated conductor so as to
be heated by it either by conduction or by radiation or both. Thus, for carbonising
filaments for incandescent electric lamps, the carbon conductor may be made as a case
or mould receiving in it or on it a number of filaments. And in like manner metals
or minerals may be subjected to heat under various conditions, and chemical changes
can be effected in gases or vapours contained in the vessel.
Dated this 23rd day of September 1886
ABEL & IMRAY,
28, Southampton Buildings, London, W.C.,
Agents for the Applicant.

page_text: I, WILLIAM MAXWELL of 34 Claybrook Road, Fulham in the County of Middlesex,
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:
My invention relates to a furnace heated by electricity arranged in such a manner
that substances can be treated in it under special conditions as to the quality and
pressure of the atmosphere surrounding them, and the amount and character of
the heat imparted to them, while they can be kept under observation during the
treatment.
For this purpose, I pass insulated through the base or sides of a closed vessel. two
electrical conducting wires or rods which within the vessel are connected to an inter-
mediate refractory conductor that extends between them. The conducting wires or
rods should be large and the holders of the intermediate conductor or the attachments
thereto should be massive so that they offer little resistance to an electric current
sufficiently powerful to heat the conductor, when required, to a very high temperature.
In order that the quality and pressure of the atmosphere within the vessel may be
varied and maintained different from that without, the holes for the conducting wires
or rods are made with stuffing boxes packed with asbestos or like material and the
vessel is provided with inflow and outflow pipes by which various gases or vapours
can be caused to pass into or through the vessel, one or both of these pipes being
connected to a pump or other apparatus by which the pressure of the fluid can be
varied. For many purposes where the pressure within the vessel is not intended
much to exceed that of the atmosphere, the vessel may consist of a glass dome fitted
on a metallic base through which the conducting wires or rods pass. When the vessel
is altogether of metal I provide in suitable places sight holes fitted with glass or tale
through which I can observe what takes place in the interior. The vessel also may
be made with double walls through which fluid may be made to circulate so as to
regulate the temperature of the atmosphere within. When very high temperatures
are employed, and especially when this is done under a glass dome, I prefer to place
within the vessel a hood or screen of refractory material wholly or partially surrounding
the heated conductor at some distance from it so as not to interfere with the objects
undergoing treatment.
The intermediate conductor is of refractory material capable of being heated to a
high temperature by the passage of an electrical current through it. Generally carbon
in some of its various forms is most suitable for this purpose. The objects to be treated
are placed on or in or near the heated conductor so as to be heated by. it either by
conduction or by radiation or by both. Substances that are to be fused may be
contained in a refractory vessel surrounding the heated conductor, or in the conductor
itself which may be made hollow for their reception. For carbonising filaments for
incandescent electric lamps, the refractory conductor may be made of carbon asia

page_text: case or mould receiving in it or on it a number of filaments. Within the furnace,
metals or minerals may be subjected to heat under various conditions as to pressure
and temperature, and chemical changes may be effected in vacuo or in gases or
vapours contained in the vessel. The form and construction of the furnace may be
varied according to the purpose for which it is intended, as I will explain referring to
the accompanying drawings.
Figure 1 is a vertical section of a simple form of furnace arranged for substances
to he operated on by a heated conductor which they surround. Fig. 14 is a
modification.
Figure 2 is a vertical section of a furnace arranged for substances to be operated on
within a hollow heated conductor.
Figure 3 is a vertical section of a furnace wherein the vessel containing the substances
operated on is mounted on trunnions.
Figure 4 is a vertical section of a furnace cased mostly with glass and adapted more
particularly for carbonising filaments for incandescent electric lamps.
Figure 5 is a part transverse section of the same.
Figure 6 is a plan of the mould for the filaments.
Figure 7 is a vertical section of a similar furnace with metal casing.
Figure 8 is a plan of a mould for the filaments.
In Figure 1A is a metallic vessel lined with refractory material B. A conductor C
passes insulated through a stuffing box packed with asbestos or equivalent material,
and is connected to a bar or tube D of refractory conducting material such as carbon,
which is in electrical connection with the vessel A. On a current of electricity being
transmitted through D, it becomes heated, and its heat acts on material E surrounding
it. H are pipes for admission and emission of air, gas or vapour, and G are sight
holes. In Fig. 14 the casing is made in two parts insulated from each other except
through D. According to the form of furnace shewn in section in Figure 2, two
conductors C and C pass through stuffing boxes in the side of the vessel A and have
attached to them clamps F which grip the ends of a refractory tube D, preferably
with a lining of good conducting metal such as copper interposed between the clamps
and the ends of the tube. A rod P having its end formed as a plug to close a lateral
hole of the tube D passes through a stuffing box; the material to be operated on is
charged into the interior of the tube D through a hole in the top or side of the vessel
A, which may have several sight holes G for observing what takes place in the interior,
and may have pipes H, by which air or other gases or vapors can be made to pass
through the vessel under various degrees of pressure. Fused material can be run out
of the tube D by withdrawing the plug rod P.
In the furnace shewn in Figure 3, within an outer vessel A an inner vessel K with
refractory lining B is mounted on tubes L L' passing through the sides of the
vessel A, so that on turning the tube L by an external hand wheel M the vessel K
can be turned as on trunnions. Through the tube L the conductor C
passes insulated
and its inner end is connected by a number of bent strips N of copper or other good
conducting metal to the top of the refractory conductor D, the lower end of which is
in connection with K and thereby with the vessel A. The tube L' may be fitted with
a piston to push in the material E to be operated on. By turning the vessel K
partly round on its trunnions the fused material E can be poured out into the outer
vessel A.
In the furnace shewn in Figure 4 A is a metallic base having deep stuffing boxes
through which pass the conducting rods CC, a central supply tube H for gas or
vapour and an exhaust tube H¹, the mouth of which opens from the upper part of the
casing which is a bell glass N resting on a packing ring on the base A. The con-
ducting rods CC are attached to clamps F which grip between them the broad ends
of the mould P, preferably with strips of copper or other good conducting metal
interposed. The mould P, Figure 6, has a groove cut in it to receive the filaments
which are covered by a slab of the same material. The mould may be screened by a
metal casing Q supported on a plate R which is bent so as to form two upright sides
supporting the screen, and a base bulging up in the middle and forming a deflector

page_text: for the gas entering by the tube H. In the modified form of furnace shewn in
Figure 7, the conductors C C¹ pass through opposite sides of the box A to heads F
on which the mould P is pressed by weights T. Additional filament moulds S such
as are shewn in plan in Figure 8, may be placed adjacent to the mould P, to be heated
by radiation and conduction from it. When the separate moulds S are used, a slab
of refractory conducting material may be substituted for the mould P. It is generally
advantageous to cover the moulds and their holders by a hood made of asbestos sheet,
so as to lessen the loss of heat by radiation.
Although I have shewn in the drawings furnaces containing only one refractory
conductor, obviously several of those might be arranged within one casing and might
be connected either parallel or in series to a circuit. Although I have shown the
leading conductors as rods, they might obviously be tubes serving for admission and
emission of the gas or other fluid circulating through the furnace. In some cases
the heated conductor, instead of having the material operated on by it in direct
contact with it, may heat by radiation or conduction a tube or screen surrounding or
enclosing it, this tube or screen being in contact with the material operated on.
The electricity employed to heat the conductor may be either a primary current
from a machine or battery, or may be a secondary current from an inductor or trans-
former. Furnaces sucli as I have described may be employed for the production of
fibres or filaments of carbon in the manner described in my Specification No. 11,997
of 1886.
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. An electric furnace consisting of an air tight casing with means of varying
the atmosphere within the casing and having leading conductors connected to a
refractory conductor within the casing, substantially as and for the purposes herein
set forth.
2. An electric furnace consisting of an air tight casing with pipes for inflow and
outflow of gases or vapours and with leading conductors passing insulated through
stuffing boxes to a refractory conductor within the casing, surrounded by or containing
the material operated on, substantially as described.
3. An electric furnace consisting of an air tight casing with pipes for inflow and
outflow of gases or vapours, and with a leading conductor passing insulated through a
stuffing box to one end of a refractory conductor within the casing, the other end of
which conductor is in electrical contact with the casing, substantially as described.
4. An electric furnace consisting of an air tight casing with pipes for inflow and
outflow of gases or vapours, the casing being made in two parts insulated from each
other and connected by a refractory conductor within the casing, substantially as
described.
5. An electric furnace consisting of an outer air tight casing with pipes for inflow
and outflow of gases or vapours, a vessel within the casing mounted on trunnions and
containing the material operated on, and leading conductors passing insulated through
stuffing boxes to a refractory conductor situated within the vessel substantially as
described.
6. An electric furnace consisting of an air tight casing partly of glass, with pipes
for inflow and outflow of gases or vapours and with leading conductors passing
insulated through stuffing boxes to a refractory conductor or mould arranged to have
in it or near it the filaments or other materials operated on substantially as described.
Dated this 16th day of June 1887
ABEL & IMRAY,
Agents for the Applicant.