Electro-thermal Conductors, Plates, Tubes, and the like.
Year: 1893

page_text: Date of Application, 21st Jan., 1893
Complete Specification Left, 30th Sept., 1893-Accepted, 2nd Dec., 1893
PROVISIONAL SPECIFICATION.
Electro-thermal Conductors, Plates, Tubes, and the like.
I, Sir CHARLES STEWART FORBES, Baronet, 28, Queen's Gate Terrace,
London, S. W. East India Agent, do hereby declare the nature of this invention
to be as follows:-
My invention consists in the use and employment of absorbent minerals of a
refractory nature capable of resisting heat, such as lime clay, china clay, unbaked
porcelain, asbestos, magnesia silicate, or oxide, and the like series in the form of
plates, grids, tubes or other suitable shape for my purpose, which are saturated
with carbon derived from the volatilization of coal gas, benzole, turpentine,
camphor or the like. I have found that if such porous substances be heated and
immersed out of contact with air in gases, fluids or solids capable of depositing
carbon by volatilization, that after drying they become electrical conductors of
high resistance but varying in a measure depending upon the degree of saturation ;
and that when suitably mounted and a current of sufficient volume and pressure is
passed through them, they will radiate heat sufficiently to enable boiling, heating,
warming or like thermal effects to be produced. Plates for instance constructed in
this manner can be raised in a few seconds to a dull red heat which is retained for a
considerable time by the refractory material after the current has ceased. Tubes
and grids also presenting considerable surface may when heated by the passage of
a current be used for warming or drying air circulated through them-the high
resistance of the material necessitating a comparatively small current.
Dated January 21st 1893.
FRANCIS M. ROGERS,
A gent...
COMPLETE SPECIFICATION.
Electro-thermal Conductors, Plates, Tubes, and the like.
1 Sir CHARLES STEWART FORBES Baronet 28 Queen's Gate Terrace
London, S. W. East India Agent, 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 consists in the use and employment of absorbent minerals of a
refractory nature, capable of resisting heat, such as lime, clay, china clay, unbaked
porcelain, asbestos, magnesia silicate or oxide, and the like series, in the form of
plates, grids, tubes, or other suitable shape for my purpose, which are saturated
with carbon, derived from the volatilization of coal gas, benzole, turpentine,
camphor or the like. I have found that if such porous substances be heated and
immersed out of contact with air, in gases fluids or solids, capable of depositing
carbon by volatilization, that after drying, they become electrical conductors of
high resistance, but varying in a measure depending upon the degree of saturation,
and that when suitably mounted, and a current of sufficient volume and pressure is
passed through them, they will radiate heat sufficiently to enable boiling, heating
warming, or like thermal effects to be produced. Plates, for instance constructed
in this manner can be raised in a few seconds to a dull red heat, which is retained
for a considerable time by the refractory material after the current has ceased.
Tubes and grids, also presenting considerable surface, may, when heated by the
passage of a current, be used for warming or drying air circulated through them,
the high resistance of the material necessitating a comparatively small current..
7

page_text: The construction and operation of my invention will be readily understood from
the following description, and by reference to the drawing in which :-
Fig. 1. shews in plan and end view, an ordinary straight electro-thermal
conductor.
Fig. 2. shews a grid in plan and side elevation.
Fig. 3. a tube in plan and sectional elevation.
Fig. 4. is a section on line A. B. Fig. 5, and shews the grid, (shewn in Fig. 2)
mounted and connected to the main supplying the current.
up
Fig. 5. is a plan of the apparatus shewn in elevation by Fig. 4.
Fig. 6. shews an arrangement for electrically connecting up rings, which may be
used for warming air, or for other purposes.
Fig. 7. is a sectional elevation shewing an electro-thermal tube mounted upon a
base.
Lime, clay, china clay, unbaked porcelain, asbestos, magnesia silicate, or oxide,
and the like series of refractory substances, or mixtures of them, are kneaded
together with plain water, treacle, coal tar, varnish, or other suitable binding
material, pressed in a mould to the required shape, and dried either in the air, or
by firing in a kiln or oven until all moisture is driven off, and the required degree
of porosity obtained. These plates, grids or tubes, formed as described, are now
heated strongly and plunged into benzole, turpentine, paraffin or equivalent; or
liquid or solid hydro-carbon may be placed in a closed iron or other suitable
vessel, which can be heated strongly by a spirit lamp, the Bunsen flame, or by a
suitable furnace.
Into this vessel, coal gas, or the vapour of any hydrocarbon is passed or is given
off by the action of heat.
Materials thus treated will absorb the carbon vapour to a greater or less
degree.
After removal from the liquid or carbonizing vessel, the plates are dried by
placing them, covered preferably with plumbago dust, in an ordinary crucible,
and firing them until the volatile carbon, with which the mixture is permeated, is
reduced.
Upon cooling, the plates, tubes or grids present a shining black appearance, are
very brittle, and of exceedingly high electrical resistance, so that a comparatively
small amount of current is required to heat them up.
The length of the plates, grids or tubes will vary in a manner depending upon
the requirements of each case, but I prefer to mount the plates and grids in the
manner shewn in Figs. 4, 5, wherein a, is a porcelain, fireclay or other base; b, is
a recess formed therein; c, c, are copper washers; d, is the grid or plate; e, a plain
or flanged plate of mica, fire clay, or other refractory insulating substance, f, the
cramp screws, which serve the double purpose of holding the grid or plate in
position, and connecting it with the leads g, g, conveying the current. The
tubes, or strips cut from them, may be conveniently fastened by metallic
holders, such as I have shewn in Fig. 7, which forms a convenient stand for
boiling purposes, and is constructed as follows:-a, is the porcelain or fire clay
base, cramp screws and holders, which also serve as terminals for electrically
connecting with the main; the ring or tube is preferably slit as at h.
Into the fire clay, porcelain or other base a, carefully insulated from the electro-
thermal tube, is inserted a metallic ring i, upon which the vessel is placed. The
object of slitting the electro-thermal tube is to compel the current to traverse its
entire length. To ensure good metallic contact between the forked holders and
cramp screws f¹, and the tube, the joint may be luted with coal tar and
plumbago.
Fig. 6, shews three electro-thermal tubes d', coupled in series and mounted in a
fire-clay or other base a, perforated as at k, for admitting air. Any number of
such tubes, may be thus connected up for warming the air passing through them.
It will be readily understood that the conductivity of plates, grids, tubes, or
other forms of absorbent and refractory minerals, can be varied by regulating the

page_text: duration of the carbonizing process. By short treatment, plates or tubes can be
produced, which are almost insulators when currents of very high voltage are
employed..
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed; I declare that what I
claim is :-
1. The use and employment for electrical heating, boiling, or like purposes, of
refractory and absorbent earths, minerals, and the like, treated with gaseous liquid;
or solid hydrocarbons, baked, mounted, and connected up in the way and manner
described.
2. In electro-thermal conductors, formed by saturating to a greater or less degree,
absorbent and refractory substances, with gaseous liquid or other hydrocarbon, the
particular form of strip and grid, shewn in Figs. 1, 2.
3. In electro-thermal conductors, formed as described, in Claim 2, the use and
employment of a plain or split tube, or tubes, mounted upon a base of refractory
material and electrically connected, substantially as shewn in Figs. 6, 7.
4. The combination in or with a strip or grid, formed and treated with hydro-.
carbon, as described, of the insulating base a, the binding screws f, for securing
and electrically connecting the plates or grids with the mains, and the insulating
guard e, substantially as shewn and described under Figs. 4, 5.
Dated September 30th 1893.
FRANCIS M. ROGERS.
Agent.