Improvements in Apparatus for Heating Purposes and Cooking by Means of Electricity.
Year: 1892

page_text: Date of Application, 23rd July, 1892
Complete Specification Left, 22nd Apr., 1893-Accepted, 2nd June, 1893
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Heating Purposes and Cooking by
Means of Electricity.
I, GUSTAV BINSWANGER of No. 71 Queen Victoria Street, in the City and
County of London, Electrical Engineer do hereby declare the nature of this inven-
tion to be as follows:
My invention relates to certain improvements in electrical heating and cooking
apparatus in which the heat, is developed by the passage of an electric curren
through a conductor of suitable resistance, and is utilized by the radiation
therefrom. The chief object of my maid invention is to provide an insulating and
refractory material to cover and partly or wholly surround the conductor or the
articles or vessels to be heated or to radiate or diffuse heat.
The substance or material I find best suited for this purpose, and whose co-efficient
of expansion nearly approximates to that of an ordinary metallic conductor of high
resistance, and further, possesses sufficient elasticity to allow for expansion and
contraction without fracture, is a solution of an alkaline silicate, such as soda, or
potash, in a silicate solution for example, into which is incorporated finely divided
asbestos or like insulating and refractory substance or material. The consistency
of the mixture of asbestos or the like with the alkaline silicate solution is that of a
stiff paste which may be readily moulded or shaped.
I inay mix with the alkaline silicate solution in lieu of the asbestos before
mentioned, clay, fossil meal, lime, magnesia, silica, alumina, or other similar
refractory and insulating substances, and I may use any two or more of these in
combination with each other. Such mixture may be prepared so as to have the
consistency of paint, and the surfaces subjected to the action of heat and to the
current of electricity generating said heat may be coated therewith to serve
the double purpose of an insulator and radiator. Successive coats of said paint may
thus be applied to the surfaces requiring it, each coat being allowed to dry or set
before the next is laid on. And in order to obtain a sufficient length of conductor,
and the corresponding resistance thereof in order to utilize the heating effect of
the current, I may alternate said layers of paint or paste of insulating material as
before described with layers of conducting material suitably disposed relatively to
the heating surface required.
As the insulating compound or compounds hereinbefore set forth are not
impervious to moisture, I prefer to employ a cap or cover of earthenware metal,
porcelain glass or similar material that is adapted to resist moisture and withstand
the heat generated by the electric current.
I wish it to be understood that I do not confine myself to any particular con-
formation of the conductor or conductors, nor to the manner of arranging it or them
relatively to the part or parts of the apparatus contiguous thereto, the essential
feature of my said invention being the employment of a refractory insulating paint
or paste to a conductor or series of conductors so that a large heating surface may
be obtained within a comparatively small area, and may be effectively used as a
heating or cooking medium without deterioration by failure of insulation or ordinary
external phenomena.
Dated this 22nd day of July 1892.
FREDK. WALKER,
11, Furnival Street, Holborn, London, E.C., Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatus for Heating Purposes and Cooking by
Means of Electricity.
I, GUSTAV BINSWANGER of No. 71 Queen Victoria Street, in the City and
County of London Electrical 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 certain improvements in electrical heating and cooking
apparatus in which the heat is developed by the passage of an electric current
through a conductor of suitable resistance, and is utilized by the radiation
therefrom. The chief object of my said invention is to provide an insulating and
refractory material to cover, and surround the conductor, or the like with such
substance or material consisting of a paste or cement, which is preferably laid on
in a plastic state, and becomes hardened and firmly attached to the conductor by
drying in a moderately heated atmosphere, without being baked, or subject to
disintegration by any subsequent heating.
In order that my invention may be clearly understood, I have appended the
accompanying sheet of drawings, in which
Figure 1 shews a conductor between two surfaces, and Figure several layers
of conductor, the insulating and refractory compound being interposed in both
cases.
Figure 3 is similarly a partly sectional view of a conductor surrounding a hollow
vessel or cylinder.
Figure 4 shews a conductor surrounding a rod or cylinder, and
Figure 5 is a partly sectional view of a case or box within which is enclosed the
conductors and the insulating and refractory material.
In carrying my invention into effect I employ suitable metallic conductors (a in
the drawings) preferably of high resistance such as platinum, German silver, iron,
or any metallic alloy possessing the requisite degree of resistance, and arrange such
conductor in coils, layers, convolutions or other suitable conformation applicable to
the especial purpose for which it is intended. I prepare a paste or cement of
refractory and electrically insulating material the co-efficient of expansion of which
is as nearly as possible equal to that of the conductor used. This paste or cement
consists of silicate of soda or potash in solution mixed with alumina, lime, clay
asbestos or other heat resisting substance or any two or more of them in combination
with the alkaline solution aforesaid. Finely divided asbestos mixed with a solution
of silicate. of soda, specific gravity about 1100 (taking water to equal 1000) makes
a paste of the consistency of ordinary paint and serves to coat the conductors
according to my invention. For large surfaces I prefer to use proportions of
60 parts asbestos, finely divided, 20 parts lime, 20 parts clay, mixed to the
consistency of paste with the alkaline solution before referred to, at a specific
gravity of about 1150.
The manner in which the composition is applied to the conductors, and the
surfaces to be heated, or foundation plates, frames or the like to which the said
conductors and their terminals are attached is as follows:
The foundation plates, frames, or the like, which may also be the heated surface
or surfaces, is first painted with the composition, one or more layers or coats being
laid on, and when properly dried, the conductor or conductors is or are placed in
position and fixed and covered by one or more layers or coatings.
When it is dry, the composition thus applied forms an insulating division between
the surface to be heated, or the foundation plates fraines or the like, and the con-
ductor or conductors, also separating the coils convolutions or layers of said
conductor or conductors. When the whole is dry the conductor or conductors are
firmly fixed in position relatively to their respective convolutions or layers, and

page_text: also to the surfaces to be heated, foundation plates, frames or the like, and are
perfectly insulated, the composition acting as a refractory and a radiating substance
also protecting the heated conductors from the oxidation incidental to atmosphere
exposure while heated.
Referring to the drawings, the two ends of the conductor a a' in the sectional
drawing, Figure 1 are coiled, bent, or convoluted in proximity to surfaces
that
are to be heated, and the compound c intervenes between the convolutions of the
conductor a and also between it and the surfaces bb' forming a protective covering
in addition to insulating it. Figure 2 shews a similar arrangement in which the
conductor a is carried in series through more than one layer so as to increase the
heating surface within the prescribed area. In both examples the surfaces b¹ may
form part of a vessel or any utensil article or tool which is required to be heated
without smoke or soot. The conductor a may be wrapped or coiled round a
hollow cylinder or vessel Figure 3, a protective covering e being provided so that
the whole of the conductor or conductors a and the interposed coating or cement c
may be protected from external injury or disintegration. The ends of the
conductor or conductors may be fixed to terminals ff, or any other means may
be adopted for the purpose of including the apparatus so forined within an electric
circuit.
In the construction of apparatus where it may be necessary to remove the article
to be heated, such as b Figure 4, the conductor a may be caused to surround it
with the insulating cement c interposed as shewu. In other cases I use a cover y
Figure 5 of metal or other suitable substance, attached to the enclosing frame
by screws, soldering, brazing or the like the insulating and refractory paste or
cement c being interposed as shown. In all the examples quoted herein, I may,
when the area of the surface to be heated does not admit of the arrangement of
one layer or coil of conductor of sufficient length to produce the desired
heating effect, employ two or more layers with the compound herein described,
interposed.
may, in preparing the paint cement or paste use fossil meal, magnesia, slate
dust, stone dust, pulverized silica, or the like, without departing from the essential
features of my invention.
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 1
claim is,
First. The combination of a paint paste or cement consisting of a mixture of
asbestos or like refractory material with an alkaline solution of silicate of soda or
potash with an electrical conductor or conductors, and interposed between layers,
coils or convolutions of these, and any surfaces or bases in connection therewith,
substantially as herein described.
Second. In heating or cooking apparatus the employment of a paint paste, or
cement made as herein described, with a conductor or conductors, and a sustaining
surface, or a surface or surfaces to be heated, and interposed therebetween
substantially as herein described.
Third. In heating or cooking apparatus the employment of a paint, paste or
cement as referred to in the preceding claim, in combination with a conductor or
conductors, and a protective covering, substantially as herein described, with
reference to Figures 3 and 5 of the appended drawings.
Dated this 20th day of April 1893
FREDK. WALKER,
Agent for Applicant.