Improvements in Electric Heaters.
Year: 1894

page_text: Date of Application, 9th Oct.,, 1891'
Complete Specification Left, 4th July, 1895 Accepted, 28th Sept:, 1895)
Improvements in Electric Heaters.,
JESSE BUCKMAN DAVIS, of 935, Sloan Street, Parkersburg, in; the County
of Wood and State of West Virginia, United States, of America, Electrical
Engineer, do hereby declare the nature of this invention, to be as follows.
The object of my invention is to provide a simple, cheap, and effective electric
heater for converting an electric current into sensible heat without the use of wire
coils, for utilization in the arts in various ways, which device shall be perfectly
durable and stable, so as to require no renewal or attention and suffer no depreciation.
To theseiends it consists in a heating medium for the current, consisting of finely
comminuted carbon particles such as pulverized. plimbago or graphite mixed: in
varying proportions with an inert refractory non-combustible material which is
also a. non-conductor: of electricity so that when the electric current is passed
through this mixture the mass is rendered partly conductive by the distribution of
carbon particles through it but is of high resistance: because of the admixture and
preponderance of the non-combustible; non-conducting inert material in which the
carbon particles are homogeneously embedded. The inert material may be composed
of slaked lime, magnesia, alumina, silica, oxide of iron, tourmaline, lava, slag,
mineral wool, pulverized coal ashes, fire clay, asbestos, or a mixture of any of
thesc.
The carbon particles are to be mixed with the above material as homogeneously
as possible, and sufficient water is added to form a mortar. or plastic mass which
subsequently hardens and becomes solid. When greater tenacity is desired; with
the mortar thus formed a proportion of asbestos, mineral wool, or other fibrous
inert material, is added which is not destroyed by the action of heat. The
proportion of the material is:-to every one hundred parts (by volume) of inert
material from ene to forty-seven pants of carbon, the proportion varying according
to the application to be made of the heat. Thus for slight warming purposes: a
very small per cent. of carbon is used, while for other purposes, where a high
degree of heat is required, the largest proportion of carbon is used and this is
sufficient to produce incandescence in the mass.
In applying the invention as a heating furnace for raising steam in a steam
boiler, or for cooking, the heat generating medium is composed of a mixture of
comminuted carbon particles with one or more of the inert inaterials named which
is mixed together with water to form a mortar that sets to in solid mass when dry.
This compound entirely surrounds the sides and bottom of the boiler. Between
this heating medium and the metal shell of the boiler is interposed a layer of some
substance which is a good' non-conductor of electricity, and is also a heat resisting
body, preferably fire-brick. It is necessary that. this should be a non-conductor of
electricity because if the current of electricity were permitted to reach the metal
shell of the boiler the current would pass by that route without being transformed
into heat instead of through the heating medium and this coating to the boiler
must also be a heat resisting medium to withstand the high degree of heat generated
within the heating material. Outside of the heating medium a thick packing of
any good-non-conductor of heat and electricity,, any of the inert substances named
being used for this purpose. This packing, which. is enclosed within an outer
casing, insulates the current and keeps it within the heating medium and also
conserves the heat by preventing loss: by external radiation.
.

page_text: To apply the electrical current, an electrode, consisting of a cast iron plate, is
embedded at the bottom of the mass of the beating medium, and another electrode,
consisting of a cast iron ring, is allowed to rest upon the top of the heating
medium. These two electrodes are connected by wires to binding posts which
receive the current from the wires of any system of distribution from dynamo
electric machines or storage batteries. The object in making the upper electrode
in the form of a ring is to give access to the central heating chamber and to permit
this electrode to settle down or gravitate always to a close contact with the heating
material as it shrinks from successive heating and cooling.
When the current is turned on, the resistance of the heating medium causes it
to become hot, depending in degree upon the relative proportion of plumbago and
inert material, and the heat so generated is utilized either for raising steam, or for
the purposes of cooking. By merely regulating the proportion of carbon to the
inert material the proportion of heat developed may be adapted to various uses.
Thus for a very slight heat, the heating mass may be compounded in such
proportions and shape as to find useful application for foot warmers, for pads, for
incubators, for artificial hot-beds in plant-culture, etc. When a high degree of
heat is required, it may be applied to steam generation, cooking, industrial chemical
operations, and also for generating steam within and exploding water cartridges or
shells in blasting and such like uses.
The advantages of my invention are:-economy in current; economy in time,
labour, and fuel; the absolute control of the electric current ; cleanliness about the
'heater; absence of smoke, dust, and ashes; absence of all gas; and risk of fire;
evenuess of heat; and saving of heat ordinarily wasted; there being practically no
heat generated beyond that which is utilized.
When the heater is to be applied to a foot warmer the outer case may be made
of wood, canvas, covered with asbestos, composite woody fibre of non-conducting
quality papier-mache, leather board, leather, hard rubber, or even .of porcelain,
slate, fire-clay, tile, or enamelled sheet metal, the case being made round and
shallow with a raised flange around its circular edge to retain the heating medium.
The foot-warmer may, however, be made of any desired shape. The case is about
2 inches deep, and is filled with a heating material which is preferably a composite
mixture of powdered plumbago and any inert and refractory material as before
described. The proportions in which the electrically conductive plumbago is mixed
with the inert and refractory material determines the amount of heat which the
foot-warmer is capable of transforming from the current, the greater the proportion
of plumbago the higher the degree of heat that will be obtained. For ordinary
uses affording a temperature of, say, 105 to 100, the proportion would be about ten
to thirty-eight per cent. of plumbago to ninety to sixty-two per cent. respectively of
refractory material.
One of the electrodes is made ring-shape and of a triangular cross-section. This
ring is embedded in the heating medium near the outer edge of the same with one
of its flat sides at the top and a sharp edge penetrating downwardly into the heating
medium. The other electrode is constructed as a conical plate with its flat base at
the top and its apex penetrating downwardly into the heating medium. The object
in making the electrodes of this shape is to cause them to penetrate the heating
medium with a tight wedging action from the pressure of the feet on the top of the
foot warmer so as to always ensure an intimate electrical contact between the
electrodes and the heating medium. The conical electrode should be exactly in
the centre of the ring-shape electrodes in order to preserve a uniform radial
distribution of the current through the heating medium, it being obvious that if the
electrodes were not concentric the bulk of the current would pass between their
sides which most closely approach, which would result in a lack of uniformity in the
heat and an excessive heating between the nearest points of the electrodes.
The current is conducted to the two electrodes by insulated wires. A thin sheet
of metal extends over the top of both electrodes and has a layer of mineral wool,
asbestos, or other nou-conductor above it, and another similar layer below it to

page_text: prevent metallic connection between the electrodes. This sheet metal plate
protects the heating medium and electrodes when walking upon the foot warmer,
thus avoiding the disintegration of the heating medium and displacement of the
electrodes. This plate also acts as a distributor of the heat, causing the upper
surface of the foot warmer to be uniformly warm. A padding of mineral wool, or
asbestos, is applied above the sheet metal plate upon which is placed an outside
covering of Brussels carpet or any other fabric or material, which is fastened
around the edges with an ornamental nickel-plated rim secured by nails, screws, or
bolts, to the flange of the outer casing. Rollers or castors are secured to the
bottom side of the foot warmer so as to facilitate moving it.
In a modification of the foot warmer for special portable use as a foot warmer or
body pad, its body or containing case is made of flexible material such as canvas or
leather covered with asbestos, and straps and buckles serve to secure it in a carriage
or around the feet or in any desired relation to the body. To permit this foot
warmer to be bent or rolled up, the electrodes are arranged parallel to each other.
and transversely to the foot warmer. The heating medium is insulated within
the flexible retaining case, and the action of this foot warmer is the same as the
other.
'
1
1
This invention will prove a great relief to old persons, invalide, and others
suffering with cold feet or rheumatism, and also has a special medicinal or
curative value, for hy dampening the feet with a sponge and placing them bare on
the foot warmer an electric foot bath may be obtained or the pad may be buckled
around the body, or otherwise applied to produce many useful effects in electrical
therapeutics.
Di
مفعل
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.
COMPLETE SPECIFICATION:
Improvements in Electric Heaters.
1, JESSE RUCKMAN DAVIS, of 935, Sloan Street, Parkersburg, in the County
of Wood, and State of West Virginia, United States of America, 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:
The object of my invention is to provide a simple, cheap, and effective electric
heater, for converting an electric current into sensible heat without the use of
wire coils, for utilization in the arts in various ways, which device shall be
perfectly durable and stable so as to require no renewal or attention and suffer no
depreciation.
To these ends it consists in a heating medium for the current consisting of finely
coniminuted' carbon particles, such as pulverized' plumbago or graphite, mixed in
varying proportions with an iuert refractory non-combustible material which is
also a non-conductor of electricity, so that when the electric current is passed through
this.mixture the mass is rendered partly conductive by the distribution of carbon
particles through it but is of high resistance because of the admixture and
preponderance of the non-combustible, non-conducting, inert material in which the
carbon particles are homogeneously embedded.
The inert material may be composed of slaked lime; magnesia, alumina, silica,
oxide of iron, tourmaline, lava, slag, mineral wool, pulverized coal ashes, fire clay,
asbestos, or a mixture of any of these.
The carbon particles are to be mixed with the above material as homogeneously
as possible, and sufficient water is added to form a mortar or plastic mass which
subsequently hardens and becomes solid. When greater tenacity is desired, with

page_text: the mortar thus formed a proportion of tasbestos, mineral wool, or other fibrous
inert material is added which is not destroyed by the action of heat. The pro-
portion of the material is to every 100 parts (by volume). of inert material,
from 1 to 47 parts of carbon, the proportion varying according to the application
to be made of the heat. Thus for slight warming purposes a very small per
centage of carbon is used, while for other purposes where a high degree of heat
is required, the largest proportion of carbon is used, and this is sufficient.to
produce incandescence in the mass..
Referring to the accompanying drawings forming part of this Specification.
Figure is a vertical central section of a heating furnace for raising steam in a
steam boiler.
Figure 2 is a similar view of a heating furnace adapted for culinary uses and
Figure 3.are sectional views of masses of the heating medium as composed of
a heterogeneous mixture of carbon particles and inert material in varying
proportions of carbon.
Figures 4 and 5 are horizontal and vertical sections of the invention arranged
for a footwarmor and
Figures 6 and 7 are similar views of the invention arranged as a foot warmer
or body ipad.
In the drawing Figure 1, A is the outer casing of an upright cylindrical shape.
D is the shell of a steam boiler which is arranged, centrally within the outer
casing. Bis the beat generating medium composed of a mixture of comminuted
carbon particles with one or more of the inert materials named which is mixed
together with water to form a mortar that sets to a solid mass when dry. This
compound entirely surrounds the sides and bottom of the boiler. Between this
heating medium and the metal shell of the boiler is interposed a layer 'C of
some substance which is a good non-conductor of electricity, and is also a heat
resisting body. I prefer fire brick for this purpose as shown. It is necessary
that this should be a non-conductor of electricity because if the current of
electricity were permitted to reach the metal shell of the boiler the current would
pass by that route without being transformed into heat instead of through the
heating medium, and this. -coating to the boiler inust also be a heat resisting
medium to withstand the high degree of heat generated within the heating
material B. Outside of the heating medium B is a thick packing P of any, good
non-conductor of heat and electricity, any of the inert substances named being
used for this purpose. This packing insulates the current and keeps it within the
heating medium B and also conserves the heat by preventing loss from external
radiation.
To apply the electrical current, an electrode consisting of a cast iron plate E is
embedded at the bottom of the mass B of the heating medium, and another
electrode consisting of a cast iron ring F is allowed to rest upon the top of the
heating medium. These two electrodes are connected by wires H and I to binding
posts which receive the current from the wires of any system of distribution from
dynamo electric machines or storage batteries.
The object in making the upper electrode in the form of a ring is to give access
to the central heating chamber and to permit this electrode to settle down or
gravitate always to a close contact with the heating material as it shrinks from
successive heating and cooling.
When the current is turned on, the resistance of the heating medium causes it to
become hot depending in degree upon the relative proportion of plumbago and
inert material, and the heat so generated is utilized either for raising steam as
in Figure 1, or for the purposes of cooking as in Figure 2.
By merely regulating the proportion of carbon to the inert material the
proportion of heat developed may be adapted to various uses.
Thus for a very
slight heat the heating mass may be.compounded' in such proportions and shape as
to find useful application for foot warmers as in Figures 4 and 5, for pads as
in Figures 6 and 7, for incubators, for artificial hot beds in plant culture'&c.

page_text: When a high degree of heat is required it may be applied to steam generation,
cooking, industrial chemical, operations, and also for generating steam within, and
exploding water cartridges or shells in blasting.and such.like uses.
The advantages of my invention are; economy in current; economy in time,
labor and fuel; the absolute control of the electric current; cleanliness about the
heater; absence of smoke, dust and ashes; absence of all gas; and risk of fire;
evenness of beat; and saving of heat ordinarily wasted, there being practically no
hent generated beyond that which is utilized.
Referring to Figures 4 and 5 which, show a foot-warmer, A'is the outer case
which may be made of wood, canvas covered with asbestos, composite woody fibre
of non-conducting quality, papier maché, leather board, leather, hard rubber, or
even of porcelain, slate, fire clay, tile or enameled sheet metal! As shown the case
is round and shallow with a raised flange around its circular edge to retain the
heating medium. The foot-warmer may, however, be made of any desired shape.
The case is about 24 inches deep, and is filled with a heating material C₁ which is
preferably a composite mixture of powdered plumbago and an inert and refractory
material as before described.
The proportions in which the electrically conductive plumbago is mixed with
the inert and refractory material determines the amount of heat which the foot
warmer is capable of transforming from the current; the greater the proportion
of plumbago the higher the degree of heat that will be obtained. For ordinary
uses affording a temperature of say 105° to 100° the proportion would be about
10 to 38 per cent. of plumbago to 90 to 62 per cent. respectively of refractory
material.
E' is one of the electrodes which is made ring-shape and of a triangular cross
section. This ring is embedded in the heating medium near the outer edge of the
same with one of its flat sides at the top, and a sharp edge penetrating downwardly
into the heating medium. D' is the other electrode, which is constructed as a
conical plate, with its flat. base at the top, and its apex penetrating, downwardly
into the heating medium. The object in making the electrodes of this shape is to
cause them to penetrate the heating medium with a tight wedging action from the
pressure of the feet on the top of the foot-warmer so as to always ensure an
intimate electrical contact between the electrodes and.the heating medium. The
electrode D' should be exactly in the centre of the ring-shape electrode E' in
order to preserve a uniform radial distribution of the current through the heating
medium, it.being obvious that if the electrodes were not concentric, the bulk of
the current would pass between their sides which most closely approach, which
would result in a lack of uniformity in the heat and an excessive heating between
the nearest points of the electrodes.
H' and I are the insulated wires which carry the current to the two electrodes.
K' is a thin sheet of metal extending over the top of both electrodes, and having
a layer of mineral wool, asbestos, or other nou-conductor above it, and another
similar layer P' below it to. prevent metallic connection between the electrodes.
This sheet metal plate K' protects the heating medium and electrodes when
treading upon the foot-warmier, thus avoiding the disintegration of the heating
medium and displacement of the electrodes. This plate K' also acts as a distributor
of the heat,, causing the upper surface of the foot-warmer to be uniformly
warm.
Over the padding P₁ of mineral wool or asbestos is an outside covering R' of
Brussels carpet, or any other fabric or material' which is fastened around the edges
with an ornamental nickel plated rim secured by nails, screws, or bolts to the
Hange of the outer casing. To facilitate the moving of the foot-warmer from place
to place, rollers or castors & are secured to its bottom side.
In Figures 6 and 7 I show a modification for special portable use as a foot-
warmer or body pad. This has its body or containing case made of flexible
material such as canvas or leather covered with asbestos, and straps M2 M2 and
buckles N N serve to secure it in a carriage or around the fect or in any desired.

page_text: relation to the body. To permit this foot-warmer or pad to be bent or rolled up
the electrodes HI are arranged parallel to each other and transversely to the
foot-warmer. The heating medium C is insulated within the flexible retaining
case, and the action of this device is the same as the other.
This invention will prove a great relief to old persons, invalids, and others
suffering with cold feet or rheumatism, and also has a special medicinal or curative
value, for by dampening the feet with a sponge and placing them bare on the pad,
an electric foot bath may be obtained or the pad may be buckled around the body,
or otherwise applied to produce many useful effects in electrical therapeutics.
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. A medium for couverting electricity into heat, consisting of a homogeneous
mixture of heterogeneous ingredients composed partly of comminuted particles of
non-combustible but electrically conductive material embedded in and homogeneously
mixed with a non-combustible and electrically non-conductive material, substantially
as shown and described.
2. A medium for converting electricity into heat, consisting of a solid
homogeneous mixture of heterogeneous ingredients, composed partly of comminuted
particles of non-combustible but electrically conductive material, embedded in and
homogeneously combined with a non-combustible and electrically non-conductive
material by the addition of water to form a mortar, substantially as shown and
described.
3. A medium for converting electricity into heat, consisting of a mixture of
comminuted carbon particles, and an inert non-conductive and non-combustible
material homogeneously mixed and reduced to solid form, substantially as shown
and described.
4. An electric heater consisting of an inner shell surrounded externally by an
electrically non-conductive and heat resisting material, an outer shell having an
internal packing of electrically non-conducting and heat resting material, a heat
generating medium placed between the packing and the covering of the inner shell
and consisting of a mixture of carbon and inert material as described and two
electrodes or conducting plates placed at the opposite ends of the heating medium,
substantially as and for the purpose described.
5. In an electric heater, the combination with the inner and outer shells, the
intermediate heating material, and the non-conducting lining or packing on each
side of the same; of two electrodes, one arranged at the bottom of the heating
material and constructed in the form of a plate, and the other arranged at the top
of the heating material and constructed in the form of a ring, substantially as and
for the purpose described.
6. A foot-warmer or pad comprising a flat layer of electrical heating medium
provided with electrodes, a flat retaining case, and insulation surrounding the heating
medium and electrodes, substantially as and for the purpose described.
7. A foot-warmer or pad comprising a flat layer of electrical heating medium
with electrodes of triangular cross section embedded therein with a flat side at
the top and sharp angle at the bottom, and an insulating containing case,
substantially as and for the purpose described.
8. A foot-warmer or pad comprising a flat layer of electrical beating medium
provided with electrodes, a hollow retaining case with insulation surrounding the
heating medium and electrodes, and a flexible top surface composed of mineral
wool or its described equivalent enclosed and retained by a flexible cover
substantially as and for the purpose described.
9. A foot-warmer or pad composed of a flat circular retaining case, a fat layer
of electrical heating medium insulated therein, and two electrodes, one made ring-
shape, and the other a central plate arranged concentrically to the ring
substantially as and for the purpose described.

page_text: 10. The combination with an electric heating foot-warner or pad having a flit.
layer of heating medium with electrodes embedded in the same; of a superposel
protecting and heat distributing plate extending over the top of the heating.
medium and electrodes, and intermediate insulation substantially as and for the
purpose described.
Dated this 4th day of July 1895
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.