Year: 1896

page_text: Date of Application, 24th June, 1996-Accented, 21st Nov., 1895
A communication by THE CHEMISCH ELEKTRISCHE FABRIK "PROMETHEUS "
GESELLSCHAFT MIT BESCHRANKTER HAFTUNG, of Bockenheim, Frankfort
on the Main, in the Empire of Germany, Electricians.
1, GEORGE CECIL DYMOND M.I.M.E. of the Firm of W. P. Thompson & Co.
of 6 Lord Street, Liverpool, and 6, Bank Street, Manchester, both in the County
of Lancaster, 118 New Street, Birmingham in the County of Warwick and
322 High Holborn in the County of Middlesex, Patent 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:-
This invention relates to electric heating devices of various kinds. Such
apparatuses were hitherto fitted with metal wires or metal strips which either
surrounded them in an open manner or were embedded in enamel in a peculiar
manner. Or a fine powder composed of metal or carbon was arranged between
two metal surfaces and the current was conducted through the powder.
In the improved heating devices which form the object of this invention, thin
resistance layers of precious metal are employed, which are formed on the insulating
body in the manner of ceramic precious metal decorations, the said insulating
bodies consisting either entirely of insulating material or of other suitable material
coated with a layer of insulating material such for instance as enamel.
These resistance layers, which are connected with their supports in a most
thorough manner, can follow all the expansions of the latter without being
destroyed. Further their mass is always extremely small in comparison with the
mass of the insulation hody so that the latter can receive in the form of heat
almost all the electrical energy conveyed to it by the resistance layers. The
insulating body imparts heat to the medium surrounding it so that no heating over
a given point can take place.
In order to protect the layers of precious metals employed from mechanical
disturbance by friction, scratching or the like they are covered with protective
coverings which may be made either in the form of a special protective covering
or as an asbestos casing, or as a coating of inorganic mixtures which are non-
conductors of electricity or organic varnish which does not decompose even at a
high temperature.
The heating devices may assume entirely different forms according to the
different objects for which they are to be employed such for instance as heating-
plates, heating-tubes, heating-funnels, evaporating-dishes, sand-baths, water-baths,
oil-baths, dye-vats, boiling-down-pans, melting-vessels, digesters, soldering irons,
smoothing irons, curling iron heaters and the like.
A number of heating devices which are intended to be used for the most varied
purposes are shown in the accompanying drawings, in which-
Figure 1 shows a simple heating plate a of porcelain, on which the resistance
layer bis arranged in the manner shown in the drawings. The ends of the
resistance strip are somewhat thickened-so that the contact clamp and the contact
plate y for instance may be soldered thereon. A spring switch arm u revoluble
on the contact pin or clamp v is mounted in proximity to the contact plate y so
that the current conductor attached to the clamps and v may be opened or closed
at will.

page_text: Figure 2 shows a heating pipe which is arranged in an entirely analogous
manner.
Figure 3 shows a heating-pipe which consists of an inner tube a provided with
the resistance layer and an outer protective casing c. The protective casing is
provided with a contact clamp and a contact plate y on which the contact
springs a y' are arranged. The latter rest at two opposite places on the resistance
layer, so that the current passes from one end of the heating pipe to the other
through the resistance layer as soon as the switch arm u rests on the contact
plate y. On the passage of the current, the air contained in the interior of the
pipe is considerably heated, so that heated air escapes from the top and is
constantly replaced from below by cold air. This pipe may also be suitably
constructed with a fan or suction device as a constantly acting drying apparatus.
Figure 4 is an entirely similar arrangement employed with a funnel which is
intended to serve for heating liquid passing through the latter. On the periphery
of the actual funnel a the resistance strip & in the form of a spiral is arranged, on
the ends of which spiral strip b springs a 21 attached to clamps 22 respectively
firmly rest and form contacts. The actual funnel is encased by a protective casing c
on which the two clamps a 22 are attached. The funnel herein before described
is particularly suitable for chemical purposes in cases where it is desired to convey
liquid at a given degree of temperature into another vessel or to heat said liquid
during the transfer."
Figures 5 and 6 show an evaporating dish for chemical purposes. This consists
of a porcelain dish of the usual form. On the outer surface of the dish a the
strip b of precious metal is arranged in the manner shown in Figure 6, in such a
way that the current passes successively through the separate parts of the
resistance strip. By this arrangement it is possible to entirely maintain a given
degree of temperature which is never exceeded even during long continued
working. For instance an automatic device might be arranged which interrupts
the current at a given temperature and at a lower temperature again switches
it on.
Figures 7 and 8 show a device intended for heating a liquid by being immersed
in the same. The current passes through the one conducting wire i into the
resistance strip band returns through the other wire to the source of current.
Figure 9 shows a similar device in which the resistance strips 66 are arranged
on the inner surface of a hollow body and are traversed in parallel by the current.
This device may also be immersed in a liquid for the purpose of imparting heat
to it, it being capable of being also used for stirring up an otherwise heated
liquid.
In Figures 10 and 11 a smoothing iron or flat iron is shown in which the electric
current through the strips of precious metal aforesaid is converted into heat. The
bottom plate g is provided with enamel e or a porcelain plate, on which the strip b
of precious metal is formed in the manner of ceramic precious metal decorations.
The supply of current takes place by means of insulated screws or terminals f
inserted in the smoothing iron, one of which serves for bringing the current and
the other for carrying it off. The casing & with its bandle k is attached to the
borse shoe shaped bottom plate g by means of screws i.
Figures 12, 13 and 13 show a curling tongs heater. Fire-proof insulating
bodies a and b are provided on their outer surface with a resistance layer and
arranged in such a way in a casing that they are interconnected firmly by means of
porcelain-, earthenware- or slate-pieces s and t, but are at the same time insulated
from the casing which consists of some suitable metal. The ends of the tubes are
conductingly connected with one another by means of a metal hand m, whilst the
contact surfaces of the other ends are connected to contact pins o and p, Figure 13ª,
inserted and insulated in the rear wall.
Figures 14 and 15 show a soldering iron. The two heating plates a and b are
provided with electric resistances and inserted in a suitable insulated casing. The
contact surfaces which approach one another are connected by means of a wire d,

page_text: whilst the supply and discharge wires are attached to terminals c and e, and are
carried through the hollow handle f.
Figures 16 and 17 show a vessel which may serve as a type for the sand-baths,
water-baths, oil-baths, dye vats, boiling-down pans, melting vessels and digesters.
The resistance strips a are arranged spirally on the bottom and the strips 6 on
the periphery of the actual vessel. The latter is surrounded by an outer or
protective casing e through which the conducting wires connected with the strips a
and b are passed.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondents, I declare that what I claim is :-
1. Electric heating devices characterized by thin layers of precious metals
formed on insulating surfaces in the manner of ceramic precious metal decorations
which layers are connected in an electrical circuit by means of spring contact
devices, clamps or the like in order that the supports of the layers of precious
metals shall receive the entire electrical energy converted into heat on the passage
of the current, and be capable of giving it off to the surrounding media.
2. As a form of construction of the heating device described in Claim 1, a
heating tube consisting of an inner tube (a) provided with a layer of enamel, the
layer of precious metals (b) being arranged on the enamel and the whole
surrounded by a protective casing (c) substantially as described.
3. As a form of construction of the heating device described in Claim 1, a
funnel consisting of an inner part (a) provided with a spiral layer of precious
metal (b) and a protective casing (c), substantially as described.
4. As a form of construction of the heating device described in Claim 1, an
evaporating dish (a) of porcelain on the periphery of which the resistance strips (6)
are so arranged that they impart the heat produced to the contents of the dish,
the surface of the dish being provided with a non-conducting coating, substantially
as described.
5. As a form of construction of the heating device described in Claim 1, a disc
or hollow body provided with a handle, which body is adapted to be immersed in
a liquid with the object of imparting heat to it whilst being simultaneously
applicable for stirring the liquid, substantially as described.
6. As a form of construction of the heating device described in Claim 1, a
smoothing iron or flat iron the bottom plate (g) of which is provided with enamel (e)
or with a porcelain plate on which the resistance layer (b) is formed with the
object of imparting heat to the bottom plate (9) of the iron, substantially as
described.
Dated this 23rd day of June 1896.
WM. P. THOMPSON & Co.,
Agents.