Improvements in Electric Resistances.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improvements in Electric Resistances.
We, JULIUS FERDINAND HEINRICH VOIGT, and JACOB ADOLF HAEFFNER,
both of Electrical Works, Bockenheim near Frankfort-on-Main, in the Empire of
Germany, Electrical Engineers, do hereby declare the nature of this invention to
be as follows:-
This invention relates to the manufacture of electric resistances and consists in
applying to porcelain, glass talc or other suitable insulating material a metallic
coating containing metal in a very finely divided condition. The resistance thus
produced may be at once employed for an electric rheostat, or when a gold or
silver coating on porcelain be employed it may be burnt before use for the purpose
of imparting to it greater durability. Large masses of the resisting material may
be formed, or even separate special. metal parts arranged at desirable points
on the resistance for the purpose of conducting to or carrying off the electric
current.
The resistances herein before described may be employed preferably as small
stationary or adjustable resistances for separate incandescent lamps. In this latter
case it is preferable to apply the metallic coating (preferably of gold) directly
onto the porcelain socket of the switching device, or on the holder and to burn
it in. :
These improved resistances are specially suitable for small unalterable resistances
for measuring purposes, and as safety fuses for protecting weak electric wires against
strong currents.
These improved resistances may be formed in any suitable manner and provided
with contacts, without thereby altering in anything the essential part of the
invention.
וי
1007
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicants.
Improvements in Electric Resistances.
We, JULIUS FERDINAND HEINRICH VOIGT and JACOB ADOLF HAEFFNER
both of Eectrical Works, Bockenheim, near Frankfort-on-Main, in the Empire of
Germany, Electrical Engineers, 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 the manufacture of electric resistances and consists in
applying to porcelain, glass, talc or other suitable insulating material a metallic
coating containing metal in a very finely divided condition. The resistance thus
produced may be at once employed for an electric rheostat, or when a gold or silver
coating on porcelain be employed it may be burnt before use for the purpose of
imparting to it greater durability.
The metallic coating may be produced by any suitable means such for instance
as the following:-
a. The metallic coating may be directly conveyed as metal on to the insulating
material, as is the case in painters' gold or solid gold.

page_text: b. The metallic coating may be applied in the form of a solution, for instance by
painting it on the insulating bodies in the same way as ordinary liquid gold or
metalliferous colours or as the usual metallic lustres or enamel colours in porcelain
manufacture and then separating the metallic substance by firing, when it is
obtained as a continuous band strip or the like.
By liquid gold, metalliferous colours, metallic lustres and enamel colours in this
sense are understood the homogeneous solution of organic metals or compounds of
previous metals, such for instance as sulphide of gold combined with balsam of
sulphur or mixtures of the same in organic solvents such as nitrobenzole with or
without the assistance of essential oils (oil of lavender, anise, cloves and rosemary).
The solutions may contain, compounds of bismuth, boric or phosphoric acid as
solvents and lavender oil as medium. In this sense also in addition to gold, silver
and platinum the following must be regarded as precious metals, namely, the
elements of the platinum group, palladium, rhodium, ruthenium, osmium and
iridium. Aluminium may also be employed.
c. The thin metallic coating may be precipitated from solutions as a coherent
metallic mass in a similar manner to the manufacture of silvered mirrors, the
metallic covering being fixed on the insulating body by means of firing.
d. Finally, the thin metallic covering may be made by decomposition from
nickel tetra carbon oxide Ni(CO) or from like metallic carbon oxides by any
suitable process such as that described in the Specification of Mond's Patent
No. 21025º
By the process herein before described, the resisting layer which is heated by the
passage of the current is applied in so thin a form to the insulating substance that
it can easily follow all the variations of expansion of the same without causing by
its own expansion the insulating layer to become cracked or burst.
In order to obtain an even section of the metallic layers produced in the methods
described in paragraphs a to d, the metallic layers may be strengthened by
electrolytic or galvanic deposits and then these supplementary deposits be
burnt on.
For the purpose of conducting the current to or from the resistances, suitablo
metal parts may be arranged on the resistances at desired points, or the metallic
coating may be formed in larger masses at such points for said purpose.
The resistances hereinbefore described may be employed preferably as small
stationary or adjustable resistances for separate incandescent lamps. In this
latter case it is preferable to apply the metallic coating (preferably of gold)
directly onto the porcelain socket of the switching device, or on the holder and to
-burn it in.
These improved resistances are specially suitable for small unalterable resistances
for measuring purposes, and as safety fuses for protecting weak electric wires
against strong currents.
These improved resistances may be made of any suitable or desired shape or
pattern and be provided with contacts, without thereby altering in anything the
essential part of the invention.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:-
Electric resistances consisting of a metallic coating burnt on, or otherwise
suitably applied to porcelain, glass, talc, earthenware or the like, substantially as
hereinbefore described and with the object set forth.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicants.