Improvements in Means for Connecting Electrical Conductors to Act as a Safety Device.
Year: 1890

page_text: Date of Application, 24th Apr., 1890
Complete Specification Left, 24th Jan., 1891-Accepted, 28th Feb., 1891
PROVISIONAL SPECIFICATION.
Improvements in Means for Connecting Electrical Conductors to
Act as a Safety Device.
I, JULIUS MARX,' of 10 Gutzkowstrasse, Sachsenhausen, Frankfurt-on-Maine,
in the Empire of Germany, do hereby declare the nature of this invention to be
as follows:-
According to my invention as applied to the connection of conducting wires or
strips to electrodes such as are used for electrolytical purposes, I place the
electrodes in a box or container so that a portion of them projects into a space in
the said box or container through which space is passed the wire or conducting
strip to be connected to the electrodes and then I fill into the said space a com-
position which is electrically conductive and can be moulded into the said space
and will attach itself both to the wire or strip and the electrodes. When this is
cool the box or container, which has acted as a mould, is removed and the wires
or strips and electrodes are found to be properly connected with each other.
A composition suitable for this purpose consists of a mixture of finely divided
conductive material and a material which forms a means of conglomerating the
finely divided metal or conductive material. As the conductive material I prefer
to use powdered or granulated carbon or graphite and as the conglomerating
material I prefer to use paraffin wax. Such compound of materials possesses the
quality of softening if the conductors should become unduly heated and when in
that state the said compound becomes less conductive or a non-conductor and this
quality renders the compound applicable as a safety means for protecting electrical
circuits from abnormal heating of the conductors and it can therefore be used in
place of the safety fuses hitherto employed as when it has become softened by the
undue heating of the conductors not only is the supply of current diminished or
discontinued but the compound remains in place (being contained in any suitable
frame box or retainer) and on cooling recovers its conductivity and therefore acts
automatically to regulate or re-establish the circuit. By proportioning the relative
quantities and mass of the materials the compound may be made to become softened
and its conductivity lowered or discontinued in accordance with any amount of
current against which it is desired to protect the circuit.
Dated this 24th day of Anvil 1890
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in Means for Connecting Electrical Conductors to
Act as a Safety Device.
I, JULIUS MARX, of Bad-Nauheim, in the Empire of Germany, late of 10 Gutz-
kowstrasse, Sachsenhausen, Frankfurt-on-Maine, in the Empire of Germany,
Chemist, 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 :-
According to my invention the connection of electrical conductors is effected by
means of a mixture, or compound, of finely divided conductive material and a
material which forms a means of conglomerating the finely divided conductive
material and which is fusible, or softened, when an undue amount of heat arises in
the electric circuit. As the conductive material I prefer, for ordinary purposes, to

page_text: use finely granulated, or powdered, čârboii; of graphite, and as the conglomerating
material I prefer to use wax, such as paraffin wax, or stearine, or pitch, or resin, but
I do not limit myself to these precise materials. For instance: for high temperatures
a glass, or enamel, of a low melting point can be used. The said mixture, or compound,
of materials possesses the quality of softening if the conductors should become unduly
heated and when in that state the said compoiiid becoines less conductive or a non-
conductor: This quality renders the mixture; or compound, applicable as a safety
means for protecting electrical circuits from abnormal heating of the conductors
and it can therefore be used in place of the safety fuses hitherto employed, as when
it has become softened by undue heating not only is the supply of current
diminished, or discontinued, but the mixture or compound remains in place (being
contained in any suitable frame, box, or retainer,) and on cooling recovers its con-
ductivity and therefore acts automatically to regulate, or re-establish; the circuit.
By proportioning the relative quantities and mass of the materials the mixture, or
compound, may be inade to become softened and its conductivity lowered, or dis-
continued, in accordance with any amount of current against which it is desired to
protect the circuit.
The following is a description of the manner in which my invention may, be
carried out, although I do not limit myself to the precise details which I shall
describe.
Powdered graphite is mixed with molten paraffin-wax and the inass; whilst in a
state in which it can be moulded, is introduced (preferably by compression) into a
frame, or receiver; or the mass is niade into the desired shape and size (for example
into a rod) and is then inserted in a tube inade preferably of glass, porcelain, or
other non-conductor. This is shewn in the accompanying drawing where the said
mass is marked a and the tube is marked b. At each end of the tube b, there is a
small space in which spaces are placed the metallic discs c; c', having connected to
them the wires d, d, to be afterwards connected with the rest of the circuit.
discs cc should be pressed against the mass whilst it is still in a mouldable condition.
I prefer to make the discs somewhat smaller than the tube b, so that I am able to
place soine of the material a, around the said discs to ensure good contact. The
remaining spaces are filled up as at e e¹ with plaster of Paris; or some other cement,
or by any other suitable means.
net.
The
To make good the contact of the conductors with the material a; I prefer to
provide the discs c; c', with extended surfaces of contact with the material ä; süch
as, for instance, with points as at f, or other projections, or grooves; or a coil as
at g. Or I may connect the mass and the wires by means of a inétallic brush or
If, in using net, it is rolled together with the material a; a very good contact
is obtained. The tube, may be a metallic pipe if desired; but then it must be
lined with an insulator: The size and shape of the device will of course be in
accordance with the conductors and with the place in which it is to be used.
powerful currents, for instance, a large size and flat form are very suitable. The
more powerful the electric current employed in the circuit the more will the length
be reduced and the diameter or thickness increased as of course the diameter and
length should be in accordance with the effects of the electric, current,
For
The quantity of paraffine (or the like) employed in the mixture should be such
as to cement the grains of the conductive powder, but there must not be so much of
the paraffine (of the like) as to make the material nonconductive.
When the device is in use the electric current will pass as long as it does not
rise higher than to the degree the device is intended for, but as soon as the current
exceeds that degree the material a, is heated so that it becomes less conductive and
the hotter it gets the less conductive it becomes until when it becomes soft enough
it interrupts the current. Under ordinary circumstances the material should not get
more than sufficiently warm to conduct only the current for which it is intended and
unlike the ordinary safety devices it does not necessarily cause à complete inter-
ruption of the current; whilst at the same time it does not admit more current than
is calculated, ör desired; for a certain circuit:

page_text: 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 :-
First. A safety device, for electric circuits, consisting of a mixture of a conductive
material with a material which softens, or fuses, when undue heating of the
conductors occurs; the said mixture being placed in the circuit, substantially as
hereinbefore described.
Second. In an electric circuit the interposition of a mixture of finely granulated,
or powdered, carbon, or graphite, and paraffin wax, stearine, pitch, resin, or the
like; substantially as, and for the purposes, hereinbefore described.
Third. A safety device, for electric circuits, consisting of a mixture of materials,
such as those referred to in the preceding claiming clauses, contained in a frame,
box, or retainer, and having the electric conductors brought into contact therewith,
substantially as hereinbefore described.
Fourth. A safety device, for electric circuits, constructed as hereinbefore described
with reference to the accompanying drawing.
Dated this 23rd day of January 1891
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, Agents.