Improvements in Electrodes.
Year: 1895

page_text: Date of Application, 19th Sept., 1895
Complete Specification Left, 13th June, 1896-Accepted, 1st Aug., 1896
Improvements in Electrodes.
1, CARL HOEPFNER of No. 36, Frankfurterstrasse, Giessen, in the Empire of
Germany, Doctor of Philosophy and Analytical Chemist, do hereby declare the
nature of this invention to be as follows:-
It is a well known fact that artificial carbons, such as have hitherto been
frequently employed in the performance of galvanic processes, made in the shape
of blocks or briquettes" from soot, tar or ground plumbago, are possessed of a
very limited power of resistance to the action of the electrical current ; more
particularly where such carbons are to serve the purpose of anodes. And,
necessarily, where the material used in their manufacture is of inferior quality, or
where their preparation has been at all defective, the drawback referred to is so
much the more seriously felt.
On the other hand, "natural" (retort) carbon, in plates or bars, or in any other
shape or form that is convenient for use, is not readily procurable and, when
obtained, generally proves too expensive in proportion to the object for which it is
required.
This invention is intended to remove these inconveniences by providing the
carbons with as large a surface as possible, in relation to their bulk. By thus
forming them, a possibility is afforded for utilizing carbons of even indifferent
quality; and more especially is this the case where comparatively small pieces of
the so-called "natural" carbon (i.e. pieces of the size easily obtainable at a
moderate cost), or other carbon (or coke) of sufficient power of resistance, are
joined together by means of artificial carbon, in such a manner, that the pieces or
lumps of the "natural" carbon may, as far as practicable, freely and fully protrude
either on one or on both sides. By this method, carbons of which the superficial
efficacy and the power of resisting electrical current are increased, may be produced
in pieces of sufficiently large dimensions and at comparatively little cost; plates,
bars, rods, or differently shaped bodies of artificial carbon having, to this end,
pieces of retort carbon (obtainable cheaply as waste) secured to one or more of
their sides. Or pieces or lumps of other sufficiently resistant carbon (or coke) may
be thus attached to them.
Inasmuch as artificial carbons may be manufactured in large dimensions, it will
be understood that, by the method just described, electrodes of any required size
may be constructed, with surfaces considerably augmented, or extended, by the
multiplication of the auxiliary pieces connected with them. An electrode of this
description will be found far more resistant than one made of artificial carbon,
since the destructive action of an electrical current will be chiefly exercised upon
raised or projecting portions consisting of resistant carbon, with the result that the
bed or ground-plate, consisting of artificial carbon will be affected thereby to a
less degree and allowed, in the main, to act as a conductor. This ground-plate
may further be protected, and sheltered from the action of the current, by being
provided with a protective coating such as paraffin, so that the raised portions of
artificial carbon are the only ones that remain exposed. The pieces of resistant
Thus, plates, bars,
carbon may be fixed to the bed-plate in any suitable manner.
or other bodies of artificial carbon may, before being burned or baked, have a
number of lumps of retort carbon, or other carbon or coke, arranged upon them

page_text: in any convenient manner, and then fixed in position by means of some suitable
cement, or by the aid of a press; the whole being then submitted to the usual
burning process, in which atmospheric air should be as completely as possible
excluded. Or the bed-plate, made of artificial carbon, may be first thoroughly
carbonized, and then the pieces of retort carbon, and the like, fitted with recesses,
grooves or apertures provided in the said plate for the purpose, wherein they
may be secured, say, by means of porcelain screws or the like. These pieces of
resistant carbon and the like may be arranged on one or more sides of the bed or
ground-plate.
It is advisable to see that the carbon surface, when thus fitted with projections
and recesses, or other unevennesses or roughnesses of any suitable outline, should
be a multiple of the original surface.
Electrodes manufactured by this process may be employed either as ordinary
electrodes, or, if desired, as partitions between two electrolytes. If the positive
pole be situated in one electrolyte, and the negative pole in the other electrolyte,
it is obvious, that the carbon electrode will serve as a double electrode, oue side
of which will be negative, and the other, positive. If such electrodes as these
be fitted in a suitable frame, and if a number of such frames be connected after
the manner of a filtering press, and an electrical pole arranged at each end of the
complete apparatus, an arrangement most convenient for the performance of
electrolytical processes, with carbon electrodes acting as double electrodes, will
be obtained. It will be understood that adequate means should be provided for
the supply and discharge of the electrolyte. Such compound carbons may more-
over, be employed as electrodes for generating electricity, in which case it will be
advantageous to make the several pieces of carbon as porous as possible.
Dated this 19th day of September 1895.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.
11
Electrodes.
I, CARL HOEPFNER, of 2 Helgoländer Ufer, Berlin, late of 36 Frankfurterstrasse,
Giessen, in the Empire of Germany, Doctor of Philosophy and Analytical 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 :-
It is a well known fact that artificial carbons, such as have hitherto been
frequently employed in the performance of galvanic processes, made in the shape
of blocks or "briquettes" from soot, tar or ground plumbago, are possessed of a
very limited power of resistance to the action of the electrical current; more
particularly where such carbons are to serve the purpose of anodes. And
necessarily, where the material used in their manufacture is of inferior quality,
or where their preparation has been at all defective, the drawback referred to is
so much the more seriously felt.
On the other hand, "natural" (retort) carbon, in plates or bars, or in any other
shape or form that is convenient for use, is not readily procurable and when
obtained, generally proves too expensive in proportion to the object for which it
is required.
This invention is intended to remove these inconveniences by providing the
carbons with as large a surface as possible, in relation to their bulk. By thus
forming them, a possibility is afforded for utilizing carbons of even indifferent
quality and more especially is this the case where comparatively small pieces of

page_text: "
the so-called "natural carbon (i.e. pieces of the size easily obtainable at a
moderate cost), or other carbon (or coke) of sufficient power of resistance or of
superior quality, are joined together by means of artificial carbon, in such a manner,
that the pieces or lumps of the "natural" carbon or of the carbon of superior
quality may, as far as practicable, freely and fully protrude either on one or on
both sides. By this method, carbons of which the superficial efficacy and the
power of resisting electrical current are increased, may be produced in pieces of
sufficiently large dimensions and at comparatively little cost; plates, bars, rods, or
differently shaped bodies of artificial carbon having, to this end, pieces of retort
carbon (obtainable cheaply as waste) secured to one or more of their sides.
Or pieces or lumps of other sufficiently resistant carbon (or coke) may be thus
attached to them.
Inasmuch as artificial carbons may be manufactured in large dimensions, it will
be understood that, by the method just described, electrodes of any required size
may be constructed, with surfaces considerably augmented, or extended, by the
multiplication of the auxiliary pieces connected with them. An electrode of this
description will be found far more resistant than one made of artificial carbon,
since the destructive action of an electrical current will be chiefly exercised upon
raised or projecting portions consisting of resistant carbon, with the result that
the bed or ground plate, consisting of artificial carbon will be affected thereby to
a less degree and allowed, in the main, to act as a conductor. This ground plate
may further be protected and sheltered from the action of the current, by being
provided with a protective coating such as paraffin, so that the raised portions of
artificial carbon are the only ones that remain exposed. The pieces of resistant
carbon may be fixed to the bed plate in any suitable manner. Thus, plates, bars,
or other bodies of artificial carbon may, before being burned or baked, have a
number of lumps of retort carbon, or other carbon or coke, arranged upon them
in any convenient manner, and then fixed in position by means of some suitable
cement, or by the aid of a press; the whole being then submitted to the usual
burning process, in which atmospheric air should be as completely as possible
excluded. Or the bed plate made of artificial carbon may be first thoroughly
carbonized, and then the pieces of retort carbon, and the like, fitted with recesses,
grooves or apertures provided in the said plate for the purpose, wherein they may
be secured, say, by means of porcelain screws or the like. These pieces of
resistant carbon and the like may be arranged on one or more sides of the bed or
ground-plate.
It is advisable to see that the carbon surface, when thus fitted with projections
and recesses, or other unevennesses or roughnesses of any suitable outline, should
be a multiple of the original surface.
Electrodes manufactured by this process may be employed either as ordinary
electrodes, or, if desired, as partitions between two electrolytes. If the positive
pole be situated in one electrolyte, and the negative pole in the other electrolyte,
it is obvious, that the carbon electrode will serve as a double electrode, one side of
which will be negative and the other positive. If such electrodes as these be fitted
in a suitable frame, and if a number of such frames be connected after the manner
of a filtering press, and an electrical pole arranged at each end of the complete
apparatus, an arrangement most convenient for the performance of electrolytical
processes, with carbon electrodes acting as double electrodes, will be obtained. It
will be understood that adequate means should be provided for the supply and
discharge of the electrolyte. Such compound carbons may moreover be employed
as electrodes for generating electricity, in which case it will be advantageous to
make the several pieces of carbon as porous as possible.
As it is understood from the above, "natural" carbon is at present considered
to be a carbon of superior power of resistance or of a superior quality, obtainable
as bye-product, for instance in the manufacture of gas (such as retort-graphite);
of course also graphite may serve as "natural" carbon; "artificial" carbon is
generally obtained by calcining a paste essentially consisting of pulverulent

page_text: carbonaceous material mixed with water or a binding agent (such as tar, molasse,
starch or the like).
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. A carbon electrode to be used as ordinary electrode or double electrode
consisting of a combination of a body of artificial carbon with sinall pieces of carbon
of sufficient power of resistance (such as natural carbon, retort carbon or the like)
so as to increase the surface of the electrode relating to its bulk substantially as
and for the purpose set forth.
2. Method of manufacturing electrodes characterized by Claim 1 consisting in
fixing pieces of natural carbon (such as retort carbon or the like) on a paste-like
mass of carbonaceous material then calcining or burning such product so as to
convert the paste-like mass into a body of solid artificial carbon thereby
uniting the pieces of natural carbon with this body substantially as and for the
purpose set forth.
3. Method of manufacturing carbon electrodes characterized in Claim 1 by
burning or calcining a paste-like mass of pulverulent carbonaceous material so as
to produce a body of solid artificial carbon and then fixing or fastening pieces of
carbon of sufficient power of resistance (such as retort-carbon or the like) in grooves
or the like arranged in the said body of artificial carbon substantially as and for
the purpose set forth.
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HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.