Improvements in the Manufacture of Electrodes for Electrolytic ̈ Processes.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Electrodes for Electrolytic ¨
Processes.
I, AUGUST ZIMMERMANN, of 9 & 10, St. Mary at Hill, in the City of London,
Merchant, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by The Chemische Fabrik auf Actien vormals E.
Schering of 170 and 171, Mullerstrasse, Berlin, in the Empire of Germany)
to be as follows:-
The object of this invention is the manufacture of electrodes consisting of a
material indifferent to the usual solvents, such as glass, porcelain, mica, stone-
ware, enamel and the like covered with an alloy of the noble metals with other
metals and burnt in firmly. Under the term noble metals are to be understood
gold, silver, platinum and the other metals of the platinum group.
Many experiments have already been made to find a cheaper substitute for
the costly massive electrodes of the noble metals. Proposals of this kind have
been made in the German Patents No. 42217 and 67754 as also in Niaudet's
work "Die Galvanischen Elemente." Thus in the Specification of the Patent
No. 42217 a "precipitation of platinum upon a suitable_non metallic body such
as glass, burnt clay, ivory slate etc." is suggested. In the expired Patent
No. 67754 electrodes "of any desired silvered metal, of lead or of silvered glass
are proposed. Niaudet lastly mentions in discussing the galvanic elements the
possibility, by burning in platinum upon porcelain to procure a substitute for
the massive platinum electrodes but adds that the electrodes so formed would
have too great a resistance.
"
The latter is in reality the case. Thus to make pure platinum firmly adhere
to porcelain by burning in the temperature must be raised to such a degree that
the glaze softens. The platinum in consequence sinks into the softened glaze
so that on cooling the metal covering does not conduct electricity or conducts
very badly because of the too high resistance.
It is quite otherwise however when in place of the pure noble metals, their
alloys with other metals which lower their melting point such as bismuth,
bismuth and boron and the like are used. Such alloys still possess the valuable
properties of the noble metals so long as the quantity of the noble metal is
sensibly greater than that of the baser metal, but in burning in upon glass
porcelain and the like they behave in an essentially different manner from the
pure noble metals, for they burn in firmly upon the backing at a much lower
temperature, therefore sensibly more easily and before the glaze or the glass
softens. As therefore it is impossible for the metallic layer to sink in although
it adheres firmly and homogeneously, the whole surface of the burnt in alloy
is fully utilized for conducting electricity.
The relative quantities of the metals in the alloys may of course be varied
according to the effect desired and according to the backing chosen.

page_text: The backing may be covered with the noble metal alloy either by mixing
pure powdered noble metals by rubbing with a suitable flux such as basic bismuth
nitrate, boric acid or phosphoric acid, then placing it upon the backing and
burning in or by producing solutions of the metals in oils, placing them on
the backing and burning in. Also one may brush with solutions of metallic 5
salts produced with other solvents with the addition of a flux and burn in so
that an alloy is produced consisting mostly of noble metals.
The electrodes made in this manner are connected with the source of current
in the well known manner.
The alloy burnt in upon the backing may be strengthened if desired by electro- 1
lytic or galvanic deposits.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Electrodes for Electrolytic
Processes.
I, AUGUST ZIMMERMANN, of 9 & 10, St. Mary at Hill, in the City of London,
Merchant, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by The Chemische Fabrik auf Actien vormals E.
Schering of 170 and 171, Mullerstrasse, Berlin, in the Empire of Germany),
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 this invention is the manufacture of electrodes consisting of a
material indifferent to the usual solvents, such as glass, porcelain, mica, stone-
ware, enamel and the like covered with an alloy of the noble metals with other
metals and burnt in firmly. Under the term noble metals are to be understood
gold, silver, platinum and the other metals of the platinum group.
Many experiments have already been made to find a cheaper substitute for
the costly massive electrodes of the noble metals. Proposals of this kind have
been made in the German Patents No. 42217 and 67754 as also in Niaudet's
work "Die Galvanischen Elemente." Thus in the Specification of the Patent
No. 42217 a "precipitation of platinum upon a suitable non-metallic body such
as glass, burnt clay, ivory, slate etc." is suggested. In the expired Patent
No. 67754 electrodes 66
of any desired silvered metal, of lead or of silvered glass"
are proposed. Niaudet lastly mentions in discussing the galvanic elements the
possibility, by burning in platinum upon porcelain to procure a substitute for
the massive platinum electrodes but adds that the electrodes so formed would
have too great a resistance.
The latter is in reality the case. Thus to make pure platinum firmly adhere
to porcelain by burning in the temperature must be raised to such a degree that
the glaze softens. The platinum in consequence sinks into the softened glaze
so that on cooling the metal covering does not conduct electricity or conducts
very badly because of the too high resistance.
It is quite otherwise however when in place of the pure noble metals, their
alloys with other metals which lower their melting point such as bismuth,
bismuth and boron and the like are used. Such alloys still possess the valuable
properties of the noble metals so long as the quantity of the noble metal is
sensibly greater than that of the baser metal, but in burning in upon glass
porcelain and the .like they behave in an essentially different manner from the

page_text: pure noble metals, for they burn in firmly upon the backing at a much lower
temperature, therefore sensibly more easily and before the glaze or the glass
softens. As therefore it is impossible for the metallic layer to sink in although
it adheres firmly and homogeneously, the whole surface of the burnt in alloy
is fully utilized for conducting electricity.
The relative quantities of the metals in the alloys may of course be varied
according to the effect desired and according to the backing chosen.
The backing may be covered with the noble metal alloy either by mixing
pure powdered noble metals by rubbing with a suitable flux such as basic bismuth
nitrate, with or without the addition of boric acid or phosphoric acid, then
placing it upon the backing and burning in or by producing solutions of the
metals in oils, placing them on the backing and burning in. Also one may brush
with solutions of metallic salts produced with other solvents with the addition
of a flux and burn in so that an alloy is produced consisting mostly of noble
metals.
The electrodes made in this manner are connected with the source of current
in the well known manner.
EXAMPLES.
1.) 95 parts of fine platinum powder and 5 parts of basic bismuth nitrate
are rubbed with thick oil (resinous turpentine oil) to a uniformly thin pulp
which is placed by means of a brush upon a backing such as porcelain and the
like, and burnt in, in a muffle.
2.) 94 parts of fine platinum powder, 1 part of basic bismuth nitrate and
5 parts of boric acid or 5 parts of anhydrous phosphoric acid are rubbed and
burned in as in Example 1.
3.) 95 parts of platinum dissolved in sulphur balsam and 5 parts of bismuth
dissolved as an organic salt in oil are mixed together, the solution being laid
on by means of a brush, and after drying burnt in, in a muffle.
Serviceable electrodes may also of course be made by replacing the platiuum
in the above examples wholly or partially with other noble metals.
The alloy burnt in upon the backing may be strengthened if desired by electro-
lytic or galvanic deposits.
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. The manufacture of electrodes by coating glass, porcelain, mica, enamel,
stoneware or other similar material with an alloy of the noble metals with
bismuth and other metals substantially as described.
2. Strengthening the metallic coating of the electrodes forming the subject of
the first claim by electrolytic or galvanic deposits of the noble metals.
Dated this 6th day of Tu... 1900
AUG. ZIMMERMANN.