An Improvement in Copper Castings for Electrical Purposes.
Year: 1894

page_text: Date of Application, 21st Aug., 1894
Complete Specification Left, 18th May, 1895-Accepted, 22nd June, 1895
PROVISIONAL SPECIFICATION.
[Communicated from abroad by Dr. EUGEN OBACH, of Friedrichroda, Thüringen,
Germany, Chemist.]
An Improvement in Copper Castings for Electrical Purposes.
We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate,
Westminster, in the County of Middlesex, Electrical Engineers, do hereby
declare the nature of this invention to be as follows:-
H
Hitherto it has been found difficult to employ cast copper articles for electrical
purposes, because pure copper does not make sound castings and the addition of any
other metal, in order to obtain homogeneous castings, has always greatly impaired
their conductivity; in consequence hereof articles in which a high standard of
conductivity is required have generally been made of forged copper, rendering
them comparatively expensive.
This invention has for its object to obviate this defect in such copper castings
and consists in mixing with the copper employed a small proportion of lead. Such
addition of lead renders the metal much more fluid when in a molten state, thus
enabling much sounder castings to be made than with ordinary pure copper.
It has been discovered that the addition of the lead detracts but very little from
the conductivity of the metal and, so far as experiments have been made, in a far
less degree than the addition of either tin or zinc, which metals have hitherto
generally been employed to improve the castings.
Dated this 21st day of August 1894.
ABEL & IMRAY,
Agents for the Applicants.
An Improvement in Copper Castings for Electrical Purposes.
We, SIEMENS BROTHERS & Co. LIMITED, of 12 Queen Anne's Gate,
Westminster, in the County of Middlesex, 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 :-
Hitherto it has been found difficult to employ cast copper articles for electril
purposes, because pure copper does not make sound castings and the addition of
most other metals in order to obtain homogeneous castings, has always greatly
impaired their conductivity; in consequence hereof articles in which a high
standard of conductivity is required have generally been made of forged copper
rendering them comparatively expensive.
This invention has for its object to obviate this defect in such copper castings,
and consists in mixing with high conductivity-copper a small proportion of pure
lead. Such addition of lead renders the metal much more fluid when in a molten
state, thus enabling much sounder castings to be made than with pure copper
alone.

page_text: It has been discovered that the addition of a certain proportion of pure lead,
preferably from 0.5 to 1.5 per cent detracts but very little from the conductivity of
the metal and, so far as experiments have been made, in a far less degree than
the addition of either tin or zinc, which metals have hitherto generally been
employed to improve the castings.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
An improved manufacture of copper castings for electrical purposes, consisting in
the admixture of a small quantity of pure lead with the high conductivity-copper,
substantially as and for the purposes set forth.
Dated this 18th day of May 1895.
ABEL & IMRAY,
Agents for the Applicants.