A NEW OR 1MPROVED PROCESS FOR INCREASING THE CONDUCTIBILITY OF AND FOR INSULATING ROUND OR FLAT CABLES OR WIRES EMPLOYED IN THE CONSTRUCTION OF MAGNETO AND DYNAMO MACHINES AND OTHER ELECTRICAL APPARATUS.
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Benjamin Joseph Barnard Mills at
the Office of the Commissioners of Patents on the 30th October 1882. A
communication to him from abroad by Théophile Chutaux of Paris in the
Republic of France.
BENJAMIN JOSEPH BARNARD MILLS of the firm of Harris and Mills of
23 Southampton Buildings in the County of Middlesex Patent Agent A NEW OR
1MPROVED PROCESS FOR INCREASING THE CONDUCTIBILITY OF AND FOR INSULATING
ROUND OR FLAT CABLES OR WIRES EMPLOYED IN THE CONSTRUCTION OF MAGNETO
AND DYNAMO MACHINES AND OTHER ELECTRICAL APPARATUS. A communication
to me from abroad by Théophile Chutaux of Paris in the Republic of France.
It being granted that sterling silver is the only metal which would procure a
maximum conductibility, in order to serve as a basis for the following comparative
description the value of conductibility is taken at 100; but the high price of this
inetal does not permit of its employment in large quantity.
The present Invention consists in giving to the conductors ordinarily employed
in the construction of electrical apparatus a conducting value approaching most
nearly to that of solid silver without being obliged to incur the cost of the latter.
Before commencing to describe the present invention I would remark that the
coppers known as "rose coppers" employed for the manufacture of round or flat
conductors and of electrical cables, insulated or not, contain for the most part, in
various but notable proportions, sulphur, arsenic, lead, antimony and other metals
whose conductibility is very low. It is not rare to find conductors. having a
conductibility of only 30 per cent at the minimum; but on the contrary it is very
rare to meet with any having at the maximum 99 per cent of chemically pure
copper.
It is easy to understand the bad condition of working of apparatus constructed
with products inferior to this latter as compared with the conductibility of silver,
when the best copper (that very rare having 99 per cent of pure copper) represents
only about 91 per cent of that of silver, even if it should be uniform in all the
parts, which is nearly impossible to procure even in a limited manufacture,
ID 571

page_text: It being granted, and a matter of notoriety, that it is not the mass represented
by the body of an electric conductor which offers conductibility for the passage of
the current, but it is the exterior surface, the inventor has had the idea, in view of
the result of electric conductibility to be obtained to take the copper conductors of
commerce and cover them by any suitable means with a coating of silver relatively
thin, to render them of a high conductibility superior to that of chemically pure
copper, and in certain cases capable even of surpassing that of the silver of
commerce which contains an alloy of copper. In addition to these advantages it
has that of having the same conducting value in all parts of a length of wire.
In the first case, by coating with silver, poor coppers of an average conductibility
of 60 per cent, there would be obtained a conducting value and consequently
superior product of 40 per cent, thus weakening the resistances, which are the
ordinary cause of the heating of coils of conductors.
Even in the event of employing conductors of 90 per cent which would be
replaced by the silvored products, the superiority of production would be about
19 per cent, and by-treating wires even of 99 per cent of pure copper, there would
be a superior value of about 12 per cent.
The invention therefore consists in the process above described and in the
application of silvered conductors, round or flat, to the manufacture of electro
magnets generally employed in the construction of electrical machines and apparatus
of all systems.
In addition to the silvering pure and simple of electric wires, the invention also
¯consists in coating-electric-wires with silver then with a coating of copper and
lastly with a conting of silver or other metal. These coatings are superposed in-
variable number according to the scientific or industrial requirements of the
apparatus employed. A wire coated with the several coatings above described
may be further coated with a layer of sulphur and lastly as a complement to the
above manufacture-the-invention-also-consists in the oxidation of the surface of the
wire by any chemical means in order to produce an insulator which can be in
certain cases sufficient in the relations of coils amongst themselves when wound
upon bobbins and dispensing with the thickness of the insulating coating ordinarily
employed.
The coating of silver being the last it is only necessary to submit the conductors
to a prolonged sulphuration.