IMPROVEMENTS IN INSULATING CONDUCTORS FOR ELECTRIC LIGHTING AND OTHER PURPOSES "
Year: 1882

page_text: LETTERS PATENT to Willoughby Smith of Wharf Road City Road, in the
County of Middlesex for an Invention of "IMPROVEMENTS IN INSULATING
CONDUCTORS FOR ELECTRIC LIGHTING AND OTHER PURPOSES
"
PROVISIONAL SPECIFICATION left by the said Willoughby Smith at the
Office of the Commissioners of Patents on the 28th December 1882.
WILLOUGHBY SMITH of Wharf Road City Road in the County of Middlesex
"IMPROVEMENTS IN INSULATING CONDUCTORS FOR ELECTRIC LIGHTING AND OTHER
PURPOSES
"
This Invention has for its object improvements in insulating conductors for
electric lighting and other purposes.
The insulation of the conductors for electric lighting is usually obtained by
covering them with gutta percha applied by passing the conductor and the gutta
percha together through a die.
The variety of gutta percha which can be worked in this way is very high in
price; attempts have been made to lessen the cost by mixing other materials with
such gutta percha but the results have hardly been satisfactory.
Now there are in the market qualities of gutta percha, which although they are
good insulators are not at present employed, otherwise than with a large admixture
of the costly variety.
This happens because such gutta percha cannot without admixture be worked
with a die.
Now I have discovered that the gutta perchas which cannot alone be applied to
a conductor by means of a die can be rendered workable by admixture with
ground coal and that so mixed they form compounds very suitable for the
insulation of such conductors as are employed in electric lighting and for other
purposes.
The gutta percha and the ground coal are thoroughly kneaded together and
the dough like mixture is then applied to the conductor in the usual manner.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Willoughby Smith in the Great Seal Patent Office on the
27th June 1883.
WILLOUGHBY SMITH of Wharf Road City Road, in the County of Middlesex.
"IMPROVEMENTS IN INSULATING CONDUCTORS FOR ELECTRIC LIGHTING AND OTHER
PURPOSES
"
This Invention has for its object improvements in insulating conductors for
electric lighting and other purposes.
The insulation of the conductors for electric lighting is usually obtained by
covering them with gutta percha applied by passing the conductor and the gutta
percha together through a die.
The variety of gutta percha which can be worked in this way is very high in
price attempts have been made to lessen the cost by mixing other materials with
such gutta percha but the results have hardly been satisfactory.
Now there are in the market qualities of gutta percha, which although they are
good insulators are not at present employed, otherwise than with a large admixture
of the costly variety.
This happens because such gutta perchas cannot without admixture be worked
with a die.
Now I have discovered that the gutta perchas which cannot alone be applied to
a conductor by means of a die can be rendered workable by admixture with
ground coal and that so mixed they form compounds very suitable for the
insulation of such conductors as are employed in electric lighting and for other
purposes.
In carrying out my invention I proceed as follows:-
I take by preference gutta percha of the cheaper sort such as cannot be used
alone in the ordinary process of covering wires and I mix the gutta percha with
finely powdered bituminous coal.
The coal which should be of good quality, is ground and sifted through sieves as
flour is prepared.
The admixture is made whilst the gutta percha is being masticated in the
ordinary way in a masticating machine; or by the use of rollers or by other means
the mixture may be brought about.
The proportions may be varied, if the object be simply to improve the working
of the composition through the covering die this object will be fully attained by
the addition of one part by weight of ground coal to from ten to five of gutta
percha but with the object of increasing the bulk of the compound and to attain
the maximum utility at a given cost the ground coal may be used in the
proportion of one part to two or three of gutta percha or even a larger proportion
of ground coal may be employed. The compound is applied to cover the wire or
strand serving as the conductor by pressing the compound out from a die through
which the wire or strand is also led. The compound is maintained in a plastic
condition by heat and the process is conducted in the same way as at present when
covering wires or strands with gutta percha.

page_text: By means of this invention electrical conductors may be well insulated at a much
smaller cost than at present.
What I claim is:-
Insulating electrical conductors by covering them through a die with a compound
of gutta percha and ground coal
In witness whereof I the said Willoughby Smith have hereunto set my
hand and seal this eleventh day of June in the year of our Lord One
thousand eight hundred and eighty three
WILLY SMITH
WILLY SMITH (19)