An Improved Insulating Compound.
Year: 1890

page_text: Date of Application, 15th Apr., 1890-Accepted, 5th July, 1890
MILEIN DIECIFICATION.
[Communicated from abroad by ADOLPHUS ALVARD KNUDSON, of Brooklyn, New
York, United States of America, Electrician.]
An Improved Insulating Compound.
I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
Southampton Buildings, in the County of Middlesex, 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 :-
I have discovered an insulating material or compound, the distinguishing feature of
which is the presence therein as an essential ingredient, of carbolic acid which is
combined with shellac or its equivalent, hereinafter described. This compound
exhibits characteristics not found in either of its component parts, and forms a highly
useful and valuable material for insulating electrical conductors, whether it be applied
directly to the same and used alone as a flexible covering or in other ways as for
saturating the fibrous coverings employed in the insulation and protection of con-
ducting wires.
I have secured the best results by using about equal parts of shellac and carbolic
acid, the resulting compound being a dense, flexible and very tough substance
resembling india-rubber but the proportions may be varied with the result of
increasing the flexibility of the compound by an excess of carbolic acid, and lessening
somewhat its tenacity by using a greater proportion of the other ingredient.
I prefer to combine the two substances by heating carbolic acid until it boils slowly
or simmers and then adding the shellac or other insulating material, and stirring it
until thoroughly mixed, but I may obtain practically the same results, by dissolving
the insulating material with such a volatile solvent as alcohol then mixing it with the
carbolic acid, and afterwards evaporating out the solvent.
Like other insulating compounds this may be applied while hot to the fibrous
materials to be used as coverings for a conductor or it may be applied directly to a
wire to form a coating or covering therefor, in the way in which gutta-percha, kerite,
and other like substances are applied for a like purpose.
The peculiar advantages of this compound as an insulator I have found to result
from the action or effect of the carbolic acid upon the insulating material with which
it is combined. For example, using it with shellac, vegetable drying oils, asphaltum,
resins or similar gums generally, I produce a semi-plastic or slightly plastic mass,
remarkably tough and tenacious, which is but to a small degree sensitive to extremes
or changes of temperature which presents a hard smooth surface, and which is an
excellent insulator.
The invention consists, therefore in combining with an insulating material, which
by heat or by the addition of alcohol, carbon bisulphide, ether, or other well known
solvents or menstrua, may be brought to a viscous condition, carbolic acid in equal
proportions or in a sufficient proportion, in each case, to impart to said material the
physical characteristics which I have above described.
Substances like paraffine, which appear either as solids or as thin fluids without
sufficient cohesion to entitle them to classification as viscous substances, I do not find
it desirable to use unless in composition with other substances, such for example, as
asphaltum inasmuch as their physical characteristics are not substantially changeless
nor do they, so far as I have been able to ascertain, unite with the carbolic acid.
The carbolic acid which I use, is the ordinary carbolic acid of commerce. This, as
is well known, is very impure, but very excellent results are secured by its use. I
wish to include, however, under the term "carbolic acid," pure carbolic acid known
also as phenol, phenic acid, phenylic alcohol or hydrate of phenyl, as also creosote,
particularly commercial creosote, which appears to consist largely of carbolic acid.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed as communicated to me
by my foreign correspondent, I declare that what I claim is :-
First. A plastic insulating compound, consisting of substantially equal proportions
of carbolic acid and an insulating substance capable of being brought to a viscous
condition, as set forth.
Second. A plastic insulating compound, consisting of carbolic acid and shellac or
its described equivalent, in substantially the proportions stated.
Third. The combination, with an electric conductor, of an insulating or protecting
covering, consisting of or containing carbolic acid united with an insulating substance,
in substantially the proportions set forth.
Dated this 15th day of April 1890.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.