IMPROVEMENTS IN THE MANUFACTURE OF COMPOUNDS TO BE USED FOR INSULATING, PROTECTING, OR ANALOGOUS PURPOSES
Year: 1883

page_text: LETTERS PATENT to Alexander Muirhead of 3 Elm Court, Temple, City of
London for an Invention of IMPROVEMENTS IN THE MANUFACTURE OF
COMPOUNDS TO BE USED FOR INSULATING, PROTECTING, OR ANALOGOUS
PURPOSES
PROVISIONAL SPECIFICATION left by the said Alexander Muirhead at the
Office of the Commissioners of Patents on the 22nd December 1883.
ALEXANDER MUIRHEAD of 3 Elm Court, Temple, City of London "IMPROVE-
MENTS IN THE MANUFACTURE OF COMPOUNDS TO BE USED FOR INSULATING
PROTECTING OR ANALOGOUS PURPOSES
"
This invention has for its object improvements in the manufacture of gutta-
percha and compounds of gutta-percha with vulcanized or oxidized oils and other
bodies for insulating and protecting electrical conductors or for other purposes
I dissolve out the gutta-percha from the raw material by means of melted
paraffin wax or other hydro-carbon at a high temperature (with the addition of
Sulphur in some cases) To the solution of Gutta-percha in paraffin wax with or
without the admixture of Sulphur I sometimes add finely powdered silicated
compounds such as blown-out furnace slag or what is known as silicated cotton.
This mixture I find valuable in the preparation of tape or canvas for the outside
covering of submarine cables.
I may also produce a form of vulcanized Gutta-Percha which is sufficiently
plastic to be put on electrical conductors through dies as in the ordinary manu-
facture of Gutta-percha covered wires.
To effect this vulcanization I first of all prepare a compound of Sulphurized
Castor oil or other similar oil with Paraffin oil or other hydrocarbon by stirring
violently a mixture of paraffin oil bi-sulphide of Carbon and Chloride of Sulphur
with the Castor oil until the action of the Chloride of Sulphur commences
The compound so produced is washed in Paraffin oil and thoroughly incorporated
by hot mixing rollers for example with some of the gutta percha to be vulcanized
and then the compound thus formed is subjected to a temperature of from about

page_text: 280° to 300° Fahrenheit for two or three hours under pressure when an elastic
compound like India-rubber is produced.
This compound I find to be valuable for mixing with the inferior qualities of
gutta percha which from their brittleness are now useless for covering wires.
Sometimes I merely mix the compound of Sulphurized oil with Paraffin oil
prepared in the manner above described with the inferior gutta percha on mixing
rollers and pass the mixture through the covering machine at a temperature high
enough to produce the partial vulcanization of the Gutta-percha.
Sometimes I add purified bitumen to the above compound to produce a cheap
material for commoner purposes.
To produce a harder compound I dissolve a quantity of a gum such as Kauri or
New Zealand Gum in the Castor oil before the treatment with Chloride of
Sulphur above described

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Muirhead in the Patent Office on the 21st June 1884.
ALEXANDER MUIRHEAD of 3 Elm Court, Temple, City of London " IMPROVE-
MENTS IN THE MANUFACTURE OF COMPOUNDS TO BE USED FOR INSULATING,
PROTECTING OR ANALOGOUS PURPOSES."
The use of gutta percha for insulating and analogous purposes is well known, but
there are certain difficulties connected with the use of the commoner qualities
which it has hitherto been found impossible to overcome.
Now the object of the present Invention is to produce in a simple and
economical manner, gutta percha compounds suitable for insulating or protecting
electrical conductors and for analogous purposes, by the use of which the difficulties
hitherto experienced will be avoided.
In carrying out my Invention with respect to the production of a compound to
be used chiefly in the preparation of tape or canvas for the outside covering of
submarine cables, I take the raw gum and dissolve out the gutta percha by means
of melted paraffin wax, or other hydro carbon at a temperature not exceeding the
boiling point of the hydrocarbons employed.
The higher the temperature at which the paraffin is maintained the greater is
its solvent power, and I therefore maintain it at as high a temperature as possible
not exceeding the limit before mentioned, in order to obtain a solution containing
the maximum amount of gutta percha.
The mixture of paraffin and gutta percba thus produced may then be treated
with hot water or steam in any well known and convenient manner to remove the
impurities held in suspension, or preferably it may be treated with bi-sulphide of
carbon according to the method adopted in the purification of refuse grease, wax
and similar materials
The purified mixture is then used in the preparation of the tape or canvas for
the outside covering of submarine cables.
When the gutta percha is of the lowest quality I find it desirable to add a small
proportion of sulphur to the paraffin wax, say from about ten to fifteen per cent.
In order to obtain a tough and more resisting surface, I add to the solution of
gutta percha in paraffin wax, some finely powdered silicated compound, such as
blown out furnace slag, or what is known as silicate cotton or slag wool.
In carrying out my Invention as applied to the coating of electrical conductors
I produce a partially vulcanized compound from gutta percha and sulphurized oil
which will be sufficiently plastic to put on the wires by passing them through dies
as in the ordinary mode of manufacturing gutta-percha-covered wires.
In preparing this compound I take paraffin oil or other hydro carbon mixed with
bisulphide of carbon, and add thereto chloride of sulphur; I them intimately mix
the whole in any suitable apparatus with vegetable oil, until an effervescent action
commences. When this action has subsided an elastic spongy mass remains.
The proportion of these materials which I find to yield a good product is
100 parts by weight of vegetable oil, say Castor oil, 25 parts of bisulphide of
carbon, 16 parts of paraffin oil, and 16 to 20 parts of liquid chloride of sulphur.
The compound thus produced is washed in paraffin oil, the excess of oil is pressed
out in any convenient manner and the compound is thoroughly incorporated by
hot mixing rollers with the gutta percha obtained as above described or in the
ordinary manner, in the proportions of 3 parts by weight of gutta percha to 2 parts
of oil compound.
The mixture thus formed is subjected to a temperature of from 280° to 300°
Fahrenheit for from 2 to 3 hours under pressure, when an elastic compound like
india rubber will be produced,

page_text: This compound when ground up in varying proportions with the inferior
qualities of gutta percha which from their brittleness are now useless for the
purpose, can be passed through dies with the wires to be coated in the usual way.
Or I may mix the sulphurized oil compound at once with the inferior quality
gutta percha on mixing rollers, and pass the mixture through the covering machine
at a temperature high enough to effect the partial vulcanization of the gutta
percha.
To produce a cheap material for common purposes such as coating wires for
electric lighting I may add to the above compound a proportion according to fancy
of purified bitumen.
If a harder compound is required I dissolve in the oil before treatment with the
chloride of sulphur a quantity of Kauri or similar gum, in the proportion of
30 parts by weight of Kauri gum to 100 parts of oil.
" and
Having now described my Invention for "Improvements in the manufacture of
compounds to be used for insulating, protecting or analogous purposes
explained the manner of carrying the same into effect I claim :-
First The compound to be used in the preparation of tape or canvas for the
outside covering of submarine cables prepared substantially as described.
Second The production of a partially vulcanized plastic compound for coating
electrical conductors substantially as described.
Third In the manufacture of compounds to be used for insulating protecting or
analogous purposes dissolving out the gutta percha from the raw material by means
of melted paraffin wax, or other hydro carbon at a high temperature, substantially
as described.
In witness whereof I the said Alexander Muirhead have hereunto set my hand
and seal the nineteenth day of June in the year of our Lord One thousand eight
hundred and eighty four.