Compounds for Electrical Purposes.
Year: 1885

page_text: Compounds for Electrical Purposes.
We ALEXANDER MUIRHEAD of N° 3 Elm Court Temple E.C. in the City of
London, Doctor of Science, Electrical Engineer and CHARLES ROMLEY ALDER
WRIGHT of N° 3 Castillain Road Maida Vale in the County of Middlesex Doctor of
Science, Consulting chemist do hereby declare the nature of our Invention for
"IMPROVEMENTS IN THE PREPARATION AND PRODUCTION OF INSULATING COM-
POUNDS FOR ELECTRICAL PURPOSES" to be as follows:-
This invention relates to improvements in the manufacture of compounds of
gutta-percha with vulcanized or "oxidised" oils or other similar bodies being a
further extension of the two Letters Patent Nos 5835 of 1883 and 8077 of 1884
granted to one of us,
The object of our present invention is firstly to produce the elastic materials
required for admixture with gutta-percha from oils and fats in a more perfect
manner than that hitherto employed and secondly to render the elastic materials so
produced perfectly free from impurities especially unaltered and imperfectly con-
verted oily matters which are liable to depreciate the insulating power and to
facilitate decay.
In carrying out this invention we employ instead of chloride of sulphur certain
metallic salts which act upon oils suitable for the purpose causing them to undergo
a change in virtue of which the elements of water are partially removed from their
composition leaving behind a more complex or "polymerised" and partially
dehydrated substance which in certain cases assumes a cartilaginous texture
becoming a tough elastic body somewhat like that produced by means of chloride
of sulphur but not containing any sulphur.
The polymerised and dehydrated oils, when freed by washing or otherwise from
the metallic salts used in their production, may be incorporated by mastication with
gutta-percha yielding products very similar in texture and properties to those
obtained by masticating together gutta-percha and oils converted by means of
chloride of sulphur. Further, by incorporating with the mass flowers of sulphur or
[Prine 621

page_text: metallic sulphides or other sulphureous materials ordinarily used in vulcanising
and then subjecting to an adequate "curing" temperature the mixtures containing
the polymerised and dehydrated oils can be vulcanised and more or less toughened
or otherwise altered in texture.
We find that, of the numerous metallic salts known, those possessing a powerful
affinity for water and readily soluble therein, such as the chloride and bromide of
zinc and the anhydrous sulphate of copper answer best for the polymerising and
dehydration of oils; thus in order to convert castor oil into a cartilaginous material
it suffices to intermix thoroughly by stirring the oil at a temperature somewhat
above 100° C. and conveniently at between 140° and 150° C. with a concentrated
solution of zinc chloride possessing a specific gravity near 2; in a short time the
whole mass becomes a stiff jelly-like brownish red solid which on continued treat-
ment with water furnishes a solution of unaltered zinc chloride and a bulky mass
consisting of nearly white shreds of somewhat cartilaginous or fibrous texture.
The quantity of zinc chloride or bromide solution absolutely necessary to produce
this change does not necessarily exceed one fourth of the weight of the oil and
even smaller quantities will often suffice; but we prefer to use a larger proportion
say from three quarters of the weight of oil to an equal weight, as with this larger
proportion there is less liability to imperfect conversion of a portion of the oil,
whilst the zinc chloride is more readily dissolved out from the product and the
formation of cartilaginous shreds takes place more rapidly. The solvent action of
water on the zinc chloride or other metallic salt employed is greatly promoted by
masticating or grinding the mass with water between rollers or in any other con-
venient way; hot water may be used with advantage but is not indispensable.
When the jelly-like mass has been so completely penetrated by water that even the
interior of each small fragment has lost the original comparatively dark tint and
become yellowish-white like the exterior portions, the solution of metallic salt
may be wrung out of the mass by means of rollers or other convenient form of
pressure; the liquid thus expressed simply requires to be concentrated by evapora-
tion in order to be fit for use over again; in this way the great majority of the
metallic salt originally used may be recovered. The cartilaginous fragments thus
partly freed from metallic solution require further washing to remove the last
portions of metallic salt. The final washing may conveniently be effected with
water containing a small quantity of alkali in solution, the removal of the last
traces of metallic salt being usually thereby facilitated.
It sometimes happens that small portions of the oil originally used escape com-
plete conversion into jelly by the treatment or that other oils or resinous matters
are present which are not similarly converted; in certain such cases the final
cartilaginous particles may be advantageously. treated with bisulphide of carbon,
benzole, benzoline, or other convenient solvent for oils and resins in any convenient
extraction apparatus permitting of the recovery of the solvent employed by
distillation.
We employ the same process of purification to remove imperfectly converted
oil from the product of the action of chloride of sulphur on oils described in the
specifications of the patents above referred to.
In some cases, on the other hand, it is convenient to mix with and dissolve in
the oil originally treated a small quantity of less readily converted oil or of resinous
matter, paraffin, or other analogous substance which will prevent the action being
exerted to as full an extent as takes place with pure or nearly pure castor oil. In
this way it is possible to obtain a firm jelly which on treatment with water, and
more especially when well masticated in hot water, does not separate completely
into shreds, but yields as the metallic salt gets washed out a less voluminous but
more plastic and more coherent mass than that obtained from pure castor oil. The
products of this texture are usually softened or even melted by the application
of heat somewhat more readily than the more bulky and less coherent particles
obtained from castor oil alone, for certain purposes we find them highly useful as
L

page_text: an ingredient in a mass intended as a cheap insulating material; thus whilst a
plastic mass capable of being used in the ordinary covering machines at tempera-
tures above the boiling point of water may be obtained by the incorporation together
of gutta-percha and the washed product of the action of zinc chloride on pure
castor oil, a much smaller proportion of gutta-percha is requisite to produce an
equally plastic and serviceable composition if instead of the product from pure oil
there be employed a mixture of that product and the more plastic mass obtained
from castor oil mixed with a small proportion of its weight of linseed oil, colophony,
kowrie gum, or analogous resinous materials.

page_text: WAS
Compounds for Electrical Purposes.
We ALEXANDER MUIRHEAD of N° 3 Elm Court Temple E.C. in the City of
London, Doctor of Science Electrical Engineer and CHARLES ROMLEY ALDER
WRIGHT of No 3 Castellain Road, Maida Vale in the County of Middlesex,
Doctor of Science, Consulting Chemist do hereby declare the nature of our said
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
This invention relates to improvements in the manufacture of so called vulcanized
or "oxidised" oils and other similar bodies suitable for admixture with gutta
percha or india rubber for the preparation of insulating compounds for electrical
purposes and also for such other purposes as gutta percha and india rubber
are ordinarily used for; being a further extension of the two Letters Patent
No 5835 of 1883 and 8077 of 1884 granted to one of us.
The object of our present invention is firstly to. produce elastic materials from
suitable oils in a more perfect manner than that hitherto employed; and secondly
to purify such elastic materials so as to free them from impurities and more
especially from unaltered oily matters which are sometimes liable to depreciate
the insulating power or to facilitate decay, or otherwise to act injuriously on the
elastic materials or the compounds prepared from them.
In carrying out this invention we employ instead of chloride of sulphur certain
metallic salts which we have found to be capable of acting upon oils suitable for
the purpose causing them to undergo a change somewhat analogous to that taking
place in the white of an egg when boiled, or in the caseine of milk when curdled,
in virtue of which a more complex or "polymerised" solidified substance is
produced; this change is sometimes accompanied by partial dehydration; that is,
the final product contains in such cases less of the elements of water than the
original material. The oils thus solidified assume a cartilaginous texture becoming
tough elastic bodies somewhat like those produced by means of chloride of sulphur
but not containing any sulphur; when freed by washing or otherwise from the
metallic salts used in their production they may be incorporated by mastication
with gutta percha or india rubber, yielding products very similar in texture and
properties to those obtained by masticating together gutta percha or india rubber
and oils converted by means of chloride of sulphur. Further by incorporating with
the mass flowers of sulphur or metallic sulphides or other sulphureous materials
ordinarily used in vulcanizing, and, by then subjecting to an adequate "curing
temperature, the mixtures containing the solidified oils can be vulcanized and more
or less toughened or otherwise altered in texture. In certain cases the sulphur
may conveniently be dissolved or suspended in the oil before treatment with the
metallic salt used so as to produce ultimately a solidified body containing sulphur
in intimate admixture or in chemical combination or both.
"

page_text: We find that of the numerous metallic salts known those possessing a powerful
affinity for water and consequently readily soluble therein and more particularly
certain salts of zinc especially the chloride and bromide answer best for this
solidification of oils; and of these latter, those containing the glycerides of linoleic,
and ricinoleic acids are best suited for the preparation of elastic solid products by
treatment with such metallic salts. Castor oil more especially is well adapted for
this purpose being readily convertible into a tough brownish-red mass intermediate
in texture between stiff jelly and horn by intimate admixture with a highly
concentrated solution of zinc chloride at temperatures between 100° and 150°
Centigrade. On treatment of the product with water the zinc chloride is
gradually dissolved out, and the mass swells and finally becomes converted into
cartilaginous or fibrous elastic nearly white shreds. The precise degree of
consistency and the general texture of the solidified oil depends on the relative
proportion of zinc chloride used, and its degree of concentration, and also on the
temperature. When solution of zinc chloride is used which has been boiled down
until the boiling point of the fluid is 175° to 180° Centigrade the solidifying action
is more rapid and energetic than with less concentrated solutions of that salt;
such a liquid when cooled and allowed to stand becomes more or less solid through
partial crystallisation of hydrated zinc chloride, but is perfectly fluid at the
temperature of 100° Centigrade and upwards. To obtain the toughest or hardest
product castor oil is heated to a temperature of close to 125° Centigrade and is
then added to about three times its weight of zinc chloride of the above named
degree of concentration, viz. such as to boil at 175°-180° Centigrade, also at the
temperature of 125° or thereabouts; the whole is well intermixed by any con-
venient appliance that will agitate the mass thoroughly; in a few minutes the
oil thickens and rapidly becomes converted into a solid mass which becomes torn
into shreds and separate clots, if the agitating arrangement is sufficiently powerful;
these are kept stirred and intermixed with the zinc chloride for some three or four
minutes after solidification so as to subject them to a sort of extra "cooking
after which the still fluid zinc chloride is drained off, whereby about two-thirds of
the quantity originally used is regained in a state fit for use over again, whilst the
remainder is mechanically retained interspersed throughout the gelatinised oil,
and may be dissolved out therefrom by means of water, yielding a solution that
only requires to be boiled down until the boiling point rises to 175°-180° to be
also fit for use over again. In carrying out this operation the temperature of the
mixture of castor oil and zinc chloride must not be allowed to rise materially
above 130° Centigrade, especially when large masses of material are used, other-
wise a further action is apt to be set up in virtue of which a further change is
produced in the gelatinised oil rendering it partially fluid again and producing a
more or less viscid sticky product after washing with water instead of tough solid
shreds.
"
By using a smaller proportion of zinc chloride than three parts to one of oil
the texture of the mass may be modified; for example equal weights of oil and
zinc chloride (boiling at 175°-180°) when intermixed and kept at a temperature of
about 125° to 130° form a tough gelatinised mass from which little or no fluid zinc
chloride can be drained but from which all the intermixed zinc chloride can be
removed by treatment with water leaving fibrous elastic shreds of cartilaginous
texture not rendered quite so thoroughly solid as those obtained by treating oil
with three times its weight of zinc chloride as above described.
By reducing the weight of zinc chloride below that of the oil somewhat softer
ultimate products are obtainable, so that when only one part of zinc chloride to
two or three of oil is used the solidified oil ultimately obtained after thorough
washing with water gives a distinctly softer mass on incorporating with a given
amount of gutta percha than is formed by similarly incorporating the oil solidified
by means of larger amount of zinc chloride. Still softer products are obtainable
by employing temperatures below 125° Centigrade. At 100° Centigrade a much

page_text: longer time is required to produce solidification of the oil than at higher tem-
peratures; so that by interrupting the process at an intermediate stage a product
of any required soft consistency may be obtained. Similar variations in consistency
may also be produced by causing the action between the zinc chloride and castor
oil to take place at bigher temperatures than 130° Centigrade; viz. at 145° to
150° Centigrade, and for longer periods; only by operating in this way the
consistency is less under control as the softening effect in this case is due to the
further action above mentioned as occurring when the gelatinised oil is over-
heated in contact with zinc chloride whilst by treating at lower temperatures
the softness is due rather to under "cooking" than to over "cooking" and can
consequently be more readily controlled. Again, variations in consistency may be
produced by using less concentrated zinc chloride solution than that above specified,
viz. liquid boiling at 175°-180° Centigrade; the lower the boiling point of the
liquid the less energetic the solidifying action.
-
The solvent action of water on the zinc chloride or other metallic salt used is
greatly accelerated by grinding the gelatinised mass between fluted rollers or in
any other convenient way so as to tear up the horny lumps and promote the access
of water to their interior; hot water may be conveniently used but is not
indispensable.
When the gelatinised oil has been so completely penetrated by water that the
interior of each small part has lost the original comparatively dark tint and
become yellowish-wbite like the exterior portions the solution of metallic salt may
be wrung out of the mass by means of rollers or other convenient means of
pressure and the shreds again washed with water and so on until completely freed
from soluble metallic salts. To diminish the cost of evaporation in the recovery of
dissolved zinc chloride it is convenient to treat the liquor methodically; moderately
strong solutions being employed for fresh solidified oil so as to yield a still stronger
solution on expression from the shreds which are then treated with weak solutions
or with fresh water, the weak liquors thus obtained being used for another batch
and so on.
It sometimes happens that small portions of the oil originally used escape
complete conversion into jelly by the treatment or that other oils or resinous
matters are present which are not similarly converted; in certain such cases the
final cartilaginous particles may be advantageously treated with bi-sulphide of
carbon, benzole, benzoline, or other convenient liquid capable of dissolving
unconverted oils and resins, but not of dissolving solidified oils, in any convenient
extraction apparatus permitting of the recovery of the solvent employed by
distillation. We employ the same process of purification to remove imperfectly
converted oil from the product of the action of chloride of sulphur on oils described
in the Specifications of the Patents above referred to.
In some cases on the other hand it is convenient to mix with and dissolve in the
oil originally treated a small quantity of less readily converted oil, or of resinous
matter, paraffin, or other analogous substance which will prevent the action being
exerted to as full an extent as takes place with pure or nearly pure castor oil. In
this way it is possible to obtain a more or less completely converted product which
on treatment with water, and more especially when well masticated in hot water,
does not separate completely into shreds but yields as the metallic salt gets
washed out a softer or more plastic mass than that obtained from pure castor oil
under the same conditions. These softer and more plastic products, whether
prepared in this way or as previously described by treating castor oil with smaller
proportions of zinc chloride or otherwise, are usually rendered semi-fluid or almost
melted by the application of heat more readily than the more solid products
obtained as above described from castor oil alone; for certain purposes we find
them useful as ingredients in a mass intended as a cheap substitute for gutta percha
as an insulating material or for other purposes; thus whilst a plastic mass capable
of being used in the ordinary covering machines at temperatures above the boiling

page_text: point of water may be obtained by the incorporation together of gutta percha or
india rubber and the most thoroughly solidified product of the action of zinc
chloride on pure castor oil; a much smaller proportion of gutta percha is requisite
to produce a plastic and serviceable composition, if instead of the most thoroughly
solidified product from pure oil, there be employed a mixture of that product and the
more plastic substances obtained as above described.
Serviceable compositions for insulating and other purposes may also be prepared
by incorporating the plastic or cartilaginous products prepared as above described
with "oxidised" oils, oils vulcanized by means of chloride of sulphur or otherwise,
resinous and bituminous matters, vulcanized gutta percha and india rubber, and
similar substances or mixtures of them: when requisite either for the purpose of
diminishing combustibility or for other reasons, mineral matters such as oxide of
zinc, powdered steatite, french chalk and analogous substances ordinarily used for
such purposes may be also incorporated in the mass.
Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed we declare that what
we claim is :-
1. The method hereinbefore described of solidifying castor or other suitable oil
so as to obtain products of varying consistence as required, cartilaginous or plastic,
by treating the oil with zinc chloride or other salt exerting a similar dehydrating
and polymerising action upon oils, substantially as above described.
2. The preparation of solidified oils containing in intimate admixture or
chemical combination sulphur by dissolving in or mixing with the oil previous
to solidification the requisite amount of that element, substantially as above
described.
3. The use of oils solidified as hereinbefore described, either alone or in con-
junction with sulphur, as ingredients in mixtures intended as substitutes for gutta
percha as insulating materials and for other purposes; and more especially in
connection with gutta percha or india rubber; or vulcanized or
" oxidised" oils;
or resinous or bituminous substances; or with vulcanized gutta percha or india
rubber; or with mixtures of such bodies; with or without the addition of mineral
matters.
4. The treatment of oils solidified as hereinbefore described or by means of
chloride of sulphur, with bi-sulphide of carbon, benzole, benzoline, or other solvents
capable of dissolving ordinary unsolidified oil or admixed resinous matters, but not
of dissolving solidified or sulphurised oil, for the purpose of purifying the products
obtained substantially as hereinbefore described.