Improved Manufacture of Electrical Insulating Material.
Year: 1899

page_text: Date of Application, 19th Sept., 1899-Accepted, 2nd June, 1900
Improved Manufacture of Electrical Insulating Material.
A communication from JOHANN JUNGBLUTH, of Cologne, Germany.
I, Alfred Julius BOULT, of 111, Hatton Garden, in the County of Middlesex,
Chartered Patent Agent, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
;
The present invention relates to an improved manufacture of insulating
material which is especially suitable for tube or tubular structures intended to
hold, protect and insulate cables and like electric conductors.
The chief requirements of such material are that it should be hard, durable,
resistent against the effects produced by soil, liquid and the atmosphere, should
withstand heat, and frost and continuous dry or wet seasons and the like, whilst
being a non-conductor and of perfect insulating power. The insulating material
therefore must not be porous, nor apt to develop internal faults, after casting,
or moulding and hardening, such as rents, fissures and the like..
As a result of experiments it has been found that powdered carbonate of cal-
cium (limestone) forming the chief percentage and representing the hard stone-
forming ingredient intimately mixed with Trinidad asphalte, or with neutralite,
-the well-known asphaltic material manufactured by Reh & Co., Asphaltgesell-
schaft San Valentino of Berlin-or a like bituminous insulating material
forming the insulating ingredient and exposed to a certain degree of heat, pro-
duces an extremely valuable insulating material. These experiments have
proved that when the ingredients are thus treated at a temperature of about
300° C. a partial alteration and molecular re-arrangement takes place, resulting
in a homogeneous mass being formed.
When at the temperature of 300° C. a small percentage of selenite or the like
is added, by which means an easy flow of the mass is obtained which renders it
more adapted for casting or moulding purposes.
The percentage of each of the ingredients varies according to their nature.
As a result of many experiments made in connection with this matter Trinidad
asphalte and the so-called neutralite have been found to possess properties of
especial value for the production of such a material when used in connection
with selenite.
As examples of such compositions, which give very satisfactory results, two
formulae are here given showing the approximate proportions of parts.

page_text: As already stated, the relative percentages of the mixture will vary according
to circumstances. A
As additional and special advantages of this material it may be mentioned
that the atmosphere has no effect on it, that the constituents, both in quantity
and quality, are such as to ensure a rapid setting, and that as regards insulating
power it fulfils all the conditions of a perfect insulating material: **
Having now particularly described and ascertained the nature of the said
invention as communicated to me by my foreign correspondent and in what
manner the same is to be performed I declare that what I claim is:-
1. The manufacture of a bituminous stone-material for insulation purposes
consisting in mixing calcium carbonate with Trinidad. asphalte or a like bitu-
minous substance, together with a small proportion of selenite or the like, at a
temperature which will produce a re-action between the constituent parts, and
forming a homogeneous, uniformly compacted mass, substantially as described..
2. An electrical insulating material consisting of a mixture of carbonate of
calcium and selenite with Trinidad asphalte, neutralite or the like in substan-
tially the proportions stated.
Dated this 19th day of September 1899.
BOULT, WADE & KILBURN,
Agents for the Applicant.