Gutta-percha.
Year: 1886

page_text: Gutta-percha.
I, ALEXANDER MELVILLE CLARK, of the firm of A. M. and Wm. Clark, of
53, Chancery Lane, in the County of Middlesex, Fellow of the Institute of Patent
Agents, do hereby declare the nature of this Invention (a communication to me
from abroad by Wirth and Company of Frankfort on the Main in the Empire of
Germany, acting as Agents for Johann Jacob Haug and Caspar Hoffmann both of
St Petersburg in the Empire of Russia,) and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
This Invention consists in the manufacture of a peculiar substance which can be
used with advantage in place of caoutchouc and gutta percha, and which has the
advantage over these substances in its greater cheapness. Skins of hares, rabbits,
and other small animals, or the waste therefrom, are cleaned in water and deprived
of the hair in lime-water or any other suitable manner; and boiled, till completely
dissolved, in a Papin's digester with five per cent, by weight, of crude glycerine
and as small a quantity of water as possible. A thick tenacious substance is then
obtained, which can either be dried on nets in a well dried room, or further
worked. Three parts, by weight of this substance are melted in a water, or steam,
bath with three parts, by weight, of crude glycerine, after which one-fourth of a
part, by weight, of a concentrated solution of potassium chromate, or bichromate,
or other salt rendering gelatine sensitive to light, is added. The fluid mass is now
poured into moulds and left to solidify under pressure. After solidifying, the cast
masses are taken out of the moulds, and dried in a dark, airy, room. The
Buperfluous water is evaporated much quicker in a dark, than in a lighted, room;
because in the latter case the surface of the objects hardens too quickly, and thus
prevents the evaporation of the water in the mass. This substance is very similar
to vulcanized caoutchouc, and it possesses this advantage that it withstands heat
much better than the latter If a substance similar to hard india-rubber is wanted,
[Price 4d]

page_text: a little less glycerine and a little more chromate of potash is added; the same
being then dried under pressure between heated and polished metal plates.
A hardness equal to that of glass is obtained if, after drying, the objects are placed
in a solution of chrome-alum and then again dried; the substitute for hard india-
rubber so manufactured can be sawn, ground and polished. If the india-rubber
substitute is to withstand acids, then thirty per cent of gum lac dissolved in
alcohol must be added to the mass. By the addition of color, imitations as with
celluloid, of coral, malachite, etc can be made. If the mass is to be used for objects
which are required to have great elasticity, and to withstand a high degree of
compression, as in railway buffers, wheel-tyres, etc; one part only of crude
glycerine, and three fourths of a part, by weight, of ground cork are mixed with it.
In the manufacture of a composition for waterproofing fabrics one fourth of a part,
by weight, of ox-gall is added, and enough soft water to give it the consistency of
thick oil; one-fourth of a part, by weight, of chromate of potassium is, in this
case, added. The treacly mass so obtained is placed in a steam jacketted bath
furnished with a revolving roller under which the fabric to be waterproofed is
carried. The fabric treated with this composition is not only waterproof, but does
not become tacky with heat.
Having now particularly described, and ascertained the nature of the said
Invention; and in what manner the same is to be performed; I declare that what
I claim is
The manufacture, substantially as herein-described, of a substitute for caoutchouc
or gutta-percha, by boiling skins, or the waste therefrom, and glycerine, under
pressure; and adding to the treacly mass, while hot, glycerine and potassium
chromate or bichromate, or equivalent salt; with or without the addition of
ground cork, ox-gall, and coloring matter, according to the purpose for which the
product is intended.