An Improved Manufacture of Gunpowder.
Year: 1897

page_text: Date of Application, 30th Oct., 1897-Accepted, 4th Dec., 1897.
An Improved Manufacture of Gunpowder.
I, JOSEPH CRAWHALL, CHAPMAN, of 70, Chancery Lane, in the County of London,
Chartered Patent Agent, do hereby declare the nature of this invention (which has
been communicated to me from abroad by Carl Walter Volney, Chemist, of
734 East 139th Street, in the City, County and State of New York, in the United
States of America), and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
My invention is applicable to all those gunpowders which contain gun cotton, or
nitrates of cellulose.
In general, the nitrates of cellulose are divided into two classes, distinguished from
each other by their degree of nitration, their solubilities and their ballistic qualities.
The higher nitrate, the hexa-nitrate, or tri-nitro cellulose, possesses great strength as
an explosive and is for ballistic purposes of limited usefulness, caused by its peculiarity
of quick combustion. The lower nitrates, comprised under the designation of
di-nitro-cellulose, burn slower and dissolve in nitro-glycerine and other kindred
substances, forming therewith compounds which retain and bind such substances and
prevent thereby, more or less, exudation and evaporation.
On account of its strength and stability, it is desirable to use tri-nitro-cellulose in
the composition of gunpowders, and I overcome the above indicated drawbacks in its
use for ballistic purposes by changing the tri-nitro-cellulose, on the surface of the
grains or shaped masses of gunpowder, into di-nitro-cellulose, so that each grain or
mass of powder consists of a core of tri-nitro-cellulose and a surface coating of
di-nitro-cellulose. By the process hereinafter described, this is effected in those
grained powders which consist of gun-cotton alone, or contain, besides gun-cotton,
other admixtures.
For this purpose, I subject the granulated powder, containing, or composed of
tri-nitro-cellulose, to the suitable action of reducing agents, whereby the tri-nitro-
cellulose on the surface of the grains or masses is reduced to di-nitro-cellulose which
readily combines, in this surface or coating of each grain, with the other constituent
parts of such grains, as nitro-glycerine, and which forms a desirable slow burning
coating, or sphere over a core of quick burning tri-nitrocellulose in each grain or
mass.
Many substances have the desired reducing effect on tri-nitro-cellulose, such as
caustic alkalies, and certain other metallic oxids, alkaline sulphite, and hydrogen
sulphite, and lower oxids of metalloids; I find that the alkaline sulphites, and hypo-
sulphites are very convenient and effective, and I prefer to use them for the described
purpose.
For the practical execution of my invention, I subject the grained gunpowder to
the action of aqueous solutions of the reducing agents in suitable vessels, providing
an intimate contact of each grain with the solution of the reducing agent. The
strength of the solution may vary; but I find a solution, containing three per cent.
In a
of ammonium, or sodium sulphite, or hypo-sulphite, sufficiently effective.
general way, stronger solutions will have to be used with precaution, so as to properly
limit the reaction on the tri-nitro-cellulose. A solution of three per cent. strength

page_text: will produce a desirable surface coating in six hours. As a rule, finely grained
powder should be exposed to the redeeming medium for a shorter time than coarse
grained powder. After the described treatment, the grains are taken from the bath,
washed in pure water, to remove all traces of the products resulting from the reducing
process, and dried. They then represent a very stable surface and may be polished,
or treated in the usual manner.
The described method is applicable to all those powders which are composed of
gun-cotton, or which do not contain substances easily soluble in water. The process
itself, however, may be used also with those powders which contain matter, too soluble
in water, and where, therefore, its use is excluded. In such cases, the moistening of
the grains with alcohol, acetone, ether, or kindred liquids, which do not dissolve any
constituent part of the grained gunpowder, and exposure of such moistened grains to
the reducing action of gaseous ammonium sulphite, or hydrogen sulphite in the
usually employed apparatus for such purposes, 'will produce the above-described
surface coating of the gunpowder grains, by reducing the tri-nitro-cellulose on the
surface to di-nitro-cellulose; for all those powders, however, which consist of gun-
cotton, or do not contain substances which are readily dissolved and extracted by
water, the herein-aboved described method of exposing the powder to a bath of
dissolved alkaline sulphites, or hypo-sulphites, is effective and preferable.
Having now particularly described and ascertained the nature of my said invention
(as communicated to me from abroad) and in what manner the same is to be performed,
Ì declare that what I claim is :
1. The process of providing grains of gunpowder, containing tri-nitro-cellulose,
with a surface coating of di-nitro-cellulose by reducing the tri-nitro-cellulose upon
such surface to di-nitro-cellulose by reducing agents, such as alkaline sulphites, for
the purpose and in the manner herein before described.
2. As a new article of manufacture, a grain of gunpowder herein described,
consisting of a core of tri-nitro-cellulose and an integral surface coating of
di-nitro-cellulose.
Dated the 20th day of October 1807