Year: 1898

page_text: Date of Application, 28th Dec., 1898-Accepted, 28th Jan., 1898
A communication from FREDRIK ALARIK LIEDBECK, Chemical Engineer, of Stockholm,
in the Kingdom of Sweden.
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 ascertained
in and by the following statement :-
According to methods hitherto known, smokeless gun-powder 18 manufactured
from pure nitro-cellulose, oxy or hydro-nitio cellulose, nitro starch on other nitrated
hydrocarbon, nitro-mannite or nitro-erythrite, by their being gelatinized by means
of some volatile solvent, for instance other and alcohol, acetic ether or acetone and
subsequently rolling the plastic mass thus produced into thin sheets or leaves which
are cut up into small flat grains, the volatile solvent being then removed by slow
evaporation. It is impossible however, to carry out the last-mentioned operation
completely, since in the rolling of the explosive material there 18 forined on the
surface of the leaves a hard layer from which the solvent has evaporated more or less
completely and which then render the removal of the remaining part of the volatile
ingredients from the interior of the grains of powder more difficult. The pure nitro-
cellulose powder, so called therefore always contains part of the solvent which
gradually evaporates only after a prolonged storeage. In consequence of this fact, a
certain, if slight degree of porosity cannot be avoided, which increases the
explosive power of the powder and causes an increased pressure in the fire-arm
The said difficulties and objections increase considerably with the thickness of
the powder. Also in practice it has been impossible to produce a gun-powder of
pure nitro-cellulose with a greater thickness of the grains than 0.8 to 1, o m/m,
dimensions, adapted principally for the guns of position and field artillery
longer and heavier pieces for fortification and navy artillery resource has as a rule
been had to powders which contain a non-volatile, explosive solvent, as nitro-
glycerine or an addition of salts having a damping action
For
The objectionable features mentioned are avoided by the method embodied in this
invention, by the application of which, on the one hand, leaves of arbitrary thickness
suited for use even in the heaviest calibers of guns, can be produced from pure
nitro-cellulose, and, on the other hand, a progressive powder, consisting of the
substances above mentioned, can be obtained.
The method consists in spreading a solution of nitro-cellulose, alone or mixed
with a solution of oxy or hydro-nitio-cellulose, nitro starch or other nitrated hydro-
carbon, nitro-mannite or nitro-erythrite, successively in very thin layers one on top
of the others and allowing the solvent to evaporate from each layer before the
next is added, the rate of evaporation being increased by conducting a current
of hot air across the surface, or by carrying out the spreading operation in a
heated chamber or vacuum. The operation is so conducted that the solvent will
be completely removed from a preceding layer before a succeeding layer is added.
In this manner a powder completely free from the solvent is obtained.

page_text: By employing the method in question a progressive powder can also be produced
This 18 accomplished by first producing a film as above described, of nitro-cellulose
etc., of a low degree of nitration, for instance containing 10% of nitrogen, and then
applying on said film a thicker layer of gun powder of a high degree of nitration
for instance containing 13.5% of nitrogen, whereupon this layer is again provided
with a coating of low nitiated gun-powder. In this manner a powder sheet 18
obtained consisting of two outer layers of low nitrated slow burning powder and one
intermediate layer of high nitrated powder, which burns more quickly, which sheet
can either be employed directly, rolled up, chiefly adapted for charges for heavy
pieces of artillery, or it may be cut into strips or pieces of suitable form for powder
for hand fire-arms and cannons Evidently more than three layers may be
arranged on the top of the other It is then only necessary to take care that
the outer layer on each side of the cake, leaf, sheet or cylinder obtained will posess
a lower degree of nitration, than the inner layers which may be nitrated all to the
same degree, or to different degrees. It is also possible to produce the progressive
powder in the shape of solid cylinders consisting of a core of a high degree of
nitration and exterior layers of a degree of nitration decreasing toward the circum-
ference of the cylinder so that the outermost layer will have the lowest degree of
nitration.
In the accompanying drawing an apparatus for the practical carrying out of the
invention is shown in Fig 1 in a vertical section on the line a-b of Fig. 2 and in
Fig. 2 in a cross-section on the line c-d of Fig. 1.
The apparatus consists of an open drum or vessel A adapted to be rotated at a high
rate of speed, said drum here being shown in an overturned position and secured to
the end of a shaft B which is journalled in a suitable framework, and provided with
means of giving rotation to the shaft. This di un is enclosed in a casing C, D which
encloses said drum, and for easy taking apart and putting together may be made in
two parts, the part D of which forming the lid or cover, can be inserted into the
druin and secured to the edge of the other part by detachable screws or eccentric or
bayonet fastenings, so as to form a tight joint The walls of the two parts of the
casing may be heated by steam, hot water or the like, for instance by making them
hollow, as shown in the drawing, and introducing the beating fluid through a pipe E,
a pipe F serving as an outlet. In a similar manner the inner side of the rotating
drum may be heated by steam or water introduced into the hollow cover D The
inner space of the casing is connected by means of a tube I or the like with an
apparatus for introducing heated air so as to increase the rate of evaporation
The air
by which the solvent has become absorbed may be conducted by a pipe G to an
apparatus for the recovery of said solvent by condensation, or by absorption. The
operation can also be carried out in a vacuum, the tube I being then omitted and the
tube (t connected with a vacuum chamber. In the space enclosed by the casing CD
a tube H introduced through an air-tight joint, either inside or outside
the cylindrical Wull of the drum, said tube being adapted to he
moved to and fro and provided with a suitable nozzle or perforations through
which the dissolved material introduced into the tube is forced out from the same, at
a suitable pressure, against the surface of the drum The nozzle may be uniformly
moved to and fro along the surface of the drum, by any suitable means which com-
municates to the tube a movement longitudinally which is in proportion to the rotary
velocity of the drum The dissolved material ejected then forms rings or spirals on
the surface of the drum which together form a solid uniform film growing into a
thicker layer as other spirals are added. By the combined influence of the spreading
of the material in extremely thin films, of the heat applied, and of the air circulation
or the operation of a vacuum, the solvent has time to evaporate completely from one
layer before a fresh one is added. The layer of gun powder formed, or the layers
when several different kinds are applied on one another, forms, or form, a solid
cylinder which can be readily removed from the surface of the drum on detaching the
lid D.

page_text: Briefly stated, the advantages of the method of manufacture above described are
as follows:
Leaves sheets or cylinders of a considerable thickness suited for the heaviest piece
of artillery, can be obtained perfectly free from pores and from any traces of the
volatile solvent
Progressive powder can be produced by this method from pure ingredients and
free from any remaining volatile additions.
The volatile solvents used can be recovered in a very simple manner
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 method of producing a homogeneous gunpowder free from solvent, from
nitro-cellulose alone, or mixed with oxy- or hydro-nitro-cellulose, nitro-starch or other
nitrated hydro-carbon, nitro-mannite or nitro-erythrite dissolved in a volatile solvent
as other and alcohol acetic ether or acetone by spreading the solution in thin layers
one on the top of the other and allowing the solvent in each layer to evaporate
before the succeeding layer is added the said evaporation being preferably hastened
by the application of heated air or gas or by carrying out the operation in a heated
vacuum.
2. In the described process of manufacturing gun-powder the formation of the
outer layers of the powder-sheet with a lower degree of nitration than the inner
layer or layers which latter may be all of the same degree or of different degrees of
nitration for the purpose of obtaining a progressive powder.
3 A homogeneous gunpowder produced according to the method described.
4. A progressive gunpowder produced according to the method described.
5 Apparatus for carrying out the methods characterised in Claims 1 and 2 con-
sisting of an open vessel adapted to be rotated and enclosed in a detachable casing,
said casing being connected with means for creating a circulation of air or gas or a
vacuum and its walls being adapted to be heated by steam, hot water or the like, and
a tube with a nozzle or perforations, introduced through the casing and adapted to
be moved to and fro along the drum, in order to enable the solution to be applied
uniformly on the wall of the drum and to allow each layer to dry before a fresh layer
18 applied substantially as described.
6. The combination and arrangement of parts constituting the apparatus for use
in the manufacture of gunpowder substantially as described and illustrated in the
accompanying drawings.
Dated this 98th day of December 1908