Improvements relating to the Manufacture of Explosives and to Apparatus therefor.
Year: 1888

page_text: Date of Application, 20th Dec., 1888
Complete Specification Left, 20th Sept., 1889-Accepted, 26th Oct., 1889
PROVISIONAL SPECIFICATION.
Improvements relating to the Manufacture of Explosives and to
Apparatus therefor.
I, HIRAM STEVENS MAXIM, of Crayford Works, Crayford, in the County of Kent
and 53 Parliament Street, in the City of Westminster, Mechanical Engineer, do
hereby declare the nature of this invention to be as follows:-
My invention relates to the manufacture of explosives and to apparatus therefor.
An important feature of my said invention is tho production of explosive material
by the combination, with pyroxyline or dissolved gun-cotton, of nitro-glycerine or
nitro-gelatine or other material which will reduce the brittleness thereof and permit of
its being moulded while in a dry state.
Another feature of my said invention is the provision of means for recovering the
whole or nearly the whole of the solvents used in the manufacture of the explosive
material.
My said invention, moreover, comprises other improvements hereinafter set forth.
In making explosive material according to one method, I first dissolve the high
grades of gun-cotton in acetone, ethylic acetate or similar solvents, and to make this
material of great strength and capable of being moulded and of yielding under
pressure when it is quite dry, I mix with the dissolved guu-cotton a small proportion
of nitro-glycerine or similar material.
By mixing these substances in varying proportions, explosive material may be pro-
duced of any degree of explosive force. By the addition of two to ten per cent. of
nitro-glycerine to gun-cotton, I make an explosive material which cannot be exploded
by detonation. The material may be otherwise modified. It may be made so that it
will flow under pressure and be more easily moulded into shape than ordinary
pyroxyline.
According to another method, I first dissolve tri-nitro-cellulose, that is to say, the
highly explosive material which is ordinarily known as insoluble gun-cotton in acetone
or ethylic acotate, until it is brought to a sufficiently thin consistency. I then add
thereto a small quantity of nitro-glycerine or nitro-gelatine. The acetone, ether or
other solvent used to dissolve the gun-cotton, dissolving the nitro-glycerine very
readily. Or I dissolve the nitro-glycerine in the acetone or ethylic acetate, before the
latter is used to dissolve the gun-cotton, or I dissolve the nitro-glycerine in pure ether
and then add it to the solution of gun-cotton. Powder or explosive material manu-
factured in this manner is so hard that it can only be exploded by being burnt from
the outside, even when it contains a considerable quantity of nitro-glycerine.
The degree of rapidity with which the material burns can be modified either by
varying the quantity of nitro-glycerine employed, or by varying the size of the grains
or pieces of the explosive material.
To produce a very slow-burning powder for use in large guns, I form fine grains of
powder composed of pyroxyline and nitro-glycerine, using soft nitro-glycerine so that
the grains of explosive material will not be too hard. To make the powder burn more
slowly, I sometimes combine with it nitrate of potash or chlorate of potash and paraffin
wax or similar materials. I have found by experiment that paraffin-wax can be used
with the utmost safety in the presence of chlorate of potash or other high explosives,
and that any degree of quickness or slowness of burning may be obtained with the
powder last above named. For instance, assuming that one half of its entire weight
consists of pyroxyline and nitro-glycerine combined as above described, and that this
mixture is incorporated in an edge-mill with a quarter of its weight of paraffin-wax,
the product would not be explosive, because there would not be enough oxygen
present to consume the paraffin. Now in order to make the mixture explosive, I mix

page_text: with it nitrate or chlorate of potash, preferably the chlorate. If the chlorate is very
thoroughly incorporated and is in the form of infinitesimal grains, then the explosion
will be very violent. If, however, the chlorate of potash exists in grains of con-
siderable size, then, when the mass is ignited, it is impossible for the explosion to travel
or for the mass to detonate, for the reason that the oxygen-bearing salt is separated
in some degree mechanically from the other material. By the use of paraffin, all
danger from premature explosion by detonation, friction and concussion is avoided.
The quantity of paraffin will be about one fourth or one fifth of the weight of the
chlorate of potash, for instance, I mix together four pounds of chlorate of potash and
one pound of paraffin. A slight excess of the chlorate of potash may be used when
there is not sufficient oxygen present in the pyroxyline for effecting the complete com-
bustion of the material.
The powder thus formed can be pressed into very hard cakes or blocks suitable for
use in large guns.
For drying the pyroxyline or the explosive material and recovering the expensive
solvents used in the production thereof, I provide the apparatus hereinafter
described.
of
One form of the said apparatus comprises a cylinder in which are arranged a series
pans. To effect the drying of the material and the recovery of the solvents without
subjecting the material to the action of heat, as heretofore practised, I use a cir-
culation of air, that is to say, I allow the air to take up the volatile solvents in a
warm chamber, and to deposit them in a cold chamber. The cold chamber is placed
in a tank or vessel through which water or other cooling liquid is caused to flow. A
suitable heater is provided for heating the air on its return to the drying chamber.
A bottle or other receptacle is placed beneath the cold chamber for the reception of
the fluid solvent. A fan-blower or other apparatus is provided for drawing the air
impregnated with the volatile solvent from the drying chamber and discharging it into
the cold chamber. The pyroxyline or explosive material may be introduced through
a pipe and flow through branches of the said pipe into the several pans ; suitable cocks
being provided where necessary.
The pan being filled, the circulation of air is started, and, as the warm air ascends
between the pans in the cylinder, it takes up a large quantity of the solvents; as it is
discharged into the cold chambers, the solvents become condensed and fall into the
said bottle or other receptacle. The cold chamber may, if desired, be traversed by a
series of tubes to increase the amount of cooling surface.
By the operation above described, all or nearly all of the solvents are recovered and
may be used again an indefinite number of times. One advantage arising from the
use of air is, that no bubbles are produced such as would be formed if the material
were heated sufficiently to effect its evaporation at a pressure of one atmosphere.
I sometimes provide a chamber containing some hygroscopic material, such as
calcium chloride, through which the air will pass from the drying chamber; all the
water is thus removed from the air and from the solvent, so that the liquid which falls
into the said bottle or other receptacle will be quite free from water, and the explosive
material that is being dried will not have its surface whitened, as is the case when the
same is dried in moist air, but will be transparent and very solid.
The pans are arranged in such a manner that they may be all lifted out. I prefer
to make the pans, or at least the bottoms of the same of glass.
I sometimes provide for recovering the solvents by placing the material in a her-
metically sealed vessel, raising the temperature to about one hundred and twenty
degrees Fahrenheit, and then, while the temperature is maintained, forming a vacuum
or partial vacuum in the said vessel, the liquids being much more easily removed in a
vacuum than under atmospheric pressure.
I provide a cylinder or other vessel for receiving the condensed liquids, and I
sometimes arrange a cooling apparatus between the pump and the said receptacle,
for the purpose of condensing the liquids which leave the pump before they are
deposited in the said receptacle.

page_text: Suitable means are, in some cases, provided for maintaining a circulation of warm
water around the hermetically sealed vessel, for the purpose of maintaining it at
the required temperature.
Dated this 20th day of December 1888.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the .Applicant.
COMPLETE SPECIFICATION.
Improvements relating to the Manufacture of Explosives and to
Apparatus therefor.
I, HIRAM STEVENS MAXIM, of Crayford Works, Crayford, in the County of Kent
and 53 Parliament Street, in the City of Westminster, Mechanical Engineer,
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:-
My invention relates to the manufacture of explosives and to apparatus therefor.
In the production of explosive material by the treatment of gun-cotton with a
solvent, such as acetone, ethylic acetate, ether or the like, considerable loss of the
solvent generally occurs in the drying of the product; thus greatly enhancing the
cost of manufacture of the explosive material.
An important object of my present invention is to provide for the recovery of the
whole, or nearly the whole of the solvents used in the manufacture of such explosive
material, and which, in the drying of the said explosive material, as heretofore
practised, are evaporated and lost. And my said invention comprises improved
methods of treating the pyroxyline or dissolved gun-cotton for this purpose.
My said invention also comprises improved apparatus hereinafter described.
According to one method of recovering the said solvents, I cause heated air or
other gas to pass over or in contact with the surface of the dissolved gun-cotton in a
drying-chamber or evaporator, so that, as the solvents are evaporated, they are taken
up or absorbed by the said air or other gas; and I then conduct the air or gas carry-
ing the volatilized solvents to a cold chamber or condenser, in which the said solvents
condense and from which they may be drawn off in a liquid state. I sometimes re-
heat the air or gas passing from the cold chamber and again cause it to pass through
the drying-chamber or evaporator, the air or gas being thus caused to circulate con-
tinuously through the entire apparatus.
According to another method I apply heat externally to a drying chamber or
evaporator in which the pyroxyline or dissolved gun-cotton is placed, and which is
hermetically closed, and from which the air is exhausted; and I convey the vapour
of the solvents from the said chamber or evaporator to a suitable cold chamber or
condenser.
In the accompanying drawings, I have shown convenient and advantageous forms
of apparatus for drying the pyroxyline or explosive material and recovering there-
from the expensive solvents used in the production of the same.
Figure 1 is a vertical longitudinal central section of one form of the said apparatus,
and
Figure 2 is a side elevation, partly in vertical longitudinal central section, of
another form or modification of the said apparatus.
Like letters indicate corresponding parts throughout the drawings.
A is the drying-chamber or evaporator in which are arranged a series of pans or
trays B, B' of any suitable shape and preferably arranged as shown, that is to say, the
said pans B, B are arranged one above another and extend alternately from either
side or end of the chamber A to within a short distance from the opposite side or end
thereof, so that the air and vapour passing through the said chamber must follow a
circuitous path.

page_text: C is the cold chamber or condenser with which the upper end of the drying-
chamber or evaporator A is connected by pipes D, D' for the passage of the
vaporized solvents.
In the apparatus shown in Figure 1, the cold chamber or condenser C is connected
by a pipe E with a heater F for heating the air during its return to the drying or
evaporating chamber A, with the lower end of which the said heater is connected by
a pipe G. The cold chamber C is placed in a tank or vessel H through which water
or other cooling liquid is caused to flow. The said cold-chamber is provided with a
discharge-pipe J having a stop-cock J', beneath which a bottle or other receptacle K
may be placed for the reception of the liquid solvent discharged from the said
chamber. A fan or blower L or other suitable apparatus is provided for causing the
continuous circulation of the air through the drying-chamber, the cold chamber or
condenser and the heater.
A small pipe a is provided above each of the pans B, B₁ for the introduction of
the pyroxyline or explosive material into the said pans. These pipes a may
communicate with a larger pipe or main, suitable cocks being provided where
necessary.
The cold chamber or condenser C is preferably constructed with a series of small
tubes C to increase the area or amount of cooling surface.
The operation of the apparatus above described is as follows, viz. :-The pans or
trays B, B being charged with pyroxyline, the fan T. is started and the air circulated
through the apparatus. The air is warmed in passing through the heater F and ascends
between the pans B, B' in the drying chamber or evaporator A, and absorbs or takes
up a large quantity of the vapour of the solvent or solvents contained in the said pans ;
the air is then discharged into the cold chamber C wherein the solvents condense and
fall into the bottle or receptacle K. The air freed from the vaporized solvents is
again passed through the heater F and evaporator A, and so on.
By the operation above described, the whole or nearly the whole of the solvent or
solvents, which would otherwise be lost, is recovered; the said solvent or solvents may
thus be used and recovered a great number of times. One great advantage arising
from the employment of a current of heated air as above described is that the evapora-
tion proceeds without the formation of bubbles such as would be formed if the material
were directly heated sufficiently to cause the solvent or solvents to evaporate at the
normal pressure of the atmosphere.
I sometimes provide in combination with the pipe G one or more chambers M con-
taining hygroscopic material, such as calcium chloride, through which the air will
pass in its circulation through the apparatus, and whereby all the aqueous vapour will
be removed from the air, so that the liquid which falls into the bottle or other recep-
tacle K will be free from water, and the explosive material which is being dried will
not undergo any change, such as having its surface whitened, as is the case when
dried in presence of moisture, but will be transparent and very homogeneous.
The pans or trays in the chamber A are removable; they are preferably arranged
in such a manner that they may be lifted out all together. I prefer to make the pans,
or at least the bottoms of the same, of glass or similar material.
The drying-chamber or evaporator A and the heater F should be enclosed in casings
of wood or other suitable material, as shown. The heater F is provided with a coil Fi
through which steam, hot water or other heating medium is to be passed.
Figure 2 shows another form or modification of my apparatus for the recovery of
the solvents used in the treatment of gun-cotton. The drying-chamber or evaporator A
is provided with an air-tight cover A¹ and is surrounded by a casing or jacket N
through which steam, hot water, heated air or other heating medium may be caused
to circulate for the purpose of heating the chamber A and maintaining the required
temperature therein."
An air-pump P is connected on the suction side with the drying chamber or
evaporator A and on the delivery side with the cold chamber or condenser C by means
of the nines D. D¹.

page_text: In treating pyroxyline by means of this apparatus, the cover A' of the chamber A
being removed, the pans or trays B, B1 are charged with the material to be treated,
being preferably removed from the chamber A for this purpose. The said pans or
trays are then replaced and the cover A¹ firmly secured on the chamber A. The steam
or other heating medium is then caused to circulate through the casing or jacket N.
When the temperature in the said chamber or evaporator A reaches about one hundred
and twenty degrees (120°) Fahrenheit, as indicated by a thermometer provided for
the purpose, the supply of steam or other heating medium is regulated so as to main-
tain this degree of temperature. The air-pump P is then started, and air exhausted
from the chamber A, thus forming a vacuuin or partial vacuum therein. The volatile
solvents in the said chamber are vaporized by the heat under the diminished pressure,
and pass over into the air-pump, whereby they are delivered into the condenser C.
The vaporized solvents being therein cooled condense and trickle or flow by gravity
through the pipe J into the collecting vessel K.
By drying the explosive material in a chamber from which air is exhausted, I
am enabled to evaporate the solvents at a lower temperature than would be
practicable at ordinary atmospheric pressure, and to thus avoid heating the said
material to such a temperature as would cause the formation of bubbles therein.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed I wish it understood
that I claim :-
11
First. The recovery of solvents used in the manufacture of explosive material,
by placing the said material in a drying chamber or evaporator, passing heated air
or other gas through the said chamber to evaporate and absorb the said solvents,
and then cooling the said air or other gas to condense the solvents with which
it is impregnated.
Second. The herein described method of recovering solvents used in the manu-
facture of explosive material, consisting in placing the said material in a drying-
chamber or evaporator which is in communication with a cold chamber or condenser
and with a heater, and causing a continuous circulation of air or other
gas through
the said heater, evaporator and condenser, for the purposes above specified.
Third. The recovery of solvents used in the manufacture of explosive material,
by drying the said material or evaporating the solvents contained therein in a vacuum
or partial vacuum and then condensing the said solvents.
Fourth. The herein described method of recovering solvents used in the manu-
facture of explosive material, consisting in placing the said material in a closed
chamber, heating the said chamber and exhausting the air therefrom, and then
drawing the vaporized solvents from the said chamber and delivering them into a cold
chamber or condenser.
Fifth. The improved apparatus constructed substantially as described with reference
to Figure 1 or to Figure 2 of the accompanying drawings and operating as, and
for the purposes, above specified.
D
土 11
1000
HIRAM STEVENS MAXIM.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.