Improvements in and relating to the Manufacture of Smokeless Explosives.
Year: 1893

page_text: Date of Application, 22nd Aug., 1893-Accepted, 14th Oct 1893
COMPLETE SPECIFICATION.
Improvements in and relating to the Manufacture of Smokeless
Explosives.
I, FRANCIS GUONEY DU PONT, a citizen of the United States of America,
residing in the City of Wilmington, County of New Castle and State of Delaware,
one of the United States of America, Powder Manufacturer, 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 improvements in explosives, to be used in small arms,
large guns, as a bursting charge for shells, or for any other explosive use to which
it may be suited, and it consists in the improved process for producing an explosive
from nitro-cellulose, by agitating therewith, wheu suspended in a liquid, in suitable
proportions, an emulsion of a solvent of the same in a suitable liquid, and
subsequently hardening the grains thus produced, which will be hereinafter fully
described, and particularly pointed out in the claims.
"In the joint application of myself and Pierre S. du Pont for Letters Patent for
improvements in explosives, filed ou even date herewith, a process for producing a
smokeless explosive was described, the distinguishing feature of which consisted in
the granulation of the nitro-cellulose by agitating therewith, when suspended in a
suitable fluid, a solvent of the same in proper proportions. Basing the process on
the tendency which was found to be inherent in the solvents of nitro-cellulose, and
especially the nitro-derivatives of the aromatic group, when mixed with a fluid in
which finely-divided nitro-cellulose is suspended, to seize the nitro-cellulose and
leave the fluid clear, forming in the fluid a more or less coherent mass, it was
discovered that when the solvent is added in proper proportions, (and the pro-
portion of three parts by weight of the solvent to one of the nitro-cellulose was
found to be a good working proportion) and the mass is slightly agitated, a well
defined granular condition was the result, the solvent collecting the particles of
nitro-cellulose into grains, and forming a coating around the same. These grains,
after they have undergone a process of hardening by rotation in a barrel, and
removal of excess of solvent and water contained in the grains by boiling, or by
rotation in a barrel in an atmosphere of steam, in which case the removal of the
excess of solvent and water contained in the grains will take place at the same
time as the rotation, become sufficiently firm to be graded as to size preparatory to
being put upon the market, and constitutes a valuable smokeless powder, the
violence of whose explosive action can be diminished by varying the duration of
the above processes, or can be still further diminished by the addition of a substance to
moderate its action. For this latter purpose nitrated rosin and nitrated turpentine,
i.e., rosin or Venice turpentine treated with nitric acid, were found to be especially
suited, and they were added in the manner and proportion stated in said
application.
The essential feature of the above process, and that which determines the
character of the explosive produced, is the granulation of the nitro-cellulose. This
granulation is effected, in the process described in said application, by pouring
nitro-benzole, or other solvent of nitro-cellulose, into a churn in which a quantity
of finely divided nitro-cellulose is suspended in a suitable liquid; said nitro-
cellulose having been uniformly distributed through said liquid by the action of
the churn. After the solvent has been added to the mixture in the churn, the
agitation of the contents of the same is continued, until the nitro-cellulose has been
deposited in the bottom of the churn in the form of granules, which are somewhat

page_text: pulpy, as they contain in the fibre of the nitro-cellulose considerable water, and as
there is an excess of solvent in connection with the same.
It is of the utmost importance in determining the characteristics of the grains
produced, that the granulation be uniform, and that all of the nitro-cellulose be
precipitated, as otherwise there is a loss of material, and the grains formed are
uneven in structure.
I have discovered that complete and uniform granulation of the nitro-cellulose
may be effected by emulsifying the nitro-benzole, or other solvent of nitro-cellulose
used, before adding the said solvent to the mixture in the churn, with a suitable
liquid. Water may be used as such liquid, and may either be pure, or may have in
solution in it any of the usual substances which are used to produce emulsions, such
as soap; or carbonate of soda liquor may be used, or any other suitable liquid. I
have found by experiment that by the use of the emulsion thus produced a more
uniform granular condition is brought about, and also a more uniform and perfect
precipitation of the nitro-cellulose obtained, than when the uneinulsified solvent
is used.
In the drawings accompanying and forming a part of this application, I have
represented the apparatus which I use to carry out my process,
Figure 1, which is taken on the line - Figure 14 looking in the direction of
the arrow, illustrating the churn in which the mixture of the nitro-cellulose with
the solvent takes place, Figure 1A being a sectional view of the same; and
Figure 2 being a representation of the rotating barrel in which the grains
formed in the churn shown in Figure 1 are hardened and rounded, and thus fitted
for use.
It is taken on the line y-y Figure 2ª.
Figure 2 is a view taken on the line - Figure 2, looking in the direction of
the arrow. It shows the double series of apertures in the inner bulkhead of the
barrel and also the series of cycloidal chutes which conduct the water of
condensation, received through the outer series of apertures in the bulkhead, to the
apertures in the central pipe forming the axis of the barrel, by which the said water
is conveyed away.
Before proceeding with a description of my process I will describe the apparatus
used in carrying it out.
Referring to Figures 1 and 1A, A represents a churn, in which, by a shaft B, are
rotated the blades b, each of which is formed with a notched outer surface to
promote currents from side to side in the contents of the churn during rotation.
Steam inlet pipes C are provided, which are relatively small in diameter, so that
the steam will be well distributed through the contents of the churn, and a single
steam outlet pipe D, which leads to the refrigerating coils E, where the vapors
which it conducts may be condensed. An opening F is provided for the admission
of material, and an opening C¹ to aid in flushing the interior of the churn when
desired. Test cocks 1, 1, are also provided, in order that the condition of the
contents of the churn may at any time be inspected.
In Figures 2 and 24, the rotating barrel is represented, in which the grains of
explosive produced in the churn just described are hardened and prepared for use.
This barrel H is provided with a tubular axis I, journaled in the supports i, i, to
which axis steam is conducted by the pipe 2, and from which steam is conveyed away
by the pipe 3. This barrel is designed to facilitate the escape of both steam and
water, the former carrying off the tolvent used, and to this end is formed with an
inner bulkhead K, which is placed in close proximity to the bulkhead H2 of the
barrel. In this inner bulkhead are formed two series of apertures, one around its
periphery 8, for the separation of water from the contents of the barrel, and one
near its center 9, for the escape of steam from the same. Between the two
bulkheads K and H2 are arranged a series of cycloidal chutes or guides L, all of
which converge toward the central axis. In the operation of the barrel, steam is
admitted to its interior through the apertures 9 in the bulkhead K, from whence
it passes through the axis I and the pipe 3. Water of condensation, as fast as
formed, passes through the outer series of apertures in the bulkhead K at the lower

page_text: part of revolution of the barrel, into the space between said bulkhead and
bulkhead H, and is conducted by the cycloidal chutes toward the axis of the
barrel, then passing out through the apertures 6 formed at this point.
Proceeding now with my process, I place in the churn A about 90 litres of
water, or other liquid, which may either be pure, or mixed with any salt. When
water is used, I sometimes dissolve in it chloride of calcium, common salt, saltpetre,
or other salt, as the characteristics of the grains produced can thus be modified in
many ways. I then add to the water about six kilogrammes of nitro-cellulose,
beating it up with the water in the churn until a thorough mixture has taken
place.
In another churn similar to that shown in Figures 1 and 14, or in any other
suitable machine, prepare an emulsion of the solvent of the nitro-cellulose which
I desire to use with water, or with other emulsifying liquid. When water is
used, add it to the solvent, such as nitro-benzole, in about the proportions
of three times the weight of the nitro-benzole. When carbonate of soda
liquor is used, I add one pound of the carbonate of soda to a gallon of water, and
use about the same weight of liquor as in the case of pure water.
When soap is
used to aid the emulsion, I add it in the proportion of about one ounce to
twenty-five pounds of nitro-benzole, and use about the same weight of water as
before.
I do not restrict myself to the use of the emulsifying agents above mentioned,
stating them merely as examples, nor to the proportions there stated of adding the
same to the solvent of the nitro-cellulose, or those in which the various ingredients
are added to water.
The emulsion thus produced is added to the mixture in churn A, a sufficient.
quantity of it being added so that the proportion of the nitro-benzole, or other
solvent used, to the nitro-cellulose is by weight about three to one, and then the
agitation of the contents of the churn is continued until the granulation of the
nitro-cellulose is complete. This granulation takes place on account of the tendency
of the nitro-benzole to gather together the particles of nitro-cellulose into granules,
and form a coating around the same, the coating when formed, preventing the
grains from becoming attached to each other, or otherwise forming one mass.
action of the solvent when emulsified in the manner above stated is much more
rapid and complete than when such solvent is added in an unemulsified form, and
results in the more perfect granulation hereinbefore described.
The
The grains thus formed, when removed from the churn, may be treated with
steam to remove the excess of solvent and the water contained in the grains, and
then be used with success for some explosive uses, but a more perfect grain is
produced by treatment of the grains produced in the churn in the rotating barrel
shown in Figures 2 and 2ª. This treatment proceeds either in the manner
described in the joint application of myself and Pierre S. du Pont above referred
to, by rotating the barrel for a greater or less time without the admission of steam,
until the grains are compacted and rounded, then filling the barrel partially with
water, and rotating it with admission of steam in such a direction as to prevent the
water from being carried away, and then changing the direction of rotation and
continuing the flow of steam until the solvent is entirely removed; or in the manner
described in the joint application of myself and Pierre S. du Pont filed on even
date herewith, in which the grains are, at some time before their final rounding and
compacting, treated with heat, but of a degree below that of the point of
vaporization of the solvent used in the production of the grains, to remove more
effectually the water condensed in the fibres of the grains. The latter method of
treatment is preferred, as resulting in a more finished product..
The explosive force of the grains thus produced may be tempered to any degree
required by the addition of a suitable moderating agent, in the manner described
in the joint applications before referred to.
While I have described the nitro-cellulose as being diffused in water, it is evident

page_text: that any other fluid which will cause a better, or as good a distribution of the nitro-
cellulose in the churn may be used instead.
I do not confine myself to the exact proportions used, nor to the particular
apparatus described, as these can be varied and changed without affecting the
merits of this invention.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The herein-described process of producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same,
granulating the nitro-cellulose by agitating therewith in proper proportions an
emulsion of a solvent of the nitro-cellulose, which is not miscible to any great
extent in the liquid used to suspend the same, in a suitable liquid in proper
proportions, and solidifying the grains thus formed, substantially as described.
2. The herein-described process of producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same,
granulating the nitro-cellulose by agitating therewith in proper proportions an
emulsion of a solvent of the same, which is not miscible to any great extent in the
liquid used to suspend the nitro-cellulose, with water in proper proportions, and
solidifying the grains thus:formed, substantially as described.
3. The herein-described process of producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same,
granulating the nitro-cellulose by agitating therewith in proper proportions an
emulsion of nitro-benzole, which is not miscible to any great extent in the liquid
used to suspend the nitro-cellulose, with a suitable liquid in proper proportions, and
solidifying the grains thus formed, substantially as described.
Dated this 22nd day of August 1893.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.

page_text: Date of Application, 22nd Aug., 1893-Accepted, 14th Oct., 1893
COMPLETE SPELTICATION.
Improvements in and relating to the Manufacture of Smokeless
Explosives.
We, FRANCIS GUONEY DU PONT and PIERRE SAMUEL DU PONT, citizens
of the United States of America, residing in the City of Wilmington, County of
New Castle and State of Delaware, one of the United States of America, Powder
Manufacturers, 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 :-
Our invention relates to improvements in explosives which are particularly
adapted for imparting a high initial velocity to the projectiles of small bore rifles,
such as the Mannlicher, the Krag-Jorgensen and the English 303, and it consists in
an improved process for producing an explosive from nitro-cellulose, consisting of
granulating the nitro-cellulose by agitating therewith, when suspended in a fluid, a
solvent of the same in suitable proportions, which will be hereinafter fully described,
and particularly pointed out in the claims.
The main object of our invention is to produce an explosive which will be
smokeless, or nearly so, which will be unaffected' by being kept for a considerable
space of time, which, while imparting a high muzzle velocity to the projectile, will
not cause undue pressure in the gun barrel at the moment of firing, and which
can be easily and safely handled and stored. Our invention has for its special aim,
however, the attainment of a higher initial velocity than has formerly been attain-
able by the use of smokeless explosives, with the aim of adapting the explosive to
use with small bore rifles, such as those mentioned above.
In our application for Letters Patent for improvements in explosives, filed on
even date herewith, we described a process for producing smokeless powder, the
distinguishing feature of which was the granulation of pure nitro-cellulose by
agitating therewith a solvent of the same in suitable proportions. Basing our
process on the tendency which we found was inherent in the various solvents of the
nitro-celluloses, and especially the nitro-derivatives of the aromatic group, when
mixed in a fluid in which finely divided nitro-cellulose is suspended, to seize the
nitro-cellulose and leave the water clear, forming in the water a more or less
coherent mass, we discovered that when the solvent is added in proper proportions,
(and we found that the proportions of three parts of the solvent to one of the nitro-
cellulose by weight was a good working proportion,) and the mass is slightly
agitated, a well defined granular condition was the result, the solvent collecting the
particles of nitro-cellulose into grains, and forming a coating around the same.
These grains, after they have undergone a process of hardening by rotation in a
barrel, and removal of excess of solvent and water contained in the grains by
boiling, or by rotation in a barrel in an atmosphere of steam, in which case the
removal of the excess of solvent and water contained in the grains will take place
at the same time as the rotation, become sufficiently firm to be graded as to size,
preparatory to being placed on the market, and constitute a valuable smokeless
powder, the violence of whose explosive action can be diminished by varying the
duration of the above processes, or it may be still further diminished by the addition
of a substance to moderate its action. We have found nitrated rosin and nitrated
turpentine especially suited for this purpose, and we add them in the manner and
proportion stated in said application.
.
We have discovered, however, that increased hardness and consolidation of the
grains thus formed may be obtained by subjecting the grains, either directly after
they have been removed from the churn in which they were formed, or after they

page_text: have been subjected to partial treatment by rotation in an atmosphere of steam in
order to remove the excess of solvent, to the action of a gentle heat, not sufficient
to cause vaporization of the solvent, but to remove some of the water condensed in
the grains, this discovery being based upon the property, which we have found the
grain possesses, of giving up its contained water before it parts with the solvent
used in its preparation, and at a lower heat.
In the drawings accompanying and forming a part of this application, we have
represented the apparatus which we use in carrying out our process; Figure 1,
which is taken on the line a-x Figure 1A, looking in the direction of the arrow,
illustrating the churn in which the mixture of the nitro-cellulose with the solvent
takes place; Figure 1A being a sectional view of the same; and Figure 2 being a
representation of the rotating barrel in which the grains formed in the churn shown
in Figure 1 are hardened and rounded and thus fitted for use. It is taken on the
line y-y, Figure 24. Figure 2 is a view taken on the line z-z, Figure 2, looking
in the direction of the arrow. It shows the double series of apertures in the inner
bulkhead of the barrel, and also the series of cycloidal chutes which conduct the
water of condensation, received through the outer series of apertures in the bulk-
head, to the apertures in the central pipe forming the axis of the barrel, by which
the said water is conveyed away.
Before proceeding with a description of our process we will describe the apparatus
used in carrying it out.
Referring to Figures 1 and 14, A represents a churn, in which, by a shaft B, are.
rotated the blades b, each of which is formed with a notched outer surface to
promote currents from side to side in the contents of the churn during rotation.
Steam inlet pipes C are provided which are relatively small in diameter, so that
the steam will be well distributed through the contents of the churn, and a single
steam outlet pipe D, which leads to the refrigerating coils E, where the vapors
which it conducts may be condensed. An opening F is provided for the admission
of material, and an opening C' to aid in flushing the interior of the churn when
desired. Test cocks 1, 1, are also provided, in order that the condition of the
contents of the churn may at any time be inspected.
In Figures 2 and 24 the rotating barrel is represented in which the grains of
explosive produced in the churn just described are hardened and prepared for use.
This barrel H, is provided with a tubular axis I, journaled in the supports i, i, to
which axis steam is conducted by the pipe 2, and from which steam is conveyed
away by the pipe 3. This barrel is designed to facilitate the escape of both water
and steam, the latter carrying off the solvent used, and to this end is formed with
an inner bulkhead K, which is placed in close proximity to the bulkhead H' of the
barrel. In this inner bulkhead are formed two series of apertures, one around its
periphery 8, for the separation of water from the contents of the barrel, and one
near its center 9, for the escape of steam from the same. Between the two bulk-
heads K and H2 are arranged a series of cycloidal chutes or guides L, all of which
converge toward the central axis. In the operation of the barrel, steam is admitted
to its interior through the aperture 5 in the central axis, passing out through the
apertures 9 in the bulkhead K, from which it passes through the axis I and the
pipe 3.
Water of condensation, as fast as formed, and also the water separated
from the grains of explosive, passes through the outer series of apertures in the
bulkhead K at the lower part of the revolution of the barrel, into the space
between the said bulkhead K and bulkhead H2, and is conducted by the cycloidal
chutes toward the axis of the barrel, then passing out through the apertures 6
formed at this point.
Proceeding now with our process, we place in the churn A about 90 litres of
water, or other liquid, which may either be pure or mixed with any salt. When
water is used, we sometimes dissolve in it chloride of calcium, common salt,
saltpetre, or other salt, as we can thus modify in many ways the characteristics of
the grains formed. We add to the water about six kilogrammes of gun cotton,

page_text: .
beating it up in the water in the churn until a thorough mixture has taken place.
When this has been accomplished, we add to the mixture nitro-benzole, or other
suitable solvent of gun cotton not miscible to any great extent in the liquid used to
suspend the gun cotton, such as nitro-toluol and nitro-xylol, to the extent of about
three times the weight of the gun cotton. When the agitation of the contents of
the churn is continued, the gun cotton assumes a well defined granular state, the
grains formed being soft and containing considerable water. During this agitation
steam may be admitted through the bottom of the churn, and this as it passes out
through the refrigerating coils carries with it a portion of the solvent, which is
recovered in the said coils. This action of the steam is not, however, essential to
the production of the grains, though it assists in their formation, and may be
omitted without detriment to the product. The size of the grains may be varied
by changing the proportions of the ingredients and the duration of treatment.
The above is an example of proportions which give good results.
Instead of placing the grains thus formed directly into the rotating barrel shown
in Figures 2 and 24 and rotating said barrel with ingress of steam until the excess
of volatile solvent has been entirely evaporated from the grains, as we do in the
process described in the application for Letters Patent for improvements in
explosives already referred to, we have found that better results as to the hardness
and degree of consolidation of the resulting grains may be obtained by subjecting
the grains to a gentle heat, ranging say from 120° to 180° F., either before the
grains are placed in the rotating barrel, or after they have been partially treated
in the same. This result is due to a property which the grains possess of parting
with the water condensed in their fibre before they part with the solvent used in
their preparation. By heating the said grains to a point not sufficient to carry away
the solvent, but only to evaporate the water contained in the fibres of the grains
most of the said contained water is separated from the grains before the grains
become hard. This they do when treated by boiling for the removal of the excess
of solvent. Since, therefore, by this means a greater proportion of the water
condensed in the fibres is removed than is the case when the grains are boiled for
removal of all excess of solvent without this primary or intermediate heating, the
resulting grains are harder and more dense, and thus become fitted to produce the
high initial velocity to the projectile which is the object of this process.
It is not material whether the grains be subjected to this gentle heat before they
have been treated by boiling for removal of excess of solvent, or after they have
been partially so treated, it being only necessary that they be so treated before the
outer envelope of the grains becomes so hard as not to permit the passage of water
through the same.
We do not confine ourselves to the temperatures mentioned, although we find
them good for the purpose intended, nor do we confine ourselves to any particular
method of exposing the grains to heat, using a rotating drier such as is used in
sugar refineries, or spreading the grains upon sieves, or adopting any other method
for the desired purpose.
After this roasting process has been carried to a greater or less extent, dependent
upon the condition of the grains and the degree of consolidation required, the
grain is treated in the usual manner, the solvent being boiled off in the steam
barrel, or in a still, or in the open air.
We have found that better results are obtained in the use of the barrel by
creating a vacuum at the steam outlet pipe, as the vapors are thereby more rapidly
conveyed away, and the amount of time required for the treatment in the barrel is
reduced.
The explosive force of the explosive thus produced may be tempered in the same
manner as was the explosive produced by our process for which application for
Letters Patent has already been referred to herein, namely, by adding from two
and one-half per cent. to ten per cent. of a moderating agent, such as nitrated rosin
or nitrated turpentine, i.e., rosin or Venice turpentine treated with nitric acid;

page_text: although we do not confine ourselves to the use of these substances, nor to the
proportions mentioned. We add this moderating agent by dissolving the same in
the solvent used in the granulation process, or, by adding it to the finished grain,
or in any other suitable manner, but it must be added in the proportion which it is
to bear to the finished product, as it is non-volatile at the temperature used.
We have described the gun cotton as being diffused in water, but it is evident
that another fluid, which will cause a better, or as good a distribution of the
particles of gun cotton in the churn may be used instead; and while gun cotton
has been described as the form of nitro-cellulose employed in the process, it is
evident that other forms of nitro-cellulose may be used instead if desired.
We do not confine ourselves to the exact proportions mentioned, nor to the
particular apparatus described, as these can be varied and changed without
affecting the merits of our process.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what
we claim is :-
1. The herein described process for producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same, granu-
lating the nitro-cellulose by agitating therewith in proper proportions a suitable
solvent of the same not miscible to any great extent in the liquid used to suspend
the nitro-cellulose, and solidifying the grains thus formed by subjecting the same to
a heat insufficient to vaporize the solvent, but sufficient to vaporize the liquid for
removal of the liquid contained in the grains, and then removing the excess of
solvent, substantially as described.
2. The herein described process for producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same, granu-
lating the nitro-cellulose by agitating therewith in proper proportions a suitable
solvent not miscible to any great extent in the liquid used to suspend the nitro-
cellulose, and solidifying the grains thus formed by subjecting the same to a heat
insufficient to vaporize the solvent, but sufficient to vaporize the liquid, for removal
of the liquid contained in the grains, and then to a heat sufficient to vaporize the
solvent, for removal of the excess of solvent, substantially as described.
3. The herein described process for producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same, granu-
lating the nitro-cellulose by agitating therewith in proper proportions a suitable
solvent not miscible to any great extent in the liquid used to suspend the nitro-
cellulose, and solidifying the grains thus formed with removal of liquid contained in
the same and excess of solvent by subjecting them to a heat ranging from 120° to
180° F., for removal of the liquid, and then boiling them for removal of excess of
solvent, substantially as described.
4. The herein described process for producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same, granu-
lating the nitro-cellulose by agitating therewith in proper proportions a suitable
solvent not miscible to any great extent in the liquid used to suspend the nitro-
cellulose, and solidifying the grains thus formed by subjecting the same to a heat
insufficient to vaporize the solvent but sufficient to vaporize the liquid for removal
of the liquid contained in the grains, and then to a heat sufficient to vaporize the
solvent for removal of the excess of solvent, the latter operation being accompanied
by agitation, substantially as described.
5. The herein described process for producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same, granu-
lating the nitro-cellulose by agitating therewith in proper proportions a suitable
solvent of the same not miscible to any great extent in the liquid used to suspend
the nitro-cellulose, and solidifying the grains thus formed by subjecting the same to
a heat insufficient to vaporize the solvent but sufficient to vaporize the liquid for

page_text: removal of the liquid contained in the grains, and then rotating the grains in
an atmosphere of steam for removal of the excess of solvent, substantially as
described.
Dated this 22nd day of August 1893.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.

page_text: Date of Application, 22nd Aug., 1893-Accepted, 14th Oct., 1893
COMPLETE SPECIFICATION.
Improvements in and relating to the Manufacture of Smokeless
Explosives.
We, FRANCIS GUONEY DU PONT and PIERRE SAMUEL DU PONT, citizens
of the United States of America, residing in the City of Wilmington County of
New Castle and State of Delaware, one of the United States of America, Powder
Manufacturers, 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 :-
Our invention relates to improvements in explosives to be used in small arms,
large guns, as a bursting charge for shells, or for any other explosive use to which it
may be suited, and it consists in an improved process for producing an explosive
from nitro-cellulose, consisting in granulating the nitro-cellulose by agitating there-
with, when suspended in a liquid, a suitable solvent of the same in proper proportions,
which will be hereinafter fully described, and particularly pointed out in the
claims.
The main object of our invention is to produce an explosive which will be
smokeless, or nearly so; which, while imparting a high muzzle velocity to the
projectile, will not cause undue pressure in the gun barrel at the moment of firing,
and which can be easily and safely handled and stored.
Nitoro-cellulose in some of its forms, usually that of gun cotton, has frequently
been used as the basis of smokeless powders, because it unites in itself so many of
the qualities which good smokeless powders must possess; that is to say, it is very
stable when properly prepared, burns or explodes with very little smoke, possesses
great power as an explosive, and is not hydroscopic enough to impair its keeping
qualities. The explosive force of gun cotton, or other nitrated fiber, when used by
itself is so great, however, and the difficulties of securing an even rate of combustion
so hard to overcome, that its use by itself is dangerous in fire arms.
Many attempts have been made to control or diminish the explosive force of gun
cotton, while preserving all of its advantageous properties. These attempts have
in general proceeded along three lines, viz.―
First: That of subjecting the gun cotton to great pressure, by which all air
spaces, in which the explosive gases might collect, are removed from it, and it is
rendered solid and compact.
Second That of mixing with the gun cotton certain substances which lessen its
rate of combustion, the substances added being less violent in explosive force than
the gun cotton. For this purpose nitro-benzole, nitro-naphthaline, camphor, and
the high boiling point ketones and acetates have been used.
Third: The solvents of gun cotton which have been added may be entirely
evaporated, leaving the gun cotton in a state resembling celluloid, in which its
condition is changed from the fibrous to the amorphous state, in which latter state
it is more compact than the original gun cotton.
Our invention belongs to the third of the classes above specified, but it differs
from all other processes now known or used in that the gun cotton is treated in a
wet way, by suspending it in a fluid and mixing with it a suitable solvent, which
produces a granular condition hereinafter described.
We have discovered that the various solvents of gun cotton, especially the nitro-
derivatives of the aromatic group, have a tendency, when mixed with a fluid in
which finely divided gun cotton is suspended, to seize the gun cotton and leave the
water clear, forming in the water a more or less coherent mass; and that when a
suitable solvent is added in proper proportions, and the mass is even slightly

page_text: agitated, a well defined granular condition is the result, the solvent collecting the
particles of nitro-cellulose into grains, and forming a coating around the same.
These grains after they have undergone a process of hardening by rotation in a
barrel, and removal of excess of solvent and water contained in the grains by heat,
the said heat being applied either before or during the process of rotation, or
by rotation in a barrel in an atmosphere of steam, in which case the removal of the
excess of solvent and water contained in the grains will take place at the same time
as the rotation, become sufficiently firm to be graded according to size, and
constitute a valuable smokeless powder, the violence of whose explosive action can
be diminished by varying the duration of the above processes, or it may be still
further diminished by the addition of a substance to moderate its action. We have
found nitrated rosin and nitrated turpentine, especially suited for this purpose, and
we add them in the manner and proportion which will be hereinafter stated.
In the drawings accompanying and forming a part of this application, we have
represented the apparatus which we use in carrying out our process,
Figure 1 which is taken on the line - Figure 14 looking in the direction of the
arrow, illustrating the churn in which the mixture of the gun cotton with the solvent
takes place ;
Figure 14 being a sectional view of the same; and
Figure 2 being a representation of the rotating barrel in which the grains formed
in the churn shown in Figure 1 are hardened and rounded, and thus fitted for use.
It is taken on the line y-y Figure 2ª.
Figure 2 is a view taken on the line z-z Figure 2, looking in the direction of
the arrow.
It shows the double series of apertures in the inner bulkhead of the
barrel, and also the series of cycloidal chutes which conduct the water of con-
densation, received through the outer series of apertures in the bulkhead, to the
apertures in the central pipe forming the axis of the barrel by which pipe the said
water is conveyed away.
Before proceeding with a description of our process, we will describe the
apparatus used in carrying it out.
Referring to Figures 1 and 14, A represents a churn, in which, on a shaft B, are
rotated the blades, each of which is formed with a notched outer surface to promote
currents from side to side in the contents of the churn during rotation.
Steam inlet
pipes C are provided which are relatively small in diameter, so that the steam will
be well distributed through the contents of the churn, and a single steam outlet
pipe D, which leads to the refrigerating coils E, where the vapours which it
conducts may be condensed. An opening F is provided for the admission of
material, and an opening C¹ to aid in flushing the interior of the churn when
desired. Test cocks 1, 1, are also provided, in order that the condition of the
contents of the churn may at any time be inspected.
In Figures 2 and 24 the rotating barrel is represented, in which the grains of
explosive produced in the churn just described are hardened and prepared for use.
This barrel, H, is provided with a tubular axis I, journaled in the supports i, i, to
which axis steam is conducted by the pipe 2, and from which steam is conveyed by
the pipe 3. The barrel is designed to facilitate the escape of both water and steam
from the interior of the same, the steam carrying off the solvent used, and to this
end is formed with an inner bulkhead K, which is placed in close proximity to the
bulkhead H2 of the barrel. In this inner bulkhead are formed two series of
apertures, one around its periphery 8 for the separation of water from the contents
of the barrel, and one near its center 9, for the escape of steam from the same.
Between the two bulkheads K and H² are arranged a series of cycloidal guides or
chutes L, all of which converge toward the central axis. In the operation of the
barrel, steam is admitted to its interior through the aperture 5 in the central axis,
and passes out through the apertures 8 and in the bulkhead K, and thence
through the axis I and pipe 3, carrying with it, as will be hereinafter explained, the
excess of the solvent found with the grains of explosive. Water of condensation, as
fast as formed, passes through the lower series of apertures in the bulkhead K at

page_text: the lower stage of the revolution of the barrel into the space between said bulk-
head K and bulkhead H2, and is conducted by the cycloidal chutes toward the axis
of the barrel, then passing out through the apertures 6 formed at this point.
Proceeding now with our process, we place in the churn A about 90 litres of a
suitable liquid, such as water, which may either be pure, or mixed with any salt.
When water is used, we sometimes dissolve in it chloride of calcium, common salt,
saltpetre, or other salt, as we can thus modify in many ways the characteristics of
the grains formed. The proportions in which these ingredients are added depends
somewhat upon which one is used. In the case of saltpetre, about a half saturated
solution will answer very well, or even one of greater strength, say a saturated
solution at a temperature of 60°. We add to the liquid about six kilogrammes of
finely divided gun cotton, beating it up with the water in the churn until a thorough
mixture has taken place, and the gun cotton is uniformly suspended in the liquid.
When this has been accomplished, we add to the mixture a suitable solvent of gun
cotton, such as nitro-benzole, to the extent of about three times the weight of gun
cotton. By the action of the solvent upon the suspended gun cotton a plastic
flocculent mass is formed, which by slight agitation becomes granulated. When
the agitation in the churn is now continued, a well defined granular product is
produced, the solvent (in this case nitro-benzole) collecting the particles of gun
cotton, and forming them into grains, which are as yet somewhat soft and pulpy,
as they contain considerable water, and as there is an excess of solvent.
agitation aids the granulation by keeping the particles of gun cotton suspended, and
thus enabling the action of the solvent to be carried on uniformly upon all the
particles of gun cotton in the churn. During this action, steam may be admitted
through the bottom of the churn, and this, as it passes out through the refrigerating
coils, carries with it a portion of the solvent, which is recovered in said coils.
This action of the steam is not, however, essential to the production of the grains,
though it assists in their formation, and may be omitted without detriment to the
product.
The
Instead of using nitrobenzole to produce the granulation, nitro-toluol or nitro-
xylol may be used, or other solvents. The solvent used, however, must not be
miscible to any great extent in the liquid in which the gun cotton is suspended, as
if it is so miscible, it will not leave the liquid readily and form the desired
granulation. The suitability of the solvent is thus determined. We do not confine
ourselves to the proportions mentioned of the gun cotton and solvent, although
these have been found to give good results, as the proportion may be altered and
still a good granulation be obtained.
The contents of the churn are now removed, and the grains are placed in the
revolving barrel shown in Figures 2 and 2^. By rotating the barrel for a greater
or less time without the admission of steam, the grains are compacted and rounded.
The barrel is then partially filled with water, and rotated in such a direction as to
prevent the cycloidal chutes from carrying off the water steam being admitted, and
When
the rotation continued until a further portion of the solvent is carried off.
this action has proceeded sufficiently far, the direction of rotation is changed, and
the flow of steam continued until the excess of solvent is entirely removed. The
action of this latter process, namely the rotation in an atmosphere of steam, is to
increase to a very great degree the density of the grain, and to round and compact
the same, fitting it for its destined use as an explosive.
The density and also the size of the grain formed may be varied by changing the
proportions of the ingredients, and by altering the length of time of the preliminary
rolling in the revolving barrel. The principle at the root of the matter is this:
If the original grains formed in the churn have a large quantity of nitro-beuzole,
or other solvent used, they will be quite plastic, and during the preliminary rolling
in the barrel will tend to gather up any loose material which may happen to be
among the grains, thus becoming larger; while if the proportion of the nitro-
benzole, or other solvent, to the gun cotton in the churn be made smaller, the
grains formed will be less plastic, and will be apt to remain nearly the same size as

page_text: when produced in the churn for the reason that they are less plastic, and have
more consistency, and consequently do not tend to pick up material, as they will if
more plastic. Furthermore, the quantity of solvent used in proportion to the gun
cotton has some influence upon the preliminary grains in the churn, the grains in
the churn always being larger when a greater percentage is used from the fact
that the combination is of a more plastic nature and tends to unite in larger
particles.
We may also remove the grains at any stage of the before-mentioned processes,
and evaporate the solvent by boiling the grain with water in the ordinary manner.
The construction of barrel described, however, is well suited for the purpose of
hardening and rounding the preliminary grains formed in the churn.
In order that the grains formed by the above process may be tempered in
explosive force to any degree required, we dissolve in the solvent used in the
granulation process from two and one-half per cent. to ten per cent. of a moderating
agent, and find especially adapted for this purpose nitrated rosin or nitrated
turpentine, i.e., rosin or Venice turpentine treated with nitric acid, though we do not
confine ourselves to the use of these substances, or to the proportions mentioned.
Instead of adding the moderating agent in the manner described, it may be added
to the grain after it is finished, by means of solution in a volatile solvent, or in any
other manner.
While we have described the gun cotton as being diffused in water, it is evident
that any other fluid which will cause a better or as good a distribution of the
particles of gun cotton in the churn may be used instead, and we do not confine
ourselves to the use of water as a suspending liquid; nor do we confine ourselves to
the use of the particular form of nitro-cellulose known as gun cotton. We also do
not confine ourselves to the particular solvents mentioned, or to the exact proportions
in which they are added, or to the particular apparatus employed.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:
1. The herein-described process of making a smokeless explosive, which consists
in suspending nitro-cellulose in a liquid not a solvent of the same. granulating the
nitro-cellulose by agitating therewith in proper proportions a suitable solvent not
miscible to any great extent in the liquid used to suspend the nitro-cellulose, and
solidifying the grains thus formed, substantially as described.
2. The herein described process of making a smokeless explosive, which consists
in suspending nitro-cellulose in a liquid not a solvent of the same, granulating the
nitro-cellulose by agitating therewith in proper proportions a suitable solvent not
miscible to any great extent in the liquid used to suspend the nitro-cellulose, and
solidifying the grains thus formed by heat, substantially as described.
3. The herein-described process of producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same, granu-
lating the nitro-cellulose by agitating therewith in proper proportions a suitable
solvent not miscible to any great extent in the liquid used to suspend the nitro-
cellulose, and solidifying the grains thus formed by agitation in an atmosphere of
steam, substantially as described.
4. The herein-described process of producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same, granu-
lating the nitro-cellulose by agitating therewith in proper proportions a suitable
solvent not miscible to any great extent in the liquid used to suspend the nitro-
cellulose, and solidifying the grains thus formed by rotation in an atmosphere of
steam, substantially as described.
5. The herein-described process of producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same, granu-
lating the nitro-cellulose by agitating therewith in proper proportions a suitable
solvent not miscible to any great extent in the liquid used to suspend the nitro-

page_text: cellulose, hardening and rounding the grains thus formed by rotation, and further
solidifying the grains by rotation in an atmosphere of steam, substantially as
described.
6. The herein described process of producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same, granu-
lating the nitro-cellulose by agitating therewith iu proper proportions, accompanied
by injection of steam, a suitable solvent not miscible to any great extent in the
liquid used to suspend the nitro-cellulose, and solidifying the grains thus formed by
agitation in an atmosphere of steam, substantially as described.
7. The herein-described process of producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same, granu-
lating the nitro-cellulose by agitating therewith in proper proportions a suitable
solvent not miscible to any great extent in the liquid used to suspend the nitro-
cellulose, solidifying the grains thus formed, and moderating the action of the same
by the addition, during the above operation, of a suitable moderating agent, substan-
tially as described.
8. The herein-described process of producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same, granu-
lating the nitro-cellulose by agitating therewith in proper proportions a suitable
solvent not miscible to any great extent in the liquid used to suspend the nitro-
cellulose, and in which is dissolved a moderating agent, and solidifying the grains
thus formed, substantially as described.
9. The herein-described process of producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid, such as water, which is not a
solvent of the same, and in which is dissolved a suitable salt, granulating the nitro-
cellulose by agitating therewith in proper proportions a suitable solvent not miscible
to any great extent in the liquid used to suspend the nitro-cellulose, and solidifying
the grains thus formed, substantially as described.
10. The herein-described process of producing a smokeless explosive, which
consists in suspending nitro-cellulose in a liquid not a solvent of the same, granu-
lating the nitro-cellulose by agitating therewith in proper proportions, during
injection of steam, a suitable solvent not miscible to any great extent in the liquid
used to suspend the nitro-cellulose and in which is dissolved a moderating agent,
and solidifying the grains thus formed by rotation, and afterwards by rotation in an
atmosphere of steam, substantially as described.
Dated this 22nd day of August 1893.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.