IMPROVEMENTS IN THE MANUFACTURE OF EXPLOSIVES
Year: 1885

page_text: I DAVID JOHNSON of 52 Fitzjohns Avenue, South Hampstead in the County
of Middlesex, Gentleman do hereby declare the nature of said invention for
"IMPROVEMENTS IN THE MANUFACTURE OF EXPLOSIVES" to be as follows:-
The employment of nitro-cellulose in the preparation of powder for sporting and
military fire-arms has hitherto been retarded by the uncertainty attendant upon
the use of such powder. This invention provides a means whereby a safe and
reliable powder may be produced, and one which is completely under the control of
the manufacturer. By my process a nitro-cellulose powder can be prepared, the
grains, cylinders or prisms of which are hardened throughout their mass, and not
simply at the surface; the combustion of the powder manufactured by this process
is slow, and it has been found by experiment that this method provides a means of
regulating the rate of combustion and of regulating and minimizing the strain upon
the weapon in which such powder may be used; the grains of powder manu-
factured by this method whilst being hard, ignite freely, there being no tendency
to hang fire, since the nitro-cellulose retains its fibrous structure. Large quantities
of the powder can be safely and efficiently treated at one time, the cost of the
material employed in the hardening process is small, and the process can be
adapted for making the powder both for sporting and military purposes.
By this invention I provide a means of giving hardness to grains, cylinders or
prisms of nitro-cellulose (either pure or in admixture with other substances used
for explosive purposes, such as nitrate of potassium or of barium) by treating the
said nitro-cellulose with camphor. The camphor may be applied for instance by
volatilizing camphor in a vessel, entirely or partially closed, containing the nitro-
cellulose, and thus permeating the nitro-cellulose with the camphor: or it may be
applied by dissolving camphor in any of its solvents or mixed solvents which boil
at temperatures below 100° C, and which solvents either of themselves or when
combined with the camphor exert little or no gelatinizing effect or detrimental
effect upon the nitro-cellulose. The granulated or otherwise manipulated nitro-
cellulose pure or in admixture with other substances is treated with such solution
of camphor in quantity sufficient to permeate the quantity of material being
operated upon.

page_text: Until the solvent is driven off the camphor does not exert any gelatinizing
action upon the nitro-cellulose. The powder thus impregnated is now placed in an
apparatus where it can be heated to temperatures not higher than 100° C, for
effecting the gelatinizing action of the camphor upon the nitro-cellulose. The
powder is finally freed from the camphor and the latter recovered if required, by
sublimation under reduced pressures, or in a current of air either moist or dry, or
under ordinary atmospheric conditions; or the camphor is removed and recovered
by being washed out of the powder with one or more of its solvents having no
action upon the nitro-cellulose or any other substance in admixture therewith.

page_text: I, DAVID JOHNSON of 52 Fitzjohn's Avenue South Hampstead in the County of
Middlesex Gentleman 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 :—
The employment of nitro-cellulose whether obtained by the nitration of cotton
or of wood or other analogous substances in the preparation of powder for sporting
and military firearms has hitherto been retarded by the uncertainty attendant
upon the manufacture and use of such powder. This invention provides a means
whereby a powder safe reliable and of any required hardness and density may be
produced, by a process which in practice has been found to be simple economical
and completely under the control of the manufacturer. By my process a powder
made from nitro-cellulose whether obtained by the nitration of cotton or of wood
or other analogous substances can be prepared in the form of grains cylinders or
prisms which are hardened throughout their mass and not simply at the surface;
the combustion of the powder manufactured may by this process be rendered slow,
and it has been found by experiment that this method provides a means of
regulating the rate of combustion and of regulating and minimizing the strain
upon the weapon in which such powder may be used while imparting the maximum
velocity to the projectile and consequently flattening or lowering the trajectory;
the grains or other forms of powder manufactured by this method whilst being
hard ignite freely, there being no tendency to hang fire since the nitro cellulose
practically retains its fibrous structure so that there is presented to the flash of the
cap a multitude of microscopic points that favour instant ignition and combustion.
Large quantities of the powder can be safely and efficiently treated at one time
the cost of the material employed in the hardening process is small, and the process
can be adapted for making the powder both for sporting and military purposes..
Further, and most important advantages gained by my invention are-that I am
enabled to manufacture explosives for use in weapons for military and sporting
purposes, not only from any of the nitro-cellulose compounds of various degrees of
nitration singly or in combination such for instance-as the tri-nitro, the di-nitro
and the mono-nitro cellulose and those of intermediate nitration-but also from
the use of di-nitro cellulose alone or in conjunction with nitro cellulose compounds
of lower degrees of nitration than the tri-nitro cellulose (that is to say without
tri-nitro cellulose as heretofore).
The ordinary guncotton now used is an imperfect tri-nitro cellulose inasmuch as
it contains proportions of other nitro cellulose of lower degrees of nitration, which
proportions practically are of a varying quantity so that it is difficult to obtain
commercially two samples alike. Although these variations may be slight yet in
practice I have found by experiment that they induce marked variable and some-
times dangerous effect in the action of the finished product when used in the fire
arm. Where hereafter I speak generally of tri-nitro cellulose it includes what is
called un cotton.

page_text: While I do not in my invention confine myself to the use of di-nitro cellulose
alone or in admixture in the manner just stated, yet I have found by experiment
that where gun cotton or tri-nitro cellulose is used as one of the essential con-
stituents of the explosive either in my invention or by the processes employed in
the preparation of the various heretofore known nitro compounds (used for fire
arms) an element of uncertainty is introduced owing to the difficulty of preparing.
commercially a true tri-nitro cellulose. An element of great uncertainty is thus
introduced into the explosive which under certain further slightly varying conditions
such as manner of loading, pressure in loading, strength of cap and shape of cart-
ridge case-render it extremely difficult and almost impossible to prepare a powder
for the above purposes, which shall not under some of these varying conditions
explode with abnormal suddenness-and thus give rise to an abnormal strain upon
the weapon-sometimes even to bursting force as has often been the case in
"practice.
An element of danger has been discovered in powders containing tri-nitro
cellulose in important quantities as in powders made from nitro-cellulose now in
the market. In regard to the amount of moisture contained in such powders there
appears in this respect to be only one condition of maximum utility and of safety.
and that is when the powder is in its average normal or air dry state.
When however such powder is subjected to extremely moist conditions and
consequently takes up more moisture than its average normal or air dry condition
would demand then there is objectionable hang fire. This moisture can be driven
off and when the powder has regained its average normal air dry state then it
regains its usefulness-but if (as has been found the case in practice) the powder
has been subjected to a warmth or heat sufficient to dry the powder below its
average normal or air dry state-then abnormal variations in the explosive force
take place varying in intensity according to the dryness and up to complete dryness
of the powder in which state also experiment has proved powders containing
tri-nitro-cellulose to be exceedingly dangerous.
The powder manufactured by the process herein set forth has the further
advantage that if it should by any chance take up an excess of moisture over the
average normal or air dry quantity-then if such powder be subjected to warmth
or heat to drive off such excess of moisture-even if the moisture be absolutely
removed the strain upon the weapon set up by such dry powder is never more than
that of ordinary black gunpowder in its ordinary shooting state-and the powder
manufactured by this process exerts in its average normal or air dry state a strain
upon the weapon much less than that from ordinary gunpowder.
In powder prepared by this improved simple and certain commercial process of
manufacture from nitro-cellulose of lower degrees of nitration than that of the
tri-nitro compound there is regularity and certainty in the finished product; and
slightly varying conditions-such as manner of loading, pressure in loading, strength
of cap shape of cartridge case and the varying amount of moisture in the powder do
not exert any marked or dangerous effect in its use-and generally in the use of a
powder prepared by this process there is a more gradual pressure during com-
bustion in the gun than in the case of a powder yielding the same projecting force
but containing tri-nitro cellulose in important quantities as in such powders now
in the market.
According to this invention provide a means of giving uniform hardness
throughout to grains cylinders or prisms of nitro-cellulose (either pure or in
admixture with other substances used for explosive purposes, such as nitrate of
potassium or of barium) and when deemed advisable according to the exact purpose
for which the explosive is to be employed with other suitable materials such for
instance as hydro-cellulose, wood flour, torrefied starch, lamp black or charcoal by
treating the said nitro-cellulose or mixture with camphor which when it has effected
the object in view is removed and can be used again. Instead of using camphor
in solution wholly I may use therewith a certain proportion of essential oils or
phenols.

page_text: In carrying this invention into effect, the nitro-compound mixed with sufficient
water to be uninflammable, such and for example as di-nitro cellulose is first mixed
by appropriate means with oxidizing agents as nitrate of potassium or of barium, and
when deemed advisable, according to the exact use to which the explosive is to be
put with other materials, such for instance as hydro-cellulose, wood flour, torrefied
starch, lamp black or charcoal. As an example for military fire arms I may mention
fifty parts by weight of nitro-cellulose, forty parts of nitrate of potassium and
ten parts of torrefied starch or lamp black. As example for sporting and shot guns
I may mention fifty parts of nitro-cellulose and twenty five parts of nitrate of
barium twenty two parts nitrate of potassium and three parts of torrefied starch
or lamp black.
The nitro-compound, either pure or in admixture with substances.such as are
mentioned above, is then brought into the form of small granules by well known
means or is moulded by more or less compression into suitable forms such for
instance as cylinders prisms or cubes. 'The granular powder hereinafter spoken of
as the grains, or the cylinders prisms or cubes hereinafter described as the blocks,
are deprived of their moisture by heat or otherwise and are then fit to undergo
the treatment about to be described. A weighed quantity of the grains or blocks
is taken and a preliminary experiment is made to determine what quantity of any
of the solvents or mixed solvents of camphor is required to saturate the grains or
blocks without these being unduly wet. The solvent or mixed solvents of camphor
chosen are such as evaporate below 100° C. and neither per se nor with the camphor
in solution exert any material gelatinizing solvent or detrimental action. upon the
explosive compound In practice light petroleum or benzoline is found both an
economical and convenient solvent for the camphor.
Various non-volatile oils, such as paraffin oil, rosin oil, or easily fusible fatty or
resinous matters may also be added to the grains or blocks as I have found that
such materials aid in effecting the desired slowing action; this is easily and con-
veniently effected by introducing the same into the camphor solution so that when
the volatile solvent or solvents is driven off, the non-volatile oily or fatty matter
remains behind in the grains or blocks together with the camphor.
Having discovered the proper saturating proportion of the solvent or mixed
solvents of camphor in relation to the grains or blocks, a solution of camphor is
prepared of a strength such that the grains or blocks when saturated with the
solution may contain that quantity of camphor which is found by experiment to
effect the production, as may be desired, of an explosive more or less hard and
respectively of a more or less slowly burning nature. In practice it is found that
a proportion of 1 part by weight of camphor and 5 parts by weight of the solvent
to 10 parts by weight of the nitro compound or mixture gives good results, but it
is to be clearly understood that the proportion is not limited to this or any other
herein expressed or unexpressed. Or instead of the 1 part of camphor I may use
say 05 part of camphor, 5 parts of the solvent and 0.5 part of phenol to ten parts
by weight of the nitro compound or mixture.
Having prepared an appropriate solution of camphor, the grains or blocks are
saturated therewith, sufficient time being allowed for the solution to thoroughly
permeate every part of the nitro compound.
The grains or blocks may be saturated with the camphor solution by pouring a
regulated quantity of the solution upon the nitro-compound and agitating to effect
proper admixture.
Or it may be effected by immersing the grains or blocks
contained in a perforated basket of wire gauze or other material, in the camphor
solution either under reduced or it may be ordinary atmospheric pressures. In
order to effect a more intimate action or penetration in the pores especially with
large blocks I may exhaust the air more or less from the space above the saturating
liquid contained in a closed vessel and from the pores of the nitro-compound placed
in that space before immersion and to admit the air again after immersion so as to
use the air pressure to complete the saturation suitable means being provided for
lowering and raising the basket into and out of the liquid while in the saturating

page_text: 4
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vessel. I then allow the excess of liquid adhering to the grains or blocks to drain
off before proceeding with the next process, viz:-that of evaporating off the
volatile solvent and collecting the same for repeated use. It is to be clearly
understood that I do not bind myself to the employment of any special form of
apparatus for effecting the evaporation and condensation of the volatile solvent, but
in practice it is found convenient to employ a circular pan heated from without by
steam or hot water, and provided with a mechanical stirrer revolving concentrically
or otherwise. Fitting closely to the circular pan is a dome of about the same
diameter and section as the lower pan. This dome has an aperture at its highest
part, by which the vapors of the volatile solvent pass into an ordinary stillhead
which may surmount and form part of the dome, and thence to an ordinary
condenser. The volatile solvent is driven off at the lowest possible temperature,
and leaves the camphor disseminated in the solid or crystalline form throughout
the grains or blocks, and even within the cell-walls of the nitro-cellulose. Up to
this stage of the process the action of the solution of camphor upon the grains
or blocks is inappreciable.
The grains or blocks, through the entirety of whose mass finely divided camphor
has thus been disseminated are now heated in a closed though not necessarily air-
tight vessel at a temperature not higher than 100° C. At this temperature the
camphor exerts a remarkable action upon the nitro-cellulose, and the grains or
blocks which at first were easily friable are by this treatment rendered very hard
or of any required hardness according to the percentage of camphor used in the
solution. The camphor may now be driven out of the grains or blocks by
sublimation or evaporation under ordinary or reduced pressures or in
current of
steam or air or other gas, or it may be washed out by treating the grains or blocks
with any appropriate solvent or solvents of camphor. When the apparatus
mentioned above is used to effect the driving off of the volatile solvent, the whole
. of the operations viz, mixing the grains or blocks with the solution of camphor
with or without the aforesaid exhaustion and readmission of air driving off and
condensing the volatile solvent, heating the grains or blocks containing solid
camphor permeated through their mass, and lastly the driving off by heat and
collecting the camphor driven off, may be conveniently carried out in the same
apparatus.
When the camphor is to be removed from the blocks or grains by washing, a
rapid process is to saturate the grains or blocks with some volatile solvent of
camphor such as light petroleum, and then expel the petroleum or other solvent
with the camphor in solution by means of centrifugal force. With this object, a
centrifugal hydro-extractor so constructed, as to allow of as little air as possible
passing through the grains or blocks may be advantageously employed. Any slight
residue of the volatile solvent left in the grains or blocks after the centrifugal
process, is expelled by means of heat.
By varying the proportion of the camphor the action of the same upon the
nitro-cellulose at and up to the temperature named is such as to afford an exactly
adjustable means of obtaining an explosive having any desired action or intensity
either sudden or more gradual or even extremely gradual.
It is to be distinctly understood that these results are obtained not by the
presence of camphor in large or small quantities in the finished explosive but by a
remarkable gelatinizing and perhaps some other action exerted by the camphor
upon the nitro-cellulose when these are heated together at varying temperatures up
to 100° C whereby the hardness and density of the explosive may be regulated at
will by the proportion of camphor used.
Where conditions are such that an explosive is required of greater density than
that obtained by the foregoing processes in the case of the grains treated as
described these are subjected en masse to a great pressure so that a cake is formed.
This cake is however easily broken up practically into the original grains, and
these are found to possess a higher density and having an augular or more or
less flattened form. conducive to rapidity of ignition.. Instead of compressing the

page_text: grains en masse the grains may be passed between accurately turned rollers so
adjusted as to exert a very considerable degree of pressure upon them having the
effect of increasing the density and giving a more or less angular or flattened form.
Or the hard, approximately spherical granules after treatment by the camphor
process may also be moulded by compression into various forms such as cylinders,
prisms cubes or spheres. In this way small cylinders for instance containing the
exact charge of powder for use in fire arts may be manufactured. Instead of
applying the compression to the hardened granules freed from camphor as above,
the granules freed from volatile solvent but still containing camphor disseminated
through the mass may be taken and compressed or moulded by compression. The
forms such as cylinders prisms cubes or spheres obtained by such compression are
then heated at temperatures not exceeding 100° C until the action of the camphor
is complete and the camphor is finally removed as far as practicable either by
sublimation or by being washed out by means of an appropriate solvent as before
described.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed I declare that what
I claim is
First. The application of camphor or its equivalents or a mixture of same as an
admixture to nitro-cellulose and preferably di-nitro cellulose for the purpose of
imparting thereto any required degree of hardness and density and thereby
regulating the energy of action or combustibility of the explosive substantially as
set forth.
Second. The manufacture of nitro-cellulose explosives having any required
degree of hardness density and combustibility by first mixing the nitro-celluloso
and preferably di-nitro cellulose with an oxidizing agent with or without a
carbonaceous admixture, then forming the composition into grains or blocks which
are saturated with a camphor solution or compound and then removing the solvent
and the camphor substantially as set forth.
Third. The manufacture of the described explosive rendered hard in the
manner described into compressed forms or blocks of any required size and shape
substantially as set forth.
Fourth. The manufacture of the described explosive rendered hard in the
manner described into compressed flattened or angular grains substantially as
set forth.
Fifth. The manufacture of nitro-cellulose explosives for use in sporting and
military fire arms substantially as set forth.