Improvements in the 'Manufacture of Explosives.
Year: 1899

page_text: Date of Application, 16th June, 1899
Complete Specification Left, 14th Apr., 1900-Accepted, 19th May, 1900
Improvements in the 'Manufacture of Explosives.
We, CHARLES HERBERT CURTIS, of 3, Gracechurch Street, London, Explosives
Manufacturer, and ARTHUR HAMILTON DURNFORD, of Hanworth Lodge, Hanworth
Road, Hounslow, Manager of Gunpowder Works, do hereby declare the nature of this
invention to be as follows:-
Our invention has for its object the production of cheap smokeless or nearly
smokeless powders.
Nitrocellulose is employed as the basis of most smokeless powders in the manu-
facture of which it is desirable to treat the pitrocellulose with a solvent. To do so
the nitrocellulose is in general practice first dried, togrid it of all the water possible.
This operation is one which requires great care as it is attended with considerable
risk of explosion. The dry nitrocellulose is then treated in suitable vessels with its
appropriate solvent, and is thus rendered more or less gelatinous. If not already
formed into grains it has to go through several processes to form them, or flake
shaped pieces in place of grains. These grains etc. are then dried in order to volati-
lize the solvent, but much difficulty is experienced in getting rid of the last trace
of it.
Nitrocellulose when stored usually contains from 25% to 30% of water. We have
discovered that if such nitrocellulose be partly dried so that it still contains from 12
to about 20 per cent. of water (which partial drying is not attended with danger) and
then (whether it is mixed with other substances or not) it is treated with a strong
solvent, under certain conditions a degree of gelatinization can be attained without
parting with the water left in the nitrocellulose; and further that by retaining such
percentage of water throughout the operations employed in making the powders
about to be described unique physical features of great importance are produced in
the grains. The quantity of solvent employed in this treatment is such that no part
of the water or solvent can be squeezed out from the mixture.
The degree of gelatinization or the putty like condition attained by this treatment
is such that the process of forming grains from it is rendered particularly easy and
simple, when dried such grains contain no trace of the solvent, they are hard and
compact and an improvement on those usually produced in the manufacture of
smokeless powders. Such grains can be employed for a sporting powder, or for other
explosive purposes.
In carrying out this invention we either use a nitro-cellulose which is soluble
(when dry) in acetone, or one soluble in a mixture of ether and alcohol. We take
for example a nitro-cellulose soluble in acetone. We use it in its wet condition and
partially dry it, until it contains from 12 to about 20 per cent. of water according to
the powder we require to make. We further find that we can by using the substances
hereinafter referred to, in addition to the nitro-cellulose, obtain valuable results..
We may then mix the nitro-cellulose with one or more of the following substances as
mentioned at A, B, C, and D and treat either mixture with strong acetone ;—

page_text: A. NIMO-certuose.
B. do.
do.
C. do.
do.
.
D. do:
do.
Mixed with an incorporated mixture of saltpetre & charcoal.
Mixed with both chalk and an incorporated mixture of salt-
petre and charcoal.
Mixed with both chalk and saltpetre.
The chalk is a valuable ingredient; it moderates the otherwise violent action of the
nitrocellulose and increases the gaseous products of explosion and is valuable in
preserving the powder and preventing acidity which sometimes takes place in powders
made from nitro-cellulose, due to a slow decomposition of such powders after long
storage.
The incorporated mixture of saltpetre and charcoal being an explosive of itself, is
valuable in giving a quick and certain ignition to the gelatinized nitro-cellulose
mixed with it, and in carrying the combustion throughout the powder grains with
regularity. It also acts as a moderator to the violent action of the nitro-cellulose.
In using this incorporated mixture of saltpetre and charcoal, we wish it to be clearly
understood that such mixture must not be confounded with gunpowder containing
sulphur, as we exclude the latter, which if used would be detrimental to my powder,
as it would produce a great deal of smoke, residue and disagreeable fumes when
exploded, and further instead of retarding the violent action of the nitro-cellulose
would be likely to accelerate it.
In treating these compounds with the solvent we may use any usual method but
we find it convenient to mill them for a short time under edge runners, until the
material is homogeneous. We then add the acetone by quickly sprinkling it over the
material while the runners are in motion, so that the mass is rapidly pounded or
incorporated while the acetone is acting upon it. The top layers of the nitro-
cellulose is at once acted upon by the acetone, and by the rapid amalgamation of
that which has been acted upon, with that which has not been acted upon, the
desired action throughout the mass is produced. The motion and action of the
runners induces a degree of gelatinization with a much smaller quantity of solvent
than would otherwise be the case.
As an alternative method the nitro-cellulose can be first thoroughly mixed with
the substances before described, in a suitable mixing apparatus, such for example as
Werner & Pfleiderers mixers, in which the material may then be treated with the
solvent, and worked together for a short time as a preliminary step, after which
the mass may be transferred to the mill and incorporated under the edge runners.
The water contained in the nitro-cellulose tends to regulate the action of the
solvent, and the substances mixed with the nitro-cellulose, besides performing their
important functions as constituents of the explosives, also tend to regulate the action
of the solvent which so regulated gives the mass a plastic or putty like condition
which is easily crumbled. After the mass has been acted upon throughout by the
solvent aided by incorporation, it is rubbed through sieves, and thus grains are
rapidly formed. The grains are then dried, and if desired can be glazed and sifted
to the required sizes. Before drying, the grains can be pressed and moulded into
blocks, prisms or various other shapes, such as are in use for military purposes, and
such shapes can then be dried.
'
As an example of the proportions of the substances which may be compounded we
find that the following make good powders :—
Nitrocellulose (soluble in acetone)
75 parts.
25 parts.
Elutriated chalk -
Nitrocellulose (soluble in acetone)
50 parts.
An incorporated mixture of saltpetre and charcoal
50 parts.
Nitrocellulose (soluble in acetone)
60 parts.
20 parts.
Elutricated chalk
An incorporated mixture of saltpetre and charcoal
20 parts.
Nitrocellulose (soluble in acetone).
60 parts.
30 parts
Saltnetre

page_text: We however do not confine' ourselves to any of the above proportions, but may
vary them according to the nature of the explosive that it is required to be made.
Dated the 15th day of June 1899.
THEO. MCKENNA,
17 & 18, Basinghall Street, London, E.C., Applicants Agent.
Improvements in the Manufacture of Explosives.
We, CHARLES HERBERT CURTIS, of 3, Gracechurch Street, London, Explosives
Manufacturer, and ARTHUR HAMILTON DURNFORD, of Hanworth Lodge, Hanworth Road,
Hounslow, Manager of Gunpowder Works, 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 has for its object the production of cheap smokeless or nearly
smokeless powders.
Nitro-cellulose is employed as the basis of most smokeless powders in the manu-
facture of which it is desirable to treat the nitrocellulose with a solvent.
To do so
the nitrocellulose is in general practice first dried, to rid it of all the water possible.
This operation is one which requires great care as it is atten led with considerable
risk of explosion. The dry nitrocellulose is then treated in suitable vessels with its
appropriate solvent and is thus rendered more or less gelatinous. If not already
formed into grains it has to go through several processes to form them, or flake shaped
pieces in place of grains. These grains etc. are then dried in order to volatilize the
solvent, but much difficulty is experienced in getting rid of the last trace of it.
Nitrocellulose when stored usually contains from 25 per cent. to 30 per cent. of
water. We have discovered that if such nitrocellulose be partly dried so that it still
contains from about 12 to about 20 per cent. of water (which partial drying is not
attended with danger) and then (whether it is mixed with other substances or not)
treated with a strong solvent (preferably acetone) a degree of gelatinization can be
attained without parting with the water left in the nitrocellulose and further that by
retaining such percentage of water throughout the operations employed in making.
the powders about to be described unique physical features of great importance are
produced in the grains. The quantity of solvent employed in this treatment should
only be such that no part of the water or solvent can be squeezed out from the
mixture.
The degree of gelatinization or the putty like condition attained by this treatment
is such that the process of formning grains from it is rendered particularly easy and
simple, when dried such grains contain no trace of the solvent, they are hard and
compact and an improvement on those usually produced in the manufacture of
smokeless powders. Such grains can be employed for a sporting powder, or for
other explosive purposes.
We take nitro-cellulose in its wet condition, and partially dry it until it contains
from about 12 to 20 per cent. of water according to the strength of the powder we
require to make.
We find that when the higher percentage of water is employed,
the strength is greater of the powder produced and its density lower. These
percentages of water enable us to a certain extent to vary the explosiveness of the
powder and afford means by which the bulkiness of the powder can be regulated.
Our chief reason however for working with these limits of moisture is that the powder
grains produced are superior in their physical features..
We further find that we can by using the substances hereinafter referred to, in
addition to the nitro-cellulose partially dried as aforesaid, obtain valuable results,

page_text: BOA
B.
do.
do.
C.
do.
do.
D. do. do.
Alixed with an incorporated mixture of salt petre and charcoal.
Mixed with both chalk and an incorporated mixture of salt petre
and charcoal.
Mixed with both chalk and salt petre.
The chalk is a valuable ingredient: it moderates the otherwise violent action of
the nitro-cellulose and increases the gaseous products of explosion and is valuable in
preserving the powder and preventing acidity which sometimes takes place in
powders made from nitro-cellulose, due to a slow decomposition of such powders after
long storage.
We are aware that chalk has been used in small quantities with nitro-cellulose and
as so used would have an effect in moderating and rendering stable the explosive but
in the larger quantities in which we propose to use it we find its decomposition on
the combustion of the nitro-cellulose adds appreciably to the volatile products of
combustion by giving off carbon di-oxide.
-
The incorporated mixture of saltpetre and charcoal being an explosive of itself, is
valuable in giving a quick and certain ignition to the gelatinized nitro-cellulose
united with it, and in carrying the combustion throughout the powder grains with
regularity. It also acts as a moderator to the violent action of the nitro-cellulose.
In using this incorporated mixture of saltpetre and charcoal we wish it to be clearly
understood that such mixture must not be confounded with gunpowder containing
sulphur, as we exclude the latter, which if used would be detrimental to our powder,
as it would produce a great deal of smoke residue and disagreeable fumes when
exploded, and further instead of retarding the violent action of the nitro-cellulose
would be likely to accelerate it. The proportion of charcoal to saltpetre to be used
are, we have found by experiment to be about 80 parts of salt petre to 20 parts of
charcoal, but these proportions may be varied.
Before treating these compounds with the solvent we may roughly mix them by
hand, then thoroughly mix them by any suitable mechanical means. We find it
convenient to mill the compounds for a few minutes under edge runners, until the
materials are homogeneous. We then add the acetone by quickly sprinkling it over
the material while the runners are in motion, so that the mass is rapidly pounded or
incorporated while the acetone is acting upon it. The nitro-cellulose in the surface
of the compound is at once acted upon by the acetone and by the rapid amalgamation
of that which has been acted upon with that which has not been acted upon, the
desired action throughout the mass is produced. The motion and action of the
runners induces a degree of gelatinization with a much smaller quantity of solvent
than would otherwise be the case.
As an alternative method the nitro-cellulose can be first thoroughly mixed with
..the substances before described, in a suitable mixing apparatus, such for example as
Werner & Pfleiderers mixers, in which the material may then be treated with the
solvent and worked together for a short time as a preliminary step, after which the
mass should be transferred to the mill and incorporated under the edge runners.
The water contained in the nitro-cellulose tends to regulate the action of the
solvent, and the substances mixed with the nitro-cellulose, besides performing their
important functions as constituents of the explosives, also tend to regulate the action
of the solvent which so regulated gives the mass a plastic or putty like condition
which is easily crumbled. After the mass has been acted upon throughout by the
solvent aided by incorporation, it is rubbed through sieves or otherwise granulated in
any usual known method and thus grains are rapidly formed. The grains are then
dried, and if desired can be glazed and sifted to the required sizes. Before drying,

page_text: We however do not confine ourselves to any of the above proportions but may vary
them according to the nature of the explosive that is required to be made.
The proportions given are those of what may be regarded as standard powders and
very suitable for sporting powder.
These proportions may be altered for the purpose of producing a definite alteration
in the resulting powder. Thus in a powder designed for military use the chalk may
be reduced in order to diminish its retarding effect upon the combustion. The
acetone may be increased in order to get a higher state of gelatinization and thereby
a more concentrated powder. It is impossible to specify all the modified proportions
which may be desirable for adapting the powder to various uses. We have however
indicated the directions in which such modifications should be made to meet the
ordinary requirements of military service. The particular change to be made in any
or all of these directions will depend upon the particular requirements and the
particular military purpose to which the powder is to be adapted.
Any increase in the proportions used of the mixture of salt petre and charcoal will
to a certain extent increase the quantity of smoke but the decreasing thereby of the
quantity of nitro-cellulose necessary makes the powder cheaper.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is :---
1. A powder manufactured as herein before described from nitro-cellulose partially
dried then mixed with elutriated chalk and then treated with a solvent in the
proportions and manner substantially as hereinbefore set out.
2. A powder manufactured as herein before described from uitro-cellulose partially
dried, then mixed with an incorporated mixture of saltpetre and charcoal and then
treated with a solvent in the proportions and manner substantially as herein before
set out.
3. A powder manufactured as herein before described from nitro-cellulose partially
dried then mixed with elutriated chalk and an incorporated mixture of saltpetre and

page_text: charcoal and then treated with a solvent in the proportions and manner substantially
as hereinbefore set out.
4. A powder manufactured as herein before described from nitro-cellulose partially
dried then mixed with saltpetre and chalk and then treated with a solvent in the
proportions and manner substantially as herein before set out.
Dated the 19th day of Anril 1000
THEO.
MCKENNA,
17 & 18, Basinghall Street, London, E.C., Applicant's Agent.