Improvements in the Manufacture of Pyroxylin Smokeless Explosives.
Year: 1896

page_text: Date of Application, 29th July, 1896
Complete Specification Left, 29th May, 1897-Accepted, 3rd July, 1897
Improvements in the Manufacture of Pyroxylin Smokeless
Explosives.
I, HUDSON MAXIM, of Thurlow Lodge, 377 Norwood Road, London, S.E., Chemist
and Mechanical Engineer, do hereby declare the nature of this invention to be as
follows:-
The object of my present invention is to produce a smokeless explosive composed
wholly or mainly of pyroxylin, that is to say of tri-nitro-cellulose, or of nitro-cellulose,
of a lower grade of nitration, or, preferably, of a mixture of tri-nitro-cellulose and
nitro-cellulose of a lower grade of nitration, the latter being chiefly employed on
account of its great solubility in certain menstrua in which tri-nitro-cellulose is
almost, if not quite, insoluble.
Heretofore, great difficulty has been experienced in making smokeless explosives
wholly of pyroxylin for guns of large calibres, such as five and six inch guns and
upwards, on account of the density of a colloid of gun-cotton and of the small extent
to which the flame of combustion will consume the explosive material. under admis-
sible pressure and during the very short time that elapses before the projectile leaves
the gun. This has made it difficult to use explosive material possessing the requisite
thickness to enable sufficiently large charges to be employed. Consequently it has
been necessary to employ a thinner explosive material in order that it may be
completely burned through and wholly consumed, and thus too large a combustion
area, relative to the weight of the charge, is presented to the initial flame of combus-
tion, with resulting excessive pressures.
Another disadvantage experienced in making smokeless explosives wholly of
pyroxylin, has been due to the difficulty with which the solvents cau be evaporated
from the explosive material unless the latter be made very thin, and in addition to
this disadvantage a further difficulty arises in the warping twisting and breaking of
the explosive material, such warping twisting and breaking being due to the more
rapid evaporation of the solvent from the surfaces of the explosive material and the
consequent shrinkage of such surfaces before the solvent has evaporated from the
deeper portions of the explosive material.
In carrying out my invention I first make a pyroxylin paper or a paper or pulp
board of fibrous pyroxylin. I may make such paper or pulp board of one particular
degree of nitration, but I prefer to employ a mixture of tri-nitro-cellulose and some
other and more soluble variety of pyroxylin. The two kinds of pyroxylin are
thoroughly commingled in a fibrous state, preferably by pulping or poaching them
together in suitable proportions, such, for example, as nine parts by weight of tri-
nitro-cellulose, to one part by weight of di-nitro-cellulose or gelatin pyroxylin.
Sheets of the paper or pulp board composed of such mixture of pyroxylins are treated
with a solvent of the di-nitro-cellulose or more soluble pyroxylin, and which is not a
solvent of the tri-nitro-cellulose. The solvent may be applied to the sheets of paper
or pulp board in any suitable manner, as for example, by submitting the sheets to an
atmosphere of a solvent or solvents, of di-nitro-cellulose, or by impregnating or
sprinkling them with the solvent or solvents, or by immersing them therein. In any
case, the sheets are preferably treated with as small a quantity of solvent as will
effect the desired result, as hereinafter set forth. When the di-nitro-cellulose or

page_text: soluble pyroxylin has become sufficiently dissolved or sufficiently plastic, then a
desired number of sheets are superimposed and submitted to such a degree of pressure
as will cause the various sheets to firmly adhere to one another or solidly unite, and
thereby cause the material to possess the required density and solidity for the
purposes of a smokeless explosive. The density of the material may be regulated as
desired by varying the quantity of the soluble or di-nitro-cellulose in pròportion to
to the insoluble or tri-nitro-cellulose, and by varying the quantity of solvents used
and the degree of pressure employed. The undissolved pyroxylin or tri-nitro-
cellulose, still remaining in a fibrous state, facilitates the drying of the explosive
material and the removal of the solvent from the deeper portions of the same, and
also prevents the explosive material from warping and cracking in drying, especially
when made of considerable thickness. The tri-nitro-cellulose by being in a fibrous
state also facilitates the ignition and combustion of the material and causes it to
burn through to a greater thickness than when made into an amorphous colloid.
When a sufficient thickness of the material has been obtained by compressing the
various sheets together, as hereinbefore stated, and before the solvent has been
evaporated from the same, the material is cut into suitable lengths strips or pieces as
desired, but preferably of lengths approximating the length of the powder chamber
of the gun in which the explosive is intended to be used. Either before or after the
material is cut into the said lengths or strips, it is formed with a large number of
small perforations depressions or holes which penetrate nearly, and preferably entirely,
through the material, the arrangement number and size of such perforations depres-
sions or holes being such that they will serve to produce the highest ballistic results
when cut into the desired lengths or strips for use in guns.
By forming the explosive material with a very large number of small perforations
depressions or holes, the evaporation of the solvent in the material is further
facilitated and a minimum of burning surface is necessarily presented to the initial
flame of combustion in comparison with or in proportion to the weight of the
explosive charge.
I may vary this method of manufacture by the employment of only one grade or
degree of nitration of nitro-cellulose, as, for example, tri-nitro-cellulose, and form the
same into sheets of paper or pulp board, sufficient solvent being employed to enable
the sheets to be united with one another to build up the explosive material of the
desired thickness by the application of suitable pressure. The material may then be
perforated and cut into strips as hereinbefore described. The large number of very
small perforations will enable the explosive material to readily dry and the explosive
to be consumed in the gun in the manner desired. I prefer however, to employ
different varieties of pyroxylin that vary in solubility, and to proceed in the manner
hereinbefore first stated.
In some cases I may employ sheets composed wholly of tri-nitro-cellulose and
others composed wholly of gelatin pyroxylin or the more soluble variety of pyroxylin
and superimpose these sheets in such a manner that a sheet of the tri-nitro-cellulose
alternates with a sheet of the gelatin pyroxylin. The sheets of gelatin pyroxylin
may be previously treated with a solvent or solvents to render them plastic or in such
a condition that they will adhere to the sheets of tri-nitro-cellulose and impregnated
them with the solvents and agglutinate the fibres thereof. The superimposed sheets
may then be subjected to pressure in the manner and for the purpose herein before
stated.
Sometimes I may manufacture a paper of tri-nitro-cellulose and provide the same
during its manufacture with a facing of the more soluble variety of pyroxylin.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C.,
Agents for the Applicant.

page_text: Improvements in the Manufacture of Pyroxylin Smokeless
Explosives.
I, HUDSON MAXIM, of Thurlow Lodge, 377 Norwood Road, London, S.E. Chemist
and 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 :-
The object of my present invention is to produce a smokeless explosive composed
wholly or mainly of pyroxylin, that is to say, of tri-nitro-cellulose or of nitro-cellulose
of a lower grade of nitration, or preferably of a mixture of tri-nitro-cellulose and
nitro-cellulose of a lower grade of nitration, the latter being chiefly employed on
account of its great solubility in certain menstra in which tri-nitro-cellulose is
almost, if not quite, insoluble.
Heretofore, great difficulty has been experienced in making smokeless explosives
wholly of pyroxylin for guns of large calibres, such as five and six inch guns and
upwards, on account of the density of a colloid of guncotton and of the small extent
to which the flame of combustion will consume the explosive material under
admissible pressure and during the very short time that elapses before the projectile
leaves the gun. This has made it difficult to use explosive material possessing the
requisite thickness to enable sufficiently large charges to be employed. Consequently
it has been necessary to employ a thinner explosive material in order that it may be
completely burned through and wholly consumed, and thus too large a combustion.
area, relative to the weight of the charge, is presented to the initial flame of combus-
tion, with resulting excessive pressures.
Another disadvantage experienced in making smokeless explosives wholly of
pyroxylin has been due to the difficulty with which the solvents can be evaporated
from the explosive material unless the latter be made very thin, and in addition to
this disadvantage, a further difficulty arises in the warping, twisting and breaking of
the explosive material, such warping, twisting and breaking being due to the more
rapid evaporation of the solvent from the surfaces of the explosive material and the
consequent shrinkage of such surfaces before the solvent has evaporated from the.
deeper portions of the explosive material.
In carrying out my invention, I first make a pyroxylin paper or a paper or pulp.
board of fibrous pyroxylin. I may make such paper or pulp board of one particular degree
of nitration, but I prefer to employ a mixture of tri-nitro-cellulose and some other
and more soluble variety of pyroxylin. The two kinds of pyroxylin are thoroughly
commingled in a fibrous state, preferably by pulping or poaching them together in
suitable proportions, such, for example, as nine parts by weight of tri-nitro-cellulose,
to one part by weight of di-nitro-cellulose or gelatin pyroxylin. Sheets of the paper
or pulp board composed of such mixture of pyroxylins are treated with a solvent of
the di-nitro-cellulose or more soluble pyroxylin, and which is not a solvent of the
tri-nitro-cellulose, such as a mixture of ether and alcohol. The solvent may be
applied to the sheets of paper or pulp board in any suitable manner, as for example,
by submitting the sheets to an atmosphere of a solvent or solvents of di-nitro-
cellulose, or by impregnating or sprinkling them with the solvent or solvents, or by
immersing them therein. In any case, the sheets are preferably treated with as
small a quantity of solvent as will effect the desired result, as hereinafter set forth.
When the di-nitro-cellulose or soluble pyroxylin has become sufficiently dissolved or
sufficiently plastic, then a desired number of the sheets are superimposed and
submitted to such a degree of pressure as will cause the various sheets to firmly

page_text: adhere to one another or solidly unite, and thereby cause the material to possess the
required density and solidity for the purposes of a smokeless explosive. The density
of the material may be regulated as desired by varying the quantity of the soluble or
di-nitro-cellulose in proportion to the insoluble or tri-nitro-cellulose, and by varying
the quantity of solvents used and the degree of pressure employed. The undissolved
pyroxylin or tri-nitro-cellulose, still remaining in a fibrous state, facilitates the drying
of the explosive material and the removal of the solvent from the deeper portions of the
same, and also prevents the explosive material, from warping and cracking in drying,
especially when made of considerable thickness. The tri-nitro-cellulose, by being in
a fibrous state also facilitates the ignition and combustion of the material and causes
it to burn through to a greater thickness than when made into an amorphorus colloid.
When a sufficient thickness of the material has been obtained by compressing the
various sheets together, as hereinbefore stated, and before the solvent has been
evaporated from the same, the material is cut into suitable lengths, strips or pieces as
desired, but preferably of lengths approximating the length of the powder chamber of
the gun in which the explosive is intended to be used. Either before or after the
material is cut into the said lengths or strips it is formed with a large number of
small perforations depressions or holes, which penetrate nearly, and preferably entirely,
through, the material, the arrangement, number and size of such perforations
depressions or holes being such that they will serve to produce the highest ballistic
results when cut into the desired lengths or strips for use in guns.
By forming the explosive material with a very large number of small perforations,
depressions or holes, the evaporation of the solvent in the material is further
facilitated and a minimum of burning surfaces is necessarily presented to the initial
flame of combustion in comparison with, or in proportion to the weight of the
explosive charge.
I may vary this method of manufacture by the employment of only one grade or
degree of nitration of nitro-cellulose, as, for example, tri-nitro-cellulose, and form the
same into sheets of paper or pulp board, sufficient solvent being employed to enable
the sheets to be united with one another to build up the explosive material of the
desired thickness by the application of suitable pressure. The material may then be
perforated and cut into strips as hereinbefore described. The large number of very
small perforations will enable the explosive material to readily dry and the explosive
to be consumed in the gun in the manner desired. I prefer, however, to employ
different varieties of pyroxylin that vary in solubility, and to proceed in the manner
hereinbefore first stated.
In some cases I may einploy sheets composed wholly of tri-nitro-cellulose, and
others composed wholly of gelatin-pyroxylin, or the more soluble variety of pyroxylin and
superimpose these sheets in such a manner that a sheet of the tri-nitro-cellulose
alternates with a sheet of the gelatin pyroxylin. The sheets of gelatin pyroxylin
may be previously treated with a solvent or solvents to render them plastic or in such
a condition that they will adhere to the sheets of tri-nitro-cellulose and impregnate
them with the solvents and agglutinate the fibres thereof. The superimposed sheets
may then be subjected to pressure in the manner and for the purpose hereinbefore
stated.
Sometimes I may manufacture a paper of tri-nitro-cellulose and provide the same
during its manufacture with a facing of the more soluble variety of pyroxylin.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, I declare that what I claim is :-
1. The process of making an explosive compound substantially as described, which
consists in making fibrous guncotton into paper, rendering the surface of the paper
adhesive, and then pressing together sheets of the paper to build up a body of
explosives of a desired thickness.
2. The herein described process of inanufacturing a smokeless explosive compound,
which consists in making into paper a mixture of pyroxylins of different solubility,

page_text: then dissolving the more soluble of the pyroxylins, and then pressing different sheets
together to produce a body of the compound of a desired thickness.
3. An explosive compound, consisting of a number of superimposed layers of
pyroxylin paper.
Dated the 29th May, 1897.