Improvements in and relating to a Process of, and Apparatus for, Treating Gun Cotton.
Year: 1897

page_text: Date of Application, 1st July, 1897-Accepted, 26th Feb., 1898
COMPLETE SPECIFICATION.
Improvements in and relating to a Process of, and Apparatus for,
Treating Gun Cotton.
I, FRANCIS GUONEY DU PONT, a Citizen of the United States of America, residing
in the City of Wilmington, County of Newcastle, and State of Delaware, 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 processes for treating gun cotton in
the manufacture of explosives, such as smokeless powder, and in other arts,
and in the apparatus used in connection therewith.
Gun cotton is used in many arts, and in a variety of ways. It is rarely, if ever,
however, used in its original form, as it requires treatment by various chemicals
to impart to it the qualities which render it valuable. In most, if not all, the
processes to which gun cotton is subjected, it has heretofore been deemed necessary
as an initial step, to thoroughly dry the gun cotton, as water acts to dilute the
chemicals used, and to prevent them from exercising their proper action upon the
gun cotton.
Aside from the cost entailed by the necessity of carefully drying the gun
cotton, there are serious disadvantages to any process which necessitates the use
of dry gun cotton, for dry gun cotton is very dangerous, and by reason of its
impalpable nature, cannot be so closely confined as to prevent it from floating
around the room in which it is kept. It cannot be decanted from one vessel
to another without forming a cloud of dust, and while, if proper precautions are
observed, no danger can result from the handling of dry gun cotton, still there is
certain to be an accident sooner or later in any establishment using it.
The process which I have devised removes all danger from processes in which
dry gun cotton has heretofore been employed, and especially from the manufacture
of smokeless powder, by rendering it possible to keep the gun cotton at all stages
in its treatment in a wet condition, when it is absolutely harmless. I dispense
entirely with the drying of gun cotton, and instead, treat wet gun cotton in such
a manner that all the water may be removed therefrom and supplanted by any
chemical, not a solvent of gun cotton, to be used in the process to which the gun
cotton is to be subjected. Thus, in the manufacture of smokeless powder, in
which alcohol and ether are to be mixed with the gun cotton, I displace the
water in the wet gun cotton with alcohol, without at any stage in the displace-
ment drying the gun cotton, and afterwards mix the ether into the alcoholized gun
cotton. In this case, an especial advantage is obtained by reason of the affinity
which ether has for alcohol, for the ether penetrates the mass of alcoholized gun
cotton much more readily and uniformly than do alcohol and ether, when mixed
together with dry gun cotton. Not only is the process of mixing the ether into
alcoholized gun cotton much easier to accomplish, but the resultant explosive is
much more satisfactory, and is more even and uniform in its qualities.

page_text: Furthermore, I accomplish the displacement of water by alcohol in the process
above described, and in general terms, the displacement of the liquid with which
the gun cotton is saturated by the other liquid with which it is desired to saturate
the gun cotton, without appreciable admixture of the two, so that my process is
economical, and can be carried on, with great certainty by a knowledge of the
amount of gun cotton under treatment.
::
It has long been known that the displacement of liquids could be accomplished
without admixture thereof in certain classesy of powders in which moisture does
not cause the powders to form lumps, in certain classes of drugs, and, a more
familiar example, in sand. This process of displacement of liquids, or percola-
tion, as it is called, has been thoroughly understood for, a number of years, and the
character of its operation and the conditions necessary to be fulfilled in order
that its operation may be possible,. have been fully observed. The attempt has
never been made, however, to use this process in connection with gun cotton, both
because the applicability of the process of percolation for commercial purposes
has been supposed to be confined to the making of extracts, and because gun
cotton, either in its dry condition or when moist, is not normally in the condition
which admits of the process of percolation being successfully carried out.
have discovered, however, that if wet gun cotton be compressed, the water or other
non-solvent liquid with which it may be saturated being carried away as rapidly
as it exudes from the gun cotton, the gun cotton will be reduced to a state of
equal porosity throughout its mass. The water or other non-solvent liquid can
then be displaced by the ordinary process of percolation, by a liquid, such as
alcohol, which is not a solvent of gun cotton. The displacement will take place
irrespective of the miscibility of the liquids, and all of the water or other non-
solvent liquid with which the gun cotton may at first be saturated will be removed
therefrom without appreciable admixture with the liquid which is displacing it.
The admixture which does take place is confined entirely to the head of the
piston-like column of displacing liquid, so that it can be allowed for in advance,
and dilution of the body of displacing liquid following avoided. The exact degree
of compression to which the gun cotton is subjected in order that percolation
may successfully take place may be varied within certain limits without affecting
the successful operation of the process, but care must be taken not to compress
the gun cotton to too great an extent, for a point is reached in the compression of
gun cotton where the process of displacement cannot be successfully carried on,
by reason of the density of the gun cotton. Compression must, however, always
be exerted in order to bring the gun cotton to a condition of equal porosity, and
this compression will be in excess of that which can be effected by the weight of
the atmosphere alone, when air is withdrawn from the chamber containing the
gun cotton.
The apparatus which I have devised in order to carry out my process, in so far
as it relates to the displacement of liquids in gun cotton, is represented in the
drawing which accompanies and forms a part of this specification, which is an
elevation, partly in section, of my press.
As a means for producing the desired compression of the gun cotton to be
treated, I have found it convenient to use a press which is constructed so as to
permit air to be withdrawn from the compression chamber. The compression can
thus be effected in two easy stages, first, that due to the pressure of the atmo-
sphere as the air is gradually withdrawn from the compression chamber; and
second, that due to the additional pressure occasioned by the manipulation of the
press. The liquid which is expressed from the gun cotton during the com-
pression thereof, I collect in glass vessels which are arranged beside the press
and connected therewith, and which are finely graduated, so as to enable the
operation of the process to be followed with exactness.
I shall first describe my press, then the glass measuring vessels, and their
connections, and finally, the operation of my process as an entirety.

page_text: Referring to the drawing, L represents a table which forms a base or support
for the press .M. The press M consists of a cylinder of brass or other suitable
material N, which is provided with two head blocks or ends D and E, both of
which are regulated as to their position by the action of the screws 1) and E¹
respectively. The screws D¹ and E¹ work through bearing plates 12 and E²
respectively, which are supported and held in position by the brackets O. In the
construction shown, the brackets extend. downward through the base plate P,
to which the cylinder N is directly bolted, and through the table; and have
attached thereto the lower bearing plate E2, as well as the upper bearing plate D².
The brackets O are shouldered, or reduced in diameter, at the point where they
pass through the base plate P, and collars Q are placed around the portions of
the brackets between the lower plate E2 and the base plate P. This construction
is advantageous, because it combines simplicity with strength. The chief feature
of my invention, however, consists in the pressure blocks D and E, which fit air
tight within the cylinder of the press. The interior of these blocks is hollowed
out to form chambers and e, which are in connection with the outside of the
press through openings and e¹ formed on the outer face of the same, and are in
connection with the interior of the press by series of perforations and e² formed
on their inner faces. Over the inner face of the blocks I stretch wire cloth of
fine mesh 3 and 3, the purpose of which will hereinafter appear. It is intended
that the pressure block D may be removed from the press, and, when removed, be
entirely separate from the screw I), so that the only connection between the two
is a recessed portion in the outer face of the block within which the end of the
screw D¹ plays. The lower pressure block E is, however, not to be removed from
the press, and as it is to be moved in both directions by the screw E, is con-
nected therewith in any suitable manner, as in the instance shown, by the ring_e,
which is attached to the under surface of the pressure block and fits around. a
portion of the screw E¹ of less diameter than the end which enters the recessed
portion of the pressure block. In order to insure the pressure block E resting
tightly against the lower end of the cylinder when drawn down to its lowest limit,
I use a strip of packing n, which is placed upon the inner peripheral flange n¹
which serves to limit the downward movement of the pressure block E.
GLASS MEASURING VESSELS.
The glass measuring vessels which I use in connection with my press to collect
the liquid which is expressed from the mass of gun cotton are represented in the
drawing by the reference characters A and B. In the glass vessel C is contained
the alcohol which is to displace the water in the gun cotton, when the gun cotton
has been compressed sufficiently to enable the process of percolation to be success-
fully carried out. All of the glass vessels are finely graduated so that their con-
tents can be determined with exactness at any time. The operation of the process

page_text: .
:
connection 8, and the tube 14 leading to the opening e¹ in the lower pressure
block E. From the glass connection 8 extend two tubes 9 and 10 respectively,
which lead to the cocks b and d respectively of the measuring vessels A and B.
From the cocks cand e respectively of the measuring vessels A and B, extend
tubes, 11 and 13, which lead to a common glass connection 12. The glass con-
nection 12 is connected to an air pump (not shown) in any suitable manner.
If the connections be traced, it will be seen that by proper adjustment of the
cocks, air can be withdrawn from one or both ends of the cylinder chamber, and
the liquid expressed from the gun cotton may be collected within either of the
measuring vessels A and B. It will also be seen that the measuring vessel C can
be connected with the upper pressure block D at the same time that liquid is being
withdrawn through the lower pressure block E.
OPERATION OF PROCESS.
In the operation of my process, the pressure block D is removed from the
press and the pressure block E lowered to its extreme limit, so that the compres-
sion chamber is ready to receive the mixture of gun cotton and water which is
then poured therein. In the treatment of gun cotton for the manufacture of
smokeless powder, the amount of alcohol to be introduced into a given weight of
gun cotton is fixed and determined by the character of the explosive which it is
desired to produce. It is convenient, therefore, to know the exact amount of gun
cotton contained in the mixture placed within the cylinder of the press, so that
I prefer to draw the mixture from a large vessel in which a known quantity of
gun cotton is held suspended in water by the action of a mechanical agitator, so
that any specimen of liquid withdrawn therefrom will represent the entire
mixture, and will contain a weight of gun cotton determined by the amount of
the mixture withdrawn. The cocks a, d, e, h, i, and j are then closed and the
vacuum pump connected with the glass connection 12 put in operation. The
water contained in the mixture of gun cotton will be withdrawn by the suction
resulting from the action of the vacuum pump,-and will be collected within the
measuring vessel A. When the withdrawal of liquid in this manner has been
carried as far as is practicable, the pressure block D is lowered into the cylinder
and the cock opened, so that a vacuum will be applied at both ends of the
cylinder of the press. Should the measuring vessel A become tiled with liquid
cocks bande may be closed and cocks d and e opened, so that the liquid discharged
will be collected within the measuring vessel B. The measuring vessel A may
then be emptied by withdrawing the cork A' and opening the cock h, in readiness
to have the flow of liquid diverted into it in a later stage of the process.
the compression produced by the vacuum has been carried as far as is practic-
able, the screw D' may be lowered, and the pressure block D forced downward until
the gun cotton is compressed to a sufficient degree to permit the process of
percolation to be satisfactorily carried out.
66
When
The alcohol which is to displace the water in the gun cotton is contained within
the glass vessel C. As a convenient means for enabling the operation of the
process to be watched with greater certainty than would otherwise be the case, I
have found it convenient to color the alcohol, and have used for this purpose the
dye called
cudbear," though almost any dye can be used. The air pump still
working, cock is closed and cock j opened. The conditions are now such that
the colored alcohol contained in the vessel C passes down the tube leading from
the lower cock of C, and finds its way to the interior of the block D, and from
thence by the perforations in the block and the wire gauze before mentioned, to
the cake of gun cotton contained in the cylinder. A very perfect displacement
now occurs, the water being drawn off by the vacuum applied, and collecting in
the vessel A, cocks and e being closed, and cocks b and c opened for this purpose.
The water flows uninterruptedly into the vessel A, until it has been entirely
removed from the cake of gun cotton, when the color of the alcohol appears in

page_text: the glass connection 6 below the cock a. This alcohol will be in a diluted con-
dition, both because of the water contained in the tube 14, and because in the
displacement of water in the mass of gun cotton by alcohol, the line of demarca-
tion between the alcohol and the water, as the former passes down through the
cake, while sharp and well defined, is frequently tipped to the hori-
zontal line to
This
a greater or less extent.
causes the alcohol to go
out on one side of the bottom of the cake a little in advance of the other,
thus causing more admixture than would otherwise occur. When the color of the
alcohol appears at the connection 6. of the tubes, the cocks are changed. band c
are closed and and e opened, thus allowing the collection of the weak alcohol
in the vessel B, which has previously been emptied of its contents. When a
small amount of the weak alcohol is collected in the vessel B, the color of the
liquid in the glass connections will be found to have deepened, and the appearance
will be that of the original colored alcohol contained in C. When matters have
progressed thus far, the cocks are again changed. d and e are closed, while band c
are opened the vessel A having been emptied of its contents in preparation for
this operation. The supply of alcohol from the glass vessel C is now shut off by
means of the cock j, the cock a is opened, and pressure is applied by means of
the upper screw D₁. The vacuum now being applied to the upper and lower
blocks of the press simultaneously, the alcohol that is squeezed out by the
pressure is collected in the measuring vessel A. The compression upon the cake
of gun cotton in the press is now only limited by the amount of the alcohol that
it is desired to leave in the cake. The alcohol which is expressed will be found
to be of the same strength as the original alcohol contained in the vessel C, and
having suffered nothing by the displacement may be used again for another pressing.
In a particular instance, when I used a mixture of gun cotton in water in which
one hundred and seventy-five grams of gun cotton were suspended in
two litres of the mixture employed, after compressing the mixture
removing the surplus water therefrom, and then displacing the
contained in the gun cotton by alcohol, I found in the neighbourhood
of two hundred and twenty c. c. of the alcohol present in the gun cotton.
I desired to have left only seventy c. c. of alcohol in the cake, one hundred and
fifty c. c. of the alcohol were expressed and collected in the measuring vessel A,
The amount of weak alcohol
from thence being transferred to the vessel C.
collected in the measuring vessel B in this instance amounted to forty c. c., an
inappreciable amount as compared with the amount of gun cotton treated. This
is an average illustration of the working of my press.
and
water
As
When the pressing is completed, the top block D is removed from the press,
and the bottom block E raised by its screw, the cake of gun cotton being elevated
out of the top of the cylinder. The block is then found to be in just the condition
required for the admixture of the ether for making an alcohol-ether smokeless
powder. The cake, though hard, is friable, and readily yields to the crushing
action of the usual methods employed. The addition of the required quantity
of ether is rendered more easy to effect on account of the affinity which ether
possesses for alcohol, as the ether finds its way readily along the lines of the
substance already wet with the alcohol. The pressure being applied while the
alcohol is in the cake, seems to result in a much more intimate mixture than is
possible with the old methods. The product obtained by this process is much
more uniform than that obtained in any other manner with which I am acquainted.
While I have described my process for displacing liquids in gun cotton_as
constituting a step in the manufacture of smokeless powder, it is apparent that
this process can be used in many arts,-in 'fact in any art in which one of the
liquids with which dry gun cotton has been heretofore treated is not a solvent of
I do not
gun cotton, and can thus serve to displace water in wet gun cotton.
limit myself, therefore, to the use of my process for displacing liquids in gun
cotton to the manufacture of smokeless powder, but may use it in any other art
for which it is adapted.

page_text: It is also evident that instead of using an air pump to effect the removal of the
surplus water from the gun cotton, and to assist the entrance of alcohol into the
compressed cake of gun cotton, other means can be employed, as this is only one
of many convenient methods of obtaining the required pressure.
It is also evident that the use of the measuring vessels which I have described
may be varied or entirely dispensed with, when a known quantity of gun cotton
is being treated, so that they do not form an essential part of the working of my
process or of the apparatus which I use.
H
...
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
12
1. The herein-described process of displacing liquids in gun cotton, which
consists in saturating the gun cotton with a liquid not a solvent thereof, com-
pressing the gun cotton until it has reached a stage of equal porosity throughout,
the liquid expressed during the operation being removed, and displacing the liquid
contained in the gun cotton by another liquid, which also is not a solvent of the
gun cotton, by percolation, substantially as described.
2. The herein-described process of treating gun cotton in the manufacture of
explosives, such as smokeless powder, or the like, which consists in displacing the
water in wet gun cotton with alcohol by percolation, and mixing ether with the
alcoholized gun cotton, Substantially as described.
3. The herein described process of treating gun cotton in the manufacture of
explosives, such as smokeless powder, which consists in compressing wet gun
cotton until it. has reached a condition of equal porosity throughout, displacing
the liquid in the gun cotton by alcohol, compressing the gun cotton till only the
desired quantity of alcohol remains therein, and mixing with the alcoholized gun
cotton the desired quantity of ether, substantially..as described.
4. In a press, the combination with a cylinder, of movable pressure blocks .con-
stituting the ends of said cylinder, said blocks being formed to permit the passage
of liquids therethrough, one of said blocks being removable, means for operating
said blocks, an air pump, measuring vessels, and connection between said pressure
blocks, said measuring vessels and said air pump, substantially as described.
נ,
5. In a press, the combination with a cylinder, of movable pressure blocks
forming the ends of said cylinder, said pressure blocks being interiorly chambered,
having perforations leading from said chambered portions to the inner faces
thereof, and passages leading from said chambered portions to the outer faces.
thereof, one of said pressure blocks being removable, screws for operating said
blocks, an air pump, measuring vessels, and connection between said pressure
blocks, said measuring vessels, and said air pump, substantially as described.
Dated this 1st day of Tule 1807
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.
...