Improvements in, and in Apparatus connected with, the Preparation and Application of Explosive Substances for Charging Shells, Torpedoes, Mine Cartridges, and the like.
Year: 1890

page_text: Date of Application, 15 h May, 1890-Accepted, 27th Sept., 1890
COMPLETE SPECIFICATION.
Improvements in, and in Apparatus connected with, the Preparation
and Application of Explosive Substances for Charging Shells,
Torpedoes, Mine Cartridges, and the like.
I, EUGÈNE TURPIN, of 18 Avenue Ménelotte, Colombes (Seine) France, Chemist
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 improved processes of preparing and applying explosive
substances, more especially for charging explosive projectiles, mining cartridges,
torpedoes, mines, etc.
The invention also relates to projectiles and apparatus used in connection there-
with.
Notwithstanding the number of explosive compounds already known, or which may
be obtained by the simple mixture of one or more combustible bodies with one or
more supporters of combustion, the mode of using them has not varied and little is
known as to the relations between the power and the sensitiveness to shock of
explosives generally, according to their chemical constitution. Ignorance of this
law, which I bave discovered, has been the cause of the failure of all attempts
hitherto made to charge hollow projectiles with "high" explosives.
Gun cotton can only be used in shells by being moistened with from 25% to 30%
of water, and, even in this condition, only relatively-low initial velocities are
admissible chiefly by reason of the quantity of dry gun cotton required for priming.
In short, only the old black gunpowder has heretofore been safe to use in shells.
By my discovery of the law governing the power and sensitiveness of explosives
generally, it is now possible to so combine or select existing explosives as to obtain
substances of any desired degree of violence, sensitiveness to shocks, to priming and
to firing in shells, as well as to obtain this sensitiveness with production of oxygen or
of carbonic oxide in excess.
In my previous Patents dated 1885 No. 15089 and 1887 No. 10655 for the
application of the explosive properties of trinitro-phenol or picric acid without the
aid of an oxidising agent and to which has been given the name of "melinite," I
have described the fundamental principles of the invention and also projectiles in
which it was applied. Although all the principles involved in my discovery as well
as their application under various forms have been sufficiently described in the
Specifications of the Patents before referred to, I have annexed to the present
Specification new drawings, which will enable both the theory and practice of my
invention to be understood at a glance.
Among the known explosive compounds I prefer, as before stated, to employ
trinitro-phenols for charging shells, especially picric acid which is the most stable
and is best suited for military uses. The explosive charge of a shell should be as
absolutely compact as possible, in order to prevent local consolidation in the shell
under the initial shock of firing the gun. If the explosive can be melted without
danger (as in the case of the trinitro-phenols which I was the first to use in this way)
the best mode of charging shells is to run in the explosive in a molten state.
As an example of the mode of application of the invention I will describe the
employment of picric acid which may serve as a basis for all other applications of
explosives generally. Picric acid is selected on account of its absolutely stable
character, the facility with which it can be prepared, and also because it affords the
nearest approach, with a slight excess of combustible (which is preferable) to the
D1171

page_text: maximum of power coupled with great insensibility to shocks which is so far
augmented by the fusion of the picric acid by heat as to necessitate the use of the
particular mode of priming indicated in. the Patents before referred to.
If the explosive be excessively insensible to shock, as are the nitrated compounds
whose positions are comprised between the numbers 0 to 7 of diagram Sheet 2
annexed. to, and forming part of this Specification, the priming of it would be too
difficult and it would be liable to miss fire. Trinitio-cresol (cresylite) which is a
trinitro-phenol, is of excessive insensibility as it requires, to bring about its detona-
tion, a large quantity of picric acid in powder, primed with my system of detonator.
Moreover cresylite is less powerful than melinite which is picric acid and to which
the appellation of "Melinite" was merely given to put others off the scent for a
time and is derived from Mel (Honey) which picric acid resembles in color.
Nitrated bodies do not generally attack metals, but if, in certain cases, it is desired
to protect the metal, the interior of the projectile should be varnished as usual but
with a special varnish able to resist the highest temperatures and composed of―
Benzene
Bitumen of Judoa
-
70 parts.
30
"
The bitumen is dissolved by heat and a sufficient quantity of the varnish is flowed
over the surface to well cover it, and then dried in a stove or oven at about 200° C.
The shell is now ready for running in the melinite (picric acid fused at about
130° C.) or other nitro-phenol or explosive compound." Projectiles thus charged
remain efficient for an indefinite period.
The following table gives the data on which I have established the law of the
sensitiveness and strength of explosive substances according to their chemical
constitution (see diagram Sheet 1). The table shews the sensitiveness to shock and
to priming of any explosive compound according to the quantity of oxygen which it
contains. From this it will be seen that the sensitiveness of an explosive compound
increases as the square of the quantity of oxygen which it contains up to the point of
complete combustion with production of carbonic acid (maximum of heat) and then
decreases more slowly in consequence of an excess of oxygen. The strength increases
as the quantity of oxygen up to the point of complete combustion in the 1st degree,
that is to say with production of carbonic oxide (greatest gaseous volume) and then
progressively decreases.

page_text: es to Diagram.
Height
of fall of
a weight
of
Detona-
tion by
means of
a prim-
ing
PANCLASTITE with base of benzene.
Pure benzene C H-78 anhydrous peroxide of
nitrogen N 02 = 46. Typical mixture dissolving
perfectly and instantaneously without reaction,
enabling compounds to be obtained of all degrees
of nitration.
ARODENUHIIKINTORSTA
4m00
3.00
3.00
0.65
0.60
250
2.50
2.00
1.50
1.00
3 gmns.C H+22 N 02-6 (CO2)+3 (H³O) +22 N+29.0
CH°+21_N_O*=6 (CO)+3(H*O)+21N+270
CH+20 N 02-6 (CO2)+3 (H2O) + 2 N+25 0
( H+19 N 0*=6 (CO)+ * (H*O)+19N+23 Đ
Ce H+ 18 N 02=6 (CO2)+3 (H2O) +18 N+21 0
C® H®+17 N O3=6 (CO)+3(H20)+17 N+19 0
CH+16 N 02=6 (CO2)+3 (H2O)+16 N+17 0
C® H®+15 N 0–6 (CO)+3(HO)+15 N+150
CH+14 N 0-6 (CO2)+3 (H2O)+14 N+13 0
C* H®+13 N O=6 (CO)+3(HẢO)+13N+110
C® H® + 12 NO=6 (CO)+3(HO)+12N+ 90
C® H®+11_NO=h (CO)+3 (HO)+11N+ .70
C® H*+10 N O=6 (CO)+3 (HO)+10N+ 50
-CH+ 9 N 0-6 (CO2)+3 (H2O)+ 9 N+ 30
CH+ 8 N 02=6 (CO2)+3 (H2O) + 8 N+0
CH+7 NO²=6 (CO2)+3 (H2O)+7 N{maximum
C® H+ 7N02_5 (CO)+((0)+3(HO)+7N
C® H® + 6NO=a(CO)+3(CO)+3(H*O)+6N
0.50
0.40
0.03
0.02
0.05
0.05
0.80
0.80
1.00
1.00
3.50
3.00
Y
3.00
4.00
(6 H+
sensitiveness
power
NO=(CO)+5 (CO)+3(H30)+5N
C® H® + NO*=6 (CO)+3(HQ)+4N{m
Smaximum
CH4N 02-C+5 (CO)+3 (H2O) + 1 N
C H+ 3 N 02-3 +3 (010)+3 (H²O)+3 N
CH+ 2 N 0-4 C+2(CO)+2(H2O)+2H+2N
CH6+ NO 5 C+ (CO)+(H2O) + H+N
CH+
NU²=6.C+(H2O)+4 H+N

page_text: LAW OF THE SENSITIVENESS AND POWER OF EXPLOSIVE SUBSTANCES IN GENERAL,
'ACCORDING TO THEIR CHEMICAL CONSTITUTION.
Taking as a basis either thermo-chemistry or admitted theories all chemical
specialists and practitioners had always previous to my investigations recommended
the introduction of the oxidising agent into all explosive compounds in such propor-
tions that oxidation was complete with production of carbonic acid in order to obtain
as was asserted the greatest possible energy. This error, added to the extreme
sensitiveness which results from the adoption of this false theory, has hitherto been
the cause of the premature explosion in the bore of the gun of projectiles charged
with high explosives, the employment of which has never hitherto been practically
attainable with any certainty. Since discovering this law I have employed picric
acid for charging shells, mine-cartridges, etc., this substance being chosen on account
of its chemical stability and being well known and also in consequence of its being
absolutely unalterable and safe to store when unmixed with any foreign substance,
while it also oxidises less than any other..
I would draw attention to the relative sensitiveness of melinite, gun-cotton, and
ordinary gunpowder.
Phenic trinitrophenol (cast picric acid termed melinite) will only detonate under
the fall of the proof hammer from a height of 1m 50 upon 2 decigrammes, and will
not detonate in the open air under the action of a priming charge of three grammes.
In fine powder, melinite commences to detonate from 1 metre or under the action of
a priming charge of 1 gramme.
Dry gun cotton detonates under a fall of Om 35 if moistened with 20% of water
under a fall of Om 90 upon 2 decigrammes.
Ordinary gunpowder fires under a fall of Om 60 and detonates under a fall of
from 1m to'lm 50 upon a small grain of the size of a pea. In detonating, the powder
produces very little flame and hardly any smoke.
In order to find or determine in a general manner, the sensitiveness and power of
an explosive compound produced chemically or by simple mixture, it is sufficient, its
formula being known to find its place in the annexed table, according to the consti-
tution of the products of its combustion. The rapidity of explosion, the conditions
under which the oxygen enters, and the quantity of inert or prejudicial matter which
is combined therewith, may cause some slight differences between several compounds
of the same order but do not in any way falsify the general law for a same compound.
Thus CO, CO2, or may be obtained in the products of combustion.
(1) In general terms an explosion is merely a rapid combustion.
Any combustible mixed or combined with a suitable oxidising agent in proper
proportions give rise to an explosive compound.
(3) The superiority of compounds chemically obtained results from the smaller
quantity of inert matter or base which they contain, except in the case of panclastites
which are in the conditions of products chemically obtained.
Sheet 2 shews the relation of the diagram in Sheet 1 to a series of nitrated
explosive compounds, the position of which in the diagram indicates, at once, by
reference to the table, their sensitiveness to shock, to priming, and their resistance in
the firing of ordnance.
LAW OF SENSITIVENESS AND POWER OF EXPLOSIVE SUBSTANCES IN GENERAL,
ACCORDING TO THEIR CHEMICAL CONSTITUTION (DIAGRAMS SHEETS 1 AND 2
CONTINUED) AND LIST OF EXPLOSIVE HYDROCARBON COMPOUNDS IN WHICH THE
OXYGEN OF THE OXIDISING AGENT IS COMBINED WITH NITROGEN ALONE.
+
Figure 1 (Sheets 1 and 2) is a graphical representation of the law of the power
of explosive compounds. This diagram refers to the axes of co-ordinates OX, Oy;

page_text: the axis of abscissas OX represents the atoms of oxygen in the combustible,
CH being taken as a basis; the axis of ordinates Oy represents the power for
equal weights of the explosive substances. In the diagram the proportion of atoms
of oxygen varies from 0 to 45 and the corresponding power of the explosive substances
from 0 to 9. Figure 2 (Sheets 1 and 2) is a graphical representation of the increase
and decrease in sensitiveness of each of the substances referred to on the diagram
Figure 1, Sheet 1, and also on the diagram Figure 1, Sheet 2. Figure 3 is a
graphical representation of the progression of the oxygen in the explosive, the atoms
of oxygen being indicated by the numerals 1 to 45 of the horizontal column, Figure 1.
Column indicates in absolute values, the sensitiveness of the various substances
and column A indicates the limit of initial speeds in metres which the explosive
compounds can support in projectiles fired from guns under the ordinary conditions
with slow-burning powders. S is the curve of sensitiveness. Each explosive
substance is indicated by a point on the diagram, Figure 1, and is distinguished
by letters of reference corresponding to those of the following list of explosive
substances

page_text: Trinitroacetonitrile.
Trinitromethane.
All the explosive substances contained in the diagram from 0 to 9 or from a to o
are compounds in which the combustible is in excess; in those comprised between
and 15 or from o to u the combustion is complete with formation of carbonic oxide
up to carbonic acid; and from 15 to 45 or from w to d the oxygen is in excess.
The
right line joining 0 to 5 represents the density (theoretical) under the same
molecular condition of explosive substances, NO2 being always heavier than the
combustible element. -
A. Turpin's theory, based on complete combustion in the first degree with production
of the maximum volume of gas and CO giving the maximum force and a practical
minimum of sensitiveness. Initial velocity supported by the explosive = 700 metres.
B. Former theory generally approved by chemists and technologists, such as
Berthelot Abel and others, based on complete combustion in the second degree
producing the maximum of heat and CO2 with a less quantity of gas (1) less force
and the maximum of sensitiveness. Initial velocity supported: 100 metres only,
at most.
=
The initial velocities above indicated apply to projectiles charged with nitrated
compounds in their natural state, liquid if they be liquid, compressed powder if
they be solid, and without the addition of foreign substances. The addition of foreign
substances, such as Kieselguhr, to nitroglycerine for example, to form dynamite is
capable of rendering the explosive substance slightly less sensitive. The compact
charging of projectiles by fusion, as described with regard to trinitro-phenols
(melinite or picric acid) greatly reduces their sensitiveness and consequently increases
the initial velocity at which these compounds may be fired by avoiding packing or
local consolidation of the explosive.
It is to be understood that the power of the priming should increase with the
insensibility of the explosive, and be greater than that indicated in the table opposite
to each of the compounds mentioned. The consolidation obtained by the fusion of
picric acid reduces its sensitiveness more than 50%. In order to ascertain the
sensitiveness to shock and the necessary strength of priming for each of these
bodies, it is sufficient to refer the point at which each is indicated to the general
table of the law and opposite the position of this point will be found the solution
desired.
Compounds with a base of nitrates, chlorates, etc., may be classed in this manner
and their relative sensitiveness and strength be thus known by their formulæ of
composition and decomposition. Their strength will always be so much the less,
weight for weight, as the oxygen is combined with a larger proportion of inert matter.
If, however, the reaction is more violent, as in the case of chlorated powders, the
strength may be proportionately increased and a certain degree of compensation
established. For similar compositions, explosive compounds in general, produce
effects increasing as the square of their rate of decomposition.
As many tables may be prepared on this principle as there are categories of
explosives, said categories being determined by the form in which the agent or
supporter of combustion, oxygen for example, enters into the compound. It will
be understood that the nearer this agent approaches a pure state, that is to say
the smaller the quantity of inert matter with which it is combined, the more powerful
will be the explosive compound, weight for weight. On this principle, explosives
may be classed according to their strength, as for example;
ist Group. Pure hydrogen and oxygen.
2nd Group. Pure hydrocarbon and oxygen.
3rd Group. Pure hydrocarbon and oxygen combined, of which glyoxylic acid may
be taken as the tyne.

page_text: 4th Group. Nitrated compounds (oxygen combined with nitrogen).
5th Group. Combustibles mixed with nitrates of ammonia, soda, potash, etc.
6th Group. Combustibles mixed with chlorates, etc.
Figure 1 (Sheet 3) represents a section of a portion of a shell provided with my
improved detonator. A is the body of the projectile B the fuse; C screw-plug
carrying the priming; K fusible material for retarding the explosion of the shell,
enclosed in a tube D of copper, aluminium, or other material as light as possible;
E nut coupling to the fuse the tube V containing picric acid in powder which is
firmly packed in the space S as far as the nut E; T priming tube held by nut E;
R priming of 1 grammes of fulminate of mercury firmly compressed and held in
place by a cardboard washer M; O washers of soft white leather: Z cavity into
which the charge of fused pieric acid has first been run.
Figure 2 represents a similar arrangement, but in this case the fulminate of mercury
is replaced by a charge of quick-burning powder T enclosed in a steel tube.
Figure 3 represents a vertical section of the apparatus for melting the picric acid.
A, pan, to contain the explosive, placed within an outer jacket B, in which steam or
hot oil is caused to circulate, the oil being heated either directly, as shewn, or
separately; EE flanges by which the jacket is fixed in the brickwork setting D;
CC thermometers; F furnace grate; P fire door; O safety plate sliding in guides R,
L baffle; K wedge shaped bricks, M outlet to chimney.
.
Figure 4 shews a vertical section of a combined funnel and core by means of which
the necessary space is reserved, in the charge of fused picric acid, for the insertion of
the priming tube. a, funnel provided with lugs and made in one with a core c
having air holes d in suitable number and position. The core has an aperture e at
the lower end, for running in the charge, while the upper part is screw-threaded, for
screwing into the nose of the projectile with which a tight joint is made by a leather
washer and a flange g.
Figure 5 shews in plan and section a ladle for pouring the fused picric acid.
Figure 6 shews a mine cartridge consisting of a metal case A with a tinned or
cap
cover B which, after the case is charged, is soldered on with a metal fusible at 90° C.,
preferable Darcet's alloy. A brass tube C is previously soldered on the cover B, to
receive the detonator D which is charged with about 1½ grammes of fulminate and
attached to a Bickford or safety fuse E.
Figures 7 to 10 (Sheet 4) shew sections of projectiles of different arrangement
and capacity relatively to their calibre. Figure 7 shews a shell made of cast iron or
other metal. Figures 8 and 9 shew shells made of stamped steel. Figure 10 shews
a shell made of cast steel either in a single piece or in two parts as shewn.
It will be understood that the application of my principle of charging shells,
according to the law which I have discovered, is not limited to a single substance
such as picric acid, which I have selected as a type, as the invention extends generally
to the application of the method consisting in always allowing the combustible agent
to be in excess in the explosive. The foregoing explanations also serve to shew that
when the oxidant is employed in the proporcions indicated in theories anterior to mine
it is impossible to fire off the shells and hence the check which has been experienced.
It is thus established that, previous to the discovery of the law before referred to, the
charging of projectiles with high explosives has never been practically possible
owing to ignorance of the causes to which the sensitiveness of the explosives was
due. Wet gun-cotton alone, by reason of the nature of the material, has given any
satisfactory results under low velocities but this substance has always been employed
under hazardous conditions and without discernment owing to the irregularity in its
composition.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what
I claim is ;-
1st. The discovery by which I have been enabled to determine that the tendency

page_text: to premature explosion in the gun or on impact is in direct ratio to the sensitiveness
of the explosive, which sensitiveness increases proportionately to the square of the
quantity of the supporter of combustion contained in the explosive compound, as
demonstrated in the tables hereunto annexed.
2nd. The application of this discovery to the charging of shells and other munitions
of war and more particularly the employment of the trinitro-phenols without the aid
of any oxidising agent.
3rd. The apparatus, shells, mine - cartridges, detonators, etc., herein-described
employed in the preparation and charging of projectiles, mine-cartridges, etc., the
whole substantially as specified with reference to the annexed drawings.
E. TURPIN.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.