Nitro Explosives: A Practical Treatise by P. Gerald Sanford

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In the manufacture of picric acid the first obvious and most necessary
precaution is to isolate the substance from other chemicals with which it
might accidentally come into contact. If pure materials only are used, the
manufacture presents no danger. The finished material, however, must be
carefully kept from contact with nitrates, chlorates, or oxides. If only a
little bit of lime or plaster become accidentally mixed with it, it may
become highly dangerous. A local explosion may occur which might have the
effect of causing the explosion of the whole mass. Picric acid can be
fired by a detonator, 5-grain fulminate, and M. Turpin patented the use of
picric acid, unmixed with any other substance, in 1885. The detonation of
a small quantity of dry picric acid is sufficient to detonate a much
larger quantity containing as much as 17 per cent. of water.

It is chiefly due to French chemists (and to Dr Sprengel) that picric acid
has come to the front as an explosive. Melinite,[A] a substance used by
the French Government for filling shells, was due to M. Turpin, and is
supposed to be little else than fused picric acid mixed with gun-cotton
dissolved in some solvent (acetone or ether-alcohol). Sir F.A. Abel has
also proposed to use picric acid, mixed with nitrate of potash (3 parts)
and picrate of ammonia (2 parts) as a filling for shells. This substance
requires a violent blow and strong confinement to explode it. I am not
aware, however, that it has ever been officially adopted in this country.
Messrs Designolles and Brugere have introduced military powders,
consisting of mixtures of potassium and ammonium picrates with nitrate of
potassium. M. Designolles introduced three kinds of picrate powders,
composed as follows:--

___________________________________________________________________
| | | | |
| | For Torpedoes | For Guns. | For Small |
| | and Shells. | Ordinary. Heavy. | Arms. |
|___________________|_______________|___________________|___________|
| | | | | |
| Picrate of Potash | 55-50 | 16.4- 9.6 | 9 | 28.6-22.9 |
| Saltpetre | 45-50 | 74.4-79.7 | 80 | 65.0-69.4 |
| Charcoal | ... | 9.2-10.7 | 11 | 6.4- 7.7 |
|___________________|_______________|___________|_______|___________|

They were made much like ordinary gunpowder, 6 to 14 per cent. of moisture
being added when being milled. The advantages claimed over gunpowder are
greater strength, and consequently greater ballistic or disruptive effect,
comparative absence of smoke, and freedom from injurious action on the
bores of guns, owing to the absence of sulphur. Brugere's powder is
composed of ammonium picrate and nitre, the proportions being 54 per cent.
picrate of ammonia and 46 per cent. potassic nitrate. It is stable, safe
to manufacture and handle, but expensive. It gives good results in the
Chassepot rifle, very little smoke, and its residue is small, and consists
of carbonate of potash. It is stated that 2.6 grms. used in a rifle gave
an effect equal to 5.5 grms. of ordinary gunpowder.

[Footnote A: The British Lydite and the Japanese Shimose are said to be
identical with Melinite.]

Turpin has patented various mixtures of picric acid, with gum-arabic,
oils, fats, collodion jelly, &c. When the last-named substance is diluted
in the proportion of from 3 to 5 per cent. in a mixture of ether and
alcohol, he states that the blocks of picric acid moulded with it will
explode in a closed chamber with a priming of from 1 to 3 grammes of
fulminate. He also casts picric acid into projectiles, the cast acid
having a density of about 1.6. In this state it resists the shock produced
by the firing of a cannon, when contained in a projectile, having an
initial velocity of 600 metres. It is made in the following way:--The acid
is fused in a vessel provided with a false bottom, heated to 130 deg. to 145 deg.
C. by a current of steam under pressure, or simply by the circulation
under the false bottom of a liquid, such as oil, chloride of zinc,
glycerine, &c., heated to the same temperature. The melted picric acid is
run into moulds of a form corresponding to that of the blocks required, or
it may be run into projectiles, which should be heated to a temperature of
about 100 deg. C., in order to prevent too rapid solidification.

When cresylic acid (or cresol, C_{6}H_{4}(CH_{3})OH.) is acted upon by
nitric acid it produces a series of nitro compounds very similar to those
formed by nitric acids on phenol, such as sodium di-nitro-cresylate, known
in the arts as victoria yellow. Naphthol, a phenol-like body obtained from
naphthalene, under the same conditions, produces sodium di-nitro-
naphthalic acid, C_{10}H_{6}(NO_{2})_{2}O. The explosive known as
"roburite" contains chloro-nitro-naphthalene, and romit, a Swedish
explosive, nitro-naphthalene.

~Tri-nitro-cresol~, C_{7}H_{4}(NO_{2})_{3}OH.--A body very similar to tri-
nitro-phenol, crystallises in yellow needles, slightly soluble in cold
water, rather more so in boiling water, alcohol, and ether. It melts at
about 100 deg. C. In France it is known as "Cresilite," and mixed with
melinite, is used for charging shells. By neutralising a boiling saturated
solution of tri-nitro-cresol with ammonia, a double salt of ammonium and
nitro-cresol crystallises out upon cooling, which is similar to ammonium
picrate. This salt is known as "Ecrasite," and has been used in Austria
for charging shells. It is a bright yellow solid, greasy to the touch,
melts at 100 deg. C., is unaffected by moisture, heat, or cold, ignites when
brought into contact with an incandescent body or open flame, burning
harmlessly away unless strongly confined, and is insensitive to friction
or concussion. It is claimed to possess double the strength of dynamite,
and requires a special detonator (not less than 2 grms. of fulminate) to
provoke its full force. Notwithstanding the excellent properties
attributed to this explosive, Lieut. W. Walke ("Lectures on Explosives,"
p. 181) says, "Several imperfectly explained and unexpected explosions
have occurred in loading shells with this substance, and have prevented
its general adoption up to the present time."

~The Fulminates.~--The fulminates are salts of fulminic acid,
C_{2}N_{2}O_{2}H_{2}. Their constitution is not very well understood. Dr
E. Divers, F.R.S., and Mr Kawakita (_Chem. Soc. Jour._, 1884, pp. 13-19),
give the formulae of mercury and silver fulminates as

OC = N AgOC = N
/ | \ | \
Hg | O and | O
\ | / | /
-C = N AgC = N

whereas Dr H.E. Armstrong, F.R.S., would prefer to write the formula of
fulminic acid

ON.C.OH.
|
C(N.OH),

and A.F. Holleman (_Berichte_, v. xxvi., p. 1403), assigns to mercury
fulminate the formula

C:N.O
Hg | |
C:N.O,

and R. Schol (_Ber._, v. xxiii., p. 3505),

C:NO
|| Hg.
C:NO

They are very generally regarded as iso-nitroso compounds.

The principal compound of fulminic acid is the mercury salt commonly known
as fulminating mercury. It is prepared by dissolving mercury in nitric
acid, and then adding alcohol to the solution, 1 part of mercury and 12
parts of nitric acid of specific gravity 1.36, and 5-1/2 parts of 90 per
cent. alcohol being used. As soon as the mixture is in violent reaction, 6
parts more of alcohol are added slowly to moderate the action. At first
the mixture blackens from the separation of mercury, but this soon
vanishes, and is succeeded by crystalline flocks of mercury fulminate
which fall to the bottom of the vessel. During the reaction, large
quantities of volatile oxidation products of alcohol, such as aldehyde,
ethylic nitrate, &c., are evolved from the boiling liquid, whilst others,
such as glycollic acid, remain in solution. The mercury fulminate is then
crystallised from hot water. It forms white silky, delicate needles, which
are with difficulty soluble in cold water. In the dry state it is
extremely explosive, detonating on heating, or by friction or percussion,
as also on contact with concentrated sulphuric acid. The reaction that
takes place upon its decomposition is as follows:--

C_{2}N_{2}O_{2}Hg = Hg + 2CO + N_{2}
(284)

According to this equation 1 grm. of the fulminate should yield 235.8 c.c.
(= 66.96 litres for 284 grms.). Berthelot and Vicille have obtained a
yield of 234.2 c.c., equal to 66.7 litres for one equivalent 284 grms.

Dry fulminate explodes violently when struck, compressed, or touched with
sulphuric acid, or as an incandescent body. If heated slowly, it explodes
at 152 deg. C., or if heated rapidly, at 187 deg. C. It is often used mixed with
potassium chlorate in detonators. The reaction which takes place in this
case is 3C_{2}N_{2}O_{2}Hg + 2KClO_{3} = 3Hg + 6CO_{2} + 3N_{2} + 2KCl.

On adding copper or zinc to a hot saturated solution of the salt,
fulminate of copper or zinc is formed. The copper salt forms highly
explosive green crystals. There is also a double fulminate of copper of
ammonia, and of copper and potassium. Silver fulminite,
C_{2}N_{2}O_{2}Ag_{2}, is prepared in a similar manner to the mercury
salt. It separates in fine white needles, which dissolve in 36 parts of
boiling water, and are with difficulty soluble in cold water. At above
100 deg. C., or on the weakest blow, it explodes with fearful violence. Even
when covered with water it is more sensitive than the mercury salt. It
forms a very sensitive double salt with ammonia and several other metals.
With hydrogen it forms the acid fulminate of silver. It is used in
crackers and bon-bons, and other toy fireworks, in minute quantities. Gay
Lussac found it to be composed as follows:--Carbon, 7.92 per cent.;
nitrogen, 9.24 per cent.; silver, 72.19 per cent.; oxygen, 10.65 per
cent.; and he assigned to it the formula, C_{2}N_{2}Ag_{2}O_{2}. Laurent
and Gerhardt give it the formula, C_{2}N(NO_{2})Ag_{2}, and thus suppose
it to contain nitryl, NO_{2}.

On adding potassium chloride to a boiling solution of argentic fulminate,
as long as a precipitate of argentic chloride forms, there is obtained on
evaporation brilliant white plates, of a very explosive nature, of
potassic argentic fulminate, C(NO_{2})KAg.CN, from whose aqueous solution
nitric acid precipitates a white powder of hydric argentic fulminate,
C(NO_{2})HAg.CN. All attempts to prepare fulminic acid, or nitro-aceto-
nitrile, C(NO_{2})H_{2}CN, from the fulminates have failed. There is a
fulminate of gold, which is a violently explosive buff precipitate, formed
when ammonia is added to ter-chloride of gold, and fulminate of platinum,
a black precipitate formed by the addition of ammonia to a solution of
oxide platinum, in dilute sulphuric acid.

Fulminating silver is a compound obtained by the action of ammonia on
oxide of silver. It is a very violent explosive. Pure mercury fulminate
may be kept an indefinite length of time. Water does not affect it. It
explodes at 187 deg. C., and on contact with an ignited body. It is very
sensitive to shock and friction, even that of wood upon wood. It is used
for discharging bullets in saloon rifles. Its inflammation is so sudden
that it scatters black powder on which it is placed without igniting it,
but it is sufficient to place it in an envelope, however weak, for
ignition to take place, and the more resisting the envelope the more
violent is the shock, a circumstance that plays an important part in caps
and detonators. The presence of 30 per cent. of water prevents
decomposition, 10 per cent. prevents explosion. This is, however, only
true for small quantities, and does not apply to silver fulminate, which
explodes under water by friction. Moist fulminates slowly decompose on
contact with the oxidisable metals. The (reduced) volume of gases obtained
from 1 kilo. is according to Berthelot, 235.6 litres. The equation of its
decomposition is C_{2}HgN_{2}O_{2} = 2CO + N_{2} + Hg.

Fulminate of mercury is manufactured upon the large scale by two methods.
One of these, commonly known as the German method, is conducted as
follows:--One part of mercury is dissolved in 12 parts of nitric acid of a
specific gravity of 1.375, and to this solution 16.5 parts of absolute
alcohol are added by degrees, and heat is then slowly applied to the
mixture until the dense fumes first formed have disappeared, and when the
action has become more violent some more alcohol is added, equal in volume
to that which has already been added. This is added very gradually. The
product obtained, which is mercury fulminate, is 112 per cent. of the
mercury employed. Another method is to dissolve 10 parts of mercury in 100
parts of nitric acid of a gravity of 1.4, and when the solution has
reached a temperature of 54 deg. C, to pour it slowly through a glass funnel
into 83 parts of alcohol. When the effervescence ceases, it is filtered
through paper filters, washed, and dried over hot water, at a temperature
not exceeding 100 deg. C. The fulminate is then carefully packed in paper
boxes, or in corked bottles. The product obtained by this process is 130
per cent. of the mercury taken. This process is the safest, and at the
same time the cheapest. Fulminate should be kept, if possible, in a damp
state. Commercial fulminate is often adulterated with chlorate of potash.

~Detonators~, or caps, are metallic capsules, usually of copper, and
resemble very long percussion caps. The explosive is pure fulminate of
mercury, or a mixture of that substance with nitrate or chlorate of
potash, gun-powder, or sulphur. The following is a common cap mixture:--
100 parts of fulminate of mercury and 50 parts of potassium nitrate, or
100 parts of fulminate and 60 parts of meal powder. Silver fulminate is
also sometimes used in caps. There are eight sizes made, which vary in
dimensions and in amount of explosive contained. They are further
distinguished as singles, doubles, trebles, &c., according to their
number. Colonel Cundill, R.A. ("Dict. of Explosives"), gives the following
list:--

No. 1 contains 300 grms. of explosive per 1000.
" 2 " 400 " " " " "
" 3 " 540 " " " " "
" 4 " 650 " " " " "
" 5 " 800 " " " " "
" 6 " 1,000 " " " " "
" 7 " 1,500 " " " " "
" 8 " 2,000 " " " " "

Trebles are generally used for ordinary dynamite, 5, 6, or 7 for
gun-cotton, blasting gelatine, roburite, &c.

In the British service percussion caps, fuses, &c., are formed of 6 parts
by weight of fulminate of mercury, 6 of chlorate of potash, and 4 of
sulphide of antimony; time fuses of 4 parts of fulminate, 6 of potassium
chlorate, 4 of sulphide of antimony, the mixture being damped with a
varnish consisting of 645 grains of shellac dissolved in a pint of
methylated spirit. Abel's fuse (No. 1) consists of a mixture of sulphide
of copper, phosphide of copper, chlorate of potash, and No. 2 of a mixture
of gun-cotton and gun-powder. They are detonated by means of a platinum
wire heated to redness by means of an electric current. Bain's fuse
mixture is a mixture of subphosphide of copper, sulphide of antimony, and
chlorate of potash.

In the manufacture of percussion caps and detonators the copper blanks are
cut from copper strips and stamped to the required shape. The blanks are
then placed in a gun-metal plate, with the concave side uppermost--a tool
composed of a plate of gun-metal, in which are inserted a number of copper
points, each of the same length, and so spaced apart as to exactly fit
each point into a cap when inverted over a plate containing the blanks.
The points are dipped into a vessel containing the cap composition, which
has been previously moistened with methylated spirit. It is then removed
and placed over the blanks, and a slight blow serves to deposit a small
portion of the cap mixture into each cap. A similar tool is then dipped
into shellac varnish, removed and placed over the caps, when a drop of
varnish from each of the copper points falls into the caps, which are then
allowed to dry. This is a very safe and efficacious method of working.

At the works of the Cotton-Powder Company Limited, at Faversham, the
fulminate is mixed wet with a very finely ground mixture of gun-cotton and
chlorate of potash, in about the proportions of 6 parts fulminate, 1 part
gun-cotton, and 1 part chlorate. The water in which the fulminate is
usually stored is first drained off, and replaced by displacement by
methyl-alcohol. While the fulminate is moist with alcohol, the gun-cotton
and chlorate mixture is added, and well mixed with it. This mixture is
then distributed in the detonators standing in a frame, and each detonator
is put separately into a machine for the purpose of pressing the paste
into the detonator shell.

At the eleventh annual meeting of the representatives of the Bavarian
chemical industries at Regensburg, attention was drawn to the unhealthy
nature of the process of charging percussion caps. Numerous miniature
explosions occur, and the air becomes laden with mercurial vapours, which
exercise a deleterious influence upon the health of the operatives. There
is equally just cause for apprehension in respect to the poisonous gases
which are evolved during the solution of mercury in nitric acid, and
especially during the subsequent treatment with alcohol. Many methods have
been proposed for dealing with the waste products arising during the
manufacture and manipulation of fulminate of mercury, but according to
Kaemmerer, only one of comparatively recent introduction appears to be at
all satisfactory. It is based upon the fact that mercuric fulminate, when
heated with a large volume of water under high pressure, splits up into
metallic mercury and non-explosive mercurial compounds of unknown
composition.

In mixing the various ingredients with mercury fulminate to form cap
mixtures, they should not be too dry; in fact, they are generally more or
less wet, and mixed in small quantities at a time, in a special house, the
floors of which are covered with carpet, and the tables with felt. Felt
shoes are also worn by the workpeople employed. All the tools and
apparatus used must be kept very clean; for granulating, hair sieves are
used, and the granulated mixture is afterwards dried on light frames, with
canvas trays the bottoms of which are covered with thin paper, and the
frames fitted with indiarubber cushions, to reduce any jars they may
receive. The windows of the building should be painted white to keep out
the rays of the sun.

Mr H. Maxim, of New York, has lately patented a composition for detonators
for use with high explosives, which can also be thrown from ordnance in
considerable quantities with safety. The composition is prepared as
follows:--Nitro-glycerine is thickened with pyroxyline to the consistency
of raw rubber. This is done by employing about 75 to 85 per cent. of
nitro-glycerine, and 15 to 25 per cent. of pyroxyline, according to the
stiffness or elasticity of the compound desired. Some solvent that
dissolves the nitro-cotton is also used. The product thus formed is a kind
of blasting gelatine, and should be in a pasty condition, in order that it
may be mixed with fulminate of mercury. The solvent used is acetone, and
the quantity of fulminate is between 75 to 85 per cent. of the entire
compound. If desired, the compound can be made less sensitive to shocks by
giving it a spongy consistency by agitating it with air while it is still
in a syrupy condition. The nitro-glycerine, especially in this latter
case, may be omitted. In some cases, when it is desirable to add a
deterring medium, nitro-benzene or some suitable gum is added.

[Illustration: FIG. 34. METHOD OF PREPARING THE CHARGE.]

The method of preparing a blasting charge is as follows:--A piece of
Bickford fuse of the required length is cut clean and is inserted into a
detonator until it reaches the fulminate. The upper portion of the
detonator is then squeezed round the fuse with a pair of nippers. The
object of this is not only to secure that the full power of the detonator
may be developed, but also to fix the fuse in the cap (Fig. 34). When the
detonator, &c., is to be used under water, or in a damp situation, grease
or tallow should be placed round the junction of the cap with the fuse, in
order to make a water-tight joint. A cartridge is then opened and a hole
made in its upper end, and the detonator pushed in nearly up to the top.
Gun-cotton or tonite cartridges generally have a hole already made in the
end of the charge. Small charges of dry gun-cotton, known as primers, are
generally used to explode wet gun-cotton. The detonators (which are often
fired by electrical means) are placed inside these primers (Fig. 35).

[Illustration: FIG. 35. PRIMER.]

One of the forms of electric exploders used is shown in Fig. 36. This
apparatus is made by Messrs John Davis & Son, and is simply a small hand
dynamo, capable of producing a current of electricity of high tension.
This firm are also makers of various forms of low tension exploders. A
charge having been prepared, as in Fig. 34, insert into the bore-hole one
or more cartridges as judged necessary, and squeeze each one down
separately with a _wooden_ rammer, so as to leave no space round the
charge, and above this insert the cartridge containing the fuse and
detonator. Now fill up the rest of the bore-hole with sand, gravel, water,
or other tamping. With gelatine dynamites a firm tamping may be used, but
with ordinary dynamite loose sand is better. The charge is now ready for
firing.

[Illustration: FIG. 36.--ELECTRIC EXPLODER.]

CHAPTER VI.

_SMOKELESS POWDERS._

Smokeless Powder in General--Cordite--Axite--Ballistite--U.S. Naval
Powder--Schultze's E.G. Powder--Indurite--Vielle Poudre--Rifleite--
Cannonite--Walsrode--Cooppal Powders--Amberite--Troisdorf--Maximite--
Picric Acid Powders, &c., &c.

The progress made in recent years in the manufacture of smokeless powders
has been very great. With a few exceptions, nearly all these powders are
nitro compounds, and chiefly consist of some form of nitro-cellulose,
either in the form of nitro-cotton or nitro-lignine; or else contain, in
addition to the above, nitro-glycerine, with very often some such
substance as camphor, which is used to reduce the sensitiveness of the
explosive. Other nitro bodies that are used, or have been proposed, are
nitro-starch, nitro-jute, nitrated paper, nitro-benzene, di-nitro-benzene,
mixed with a large number of other chemical substances, such as nitrates,
chlorates, &c. And lastly, there are the picrate powders, consisting of
picric acid, either alone or mixed with other substances.

The various smokeless powders may be roughly divided into military and
sporting powders. But this classification is very rough; because although
some of the better known purely military powders are not suited for use in
sporting guns, nearly all the manufacturers of sporting powders also
manufacture a special variety of their particular explosive, fitted for
use in modern rifles or machine guns, and occasionally, it is claimed, for
big guns also.

Of the purely military powders, the best known are cordite, ballistite,
and the French B.N. powder, the German smokeless (which contains nitro-
glycerine and nitro-cotton); and among the general powders, two varieties
of which are manufactured either for rifles or sporting guns, Schultze's,
the E.C. Powders, Walsrode powder, cannonite, Cooppal powder, amberite,
&c., &c.

~Cordite~, the smokeless powder adopted by the British Government, is the
patent of the late Sir F.A. Abel and Sir James Dewar, and is somewhat
similar to blasting gelatine. It is chiefly manufactured at the Royal
Gunpowder Factory at Waltham Abbey, but also at two or three private
factories, including those of the National Explosives Company Limited, the
New Explosives Company Limited, the Cotton-Powder Company Limited, Messrs
Kynock's, &c. As first manufactured it consisted of gun-cotton 37 per
cent., nitro-glycerine 58 per cent., and vaseline 5 per cent., but the
modified cordite now made consists of 65 per cent. gun-cotton, 30 per
cent. of nitro-glycerine, and 5 per cent. of vaseline. The gun-cotton used
is composed chiefly of the hexa-nitrate,[A] which is not soluble in nitro-
glycerine. It is therefore necessary to use some solvent such as acetone,
in order to form the jelly with nitro-glycerine. The process of
manufacture of cordite is very similar, as far as the chemical part of the
process is concerned, to that of blasting gelatine, with the exception
that some solvent for the gun-cotton, other than nitro-glycerine has to be
used. Both the nitro-glycerine and the gun-cotton employed must be as dry
as possible, and the latter should not contain more than .6 per cent. of
mineral matter and not more than 10 per cent. of soluble nitro-cellulose,
and a nitrogen content of not less than 12.5 per cent. The dry gun-cotton
(about 1 per cent. of moisture) is placed in an incorporating tank, which
consists of a brass-lined box, some of the acetone is added, and the
machine (Fig. 29), is started; after some time the rest of the acetone is
added (20 per cent. in all) and the paste kneaded for three and a half
hours. At the end of this time the Vaseline is added, and the kneading
continued for a further three and a half hours. The kneading machine (Fig.
29) consists of a trough, composed of two halves of a cylinder, in each of
which is a shaft which carries a revolving blade. These blades revolve in
opposite directions, and one makes about half the number of revolutions of
the other. As the blades very nearly touch the bottom of the trough, any
material brought into the machine is divided into two parts, kneaded
against the bottom, then pushed along the blade, turned over, and
completely mixed. During kneading the acetone gradually penetrates the
mixture, and dissolves both the nitro-cellulose and nitro-glycerine, and a
uniform dough is obtained which gradually assumes a buff colour. During
kneading the mass becomes heated, and therefore cold water is passed
through the jacket of the machine to prevent heating the mixture above the
normal temperature, and consequent evaporation of the acetone. The top of
the machine is closed in with a glass door, in order to prevent as far as
possible the evaporation of the solvent. When the various ingredients are
formed into a homogeneous mass, the mixture is taken to the press house,
where in the form of a plastic mass it is placed in cylindrical moulds.
The mould is inserted in a specially designed press, and the cordite paste
forced through a die with one or more holes. The paste is pressed out by
hydraulic pressure, and the long cord is wound on a metal drum (Fig. 38),
or cut into lengths; in either case the cordite is now sent to the drying
houses, and dried at a temperature of about 100 deg. F. from three to fourteen
days, the time varying with the size. This operation drives off the
acetone, and any moisture the cordite may still contain, and its diameter
decreases somewhat. In case of the finer cordite, such as the rifle
cordite, the next operation is blending. This process consists in mounting
ten of the metal drums on a reeling machine similar to those used for
yarns, and winding the ten cords on to one drum. This operation is known
as "ten-stranding." Furthermore, six "ten-stranded" reels are afterwards
wound upon one, and the "sixty-stranded" reel is then ready to be sent
away, This is done in order to obtain a uniform blending of the material.
With cordite of a larger diameter, the cord is cut into lengths of 12
inches. Every lot of cordite from each manufacturer has a consecutive
number, numbers representing the size and one or more initial letters to
identify the manufacturer. These regulations do not apply to the Royal
Gunpowder Factory, Waltham Abbey. The finished cordite resembles a cord of
gutta-percha, and its colour varies from light to dark brown. It should
not look black or shrivelled, and should always possess sufficient
elasticity to return to its original form after slight bending. Cordite is
practically smokeless. On explosion a very thin vapour is produced, which
is dissipated rapidly. This smokelessness can be understood from the fact
that the products of combustion are nearly all non-condensible gases, and
contain no solid products of combustion which would cause smoke. For the
same muzzle velocity a smaller charge of cordite than gunpowder is
required owing to the greater amount of gas produced. Cordite is very slow
in burning compared to gunpowder. For firing blank cartridges cordite
chips containing no vaseline is used. The rate at which cordite explodes
depends in a measure upon the diameter of the cords, and the pressure
developed upon its mechanical state. The sizes of cordite used are given
by Colonel Barker, R.A., as follows:--

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