Text
Explosives and Their Power.
Translated and Condensed From the French of M. BERTHELOT
By C Napier Hake and William Macnab
London: John Murray 1892
( 518 )
CHAPTER XI.
POWDERS WITH CHLORATE BASE.
§ 1. GENERAL NOTIONS.
1. BERTHOLLET, after having discovered potassium chlorate, and
recognized the oxidizing properties so characteristic of this salt,
thought of utilizing it in the manufacture of service powders. He
made several attempts in this direction, but immediately suspended
them after an explosion which happened during the manufacture
carried on at the Essonnes powder factory, an explosion in which
several persons were killed around himself. The same attempt has
been revived at various periods, with certain variations in the
composition.
But in every case explosions, followed by loss of lives-such, for
instance, its those which happened during the siege or Paris in
1870, and at L’ Ecole de Pyrotechie in 1877-- happened before
long in the course of its manufacture.
it is thus clear that potassium chlorate is an extremely dangerous
substance, which is only natural, because its mixture with
combustible bodies is sensitive to the least shock or friction. The
catastrophe in the Rue Beranger (see p. 46), produced by an
accumulation of caps for children's playthings, [Armstongs Mixture
djh] containing potassium chlorate, has helped to confirm these
ideas. Chlorate powders are, generally speaking more easily
ignited, and burn with more vivacity than black powder. They
explode, like the latter, on contact with an ignited body. They are
hardly used at the present day, [<1892! djh] except as fuses for
fireworks, or to produce shattering effects in torpedoes, for
instance. A powder of this kind has even been proposed in America
as motive agent of forge-hammers or pile-drivers. In this case the
cartridge is placed between the head of the pile and the ram, when
the explosion drives in the one and sends the other upwards. Their
strength is superior to that of nitrate base powders, but less than
that of dynamite or gun-cotton.
2. We shall first state the general properties of chlorated
compositions. Potassium, chlorate, which is the essential
ingredient, is a salt fusible at 334, and which decomposes regularly
at 352'. Nevertheless, it may become explosive by itself under the
influence of a sudden heating, or a very violent shock (p. 406).
We have seen that it yields 39-1 per cent. of oxygen and 60-9 of
chloride of potassium—
ClO3K = KCl + 03,
liberating, at the ordinary temperature, 11 Cal. for each equivalent
of oxygen (8 grms.) fixed; or 1.4 Cal., per gramme of oxygen; or
0-54 Cal. per gramme of potassium chlorate.
These quantities of heat must therefore, generally speaking, be
added to those which would be produced by free oxygen, when
developing the same reaction at the expense of a combustible
body (p. 134). But the presence of the potassium chloride, which
acts as inert matter, tends to lessen this advantage.
3. The extreme facility with which potassium chlorate powders
explode under the influence of the least shock is a consequence of
the great quantity of heat liberated by the combustion of the
particles which are ignited at the very outset and their low specific
heat; this heat raises the temperature of the neighbouring portions
higher in the case of chlorate than of nitrate powder, and it
therefore more easily propagates the reaction. The influence is the
more marked the lower the specific heat of the compounds, [1] and
as the reaction commences, according to the known facts, at a
lower temperature with the chlorate than with) the nitrate of
potassium.
Everything, therefore, combines to render the inflammation of the
powder with chlorate base easier.
Therefore the substances of which they are formed should not be
pulverised. or crushed together, but pulverized separately and
mixed by screening.
The drying in the stove of these powders is dangerous. The
presence of powdered camphor, so efficacious with gun-cotton,
does not lessen the sensitiveness of chlorate powders.
4. Not, only is the chlorate powder more energetic and
inflammable, but its effects are more rapid; it is a shattering
powder. Theory again is able to account for the property. In fact,
the compounds formed by the combustion of chlorate powder are
all binary compounds, the simplest and most stable of all, such as
potassium chloride, carbonic oxide, and sulphurous acid. Such
compounds will undergo dissociation at a higher temperature and
in a less marked manner than the more complex and advanced
combinations, such as potassium sulphate and carbonate, or
carbonic acid, which are produced by nitrate powder. It is for this
reason that the pressures developed in the first instance will be
nearer the theoretical pressures with chlorate than with nitrate
powder, and the variation in the pressures produced during the
expansion of the gases will be more abrupt, being less checked by
the action of the combinations successively reproduced during the
cooling.
5. The explanations just given apply not only to powders in which
potassium chlorate is mixed with charcoal and sulphur, compared
with analogous powders with nitre as base, but also comprise all
powders formed by the association of the same salts with other
substances. It can be shown that this is so, without entering into
special calculations, for which the exact values would in the
majority of cases be wanting.
Now, our comparisons are based on the following data, which
present a general character: —
1st. Both salts employed in equal weights supply to the bodies
which they oxidise the same quantity of' oxygen. 122-6 grins. of
chlorate yield 6 equiv. or 41 grins. of oxygen; that is to say, 8 grins.
of oxygen for 20 grins. of chlorate; whilst 101 grins. of potassium
nitrate yield only 5 equiv., or 40 grins. of available oxygen, viz. 8
grins. of oxygen to 20-2 grins. of salt. Hence it follows that both
salts must be employed in equal weights in the greater number of
cases.
Now, one and the same weight of oxygen, 8 grams., yielded by
potassium chlorate liberates + 11 Cal. more than free oxygen; if it
be yielded by the nitrate, it produces 19.3 Cal., or 6.95 Cal. per
gramme of Salt employed.
The formation of the same compounds will therefore liberate more
heat with the chlorate than with the nitrate, and the excess will
subsist, even in taking into account the union of the acids of
sulphur and carbon with the potash of the nitrate.
This greater quantity of heat will give rise to a higher temperature,
since the mean specific heat of the products is less with the
chlorate than the nitrate. The mean specific heat of the products at
constant volume may be calculated theoretically by multiplying the
number of atoms by 2-4, and dividing the product by the
corresponding weight. Now, the weight of the combustible body
being the same will require the same respective weights of nitrate
and chlorate, according to what has just been said; but the latter
will correspond to a less number of atoms, since the equivalent of
chlorine is greater than that of nitrogen.
2nd. The volume of the permanent gases is greater, or at the
lowest equal, with potassium chlorate than with the nitrate,
because the potassium of the former salt remains in the form of
chloride, the whole of the oxygen acting on the sulphur and carbon
to produce gases; whereas the potassium of the nitrate retains a
part of the oxygen, at the same time as it brings. a portion of the
sulphur and carbon to the state of saline and fixed compounds, the
formation of the salts more than compensating, for the volume of
nitrogen set free.
3rd. In the case where only the carbon or 6, hydrocarbon burns, the
compensation in the gaseous volumes is exactly effected because
each volume of nitrogen liberated from the nitrate replaces an
equal volume of carbonic acid combined with the potassium yielded
by the said nitrate. Nevertheless the pressure will be increased,
even in this case, with the chlorate, because its temperature is
higher.
4th. The compounds formed with the chlorate being in general
simpler than with the nitrate, dissociation will be less marked, and
consequently the action of the pressures will be at once more
extended, because the initial pressure is greater, and more abrupt,
because the state of combination of the elements varies between
narrower limits. Hence arise shattering effects rather than those of
dislocation or projection.
6. Potassium chlorate possesses another property which has
sometimes been utilized. Its mixture with organic substances, or
with sulphur or other combustible bodies, takes fire under the
influence of a few drops of concentrated sulphuric acid ; which is
due to the formation of chloric acid, which is immediately
decomposed into hypochloric acid, an extremely explosive
compound and a very powerful combustive.
This property has been utilized to cause the ignition by shock of
torpedoes and hollow projectiles charged with potassium chlorate
powder. It is sufficient to place in them a tube or glass balls, filled
with concentrated sulphuric acid.
This artifice may even be employed to ignite chlorate fuses for
exploding dynamite or gun-cotton.
But all these arrangements are very dangerous for those who put
them into execution, and they have not been practically adopted.
7. We have yet to say a few words about potassium perchlorate,
which is generally regarded as equivalent to the chlorate, but by a
mere theoretical generalization, for it is a salt which is expensive,
difficult to prepare pure, and it has hardly formed the object of real
experiments as an explosive agent.
Weight for weight it yields a little more oxygen than the chlorate;
about a sixth, viz. 46.2 per cent instead of 39.1.
ClO4 = KCl + 04,
But this liberation of oxygen absorbs heat; - 7.5 Cal. per equivalent
of salt, or - 0.9 Cal. per equivalent of oxygen, instead of liberating
it.
From this point of view, therefore, the perchlorate acts almost like
free oxygen, with the disadvantage of half of it being useless inert
matter.
Pure perchlorate is not explosive either by shock or inflammation,
as the chlorate. Further, its mixtures with organic substances are
far less sensitive to shock, friction, the action of acids, etc. They
ignite with more difficulty and burn slower.
[1] The fact, these two powders only differ by the substitution of the
chlorate, the specific beat of which is 0.209, for the nitrate, the
specific heat of which is 0.239.
[2] Supposing it to act upon a carbonated body, the carbon of
which is changed into potassium carbonate.
--
donald j haarmann
----------------------------
A man would create another man if one did not
already exist, but a woman might live an enternity
without even thinking of reproducing her own sex.
Johann Volfgang Goethe
|
!!!
Most metal
piping is welded btw and not seamless, can't tell for sure from the photo, but it looks like ordinary plumbing pipe which is probably welded. This
thing wouldn't survive blackpowder, let alone a chlorate based propellant...Even if it would survive a couple of blackpowder shots, the material will
fracture (as it wasn't meant for this) and may suddenly give in while you are holding it. Recipe for getting seriously hurt.
