The Express.
London, England, 1846-11-16 00:00:00

the titrf, and the

' • 444 quattos
• _ IrtreX
Thigpeittli ae*rii,Vlll.°•
nee in gunpowder further titan hs a am,
sary accompatuement ta- the nitric acid, it_does
not in any way contribute to the force of the
explosion ; but, on the contrary, considerably in-
inferes with it; and further, its pressure is objec-
tionable, because as being fixed and not dissipated by
*bast, the greater part of the potash remains as a solid
residuum, when powder is fired.
Gun Cotton consists of woody fibre and nitric acid.
It contains, therefore, all the elements of gunpowder ;
cotton consists wholly of combustible matters, capable
of burning with a flame, and therefore burning with
rapidity when supplied with oxygen enough to cause
its entire combustion; and the nitric acid with which
it is combined, contains enough oxygen stored up in
a very small bulk, to ensure the entire combustion of
the cotton, and its complete and instantaneous conver-
sion into a large volume of gaseous matter. The nitric
acid in gun cotton is not, like the nitric acid of gunpow-
der, combined with a fixed alkali: it is directly com -
bined with the combustible matters, and, therefore,
when decomposed, as in firing the cotton, it leaves no
solid residue, but is wholly resolved into gas.
The advantages which gun cotton possesses over
ordinary gunpowder, are, Ist. That if well made, it
leaves no residue. 2nd. That when fired, its com-
bustion is perfect, and that it consequently produces
very little smoke. 3rd. That in its combustion, the
gases produced are comparatively harmless, an advan-
tage of great importance in mining operations when
the sulphurous acid gas, r&c., produced by gunpowder,
is a serious inconvenience ; and 4th, That it is
.quite
insoluble in water, and therefore not at all injured by
being wetted, whilst gunpowder of course is corn-
pletely spoiled.
I As regards the comparative cost of gun cotton, and
powder, it is hardly necessary to say anything
Prepared cotton is necessarily expensive, but there
are many other substances similar in nature
which are far cheaper, and which may be used
'for the manufacture of explosive compounds; whilst
on the other hand, in the case of those uses for
which gun cotton is decidedly superior to gunpowder,
the former will be used even though it shall be found
in practice to be more expensive. The best gun
cotton is for many purposes too explosive, it goes off
too rapidly, and resembles fulminating mercury rather
than gunpowder in its mode of action ; its explosive
force, therefore, is confined to a smaller space, is active
for a shorter period of time, and consequer.tly has a
less projectile power than gunpowder ; but then on the
other hand, very great facilities exist of preparing it
of different degrees of power, by the use of different
materials, and by modifications of the process of ma-
nufacture.
The disadvantages of gun cotton, or rather the ob-
i jections to its use as a substitute for gunpowder, are
various. The most important are the following :—lt
explodes at a far lower temperature than gunpJwder;
even the least explosive gun cotton requiring a heat
very considerably below redness for its explo-
sion, whilst some of the varieties can be fired by
the heat of boiling water. This a serious objection in
all eases where any number of charges have to be
fired in succession, as the heat caused by the explos
sions very soon raises the temperature of the gun
above that point at which it is hot enough to cause
the charge to explode spontaneously, thus rendering
its use exceedingly inconvenient and dangerous. The
great faci:ity with which gun cotton explodes, even
when not perfectly dried, would, of course, render its
manufacture more hazardous than that of powder ; and
for the same reason, its pnservation in bulk, when of
necessity it must be kept in a state of compression,
would be attended with a considerable degree of risk ;
for it is very probable that any mass of gun cotton or
othersimilarcombustible compound, particularly when
compressed, would have a tendency to undergo sponta-
neous combustion; and there can be no dout that a
magazine of gun cotton would be fur more dangerous
than a powder magazine. It is more than probable
that, under some circumstances, comparatively trifling
conditions, which would have no influence upon ordi-
nary powder, would be sufficient to cause the explo-
sion of gun cotton. A very considerable quantity
of steam is produced by the explosion of gun
cotton, so much in fact, that the inside of the
gun becomes quite wet ; the inconvenience of this
is obvious. A last objection, and ono which it is
to be feared may interfere with some of the most
valuable applications of this very interesting substance,
is the production of acid vapours when it is fired. It
is generally stated that gun cotton leaves no residue,
and produces no noxious fames when fired. As re-
gards the first statement it is practically true, for
when tried against gunpowder, it does leave no residue.
The minute quantity of solid matter left after its explo-
sion, is as nothing compared with the saline residue
of gunpowder. It is also true that gun-cotton, being
free from sulphur, no sulphurous acid gas
is formed when it is fired, and hence none of
those suffocating fumes arc perceived, which
result from the explosion of powder, in which
various alkaline salts are mechanically suspended
in an atmosphere loaded with sulphurous acid gas,
and hence no inconvenience is felt when gun
cotton is fired in a mine. At the same time, a
small quantity of nitric and nitrous acids is always
produced, sufficient to interfere with its use, in those
cases where the presence of acid vapour would do in-
jury. It is, however, possible that for sharp-shooting,
and other purposes where the absence of.smoke ren-
ders gun cotton superior to powder, that this objection
might be overcome.
On the whole, therefore, it appears that this very
curious discovery is not likely to prove so important
as was at first anticipated ; and it is evident that the
gun cotton, though an agent of eery great power, is
too dangerous and unmanageable for most military
purposes. For mining, and some other uses, it will
ioubtless be found of very great value.

NorniNG more positive has arrived from Mexico by
the American mail. The glories of Monterey still
fed the columns of the journals. There is the usual
abuse of ANIPCDIA, mingled criticism of General
TAYLOR with projects and rumours of all kinds.
According to some, AMPUDIA was to make another
stand at Saltillo; to others, he had gone to form a union
with SANTA ANNA at St. Luis de Potosi. The strategists
of the American press fix this spot as the Waterloo of
Mexico, and they dot down the stages to it from
Monterey, and from it to Mexico, reckoning 330
miles from Saltillo to San Luis, and 396 from San
Luis to Mexico. General TAYLOR'S 6,000 are to be
joined by General Wooes force, from the conquest
of Chihuahua, which will swell them to 10,000.
General PATTF.usoN is to take Tampico, and march
4,000 to join TAYLOR at San Luis, and then they are
to march upon the capital.
Such calculations are absurd, and such forces'
utterly disproportionate to the task. The Spanish
army, during the war of insurrection, were 20,000
strong, and were at first supported by 20,000 militia,
yet both could not keep down the guerillas or extin-.
guish resistance. And when the militia fell off, the
20,000 Spaniards were beaten out of the coun-
try. An equal force of Americans could not
effect the conquest of Mexico, were the spirit
liof the population fully roused ; and that it is so
mused, every day affords fresh symptoms. Many of
the journals still, however, rely upon peace being
made with SANTA ANNA. This is, after all, we think,
the Americans' best chance : for, although they may
have the means and the valour to subdue Mexico,
should they employ the due time and resources, they
have by no means put forth strength and taken pre-
cautions sufficient for the immediate annexation of
so vast an empire by forces.