composed of sulfur and saltpeter. Few persons are acquainted
with the mechanical power of gunpowder. Now this is precisely
what is necessary to be understood in order to comprehend the
importance of the question submitted to the committee.
A litre of gunpowder weighs about two pounds; during combustion
it produces 400 litres of gas. This gas, on being liberated and
acted upon by temperature raised to 2,400 degrees, occupies a
space of 4,000 litres: consequently the volume of powder is to
the volume of gas produced by its combustion as 1 to 4,000.
One may judge, therefore, of the tremendous pressure on this
gas when compressed within a space 4,000 times too confined.
All this was, of course, well known to the members of the committee
when they met on the following evening.
The first speaker on this occasion was Major Elphinstone, who
had been the director of the gunpowder factories during the war.
“Gentlemen,” said this distinguished chemist, “I begin with
some figures which will serve as the basis of our calculation.
The old 24-pounder shot required for its discharge sixteen pounds
of powder.”
“You are certain of this amount?” broke in Barbicane.
“Quite certain,” replied the major. “The Armstrong cannon
employs only seventy-five pounds of powder for a projectile
of eight hundred pounds, and the Rodman Columbiad uses only one
hundred and sixty pounds of powder to send its half ton shot a
distance of six miles. These facts cannot be called in question,
for I myself raised the point during the depositions taken before
the committee of artillery.”
“Quite true,” said the general.
“Well,” replied the major, “these figures go to prove that the
quantity of powder is not increased with the weight of the shot;
that is to say, if a 24-pounder shot requires sixteen pounds of
powder;– in other words, if in ordinary guns we employ a
quantity of powder equal to two-thirds of the weight of the
projectile, this proportion is not constant. Calculate, and you
will see that in place of three hundred and thirty-three pounds
of powder, the quantity is reduced to no more than one hundred
and sixty pounds.”
“What are you aiming at?” asked the president.
“If you push your theory to extremes, my dear major,” said J. T.
Maston, “you will get to this, that as soon as your shot becomes
sufficiently heavy you will not require any powder at all.”
“Our friend Maston is always at his jokes, even in serious
matters,” cried the major; “but let him make his mind easy, I am
going presently to propose gunpowder enough to satisfy his
artillerist’s propensities. I only keep to statistical facts
when I say that, during the war, and for the very largest guns,
the weight of the powder was reduced, as the result of
experience, to a tenth part of the weight of the shot.”
“Perfectly correct,” said Morgan; “but before deciding the
quantity of powder necessary to give the impulse, I think it
would be as well—-”
“We shall have to employ a large-grained powder,” continued the
major; “its combustion is more rapid than that of the small.”
“No doubt about that,” replied Morgan; “but it is very
destructive, and ends by enlarging the bore of the pieces.”
“Granted; but that which is injurious to a gun destined to
perform long service is not so to our Columbiad. We shall
run no danger of an explosion; and it is necessary that our
powder should take fire instantaneously in order that its
mechanical effect may be complete.”
“We must have,” said Maston, “several touch-holes, so as to fire
it at different points at the same time.”
“Certainly,” replied Elphinstone; “but that will render the
working of the piece more difficult. I return then to my
large-grained powder, which removes those difficulties.
In his Columbiad charges Rodman employed a powder as large
as chestnuts, made of willow charcoal, simply dried in cast-
iron pans. This powder was hard and glittering, left no trace
upon the hand, contained hydrogen and oxygen in large proportion,
took fire instantaneously, and, though very destructive, did not
sensibly injure the mouth-piece.”
Up to this point Barbicane had kept aloof from the discussion;
he left the others to speak while he himself listened; he had