The Question Of The Powders

: From The Earth To The Moon

There remained for consideration merely the question of powders.

The public awaited with interest its final decision. The size

of the projectile, the length of the cannon being settled, what

would be the quantity of powder necessary to produce impulsion?



It is generally asserted that gunpowder was invented in the

fourteenth century by the monk Schwartz, who paid for his grand

discovery with his life. It is, however, pretty well proved

that this story ought to be ranked among the legends of the

middle ages. Gunpowder was not invented by any one; it was the

lineal successor of the Greek fire, which, like itself, was

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

evidently got an idea. He now simply said, "Well, my friends,

what quantity of powder do you propose?"



The three members looked at one another.



"Two hundred thousand pounds." at last said Morgan.



"Five hundred thousand," added the major.



"Eight hundred thousand," screamed Maston.



A moment of silence followed this triple proposal; it was at

last broken by the president.



"Gentlemen," he quietly said, "I start from this principle, that

the resistance of a gun, constructed under the given conditions,

is unlimited. I shall surprise our friend Maston, then, by

stigmatizing his calculations as timid; and I propose to double

his 800,000 pounds of powder."



"Sixteen hundred thousand pounds?" shouted Maston, leaping from

his seat.



"Just so."



"We shall have to come then to my ideal of a cannon half a mile

long; for you see 1,600,000 pounds will occupy a space of about

20,000 cubic feet; and since the contents of your cannon do not

exceed 54,000 cubic feet, it would be half full; and the bore

will not be more than long enough for the gas to communicate to

the projectile sufficient impulse."



"Nevertheless," said the president, "I hold to that quantity

of powder. Now, 1,600,000 pounds of powder will create

6,000,000,000 litres of gas. Six thousand millions!

You quite understand?"



"What is to be done then?" said the general.



"The thing is very simple; we must reduce this enormous quantity

of powder, while preserving to it its mechanical power."



"Good; but by what means?"



"I am going to tell you," replied Barbicane quietly.



"Nothing is more easy than to reduce this mass to one quarter of

its bulk. You know that curious cellular matter which

constitutes the elementary tissues of vegetable? This substance

is found quite pure in many bodies, especially in cotton, which

is nothing more than the down of the seeds of the cotton plant.

Now cotton, combined with cold nitric acid, become transformed

into a substance eminently insoluble, combustible, and explosive.

It was first discovered in 1832, by Braconnot, a French chemist,

who called it xyloidine. In 1838 another Frenchman, Pelouze,

investigated its different properties, and finally, in 1846,

Schonbein, professor of chemistry at Bale, proposed its employment

for purposes of war. This powder, now called pyroxyle, or

fulminating cotton, is prepared with great facility by simply

plunging cotton for fifteen minutes in nitric acid, then washing

it in water, then drying it, and it is ready for use."



"Nothing could be more simple," said Morgan.



"Moreover, pyroxyle is unaltered by moisture-- a valuable

property to us, inasmuch as it would take several days to charge

the cannon. It ignites at 170 degrees in place of 240, and its

combustion is so rapid that one may set light to it on the top

of the ordinary powder, without the latter having time to ignite."



"Perfect!" exclaimed the major.



"Only it is more expensive."



"What matter?" cried J. T. Maston.



"Finally, it imparts to projectiles a velocity four times

superior to that of gunpowder. I will even add, that if we mix

it with one-eighth of its own weight of nitrate of potassium,

its expansive force is again considerably augmented."



"Will that be necessary?" asked the major.



"I think not," replied Barbicane. "So, then, in place of

1,600,000 pounds of powder, we shall have but 400,000 pounds of

fulminating cotton; and since we can, without danger, compress

500 pounds of cotton into twenty-seven cubic feet, the whole

quantity will not occupy a height of more than 180 feet within

the bore of the Columbiad. In this way the shot will have more

than 700 feet of bore to traverse under a force of 6,000,000,000

litres of gas before taking its flight toward the moon."



At this juncture J. T. Maston could not repress his emotion; he

flung himself into the arms of his friend with the violence of

a projectile, and Barbicane would have been stove in if he had

not been boom-proof.



This incident terminated the third meeting of the committee.



Barbicane and his bold colleagues, to whom nothing seemed

impossible, had succeeding in solving the complex problems of

projectile, cannon, and powder. Their plan was drawn up, and it

only remained to put it into execution.



"A mere matter of detail, a bagatelle," said J. T. Maston.