human
Gentlemen, said this distinguished chemist,
gpt
I begin with some figures which will serve as the basis of our calculation. The old 24-pounder shot required for its discharge 16 lbs. of powder.
human
You are certain of the amount?
gpt
Quite certain, replied the major.
human
The Armstrong cannon employs only 75 lbs. of powder for a projectile of 800 lbs., and the Rodman Columbiad uses only 160 lbs. 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.
gpt
Quite true,
human
Well, replied the major,
gpt
What are you aiming at?
human
If you push your theory to extremes, my dear major, said J. T. Maston,
gpt
Our friend Maston is always at his jokes, even in serious matters, cried the major;
human
Perfectly correct, said Morgan;
gpt
We shall have to employ a large-grained powder, continued the major,
human
No doubt about that, replied Morgan,
gpt
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.
human
We must have, said Maston,
gpt
Certainly, replied Elphinstone;
human
Well, my friends, what quantity of powder do you propose?
gpt
Two hundred thousand pounds,
human
Five hundred thousand,
gpt
Eight hundred thousand,
human
Gentlemen, he quietly said,
gpt
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 lbs. of powder.
human
Sixteen hundred thousand pounds?
gpt
Just so.
human
We shall have to come then to my ideal of a cannon half a mile long; for you see 1,600,000 lbs. 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.
gpt
Nevertheless, said the president,
human
I hold to that quantity of powder. Now, 1,600,000 lbs. of powder will create 6,000,000,000 of litres of gas. Six thousand millions! You quite understand?
gpt
What is to be done then?
human
The thing is very simple; we must reduce this enormous quantity of powder, while preserving to it its mechanical power.
gpt
Good; but by what means?
human
I am going to tell you, replied Barbicane quietly.
gpt
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 vegetables? 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, becomes 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 Bâle, 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.
human
Nothing could be more simple,
gpt
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 ordinary powder, without the latter having time to ignite.
human
Perfect!
gpt
Only it is more expensive.
human
What matter?
gpt
Finally, it imparts to projectiles a velocity four times superior to that of gunpowder. I will even add, that if we mix with it one-eighth of its own weight of nitrate of potass, its expansive force is again considerably augmented.
human
Will that be necessary?
gpt
I think not, replied Barbicane.
human
So, then, in place of 1,600,000 lbs. of powder, we shall have but 400,000 lbs. of fulminating cotton; and since we can, without danger, compress 500 lbs. of cotton into 27 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 towards the moon.