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 look 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 lbs. 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 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." "Nevertheless," said the president, "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?" "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 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." "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 ordinary powder, without the latter having time to ignite." "Perfect!" exclaimed the major.