JULES VERNE: 25 Greatest Books in One Volume (Illustrated Edition). Жюль Верн

on the shore, glass–wort, ficoides, and all those fucaceae which form wrack. A large quantity of these plants was collected, first dried, then burnt in holes in the open air. The combustion of these plants was kept up for several days, and the result was a compact gray mass, which has been long known under the name of “natural soda.”

      This obtained, the engineer treated the fat with soda, which gave both a soluble soap and that neutral substance, glycerine.

      But this was not all. Cyrus Harding still needed, in view of his future preparation, another substance, nitrate of potash, which is better known under the name of salt niter, or of saltpeter.

      Cyrus Harding could have manufactured this substance by treating the carbonate of potash, which would be easily extracted from the cinders of the vegetables, by azotic acid. But this acid was wanting, and he would have been in some difficulty, if nature had not happily furnished the saltpeter, without giving them any other trouble than that of picking it up. Herbert found a vein of it at the foot of Mount Franklin, and they had nothing to do but purify this salt.

      These different works lasted a week. They were finished before the transformation of the sulphuret into sulphate of iron had been accomplished. During the following days the settlers had time to construct a furnace of bricks of a particular arrangement, to serve for the distillation of the sulphate or iron when it had been obtained. All this was finished about the 18th of May, nearly at the time when the chemical transformation terminated. Gideon Spilett, Herbert, Neb, and Pencroft, skillfully directed by the engineer, had become most clever workmen. Before all masters, necessity is the one most listened to, and who teaches the best.

      When the heap of pyrites had been entirely reduced by fire, the result of the operation, consisting of sulphate of iron, sulphate of alumina, flint, remains of coal, and cinders was placed in a basinful of water. They stirred this mixture, let it settle, then decanted it, and obtained a clear liquid containing in solution sulphate of iron and sulphate of alumina, the other matters remaining solid, since they are insoluble. Lastly, this liquid being partly evaporated, crystals of sulphate of iron were deposited, and the not evaporated liquid, which contained the sulphate of alumina, was thrown away.

      Cyrus Harding had now at his disposal a large quantity of these sulphate of iron crystals, from which the sulphuric acid had to be extracted. The making of sulphuric acid is a very expensive manufacture. Considerable works are necessary—a special set of tools, an apparatus of platina, leaden chambers, unassailable by the acid, and in which the transformation is performed, etc. The engineer had none of these at his disposal, but he knew that, in Bohemia especially, sulphuric acid is manufactured by very simple means, which have also the advantage of producing it to a superior degree of concentration. It is thus that the acid known under the name of Nordhausen acid is made.

      To obtain sulphuric acid, Cyrus Harding had only one operation to make, to calcine the sulphate of iron crystals in a closed vase, so that the sulphuric acid should distil in vapor, which vapor, by condensation, would produce the acid.

      The crystals were placed in pots, and the heat from the furnace would distil the sulphuric acid. The operation was successfully completed, and on the 20th of May, twelve days after commencing it, the engineer was the possessor of the agent which later he hoped to use in so many different ways.

      Now, why did he wish for this agent? Simply to produce azotic acid; and that was easy, since saltpeter, attacked by sulphuric acid, gives azotic, or nitric, acid by distillation.

      But, after all, how was he going to employ this azotic acid? His companions were still ignorant of this, for he had not informed them of the result at which he aimed.

      However, the engineer had nearly accomplished his purpose, and by a last operation he would procure the substance which had given so much trouble.

      Taking some azotic acid, he mixed it with glycerine, which had been previously concentrated by evaporation, subjected to the water–bath, and he obtained, without even employing a refrigerant mixture, several pints of an oily yellow mixture.

      This last operation Cyrus Harding had made alone, in a retired place, at a distance from the Chimneys, for he feared the danger of an explosion, and when he showed a bottle of this liquid to his friends, he contented himself with saying,—

      “Here is nitro–glycerine!”

      It was really this terrible production, of which the explosive power is perhaps tenfold that of ordinary powder, and which has already caused so many accidents. However, since a way has been found to transform it into dynamite, that is to say, to mix with it some solid substance, clay or sugar, porous enough to hold it, the dangerous liquid has been used with some security. But dynamite was not yet known at the time when the settlers worked on Lincoln Island.

      “And is it that liquid that is going to blow up our rocks?” said Pencroft incredulously.

      “Yes, my friend,” replied the engineer, “and this nitro–glycerine will produce so much the more effect, as the granite is extremely hard, and will oppose a greater resistance to the explosion.”

      “And when shall we see this, captain?”

      “To–morrow, as soon as we have dug a hole for the mine, replied the engineer.”

      The next day, the 21st of May, at daybreak, the miners went to the point which formed the eastern shore of Lake Grant, and was only five hundred feet from the coast. At this place, the plateau inclined downwards from the waters, which were only restrained by their granite case. Therefore, if this case was broken, the water would escape by the opening and form a stream, which, flowing over the inclined surface of the plateau, would rush on to the beach. Consequently, the level of the lake would be greatly lowered, and the opening where the water escaped would be exposed, which was their final aim.

      Under the engineer’s directions, Pencroft, armed with a pickaxe, which he handled skillfully and vigorously, attacked the granite. The hole was made on the point of the shore, slanting, so that it should meet a much lower level than that of the water of the lake. In this way the explosive force, by scattering the rock, would open a large place for the water to rush out.

      The work took some time, for the engineer, wishing to produce a great effect, intended to devote not less than seven quarts of nitro–glycerine to the operation. But Pencroft, relieved by Neb, did so well, that towards four o’clock in the evening, the mine was finished.

      Now the question of setting fire to the explosive substance was raised. Generally, nitro–glycerine is ignited by caps of fulminate, which in bursting cause the explosion. A shock is therefore needed to produce the explosion, for, simply lighted, this substance would burn without exploding.

      Cyrus Harding could certainly have fabricated a percussion cap. In default of fulminate, he could easily obtain a substance similar to guncotton, since he had azotic acid at his disposal. This substance, pressed in a cartridge, and introduced among the nitro–glycerine, would burst by means of a fuse, and cause the explosion.

      But Cyrus Harding knew that nitro–glycerine would explode by a shock. He resolved to employ this means, and try another way, if this did not succeed.

      In fact, the blow of a hammer on a few drops of nitro–glycerine, spread out on a hard surface, was enough to create an explosion. But the operator could not be there to give the blow, without becoming a victim to the operation. Harding, therefore, thought of suspending a mass of iron, weighing several pounds, by means of a fiber, to an upright just above the mine. Another long fiber, previously impregnated with sulphur, was attached to the middle of the first, by one end, while the other lay on the ground several feet distant from the mine. The second fiber being set on fire, it would burn till it reached the first. This catching fire in its turn, would break, and the mass of iron would fall on the nitro–glycerine. This apparatus being then arranged, the engineer, after having sent his companions to a distance, filled the hole, so that the nitro–glycerine was on a level with the opening; then he threw a few drops of it on the surface of the rock, above which the mass of iron was already suspended.