The Mysterious Island, Jules Verne [classic novels .txt] 📗

cinders, was placed, in a basin full of water. Having stirred up the mixture, they let it settle, and at length poured off a clear liquid holding the sulphates of iron and alumina in solution. Finally, this liquid was partly evaporated, the sulphate of iron crystalized, and the mother-water was thrown away.

Smith had now a quantity of crystals, from which the sulphuric acid was to be extracted.

In commerce this acid is manufactured in large quantities and by elaborate processes. The engineer had no such means at his command, but he knew that in Bohemia an acid known as Nordhausen is made by simpler means, which has, moreover, the advantage of being non-concentrated. For obtaining the acid in this way, all the engineer had to do was to calcinize the crystals in a closed jar in such a manner that the sulphuric acid distilled in vapor, which would in turn produce the acid by condensation.

It was for this that the refractory jars and the furnace had been made. The operation was a success; and on the 20th of May, twelve days after having begun, Smith was the possessor of the agent which he expected to use later in different ways.

What did he want with it now? Simply to produce nitric acid, which was perfectly easy, since the saltpetre, attacked by the sulphuric acid, would give it by distillation.

But how would he use this acid? None of the others knew, as he had spoken no word on the subject.

The work approached completion, and one more operation would procure the substance which had required all this labor. The engineer mixed the nitric acid with the glycerine, which latter had been previously concentrated by evaporation in a water-bath, and without employing any freezing mixture, obtained many pints of an oily yellow liquid.

This last operation Smith had conducted alone, at some distance from the Chimneys, as he feared an explosion, and when he returned, with a flagon of this liquid, to his friends, he simply said:—“Here is some nitro-glycerine!”

It was, in truth, that terrible product, whose explosive power is, perhaps, ten times as great as that of gunpowder, and which has caused so many accidents! Although, since means have been found of transforming it into dynamite, that is, of mixing it with clay or sugar or some solid substance sufficiently porous to hold it, the dangerous liquid can be used with more safety. But dynamite was not known when the colonists were at work on Lincoln Island.

“And is that stuff going to blow up the rocks?” asked Pencroff, incredulously.

“Yes, my friend,” answered the engineer, “and it will do all the better since the granite is very hard and will oppose more resistance to the explosion.”

“And when will we see all this, sir?”

“To-morrow,” when we have drilled a hole,” answered the engineer.

Early the next morning, the 21st of May, the miners betook themselves to a point which formed the east bank of Lake Grant, not more than 500 feet from the coast. At this place the plateau was lower than the lake, which was upheld by the coping of granite. It was plain that could they break this the waters would escape by this vent, and, forming a stream, flow over the inclined surface of the plateau, and be precipitated in a waterfall over the cliff on to the shore. Consequently, there would be a general lowering of the lake, and the orifice of the water would be uncovered—this was to be the result.

The coping must be broken. Pencroff, directed by the engineer, attacked its outer facing vigorously. The hole which he made with his pick began under a horizontal edge of the bank, and penetrated obliquely so as to reach a level lower than the lake’s surface. Thus the blowing up of the rocks would permit the water to escape freely and consequently lower the lake sufficiently.

The work was tedious, as the engineer, wishing to produce a violent shock, had determined to use not less than two gallons of nitro-glycerine in the operation. But Pencroff and Neb, taking turns at the work, did so well, that by 4 o’clock in the afternoon it was achieved.

Now came the question of igniting the explosive. Ordinarily, nitro-glycerine is ignited by the explosion of fulminated caps, as, if lighted without percussion, this substance burns and does not explode.

Smith could doubtless make a cap. Lacking fulminate, he could easily obtain a substance analogous to gun-cotton, since he had nitric acid at hand. This substance pressed in a cartridge, and introduced into the nitro-glycerine, could be lighted with a slow match, and produce the explosion.

But Smith knew that their liquid had the property of exploding under a blow. He determined, therefore, to make use of this property, reserving the other means in case this experiment failed.

The blow of a hammer upon some drops of the substance spread on a hard stone, suffices to provoke an explosion. But no one could give those blows without being a victim to the operation. Smith’s idea was to suspend a heavy mass of iron by means of a vegetable fibre to an upright post, so as to have the iron hang directly over the hole. Another long fibre, previously soaked in sulphur, was to be fastened to the middle of the first and laid along the ground many feet from this excavation. The fire was to be applied to this second fibre, it would burn till it reached the first and set it on fire, then the latter would break and the iron be precipitated upon the nitro-glycerine.

The apparatus was fixed in place; then the engineer, after having made his companions go away, filled the hole so that the fluid overflowed the opening, and spread some drops underneath the mass of suspended iron.

This done, Smith lit the end of the sulfured fibre, and, leaving the place, returned with his companions to the Chimneys.

Twenty-five minutes after a tremendous explosion was heard. It seemed as if the whole island trembled to its base. A volley of stones rose into the air as if they had been vomited from a volcano. The concussion was such that it shook the Chimneys. The colonists, though two miles away, were thrown to the ground. Rising again, they clambered up to the plateau and hurried towards the place.

A large opening had been torn in the granite coping. A rapid stream of water escaped through it, leaping and foaming across the plateau, and, reaching the brink, fell a distance of 300 feet to the shore below.

CHAPTER XVIII.

PENCROFF DOUBTS NO MORE—THE OLD OUTLET OF THE LAKE—A SUBTERRANEAN DESCENT—THE WAY THROUGH THE GRANITE—TOP HAS DISAPPEARED—THE CENTRAL CAVERN—THE LOWER WELL—MYSTERY—THE BLOWS WITH THE PICK—THE RETURN.

Smith’s project had succeeded; but, as was his manner, he stood motionless, absorbed, his lips closed, giving no sign of satisfaction. Herbert was all enthusiasm; Neb jumped with joy; Pencroff, shaking his head, murmured:—

“Indeed, our engineer does wonders!”

The nitro-glycerine had worked powerfully. The opening was so great that at least a three times greater volume of water escaped by it than by the former outlet. In a little while, therefore, the level of the lake would be lowered two feet or more.

The colonists returned to the Chimneys, and collecting some picks, spears, ropes, a steel and tinder, returned to the plateau. Top went with them.

On the way the sailor could not resist saying to the engineer:—

“But do you really think, Mr. Smith, that one could blow up the whole island with this beautiful liquid of yours?”

“Doubtless,” replied the other, “island, continents, the world itself. It is only a question of quantity.”

“Couldn’t you use this nitro-glycerine to load firearms.”

“No, Pencroff, because it is too shattering. But it would be easy to make gun-cotton, or even common powder, as we have the material. Unfortunately, the guns themselves are wanting.”

“But with a little ingenuity!—”

Pencroff had erased “impossible” from his vocabulary.

The colonists having reached Prospect Plateau, hastened at once to the old outlet of the lake, which ought now to be uncovered. And when the water no longer poured through it, it would, doubtless, be easy to explore its interior arrangement.

In a few moments they reached the lower angle of the lake, and saw at a glance what the result was.

There, in the granite wall of the lake, above the water-level, appeared the long-looked for opening. A narrow ledge, left bare, by the subsidence of the water, gave them access to it. The opening was twenty feet wide, though only two feet high. It was like the gutter-mouth in a pavement. It was not open enough for the party to get in, but Neb and Pencroff, with their picks, in less than an hour had given it a sufficient height.

The engineer looked in and saw that the walls of the opening in its upper part showed a slope of from 30° to 35°. And, therefore, unless they became much steeper it would be easy to descend, perhaps, to the level of the sea. And if, as was probable, some vast cavern existed in the interior of the massive granite, it was possible that they could make use of it.

“What are we waiting for, Mr. Smith,” cried the sailor, all impatience to begin the exploration, “Top, you see, has gone ahead!”

“We must have some light,” said the engineer. “Go, Neb, and cut some resinous branches.”

The negro and Herbert ran to some pine and evergreens growing upon the bank, and soon returned with branches which were made into torches. Having lit them, the colonists, with Smith leading, entered the dark passage, but recently filled with water.

Contrary to their expectation, the passage grew higher as they advanced, until soon they were able to walk upright. The granite walls, worn, by the water, were very slippery, and the party had to look out for falls. They, therefore, fastened themselves together with a cord, like mountain climbers. Fortunately, some granite steps made the descent less perilous. Drops of water, still clinging to the rocks, glistened like stalactites in the torchlight. The engineer looked carefully at this black granite. He could not see a stratum or a flaw. The mass was compact and of fine grain, and the passage must have been coeval with the island. It had not been worn little by little by the constant action of water. Pluto, and not Neptune, had shaped it; and the traces of igneous action were still visible upon its surface.

The colonists descended but slowly. They experienced some emotion in thus adventuring into the depths of the earth, in being its first human visitants. No one spoke, but each was busied with his own reflections and the thought occurred to more than one, that perhaps some pulp or other gigantic cephalopod might inhabit the interior cavities which communicated with the sea. It was, therefore, necessary to advance cautiously.

Top was ahead of the little troop and they could rely on the dog’s sagacity to give the alarm on occasion. After having descended 100 feet, Smith halted, and the others came up with him. They were standing in a cavern of moderate size. Drops of water fell from the roof, but they did not ooze through the rocks, they were simply the last traces of the torrent which had so long roared through this place, and the air, though humid, emitted no mephitic vapor.

“Well, Cyrus,” said Spilett, “here is a retreat sufficiently unknown and hidden in the depths, but it is uninhabitable.”

“How, uninhabitable?” asked the sailor.

“Why, it is too small and too dark.”

“Cannot we make it bigger, blast it out, and make openings for the light and air?” answered Pencroff, who now thought nothing impracticable.

“Let us push on,” said Smith. “Perhaps lower down, nature will have spared us this work.”

“We are only a third of the way down,” observed Herbert.

“But 100 feet,” responded Cyrus; “and it is possible that 100 feet lower—.”

“Where is Top?” asked Neb, interrupting his master.

They looked about the cavern. The dog was not there.

“Let us overtake him,” said Smith, resuming the march. The engineer noted carefully all the deviations of the route, and easily kept a general idea of their direction, which was towards the sea. The party had not descended more than fifty feet further, when their attention was arrested by distant sounds coming from the depths of the rock. They stopped and listened. These sounds, borne along the passage, as the voice through an acoustic tube, were distinctly heard.

“Its Top’s barking!” cried Herbert.

“Yes, and the brave dog is barking furiously,” added Pencroff.

“We have our spears,” said Smith. “Come on, and be ready.”

“It is becoming more and more interesting,” whispered Spilett to the sailor, who nodded assent.

They hurried to the rescue of the dog. His barks grew more distinct. They could hear that he was in a strange rage. Had he been captured by some animal whom he had disturbed? Without