L'île mystérieuse. English

by Jules Verne

  Chapter 17

  The next day, the 7th of May, Harding and Gideon Spilett, leaving Neb toprepare breakfast, climbed Prospect Heights, while Herbert and Pencroftascended by the river, to renew their store of wood.

  The engineer and the reporter soon reached the little beach on which thedugong had been stranded. Already flocks of birds had attacked the massof flesh, and had to be driven away with stones, for Cyrus wished tokeep the fat for the use of the colony. As to the animal's fleshit would furnish excellent food, for in the islands of the MalayArchipelago and elsewhere, it is especially reserved for the table ofthe native princes. But that was Neb's affair.

  At this moment Cyrus Harding had other thoughts. He was much interestedin the incident of the day before. He wished to penetrate the mysteryof that submarine combat, and to ascertain what monster could have giventhe dugong so strange a wound. He remained at the edge of the lake,looking, observing; but nothing appeared under the tranquil waters,which sparkled in the first rays of the rising sun.

  At the beach, on which lay the body of the dugong, the water wastolerably shallow, but from this point the bottom of the lake slopedgradually, and it was probable that the depth was considerable in thecenter. The lake might be considered as a large center basin, which wasfilled by the water from the Red Creek.

  "Well, Cyrus," said the reporter, "there seems to be nothing suspiciousin this water."

  "No, my dear Spilett," replied the engineer, "and I really do not knowhow to account for the incident of yesterday."

  "I acknowledge," returned Spilett, "that the wound given this creatureis, at least, very strange, and I cannot explain either how Top wasso vigorously cast up out of the water. One could have thought that apowerful arm hurled him up, and that the same arm with a dagger killedthe dugong!"

  "Yes," replied the engineer, who had become thoughtful; "there issomething there that I cannot understand. But do you better understandeither, my dear Spilett, in what way I was saved myself--how I was drawnfrom the waves, and carried to the downs? No! Is it not true? Now, Ifeel sure that there is some mystery there, which, doubtless, we shalldiscover some day. Let us observe, but do not dwell on these singularincidents before our companions. Let us keep our remarks to ourselves,and continue our work."

  It will be remembered that the engineer had not as yet been able todiscover the place where the surplus water escaped, but he knew it mustexist somewhere. He was much surprised to see a strong current at thisplace. By throwing in some bits of wood he found that it set towards thesouthern angle. He followed the current, and arrived at the south pointof the lake.

  There was there a sort of depression in the water, as if it was suddenlylost in some fissure in the ground.

  Harding listened; placing his ear to the level of the lake, he verydistinctly heard the noise of a subterranean fall.

  "There," said he, rising, "is the discharge of the water; there,doubtless, by a passage in the granite cliff, it joins the sea, throughcavities which we can use to our profit. Well, I can find it!"

  The engineer cut a long branch, stripped it of its leaves, and plungingit into the angle between the two banks, he found that there was a largehole one foot only beneath the surface of the water. This hole was theopening so long looked for in vain, and the force of the current wassuch that the branch was torn from the engineer's hands and disappeared.

  "There is no doubt about it now," repeated Harding. "There is theoutlet, and I will lay it open to view!"

  "How?" asked Gideon Spilett.

  "By lowering the level of the water of the lake three feet."

  "And how will you lower the level?"

  "By opening another outlet larger than this."

  "At what place, Cyrus?"

  "At the part of the bank nearest the coast."

  "But it is a mass of granite!" observed Spilett.

  "Well," replied Cyrus Harding, "I will blow up the granite, and thewater escaping, will subside, so as to lay bare this opening--"

  "And make a waterfall, by falling on to the beach," added the reporter.

  "A fall that we shall make use of!" replied Cyrus. "Come, come!"

  The engineer hurried away his companion, whose confidence in Harding wassuch that he did not doubt the enterprise would succeed. And yet, howwas this granite wall to be opened without powder, and with imperfectinstruments? Was not this work upon which the engineer was so bent abovetheir strength?

  When Harding and the reporter entered the Chimneys, they found Herbertand Pencroft unloading their raft of wood.

  "The woodmen have just finished, captain." said the sailor, laughing,"and when you want masons--"

  "Masons,--no, but chemists," replied the engineer.

  "Yes," added the reporter, "we are going to blow up the island--"

  "Blow up the island?" cried Pencroft.

  "Part of it, at least," replied Spilett.

  "Listen to me, my friends," said the engineer. And he made known to themthe result of his observations.

  According to him, a cavity, more or less considerable, must exist inthe mass of granite which supported Prospect Heights, and he intendedto penetrate into it. To do this, the opening through which the waterrushed must first be cleared, and the level lowered by making a largeroutlet. Therefore an explosive substance must be manufactured, whichwould make a deep trench in some other part of the shore. This was whatHarding was going to attempt with the minerals which nature placed athis disposal.

  It is useless to say with what enthusiasm all, especially Pencroft,received this project. To employ great means, open the granite, create acascade, that suited the sailor. And he would just as soon be a chemistas a mason or bootmaker, since the engineer wanted chemicals. He wouldbe all that they liked, "even a professor of dancing and deportment,"said he to Neb, if that was ever necessary.

  Neb and Pencroft were first of all told to extract the grease from thedugong, and to keep the flesh, which was destined for food. Such perfectconfidence had they in the engineer, that they set out directly,without even asking a question. A few minutes after them, Cyrus Harding,Herbert, and Gideon Spilett, dragging the hurdle, went towards the veinof coals, where those shistose pyrites abound which are met with in themost recent transition soil, and of which Harding had already found aspecimen. All the day being employed in carrying a quantity of thesestones to the Chimneys, by evening they had several tons.

  The next day, the 8th of May, the engineer began his manipulations.These shistose pyrites being composed principally of coal, flint,alumina, and sulphuret of iron--the latter in excess--it was necessaryto separate the sulphuret of iron, and transform it into sulphate asrapidly as possible. The sulphate obtained, the sulphuric acid couldthen be extracted.

  This was the object to be attained. Sulphuric acid is one of the agentsthe most frequently employed, and the manufacturing importance of anation can be measured by the consumption which is made of it. This acidwould later be of great use to the settlers, in the manufacturing ofcandles, tanning skins, etc., but this time the engineer reserved it foranother use.

  Cyrus Harding chose, behind the Chimneys, a site where the groundwas perfectly level. On this ground he placed a layer of branches andchopped wood, on which were piled some pieces of shistose pyrites,buttressed one against the other, the whole being covered with a thinlayer of pyrites, previously reduced to the size of a nut.

  This done, they set fire to the wood, the heat was communicated to theshist, which soon kindled, since it contains coal and sulphur. Then newlayers of bruised pyrites were arranged so as to form an immenseheap, the exterior of which was covered with earth and grass, severalair-holes being left, as if it was a stack of wood which was to becarbonized to make charcoal.

  They then left the transformation to complete itself, and it wouldnot take less than ten or twelve days for the sulphuret of iron to bechanged to sulphate of iron and the alumina into sulphate of alumina,two equally soluble substances, the others, flint, burnt coal, andcinders, not being so.

&nbs
p; While this chemical work was going on, Cyrus Harding proceeded withother operations, which were pursued with more than zeal,--it waseagerness.

  Neb and Pencroft had taken away the fat from the dugong, and placed itin large earthen pots. It was then necessary to separate the glycerinefrom the fat by saponifying it. Now, to obtain this result, it had tobe treated either with soda or lime. In fact, one or other of thesesubstances, after having attacked the fat, would form a soap byseparating the glycerine, and it was just this glycerine which theengineer wished to obtain. There was no want of lime, only treatment bylime would give calcareous soap, insoluble, and consequently useless,while treatment by soda would furnish, on the contrary, a soluble soap,which could be put to domestic use. Now, a practical man, like CyrusHarding, would rather try to obtain soda. Was this difficult? No; formarine plants abounded on the shore, glass-wort, ficoides, and allthose fucaceae which form wrack. A large quantity of these plantswas collected, first dried, then burnt in holes in the open air. Thecombustion of these plants was kept up for several days, and the resultwas 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 asoluble soap and that neutral substance, glycerine.

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

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

  These different works lasted a week. They were finished beforethe transformation of the sulphuret into sulphate of iron had beenaccomplished. During the following days the settlers had time toconstruct a furnace of bricks of a particular arrangement, to serve forthe distillation of the sulphate or iron when it had been obtained. Allthis was finished about the 18th of May, nearly at the time when thechemical transformation terminated. Gideon Spilett, Herbert, Neb, andPencroft, skillfully directed by the engineer, had become most cleverworkmen. Before all masters, necessity is the one most listened to, andwho teaches the best.

  When the heap of pyrites had been entirely reduced by fire, the resultof 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 obtaineda clear liquid containing in solution sulphate of iron and sulphate ofalumina, the other matters remaining solid, since they are insoluble.Lastly, this liquid being partly evaporated, crystals of sulphate ofiron were deposited, and the not evaporated liquid, which contained thesulphate of alumina, was thrown away.

  Cyrus Harding had now at his disposal a large quantity of these sulphateof iron crystals, from which the sulphuric acid had to be extracted. Themaking of sulphuric acid is a very expensive manufacture. Considerableworks are necessary--a special set of tools, an apparatus ofplatina, leaden chambers, unassailable by the acid, and in which thetransformation is performed, etc. The engineer had none of these at hisdisposal, but he knew that, in Bohemia especially, sulphuric acid ismanufactured by very simple means, which have also the advantage ofproducing it to a superior degree of concentration. It is thus that theacid 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 thesulphuric 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 woulddistil the sulphuric acid. The operation was successfully completed, andon the 20th of May, twelve days after commencing it, the engineerwas the possessor of the agent which later he hoped to use in so manydifferent ways.

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

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

  However, the engineer had nearly accomplished his purpose, and by alast operation he would procure the substance which had given so muchtrouble.

  Taking some azotic acid, he mixed it with glycerine, which had beenpreviously concentrated by evaporation, subjected to the water-bath, andhe obtained, without even employing a refrigerant mixture, several pintsof an oily yellow mixture.

  This last operation Cyrus Harding had made alone, in a retired place, ata 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 contentedhimself with saying,--

  "Here is nitro-glycerine!"

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

  "And is it that liquid that is going to blow up our rocks?" saidPencroft incredulously.

  "Yes, my friend," replied the engineer, "and this nitro-glycerine willproduce so much the more effect, as the granite is extremely hard, andwill 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 theengineer."

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

  Under the engineer's directions, Pencroft, armed with a pickaxe, whichhe handled skillfully and vigorously, attacked the granite. The hole wasmade on the point of the shore, slanting, so that it should meet amuch lower level than that of the water of the lake. In this way theexplosive force, by scattering the rock, would open a large place forthe water to rush out.

  The work took some time, for the engineer, wishing to produce a greateffect, intended to devote not less than seven quarts of nitro-glycerineto the operation. But Pencroft, relieved by Neb, did so well, thattowards 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 inbursting cause the explosion. A shock is therefore needed to producethe explosion, for, simply lighted, this substance would burn withoutexploding.

  Cyrus Harding could certainly have fabricated a percussion cap. Indefault of fulminate, he could easily obtain a substance similar toguncotton, since he had azotic acid at his disposal. This substance,pressed in a cartridge, and introduced among the nitro-glycerine, wouldburst 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 notsucceed.

  In fact, the blow of a hammer on a few drops of nitro-glycerine, spreadout on a hard surface, was enough to create an explosion. But theoperator could not be there to give the blow, without becomin
g a victimto the operation. Harding, therefore, thought of suspending a mass ofiron, weighing several pounds, by means of a fiber, to an upright justabove the mine. Another long fiber, previously impregnated with sulphur,was attached to the middle of the first, by one end, while the other layon the ground several feet distant from the mine. The second fiber beingset on fire, it would burn till it reached the first. This catchingfire in its turn, would break, and the mass of iron would fall on thenitro-glycerine. This apparatus being then arranged, the engineer, afterhaving sent his companions to a distance, filled the hole, so that thenitro-glycerine was on a level with the opening; then he threw a fewdrops of it on the surface of the rock, above which the mass of iron wasalready suspended.

  This done, Harding lit the end of the sulphured fiber, and leaving theplace, he returned with his companions to the Chimneys.

  The fiber was intended to burn five and twenty minutes, and, in fact,five and twenty minutes afterwards a most tremendous explosion washeard. The island appeared to tremble to its very foundation. Stoneswere projected in the air as if by the eruption of a volcano. The shockproduced by the displacing of the air was such, that the rocks of theChimneys shook. The settlers, although they were more than two milesfrom the mine, were thrown on the ground.

  They rose, climbed the plateau, and ran towards the place where the bankof the lake must have been shattered by the explosion.

  A cheer escaped them! A large rent was seen in the granite! A rapidstream of water rushed foaming across the plateau and dashed down aheight of three hundred feet on to the beach!