"Here is a branch, with the flower, of a tree, and the smell is very familiar."
"That is from a camphor tree; do you not recognize it?"
"So it is; I know camphor is good for a great many things."
"It would take some time to enumerate the things camphor is used for. Indeed, there are so many that Raspail, a French chemist, years ago found a system of medicine largely on the camphor plant, claiming that it was nature's universal remedy."
"Here is a sample of plant which we found growing in bushes; there were also a few trees with the flowers. It is bitter to the taste."
"This is the Calisaya, one of the varieties of the plant from which the well-known quinine is made. There are at least forty varieties of the plant. This is indeed a valuable find. But I see you have some beans there?"
"Yes; are they good to eat?"
"In South America, particularly in the Argentine Republic, it is eaten as a fruit, and the seeds are fed to cattle. Our yaks would relish them."
"We saw them everywhere on the other side of the river."
"The dry pulp of the seed is very nutritious, and is supposed to have been the food of St. John while in the wilderness, as it is the same kind of locust bean that grows in Palestine, and in various parts of Asia Minor. The Spanish name is Algoraba, or Carob-tree."
"We have brought only one more sample, and it looks very familiar, but I never saw any beans or pods on it like this."
"Don't you recognize Smilax? Of course, it is somewhat different from the kind you know. The root of this kind of Smilax is called Sarsaparilla, and the bean is good to eat."
"Well, I am going to lay in a supply."
The boys could not forget the animal they had shot when morning came, so at the Professor's suggestion, they improvised a raft, which was loaded on the wagon, and a start made for the river.
Tethering the team the raft was launched, and the Professor accompanied them across. A light skid had been made for use in transporting the hide, so they would not be compelled to carry it the entire distance. Before they had reached the spot pointed out by the boys, they stumbled on the animal.
"Why," said the Professor, "this is an Ocelot, very dangerous when attacked, and just the kind of beast to elude you. I commend you for the good judgment in adopting the course you did."
"See here, Harry; I don't understand this. You will remember when we examined him, just before leaving him here, that we found only one bullet hole between the shoulders; this has two bullet wounds, one in the head and the other in the neck."
"Why this is not the place we shot him. This must have been shot by some one else."
"Do you remember what you selected as your marking for the spot?"
Harry looked about, and finally said: "I remember two trees, standing about ten feet apart, east and west of each other."
"That is the place, I am sure," was George's conclusion, after they had made a circuit around the spot; "yes, I am sure those are the trees."
"There it is; I see it."
Surely enough, close to the two trees an animal was found, larger than the one they had just left.
"So it seems you killed two of them," and the Professor was so much amused he could not help laughing as he saw the amazement on the boys' countenances. "You are certainly fine hunters."
"I think—yes; here is the shot in the shoulder—this is the last one we shot. The other one, over there, was the one we followed so long and took our first shot at."
Within two hours the skins were ready, packed on the skid, and delivered at the raft, and after a hard forenoon's work the Cataract was reached shortly after noon.
One night, while engaged in the usual evening discussion, many topics were mentioned, things connected with the day's adventures talked over, and plans for the following day considered.
As usual, George was the persistent questioner, but Harry was the one to utilize the meaning, and generally the first to take advantage in a practical way of the information thus obtained.
We have stated heretofore that George was the theorist and Harry the practical one. George delighted to delve down into mysteries; but Harry utilized the knowledge in constructing and building articles. Both, therefore, had useful accomplishments. To learn and to do are the great things in life.
During the day the boys had turned out a nice sample of bread, and George, as usual, began the questioning:
"Professor, you said the other day, that fermentation caused a change in the dough, and that it was due to heat. I am curious to know why heat should cause it to ferment?"
"Heat develops bacteria, a tiny germ, which grows so rapidly in a short time, that millions are produced. These living organisms cause gases to form, and they continue to breed and grow and multiply so long as they have anything to feed on."
"And we eat all that stuff and call it good?"
"Yes; and why not? Every part of your body contains the little creatures, and they really keep you alive, and preserve your health, as well as prevent diseases."
"Why so?"
"Most germs are of the harmless type, and it is because of the vast numbers of the harmless ones that the few poisonous or disease germs are killed. Water has millions of them in every cubic inch. Professor Dewar, a great English chemist, calls them nature's policemen. If a typhoid fever germ, for example, should be introduced among so many germs, as is the case every day, a fight at once takes place, and where a person is finally attacked with the fever, it is because the germs escaped the policemen who were on duty."
"That sounds like a romance."
"Yes; the life history of those germs is really a wonderful thing, and books have been written about them. They exist in tribes, as it were; some of them can live only where oxygen is present, and some live on nitrogen only; others on carbon. But that is not all. Man has learned to use them, so they will work just as surely as our yaks work for us under our direction."
"How interesting! In what way do we use them?"
"In what is called the septic system of treating sewage. You know that sewage from the kitchen contains all kinds of meat and vegetables, and the more it has fermented the stronger becomes the odor and the greater are the number of bacteria in the sewage. The sewage in the liquid state is first placed in a reservoir, and at a certain temperature the germs grow very rapidly, and, of course, eat up the vegetable and animal matter until it is nearly all consumed. Then it is run off into another reservoir which has another tribe of germs in it, those that live on carbon, and which are not harmful to man, and when these two tribes meet war is declared, and they fight to the death. The harmless germs are victorious in every battle, and when the sewage is discharged into a stream, or used for irrigating purposes, few, if any, of the harmful germs remain."
"So in using germs the object is to cultivate one kind to kill another kind?"
"Not always; chemists have found out that man and animals absorb oxygen and expel nitrogen, in order to live; and that plants take in and live on nitrogen, and give out oxygen. They further learned that certain germs make nitrogen, just the same as we found that certain germs made carbonic gas in the dough; so that the United States Department of Agriculture, through its chemical division, concluded to set the germs to work, and the department will now send a box containing millions of the tiny creatures to any farmer who applies for them."
"When they get them, how do they set them to work?"
"The germs are thrown into a tub of water, and the seed, like corn, is put into the water and allowed to remain for a certain length of time. When the seed is taken out, more or less of the germs remains on each kernel, and when it is put into the ground the germs keep on working, making nitrogen which the growing plant absorbs. It is wonderful to see the effect in a field where one row has these germ-infected seeds, and the other rows are not so treated."
It was now May, and the weather was slightly cooler, but there was neither snow nor frost. North of the equator it was growing warmer, because the winter had passed. Here the summer had gone, and winter was coming on. From every indication they were not in a cold climate.
"Why do you think we shall not have any snow?" was Harry's inquiry.
"I notice too many trees, as well as shrubs and flowers, which could not live if we had frosts or freezing weather. Many of the trees about here do not shed their leaves, and the kind of animals which we now know exist here are sufficient evidence that we need not fear cold weather."
For more than a week the boys and the Professor put in their time prospecting in the hills and in carting various ores and mineralogical samples to their workshop.
The pelts which were on hand needed curing and besides there were also four yak pelts which had to be tanned, as shoe leather was badly needed. The hide originally dehaired was long ago ready for tanning, as well as the later ones.
"What shall we use for the tanning process?"
"The bark of certain trees must be procured, so if you can find either oak, hemlock, birch or beech trees, we can probably make a tanning compound which will serve our purpose."
"In what way will the bark of those trees tan the leather?"
"All the barks named contain what is called tannic acid. Other elements also are used, such as gallic acid, alum, sulphate of iron, and copper, salt, and other agents."
"What are the chemicals for?"
"The tannic acid or the chemicals act on the skins, or, rather on the gelatin, glutin and albumen in the skins, and thus harden the texture and preserve it. Where tannin is not used and only the chemicals are employed, it is called 'tawing' the leather, instead of 'tanning.'"
"Well, we can get the bark; I know where there are several oak trees, and also a number of beech trees."
"Then gather the bark by all means, and by the way, if you can find gall nuts we could use them to advantage."
"We don't know what they are."
"Then, if you can get some sumac, we can use that."
"Yes, I know; the kind with the long, red leaves."
"That is what I mean."
"Do the gall nuts have tannic acid?"
"Yes; but principally gallic acid, but gallic acid will also tan the skins so as to make leather. The principal use of the gall nut is for making ink."
"What kind of tree does the gall nut grow on?"
"On any kind of tree or bush."
"That is rather odd."
"It is not the fruit of any tree, but is produced by the gall fly, which punctures almost any kind of tree or shrub. In this puncture the insect lays its eggs, and the tree in trying to treat the wound covers up the egg, and the sap, flowing from the tree, forms a sort of nut which finally hardens and produces a most bitter substance deposited by the fly. The nut is about the size of a marble, and must be gathered before the larva is hatched out. It is the most valuable nut in the world."
The necessary bark for the tanning process was ready within the next two days, and a tank prepared in which the hides were laid spread out, with the bark between them and covered with water.
"In our conversations, Professor, you have the habit in describing plants, and especially the leaves to call them by certain names. It would help us if we knew just what you meant by the different names you give them."
"That is a wise suggestion, because it has been said that the basis of knowledge, or of true science, is correct definitions.[1] What is meant by that is this: We should both have an understanding of the term used to describe a thing. In our talks I have tried to avoid the use of what is called technical terms, but it is difficult to describe some things without using such terms, and I have for some time thought of making a list of the things we are talking about, and defining them, so you can at any time go there and look up the definition."
"If you would make drawings of the different kinds of leaves and give their names we could hang them up and could look at them any time."
"The leaf is the proper part to commence on, because it is the most important thing of every plant, or tree, or shrub."
"What, more important than the fruit or the flower, or the nut that grows on the tree?"
"That is just what I mean. When you smell the rich red flower of the rose, or look at the pure white petals of the lily, or the sweet-smelling blossoms of the orange or the jasmine, you are simply seeing or smelling leaves. The fruit itself, whether in the form of an apple, or a berry or a nut, is simply a form of leaf, a perfected form of the plant, or bush, or tree. Originally all these fruits, flowers and nuts were but leaves in an undeveloped state."
"I never heard of such a thing before."
"It is a subject treated of in botanical knowledge which is called Morphology, and the object is to show that every fruit and flower was developed, in accordance with a well-known law, from the particular shape or form of the leaf. We can go into that branch of the subject later on. What we now want is to know something about the shape of the leaf, so we can have a starting point. There are two particular things about leaves; one has reference to the shape of the leaf, and the other to the way in which the edges are formed. To simplify the explanation, the drawings which I make pertain only to the edges. That will be sufficient for one time.
"Look at Fig. 14. The edges are like the teeth of a saw. This is called the serrate leaf. The rose and the common nettle have such leaves.
"Fig. 15 shows a leaf with a saw tooth edge wherein the teeth themselves have a lot of little saw teeth, as in the nettle-leaved bell-flower, and this is called bi-serrate.
"Fig. 16 has very large, sharp teeth, not pointing in any particular direction, like the oak leaf. This is called the dentate, or tooth.
"Fig. 17 has rounded projections instead of angular teeth, and is called crenate. Ground ivy and horseradish have such leaves.
"When we make drawings of the shapes of the leaves that will take us along another step, and thus enable us to find out just what kind of tree or plant we are talking about."
The following day Harry proposed a trip over to the cave which George had discovered at the time he found the big air pocket that shot water and spray out into the ocean.
"I am interested," he said, "in seeing the air pocket George spoke about, and we might as well take our vacation to-day."
"As the distance is not great we need not bother about taking our luncheon along." And off they started, with the Professor bringing up the rear.
The course was first to Observation Hill, where they had erected a new and a larger pole than the one which had so mysteriously disappeared two months before. On every such visit it was the duty of the one who made the trip to scan the horizon in every direction.
It must not be inferred that because the boys were engaged in work which was all-absorbing that they had no thoughts of home, and had given up all hopes of a final rescue. If they could only let the people at home know they were alive and happy—that is, in learning the secrets of nature and in the exciting exploring trips, they would be satisfied.
They had no time to think of these things when they were at work, but in the night their thoughts often wandered back again to their homes and friends. Could they be blamed for that homesick feeling which came over them?
"Now lead the way, George; we want to see some more of your mysteries. Isn't it fortunate that the tide is out? It will give us a good chance to investigate."
The path which George had taken was farther to the right, but as he was in a hurry to get down as quickly as possible he followed a course, which was much steeper, with Harry and the Professor close on his heels.
When the bottom was reached there was no sign of a pocket, or a cave, or anything of that kind. George was very much annoyed. He could not be mistaken in the position, as it was directly to the right of Observation Hill, and not three hundred feet from the spot where Harry had landed on his first trip to the island.
"It seems to me, George, we are too low down. At high tide this place is all covered with water. It must he higher up in the cliff sides."
Harry scrambled up again part way, and shortly afterwards cried out: "I have found something here; come up at once."
He was distant not more than twenty feet above them, but so rugged were the cliffs that the opening was entirely hidden from below.
"This is an example of the corrosive effects of the sea, and of the elements in the water and in the rock. As these rocks are limestone formations, we may be able to see some beautiful decorations within, if the cave is of any extent."
"It is awful dark in there. I wish we hadn't forgotten the candles," he said, as he glanced at the Professor, who seemed to be quite absorbed in examining the rocks.
"Don't you think we had better go in?"
"I should like to do so, but we haven't any candles."
"I thought you came here for the purpose of examining the cave?"
"So we did."
"And came without making any preparations for it?" As he said this he drew out one of the small candles which they had been making and using for their evening work and recreation.
George and Harry were both very much ashamed of their carelessness. The Professor, on the other hand, did not make another remark on the subject. No doubt the silent rebuke was a lesson they would retain much better than if it should be more forcibly presented.
The boys, be it said to their credit, never resented any word or action on the part of the Professor. They had only love and veneration for him; and the Professor, by his constant attitude toward them, showed that even these careless actions or any other examples of thoughtlessness on the part of the boys, were part of the training that would teach lessons of value.
Below the mouth of the cave were little streams of water which looked like springs, and the Professor was of the opinion that the floor or interior of the cave must be lower than the entrance.
"Why do you think so?" was the inquiry.
"The springs below seem to indicate that when the high tide fills the cave, the bottom of the cave leaks enough to let out the water. The height of the mouth from the normal level of the water is much above the usual high tide level of the water, and it is only when there is an abnormally high tide, as on the day that George saw it, when the cave could be filled with water."
"Who will go in first?" said George. "I have no objection to taking the lead; so here goes."
George moved forward cautiously, holding the candle, and Harry followed with another. The opening was fully ten feet high, and at least that much in width, but irregularly formed. They went in straight for twenty feet or more, when George announced that he had reached a wall. The Professor, who was in the rear, called out: "Look to the right, there is a turn here."
Such was the case, but the broken up character of the sides and floor prevented them from readily grasping the formation. After making a jog the cave again turned into the cliff, practically on a line with the opening section or mouth of the cave. It was dark at first, but now, for some peculiar reason, it grew lighter as they advanced, and finally George stopped.
"What makes that peculiar light?"
"It is not a light; it is merely white walls and ceilings."
"What causes it?"
"Carbonate of lime, or chalk, which is caused by lime water coming from above and trickling down through to openings or crevices, and leaving the deposits there. It is not an uncommon thing in caves, and I foreshadowed it in the cave when I stated that the rocks were of limestone formation. You will remember we made lime from this kind of rock."
A loud splash and a groan-like noise put further conversation at an end. "What was that?" asked George, as he retreated. In doing so he tripped, and, in falling, the light he carried was extinguished as it flew from his hand.
Clearly there was water ahead. "Let us go forward, a little closer," said the Professor. "You might get your guns ready, in case of necessity."
Within thirty feet of them was the edge of water, and the light threw a beam beyond for a hundred feet or more.
"It seems as though we have reached the end of our explorations here." As they looked, the water was agitated, and it was plain that some aquatic animal was within the cave.
To return was the only thing to do, and as they went back the sides of the cavern were examined, and the Professor took a number of samples, as he said: "Don't lose the candle until we get where we can see daylight. Although we are not more than two hundred feet from the mouth of the cave, the remarkable bend or jog near the mouth of the cave makes it as dark as though we were in a thousand feet."
"What sort of animal do you suppose that was?"
"Possibly a sea lion, or a seal."
After the open air was reached the Professor said: "I do not see how this cave would account for the phenomena that George saw the other day."
"Why not?"
"The cave is too deep. It is not a true air pocket, and——"
"What is this? Here is another one, still larger, and lower down. Here, hold the candle." Harry was down in an instant.
"Probably this is what George saw."
True enough; it was an air pocket which extended in about fifty feet, and had no passageway beyond.
The knowledge that some marine animal inhabited the cave was now a constant topic, particularly with George, who was determined, sooner or later, to find out something more about it. With this end in view he made secret preparations, particularly in constructing a lamp which would not be liable to overturn or be put out by wind or in falling.
Thus far the only light available was obtained from candles made from the fat of the animals, and it was not the kind of illuminating material they had been used to. When people knew nothing better than tallow candles, that light was satisfactory, but when petroleum was once used tallow candles were entirely unsuitable and too primitive.
The statement by the Professor that the hole into which George fell, some months before, contained asphaltum, hinted at a possible source of petroleum, and through the persistent efforts of George, the Professor agreed to accompany him to the place to make an investigation.
The yaks were yoked, and a good luncheon put up, prepared for a day's jaunt, the trip being planned for the day of the week which had been set apart for exploration purposes. Within an hour the team was tethered at the spot where Harry and George put up the team when they started out on their former tour of investigation.
"Now, George, we shall have to depend on you to lead the way."
"When I left Harry we were on the little hill beyond that clump of bushes."
"We must have been much farther away," was Harry's opinion.
"Let us go over at any rate, and we can probably get our bearings from there."
The spot pointed out was just as much a mystery after reaching it as before. It was suggested that, as neither knew how to determine the direction of the "hole" from that point, time might be saved by each taking a different direction, with the understanding that if anything was discovered a shot should be fired as a signal.
After carefully noting the two large trees where the team was located, they separated, Harry going to the north, George to the northwest and the Professor directly west. The ridge on which they were ran north and south, and to the west was a decline. It was considerably south of the trail taken on their former trips, so it was really undiscovered territory.
The Professor passed down the long incline, carefully noting every set of bush, such as George declared he had passed through at the time he was deposited in the "hole." When the bottom of the ravine was reached he turned to the right, working his way diagonally up the hill.
George, on the other hand, made for some bush ahead of him, which looked familiar, but in this he was disappointed, and going to the left, considerably farther down the hill, was rewarded by the rediscovery of the "hole." Without waiting he fired a shot, and to his surprise found the Professor within a hundred feet.
"I have found it. See, that is the place I went through."
Harry was not far away, and he rushed up out of breath. The bushes were swept aside and George went in, followed by the Professor and Harry. He had not gone five feet when he stopped.
"This isn't the place. There is a big rock here; not a hole."
This was indeed the case.
George's countenance was a study. The Professor and Harry had a good laugh at the discomfiture of George.
"So you think you fell into a hole? It must have been a pretty solid hole." The rock was about ten feet across, and flat on top, and the bush grew all around it, thus entirely screening it from observation.
"Well, we must try again."
"I would like to know why vegetation accumulates around a stone, or around a hole, and gets so much larger than at other places?"
"It is accounted for by the little germs we talked about the other day. Did you ever notice the musty smell that comes up from an overturned stone?"
"Yes, and I have often wondered what it was."
"There is always more or less moisture under the stone, so that the germs are readily bred, and as they form carbonic and nitrogenous gases, which the plant must have, you can readily see why vegetation thrives around the stones."
"But where there is a hole it is drier, and the same thing occurs there?"
"That is a good observation. Two things are required to cultivate the germs, aside from the food. One is moisture and the other is heat. The earth is full of bacteria from which plants get their food; some places the bacteria go down only one or two feet; at other places, where it is warm, as in the tropics, they have been found five or six feet below the surface. When a hole is made, and the sun strikes it, the bottom of the hole gets warm, and thus facilitates the growth of the germs around the hole, so that the plants in the immediate vicinity get an extra supply of nitrogen."
"But where do they get the moisture?"
"That is another one of nature's great surprises, and shows how every contingency seems to be provided for. I suppose you have both cultivated corn—that is, have gone between the rows with a cultivator, and stirred up the earth. You did this, as you were told, to keep down the weeds. That was one reason, but it is not the principal one. A dry crust forms over the surface of the ground, owing to the heat of the sun. When the cultivator breaks up the crust the heat from the sun draws up the moisture from below, and you are therefore watering your corn, and what is more, you are breeding bacteria so as to supply food for the plants."
"After learning this I am glad we discovered the stone."
A more persistent search was now made, and George's "hole" was really found to exist. It was just as he described it. Everywhere along the hillside were rocks projecting out from the surface, but here was a depression, or hole, fully fifteen feet square, with rocky sides, the wall on the upper side of the hill being fully fifteen feet high, whereas the lower margin of the hole had a wall not over four feet high, so that it will be seen George had no difficulty in getting out after he had recovered from his fall.
The Professor was in the hole in an instant. The growth about the depression was so dense that it made the hole dark, but there was an unmistakable odor of asphaltum. Some of the overhanging branches were trimmed off, and every portion of the walls examined.
"What do you think made this? Was it washed out?"
"Some one dug this hole," was the Professor's response.
"What makes you think it was dug out?"
"There is plenty of evidence to show that. Look at the marks of tools on the walls all about you."
"Do you suppose it was made to get oil?"
"No; but to get metals."
"What kinds, do you think?"
"Gold or silver; most likely silver."
"Do you think we have silver here?"
"Unquestionably; we have some samples of it at the Cataract now."
"When did you get it?"
"At the time we found the lead ore. Silver is usually a partner of lead, and from my examination of the samples we have it is rich in silver. It is likely that the indications of lead and silver all along this ridge attracted the attention of a mining engineer, and this was a test hole in prospecting for the ore."
"But if this hole was dug out, as you say, where did they put the dirt and rock which came out of it?"
"Examine below and you will see."
Below the hole the side was rather steep, but when the surface of the hill was examined there was no longer any doubt of the human agency which made it.
It was with a certain sense of joy that the boys heard this news. The island had been explored by white people; it might again be visited by some wanderers on the sea. This was a comforting assurance. It had the effect of giving new courage, as no other event had, since they reached the rocky shore during that tempestuous night, nearly eight months before.
"Don't you think we can get kerosene here?" was George's inquiry.
"I do not think it is likely. What we see here is a mere trace of surface oozing, found in many places, and it generally indicates petroleum at some depth, but whether in sufficient quantities to pay cannot be determined without boring."
George's hope of a better light faded.
Under the direction of the Professor the balance of the day was spent in gathering samples of minerals, and George, in one of his searches, brought a sample of very peculiar greenish ore, interlaid with patches of brown substance. The Professor was much delighted with this.
"You have found a fine sample of zinc, and if you direct us to the place we must take a quantity of it. I have been specially looking out for samples of this."
The ore was readily found, and a sufficient amount uncovered to complete their load, and late that evening they reached home very tired, but happy.
"Let us do some preliminary work with the furnaces to-day," was the Professor's first observation. "The ore we found yesterday is too good a thing to lie idle. You will remember I told you some time ago that we want some of these metals to be working for us?"
"Just like the germs do?"
"Not just in that way, but nevertheless they must serve us."
"If people get to know so much and have the different things do all the work there will not be much left for us to do?"
"Do you think so?"
"If one thing after the other is discovered, and it is found that one or two elements can be made to do our work, the time may come when everybody will know so much that man will do nothing but——"
"But direct?"
"Yes."
"Isn't that something? Working with the hands or thinking are not the only things which man can do, in order to go forward and to advance."
"What I mean is this: We are told that idleness is wrong, and that people are happier when they are busy at some useful occupation."
"If that is a good definition of happiness, then we should make everything we use as crude and primitive as the people used to make them a thousand years ago. There would be no object in learning, because learning makes people discontented."
"I heard a story once about some wise man who offered his fortune to the man who could prove he was contented. The first applicant wanted the fortune, because he said he was contented. The wise man answered by saying, that if he was contented he would not want the fortune."
"Quite true; the contented man does not exist, because it is not human nature to be so. That is one of the qualities which distinguishes man from the rest of the animal creation."
"But is it true that the invention of labor-saving tools has caused a lot of misery to working people?"
"Do you know of any tools that are not labor-saving? The mason's trowel is a labor-saving tool, invented to prevent him from using his hands to put on the mortar; the bolo or the knife is just as much a labor-saving tool as the planing machine; the sickle saves labor and so does the reaper. The difficulty is that some people do not stop to think that the saving of labor applies just as forcibly to a simple tool as to a complicated one."
"What shall we try in our furnace to start with?"
"The ore you found yesterday. The first thing to do is to crush it up as fine as possible. When that is done we can put it in the round furnace."
"You mean in the firebrick furnace?"
"Yes; although we do not need such a high heat. Almost any furnace would do, as the roasting of the ore does not require a high heat."
"What is the best way to roast it?"
"It will be necessary to put it on one of the iron plates, and great care must be taken to keep it a uniform heat, but not too intense."
The process of roasting is a very particular one and requires quite a time to get the best results. When this was done the next step was to take the roasted ore, and mix it with half its weight of powdered coke. They had a good quantity of the coke on hand, which was also crushed.
"You remember, George, we had a crucible made with a hole at the bottom. Get that and also some fire clay dust, and moisten the dust so we can make a stiff mortar from it. We must make a tubular connection with the hole in the bottom of the crucible."
When this was done the crucible was put into the furnace, after it had been charged with the coke dust and crushed zinc ore.
"Why is it necessary first to crush the ore and roast it, and then afterwards put it in the crucible with the crushed coke?"
"Zinc is not found in a native state. This ore is in the form of an oxide, as it is called. In roasting, certain of the impurities are driven off in gases, and mixing it with charcoal or coke and then applying heat to the confined mass, causes the zinc to melt and finally go off into a gas, as we shall presently see."
After the heat had been applied for some time a white smoke began to appear at the mouth of the clay tube, and a little later a blue vapor appeared.
"Now bring that pan here, so we can catch it."
Soon the dripping commenced, and as it ran out and came into contact with the air, it turned into a solid, greyish color.
"This is what is called spelter, or the pig of zinc, and this is what is sold to refiners, who take out all the dross or impurities so it can be rolled or used for galvanizing iron, or for other purposes."
"I do not see how we can use this metal, now that we have it."
"You said the other night that you wished we had a better light."
"That was the reason I was so anxious to see whether we couldn't get some kerosene at the 'hole.'"
"As we didn't succeed in finding petroleum we shall have to depend on our zinc, I suppose."
"What, light out of zinc?"
"No; but by the zinc route."
That was another new development to the boys.
"Harry made a sage remark some months ago. It was to the effect that in order to start to make anything we had to make something that made something to make something with. In order to make electricity by means of a battery, we had to go through all this process of turning out the zinc, which we have just completed; then, if you have not forgotten it, we had quite a time in converting our copper ore into a copper which we could use. We were compelled to make charcoal, and then coke, with the aid of the charcoal; and now that we have coke, we must again grind it up and make a mortar, so we can form it into little plates or slabs. From the copper we got a liquid, which I asked you to save, and that is vitriol, or sulphate of copper. You see, all these things are necessary before we could possibly attempt to set up a primary battery, and start the first lighting plant."
Not an hour was lost at the Cataract home and factory. All took the keenest delight in forwarding any new enterprise and in looking out for new things to do which would contribute to their pleasure and comfort. The boys now learned what they had never dreamed of before; that life is a most complex problem; that to secure pleasures toil is necessary, and that the greatest happiness comes from knowing you have succeeded. Pursuit, not possession, is man's greatest joy. To the brute the reverse is true.
"Where is the Professor? I have been bitten by a cat."
"A cat, Harry? Where did you find the cat?"
"Across the river, where I was cutting the oak log."
The Professor was soon at hand. "What is this? A cat, you say?"
"It looked just like a big cat, about two feet long?"
"Did it have a pointed nose?"
"Then it must have been a Zibet, a specie not unlike the American civet. It is a cat, but not what is known as the 'wildcat,' and can be tamed."
"Do you think there is any danger from the bite?"
"Some animals have a species of rabies, like those possessed by mad dogs, and cats have been known to be infected. I do not think we need to have any fear from that source. The wound should, however, be cleansed."
As the boys grew more and more familiar with the island the greater was its store of abundance shown to them. Each journey to the interior brought some surprise in the way of fruit, flower or vegetable. Some were of species well known to them; others unknown, and most of such came to them under names of chemicals only.
"There is one plant, at any rate," said Harry, "that makes this seem like home, and that is the thistle."
"Yes, and it is the one common enemy of man in every part of the world. It is the most successful business plant, in this particular, that it is equipped to resist attacks from other plants and from animals as well."
"But donkeys and some cattle will eat them."
"For the reason that nature has given such animals the proper coating and linings of mouth and stomach that the thorns do not affect them. There is hardly a plant which is as nutritious as the thistle. In England, the thistle leaves, in early days, were used as salads."
Harry was an ardent admirer of flowers, and was constantly bringing in some specimen for examination. "Here is a very pretty flower which is differently colored from any that I have seen before. It looks like the wood sorrel."
"It is the sorrel, but if you should be in Ireland, the people there would call it the shamrock. St. Patrick taught the people that it typifies the trinity with its three leaves. The plant has some very peculiar qualities. It actually goes to sleep at night. It folds up its leaves. It is so sensitive to light that it has at least four different methods by which it can adjust itself with the greatest nicety to the amount of light which it receives."