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The Wonder Book of Chemistry by  Jean Henri Fabre


 

 

THE SLICE OF TOAST

[26]

T
HE boys had made their little artificial volcano, and it had proved to be a success, the mole-hill of moist earth becoming much heated, cracking open, and giving vent to spurts of steam accompanied by sharp hissings. All had turned out to the complete satisfaction of the young experimenters, and the resulting sulphid of iron, on being examined at leisure and subjected to every test their imagination could suggest, was declared to be the same substance as that produced by their uncle. At this point he joined them.

"In the black powder now remaining at the heart of your artificial volcano," said he, "there is iron and there is sulphur. No possible doubt as to that can lurk in your minds after you have seen this substance prepared and, what is more, have prepared it yourselves with your own hands. Nevertheless, there is no sign of either any iron or any sulphur in this black powder, so utterly different is it in color and general appearance from both those substances. Had I begun by showing you this powder already made, without telling you of what it was composed, you would most certainly never have suspected it to contain any sulphur or any [27] iron; and had I told you its ingredients without letting you witness the combining process, you would, I am sure, have taken your uncle's word for it, but at the same time you would have been no little astonished. 'What,' you would have exclaimed, 'sulphur in that stuff, there, which is not in the least yellow and will not burn? And iron, too, where there isn't the faintest shine of iron and nothing sticks to the magnet?' In short, you would have believed me because of your trust in my word, but you would not have had the certainty that comes from seeing the thing done.

"This certainly I have given you by means of the experiment performed before you very eyes, and you have further strengthened that certainty by performing the experiment yourself. We are, then all three of us, firmly convinced that in this black substance before us there are both sulphur and iron. And now another question arises: Is it possible to make the iron and the sulphur here combined resume each its original form? Can the combination be undone and the two ingredients recovered as they were in the beginning? Yes, my young friends, the thing is possible, but no simple process of sorting will suffice to disunite the two substances. You remember how all your attempts to accomplish this were so much wasted effort. What combination has joined together, no sorting can put asunder. To effect the separation, it is necessary to resort to scientific methods belonging to the domain of chemistry; and as your acquirements in that domain are still of the slightest, I [28] will not invoke the aid of those methods. Besides, for our present purposes the actual separation of the sulphur and the iron is of very little importance. Inasmuch as the black powder does really contain them, it is incontestable that they can, by the requisite means, be obtained from that powder; and that is all I wish to impress upon you at present."

"There can't be any doubt," Jules assented, "that a substance made of iron and sulphur must furnish iron and sulphur when properly treated. No one could dispute that. All the same, I should like to see the iron filings come back as iron and the flowers of sulphur come back as sulphur."

"I repeat, my dear child, that the operation would not be difficult, but it would call for drugs quite unknown to you and would be a mysterious and perplexing performance in your eyes. Let us see but little at a time and see that little plainly; that is the way to acquire substantial and lasting knowledge.

"But, now that we are on the subject, I will say to you that what is done by combination is not always the easiest thing in the world to be undone. These chemical marriages, signalized by manifestations of heat and light, unite substances in bonds so close that to sever them it is necessary to employ methods known only to advanced science. However easy the act of union, the disunion is difficult. Combination takes place of itself; separation is a more arduous undertaking. We have lately seen the iron and the sulphur combine in a short time with no aid [29] from us; but if now we should try to separate them, we should meet with enormous resistance, which only the most skilful methods could overcome.

"There are instances, however, in which quite the opposite is to be noted, combination being so difficult and delicate a process as to defy our utmost endeavors, but separation offering so little of resistance that a mere nothing , almost, will accomplish it. There are substances that dissolve their partnership with peculiar ease: a shock, a jar, a breath, an imperceptible trifle, will suffice to effect the severance. You touch them, you merely move them a little, and piff!  there is an explosion before you can snatch your hand away, with a flying of particles in this direction and that as if no such thing as union had ever existed. There are chemical marriages between incompatible natures that sigh only for divorce."

"And are there really," asked Emile, "substances that fly apart, that go piff!  just from being touched?"

"Yes, my child, there certainly are. You yourself are familiar with some of them. Those New Year's bonbons done up in particolored paper and known to you as snappers—don't they recall anything to your mind?"

"Why, yes; each bonbon has a rebus to be guessed, and then there's a little strip of parchment that gives a pop when you pull it by both ends at once. What is it that makes the little explosion?"

"It is a substance made by combining different [30] ingredients which fly asunder as soon as they are disturbed by the parting of the two pieces of parchment forming the strip. You see how easy the act of separation is in this case: just disturb the slumbers of the explosive material by pulling at the two ends of the strip, and that is enough to cause a disruption accompanied by a sharp report. In like manner a house of cards collapses at a mere touch.

"A similar substance causes the explosion of the toy torpedoes that give a pop when you throw them on the ground, and to this substance is due also the explosive quality in the percussion-caps of guns, the cap being ignited by the fall of the hammer when the trigger is pulled. A quick spurt of flame is produced, and this penetrates the touch-hole and discharges the powder in the gun-barrel. Consider for a moment the construction of these percussion-caps. At the bottom of the little cup-shaped bit of copper forming the cap you can see a white substance deposited in a thin coating on the metal. It is the fulminating-powder, made of several ingredients carefully combined in accordance with chemical science and ready to fly apart with violence at the mere shock imparted by the hammer. But this is enough about these touchy and noisily dangerous substances, so prone to separate into their elements with a loud report as soon as we have joined those elements together. Let us proceed to something harmless. What should you say there is in a slice of bread?"

"I should say—I should say," Emile hastened to [31] answer, "that there is flour." And with that he thought he had said the last word on the subject.

"True," assented his uncle, "but what is there in flour?"

"In flour? What can there be in it except flour?"

"But what if I told you there was carbon, or what amounts to the same thing, charcoal, in flour?"

"What, charcoal in flour?"

"Yes, my boy, charcoal,—a lot of it."

"Oh, Uncle, you are only in fun! We don't eat charcoal."

"Ah, my young sir, you don't believe it? But didn't I tell you that chemical combination can turn black to white, sour to sweet, the uneatable to nourishing food? Furthermore, I will show you some of this charcoal that is found in bread; or, rather, I don't need to do that, as you have seen it hundreds of times and it will be enough now to jog your memory. Tell me: don't you often toast your bread a little over the fire before crumbling it into milk for your breakfast?"

"Why, yes, I let it get crisp and brown. It's ever so much better that way; it goes better with milk when it is toasted just enough to make a crunching sound when you break it. In the winter, when the stove is hot, you can do it just right."

"But what if you forget your slice of bread on the stove? What if you let it toast too long? What happens to it then? Come, now, tell me, from your own remembrance of the thing, for I wouldn't on any account influence your opinion in this serious [32] matter. What would happen if your bread stayed on the stove a whole hour?"

"That's easy enough to answer: it would all turn to charcoal. I've seen it happen lots of times."

"Well, then, tell me, where did the charcoal come from?—out of the stove?"

"Oh, no, not at all!"

"Then from the bread itself?"

"Yes, it must have come from the bread."

"But from no substance can there come anything that was not there before; nothing can furnish what it does not already have. Consequently, bread, which yields charcoal after being exposed some time to the action of fire, must itself contain charcoal, or carbon if we choose to use that word."

"Why, that's so! I hadn't thought of it before."

"There are many other things, my little lad, that you have seen again and again without grasping their significance, because no one has set you on the right road. I shall often turn these common occurrences to account by showing you to what important truths they open the way when you reflect on them a little. Reflection now makes you aware that bread contains quantities of carbon."

"I admit that bread contains carbon," assented Jules. "The proof is there before your eyes, plain enough. But, as Emile says, we don't eat charcoal, and we do eat bread; charcoal is black, and bread is white."

"If the charcoal, or the carbon, were alone," re- [33] plied his uncle, "it would be black and uneatable, as you have described it, and it would remain so indefinitely. But it is not alone and by itself in bread; it is associated or combined with other things, and the combination has none of the qualities you have named as belonging to charcoal, just as sulphid of iron has none of the qualities belonging to sulphur and iron. These other qualities found in bread are driven out by excessive heat, and the charcoal remains, with all the characteristics peculiar to it,—blackness, hardness, brittleness, unpalatability,—in short, unmistakable charcoaliness. The heat of the stove undoes the work of combination, sundering what was joined together in the bread. That is the whole secret of the transformation of a slice of bread into a slice of charcoal when the toasting process has gone too far. Now let us inquire into the other things that accompany the carbon in white bread. They are known to you; you have seen them, and you have smelt their disagreeable odor when heat drives them out."

"I don't quite understand you," said Jules, "unless you mean that bad-smelling smoke that comes from bread when it is turning to charcoal."

"Exactly; you have my meaning. That smoke was part of the bread it came from. The charcoal and the offensive fumes you know so well would, if recombined as they were at first, constitute precisely the slice of bread as it was before being subjected to the action of heat. Heat wrought the separation, dissipating some of the constituent [34] elements in the air and leaving behind, stripped of its previous disguise, the black and uneatable substance so well known to you as charcoal."

"Then those bad-smelling fumes and the charcoal, with nothing else, make bread, and two things that couldn't be eaten separately form by their union our chief food?"

"You have put it quite correctly: substances that by themselves, far from yielding nourishment, would be positively harmful if eaten, become by combination transformed into excellent food."

"I must believe you, Uncle Paul, because you say it is so; but—but—"

"I understand, my young friend, your hesitation and your 'buts'. On first hearing these things one can hardly believe them, so at variance are they with accepted notions. Therefore I do not ask you to take my bare word; you must be convinced by something other than my authority. Did I not at the very beginning prepare the way for these startling developments by means of a perfectly conclusive experiment? Recall the black substance that we obtained in the medicine-bottle. Recall that sulphur now no longer sulphur and that iron now no longer iron. Why should there be anything more surprising in the fact that charcoal and some bad-smelling fumes can cease to be what they now are, and can become bread?"

"You are right, Uncle, and the best thing to do is to take your word for it."

"To take my word for it sometimes may be necessary, as when the proof of an assertion would entail [35] explanations too difficult for you to follow; but as far as possible I shall impose nothing on you as an article of faith, choosing rather to let you see, touch, and conclude for yourselves. I wish you to see the light and to witness the evidence, not to retain a mere mass of truths accepted on the authority of my word. In bread decomposed by heat I show you charcoal and call your attention to certain peculiar odors or fumes. What, now, is the natural inference?"

"That bread consists of that charcoal and those fumes united. It is too plain to be doubted."

"Yes, when facts speak we must accept what they say without heeding the counter-suggestions of long habit. These facts tell us that bread may be resolved by the action of heat into charcoal and certain vapors. Let us grasp that truth and acknowledge ourselves convinced.

"One other thing puzzles me," said Jules, "and it is the hardest puzzle yet. You say that the charcoal and the vapors separated by heat would, if recombined, make the bread again as it was before. Then, doesn't fire destroy any of the bread?"

"The word 'destroy' has more than one meaning, my boy. If in using it you mean that a slice of bread, after being subjected to intense heat, no longer exists as bread, you are quite right: the resultant charcoal and vapors are in no sense bread, but merely the substances of which bread is formed. If, on the other hand, you mean that the bread is reduced to nothing, you are greatly mistaken, for there is not a particle of matter in existence that [36] can by any force or device at our command be put out of existence."

"But that was just what I meant,—reduced to nothing, put out of existence. We speak of fire as destroying or annihilating everything."

"Then, in the literal sense of those words, we talk foolishly, for again I assure you that nothing in the whole universe, not even the tiniest grain of sand, is ever annihilated. Neither fire nor any other agency can annihilate even the finest thread of a spider's web."

"Listen, now, with close attention, for the subject is worth it. We will suppose a fine house is built, with spacious halls, splendid apartments, chambers, kitchen, vestibule, piazza, doors, windows,—in short, everything belonging to a comfortable and attractive abode. In building it the workmen had to place in their proper positions countless materials, such as cut stone, brick, rubble-stone, mortar, tiles, beams, boards, laths, plaster, metal fixtures, and so on. The house stands there, stanch [should be staunch] and proud and suited to the requirements of the most exacting. Can it be destroyed? All to easily. Call back the masons with their picks and crowbars and hammers, and if necessary they will tear down the building much more quickly than they put it up. The fine mansion will soon be nothing but a shapeless pile of ruins, or rubbish; it will be destroyed as a house.

"But will it be annihilated, reduced to nothing? Evidently not. Does there not remain an enormous heap of materials,— of stone, brick, wood, iron,— [37] of everything, in fact, that went to the building of the house? The house, then, is not annihilated, and what is more, not a particle that entered into its construction has been reduced to nothing. Even the last grain of sand used in mixing the mortar is sure to be in existence somewhere. The wind may have blown away some of the plaster-dust as the house was being torn down; but that dust, of a fineness hardly visible, is nevertheless undestroyed, however widely dispersed by the wind; and if it cannot now be gathered up, we can at least see it in our mind's eye, scattered in this direction and that. Of the entire building, therefore, that has been demolished not a particle of dust has been annihilated.

"Well, now, fire in its turn is a demolisher, but nothing more. It demolishes buildings made of many materials combined, but it never reduces to nothing the smallest particle, the minutest grain of dust, in those materials. We subject to its destructive power a mouthful of bread, and destruction follows, but never anything like annihilation; for what is left, after the fire has played its part, is just as truly matter as was the bread itself. That residue is in the form of charcoal and certain fumes or vapors, the charcoal remaining in a little mass by itself, the vapors being dissipated and no longer traceable, even as the plaster-dust was lost to view. Rid yourselves, then, forever, of the foolish notion of annihilation."

"But—"

"There goes Jules again with another of his [38] 'buts'! What is your difficulty this time, my lad?"

"When you burn a stick of wood in the fireplace, isn't it reduced to nothing, or almost nothing? There's only a pinch of ashes left at the end. I see how the ashes come from what was once wood, but they amount to so little they can't represent all that has been demolished by the fire. The greater part of the wood, then, must have been reduced to nothing."

"Your observation shows a thoughtful mind, and is of the kind I like. Accordingly, I hasten to answer you. I just spoke of the plaster-dust blown away by the wind in the demolition of our supposed house. Is it not plain that, the walls being built largely of powdery materials capable of being caught up by a passing breeze, a considerable part would be thus borne away in various directions, leaving behind a proportionately diminished heap of refuse?"

"Certainly; I admit that."

"If, now, it were possible in a work of masonry for the whole structure to be swept away as impalpaple dust, what would remain?"

"Nothing, of course."

"But would the building on that account have been reduced to nothing?"

"Why, no; it would have been turned into fine dust scattered all about."

"Just so with your stick of wood, my little friend: fire resolves it into its constituent elements, some of which are far more impalpable that the finest dust. These are lost to view, being dissipated here and [39] there in the boundless atmosphere, and as we find nothing left but a handful of ashes we are prone to believe the rest has been annihilated, whereas it still exists, indestructible, floating in the atmosphere and having a limpidity, a colorlessness, as complete as that of the air itself."

"Then a stick of wood that has just been burnt up in the fireplace is mostly scattered in the air in a sort of fine dust that we can't see?"

"Yes, my boy; and the same is to be said of all fuel that we burn to obtain either heat or light."

"Now I see why wood, when it is burned, seems to be reduced to nothing. What was the wood has, as you say, been mostly carried away without our seeing it, somewhat as the plaster-dust of a house that is being torn down is blown away by the wind."

"Note also, my boys, that out of the materials left when a house is torn down, another house can be built, different in form and on another site if desired. The heap of ruins will thus become once more a finished structure. But, further, there is no reason why these same materials could not be used for making other things, the stones for one purpose, the bricks for another, the wood for still another, so that the ruins of our demolished house would enter into various constructions having each its own form and purpose and character.

"Somewhat thus is it with matter in general. Let us suppose two, three, or four substances, each of a different nature from the others, to enter into combination. They function all together in a certain manner; they dispose themselves so as to form what [40] I will call a kind of building; and by thus associating they produce a substance quite different from any of the constituent substances, just as our finished house is neither sand nor lime, nor plaster, nor brick, nor, in fine, any of the materials used by the builders.

"After a while, for some reason or other, these combined substances separate, and the chemical structure is demolished. The ruins are left; there has been no loss of matter. What will nature do with these ruins? Perhaps any one of a thousand things; perhaps use a little of this ingredient for one purpose, a little of that for another, and so on until the result is a great variety of productions, all very different from the original substance. What went to make something black, will, it may be, now enter into the formation of a white substance; what was a part of something sour, may contribute to the making of something sweet; and what helped to constitute a poison, is likely enough to be found again in an article of food, just as the bricks of a former conduit may by a totally different application serve in the construction of a chimney and thus make a passage for smoke and flames instead of for water.

"Thus it is that nothing is ever annihilated, despite all appearances to the contrary, appearances that so often deceive us because we do not observe accurately. Let us pay closer attention, and we shall perceive that all matter persists, indestructible. It enters into an infinite variety of combinations, forever uniting and separating and uniting [41] again, some of its manifold forms being every moment destroyed and every moment renewed, in an endless series of transformations, without the loss or gain of a single particle in the whole universe."


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