|The Wonder Book of Chemistry|
|by Jean Henri Fabre|
|Starting with a mixture of iron filings and sulphur, Uncle Paul awakens in his young nephews an eagerness to learn more about the properties of the elements. Through a series of carefully-devised experiments and conversations about the experiments, he leads the boys to an understanding of some of the basic principles of chemistry. Excellent as a follow-on to 'The Story Book of Science' and 'The Secret of Everyday Things' by the same author. Ages 11-15 |
THE SLICE OF TOAST
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
 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
 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
 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
"And are there really," asked Emile, "substances that
fly apart, that go piff! just from being
"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
"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
 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
"I should say—I should say," Emile hastened to
 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
"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
"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
 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-  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
 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
"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
"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
 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
 can by any force or device at our command be put out of
"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,—  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
"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."
"There goes Jules again with another of his
 '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
 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
"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
 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
 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."
Hundreds of additional titles available for
online reading when you join Gateway to the Classics