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ITH the materials of his handicraft—with stones,
bricks, mortar, and plaster—a mason can build, at his
will, vault, bridge, wall, reservoir, shed,
coach-house, factory, cellar, terrace, hut, castle, or
palace; and each of these constructions, although of
like materials, will differ in form, purpose, and other
qualities. In similar manner, will the threescore
elements at her disposal, nature fashions all the
things that come from her hand, in the animal, the
vegetable, and the mineral kingdoms. An artisan of
sublime achievements, she demands but a few materials;
and not even all of these does she often use at once,
in order to obtain results of infinite variety.
Combined in countless ways, these elements or simple
substances form everything on and in the earth.
Nothing, absolutely nothing is known to us that, when
decomposed (if it be not simple to begin with), fails
to resolve itself into a certain number of metals or
metalloids or both."
"Then everything comes from these same simple
substances?" asked the children.
"Everything that is not already a simple substance.
Consider for a moment the element that
 you see most often under one or another of its various
disguises,—carbon. I have shown it to you as forming a
part of bread. You know, to, that wood contains it, as
can be seen from the charred fagots in the open fire.
Now, the carbon in bread and that in the trunks and
branches of trees are exactly the same, so that in the
ever-changing combinations of nature the carbon in the
loaf of bread might reappear in an oak fagot, and that
in the oak fagot might turn up again in the loaf of
"And so," observed Emile, more in jest than in earnest,
"when we eat a slice of bread and butter, we are eating
what might have made a knotty stump."
"Who knows, then, my little lad," his uncle took him
up, "how many knotty stumps you have eaten in your
lifetime? I hope soon to show you that your jesting
remark comes nearer the truth than you thought."
"Uncle Paul, I won't say anything more! Your simple
substances are too much for me."
"Too much for you? Not at all. But perhaps you feel
yourself, for the moment, a little dazzled by the
blinding light of a new truth, just as a strong ray of
sunshine dazzles the eyes. Let us continue, and
gradually everything will appear clear to you. The
carbon is an oak fagot—why should it not have gone to
the making of a pear, an apple, or a chestnut? Is
there not carbon in those?"
"Yes, there is," replied Jules. "When you leave
chestnuts on the coals too long they turn to charcoal,
and if you forget apples or pears put to bake
 in the oven you find them nothing but lumps of
"Again, this charred chestnut, apple, or pear is of the
same substance as that in firewood and in bread. Do
you now begin to glimpse the fact that it is possible
to eat what, by a change of destination, might have
become a stump or a stick for the fire?"
"I can more than glimpse it," Emile answered; "I see
"And you will soon see it clearer. If instead of using
olive-oil on our salad or for frying fish, we put it
into a lamp, it will burn and give light. Now let us
hold a piece of window-glass or a plate over the flame.
Instantly a coating of black dust collects on it."
"I know, that is lampblack. I make my glasses dark
with it when I want to look at the sun in an eclipse."
"And what is this lampblack?"
"It looks very much like charcoal-dust."
"It really is charcoal, or carbon. And where does this
carbon come from, if you please?"
"I don't see where it could come from, unless from the
oil burned in the lamp."
"It does come from the oil, that is plain; from the oil
decomposed by the heat of the flame. So there is
carbon in oil. Needless to add, this carbon differs
not at all from other carbon. It is found in grease,
in tallow, for candles and tapers give lampblack just
as does the oil-burning lamp. It is also in resin,
which burns with a thick black smoke; it is in—But I
should never get to the end if I tried to give
 a complete list. I will mention finally the
muttonchops you have seen so often on the dinner-table.
If the cook is not careful, what becomes of them on the
"Why, that's so!" Emile exclaimed. "I hadn't thought
of it. If you let them cook too long, the chops all
turn to charcoal."
"What, then, do we infer from that? asked Uncle Paul.
"We infer that there is carbon in meat. It must be
"Everywhere?" Oh, no! Far from it. But carbon occurs
very often. You will find it especially in all animal
and vegetable products. All these substances, when
decomposed by fire, leave carbon in their ashes. So
you can easily make out as long a list as you choose of
substances containing this element."
"Paper, white as it is, must have some, for it turns
black when you burn it. But, tell me, does paper come
"Yes, my child, it comes from vegetable matter, being
made out of old rags, and these old rags are the
remnants of fabrics woven of linen or cotton."
"Milk," asked Jules, "which is still whiter than
paper—does that too have carbon in it? I have seen
the foam turn black at the edge of the saucepan when
the fire was too hot."
"Yes, milk too contains carbon, I can assure you. But
let that do for the present. Further examples are not
needed to show you what varied uses carbon can serve at
the hands of Mother Nature. Now will
 Emile recite the fable he has been learning by heart
the last few days?"
"The one about the sculptor and the statue of Jupiter."
"Oh, yes, I know:
"A block of marble, fair to see,
Filled with delight a sculptor's soul.
He bought it. 'Now what shall it be,
A god, a table, or a bow?
" 'A god were best, an awful god,
With thunderbolt in lifted hand.
Mankind shall tremble at his nod,
His name be feared in every land.' "
Here Uncle Paul stopped the reciter: "That is enough,
my boy. You have a good memory. What does the good La
Fontaine tell us? He tells us that a sculptor,
viewing the superb block of marble he had just bought,
asked himself what he should do with his purchase. His
chisel could make of it at will a bath for sumptuous
palace, the bowl of a fountain for a princely garden,
or a modest slab, a commonplace bureau-top or
mantelpiece. He decided on a god. The block of marble
which could become a bowl in which to wash face and
hands, shall be Jove the Thunderer, before whom all
mankind falls prostate. Out of one and the same
material the chisel is to bring forth, not a trivial
piece of furniture, but a noble statue. In like manner
does Nature proceed, able as she is to make whatever
she chooses out of the chemicals at her disposal.
 A little carbon, let us say, is at hand. 'What shall
my art make of it?' she asks. 'Shall it be a flower,
turnip, flesh, or hair of an animal? It shall be a
flower; more than that, it shall by its coloring and
perfume be the queen of the flower garden.' And the
splendid rose comes forth from the carbon that might
have become sheep's tallow or part of a donkey's horny
"But there's something else in the rose besides this
carbon that makes so many things, isn't there?" asked
"Certainly; otherwise the carbon would remain carbon
and nothing more. It is combined with other simple
substances. The same must be said of it in all the
other things we have just named as containing carbon."
"Then," said Jules, summing up what his uncle told
them, "bread, milk, grease, oil, fruit, flowers, linen,
cotton, paper, and lots of other things, all contain
carbon and also various other elements that never
change their nature, whether they are in a flower or in
a lump of tallow, in a piece of paper or in a stick of
wood. They are always the same metals and the same
metalloids. And are our bodies too made of these
"As far as matter is concerned, man does not differ
from the rest of creation. His body has for its
constituents exactly the same metals and metalloids."
"What!" cried Emile, surprised at this human
chemistry. "Are there metals in us? Are our bodies
mines? I could believe it if we were all
 sword-swallowers like the jugglers we see at the fair;
but we haven't quite come to that yet."
"Agreed. Nevertheless, there is iron in us,—precisely
the same metal as is swallowed by the jugglers you
speak of. And iron is so indispensable t us that
without it we should find it impossible to live at all.
It is iron, let me add in this connection, that gives
to our blood its red color."
"I know that our blood is colored red somehow or other;
but, all the same, I know that nobody can eat metals,
not even the juggler who fools us with his cleverness.
Where does this coloring matter come from, then?"
"Like carbon, sulphur, and whatever other elements the
body needs, it comes from our food, which contains it,
a little here and a little there, without our knowing
it. And are you quite sure that we never take iron,
real iron without any disguise? At your age, when the
mere work of growing is something considerable, and
strength is none to great, the doctor often orders
iron, which is taken in the form of a very fine powder,
or is given to us to drink in water that has had old
iron in it for some time, and has thus become slightly
charged with the rust. That is not exactly the same as
swords, but it is eating iron nevertheless."
"I am ready now to believe we eat as many metals as you
please," Emile assented.
"Not so fast! Don't let us make the human body a mine,
as you called it just now. I am speaking only of iron,
to which might be added three or four
 other metals that, unfortunately, you know nothing
about as yet. There are metals familiar to us all,
such as lead, copper, zinc, gold, and silver, that have
no place in the human body or in animals or in plants.
Certain metals, indeed, if they were introduced into
the body, would endanger life, for they are poisons. I
keep iron, then, and will add that very little of it is
enough to give color and other peculiar properties to
the blood,—so little, in fact, that the body of an
animal the size of an ox would furnish hardly enough
iron to make a nail. I will add that this nail would
cost a fabulous sum, so much labor and pains would have
to be expended in the mining of this animal ore. If
necessary, the thing could be done, which is all I wish
to make you understand.
"We have now reached the point where you ought to begin
to perceive that simple substances, by combining in
many ways, produce a vast variety of other substances
endowed with widely varying properties. These
substances are called compound because they are each
composed of a number of elements. Water is a compound
substance; so are flour, wood, and paper, oil and
grease, pine resin, animal flesh and horn, the essence
of the rose, and, in short, such a multitude of things
that the list would never come to an end. Water is
composed of oxygen and hydrogen, two metalloids that we
shall take an early opportunity to become acquainted
with. The other things I have just named contain
carbon among their elements."
"So vast is the number of compound substances
 that we might almost call it infinite. At any rate,
no limit is known. And yet all these compounds come
from the mixing together of two or more of those simple
substances that do not number so very many, some
threescore in all. Furthermore, many of these simple
substances play so unimportant a part that their entire
omission would make no appreciable difference in the
grand total of the world's material riches. Among
these minor elements I will mention gold. Confining
ourselves to the fundamentals, we can see that, at
most, only about a dozen simple substances contribute
to form the immense majority of the products of
"But there's one difficulty, it seems to me," objected
Jules; "and it strikes me all the more after what you
have just said. I was wondering how such a lot of
different things—so many that perhaps they couldn't be
counted—can all come from sixty elements. And now I
wonder still more how the great majority of these
countless things can come from only a dozen elements."
"I was expecting this objection to be raised, and was
about to answer it in advance when you got ahead of me;
for which, in truth, I am very glad, as thus I receive
a fresh proof of the reflective quality of your mind.
I have proposed a puzzle to you, and now I will use an
illustration that will help you to solve it. Our
alphabet has twenty-six letters. How many words can be
formed with these characters?"
"Why—I—I don't know what to say. I have never counted
them, for a dictionary, even a small
 one, has lots and lots of words. Let us say ten
"We will let it go at that—ten thousand, in round
numbers. It is not necessary to be very exact in this
matter. You will notice that we are speaking only of
our own language; but the same characters could be
used for writing all the languages of the world that
have been spoken in the past, that are spoken to-day,
or that may be spoken in the future. I omit certain
instances of peculiar pronunciation, which are
negligible in this connection. With our twenty-six
letters, then, Latin, French, English, Italian,
Spanish, German, Danish, Swedish, and many other
languages are written. The same letters, too, could be
used for Greek, Chinese, Hindustani, Arabic, and all
other tongues with written characters differing from
ours only in form. There is no language, even to the
lowest Negro dialect, that could not be represented in
some sort by our alphabet. In this grand total of
languages and dialects what multitudes of words there
"We should have to count them," said Jules, "not by
tens of thousands, but by millions and millions."
"Now, imagine of the moment, my boy, that these letters
represent our simple substances, while words represent
the compound substances. The comparison is not so very
far-fetched, for just as words having each its own
value, its peculiar meaning, are formed by combining
letters in groups of two, three, four, or more, and in
such and such an order, so compound substances are made
by combining certain element which, according to their
 number, and the manner of their grouping, determine the
nature of the compound."
"Simple substances, then," put in Jules, "are the
elements of material things just as letters are the
elements of words."
"Yes, my boy."
"Then the number of compound substances must be as
immense as the number of words in all the languages of
the world. Still, I should say they alphabet would
give the greater variety. It has twenty-six letters,
and you have just told us that most compound substances
are made from a dozen elements at most. Twenty-six
ought to give more combinations than twelve."
"I will ask you to note that the number of letters
might be considerably reduced and still the alphabet
would represent all the various vocal sounds. What
difference is there, I ask you, in the pronunciation
of k, q and hard c? None. One of these
characters is necessary, the others are superfluous.
In like manner soft c is the same as the hissing
s, and x is simply ks, nor does
y as a
vowel differ from i. Rid of its duplicating
characters, the alphabet could, as you see, be reduced
a good deal and still be rich enough to furnish the
elements of innumerable words. But I admit that even
so there remain more letters that there are simple
substances forming the great majority of compounds. In
their modes of grouping, however, the elements enjoy a
great advantage over the letters of the alphabet.
"To make a word, we usually group two, three, four,
often five or six, and even more letters. Take
 for example, that long and cumbrous word,
intercommunicability. One must draw a good breath
in order to pronounce it all. There are twenty letters
in the word, or almost as many as there are in the
whole alphabet, though it is true that some of these
letters are repeated which reduces the number of
separate characters to thirteen. Chemical combination
scorns such cumbrous piling up of elements, and imposes
upon itself a rigid rule never to resort to it, holding
that complicated mixtures are none of its business. To
form compound substances it groups only simple ones, or
sometimes three, very rarely four. Imagine a language
with words of only two, three, or at most four letters,
and you will get a notion of the compound substances
resulting from the union of chemical elements. Sulphid
of iron is a compound of two elements,—a word of two
letters, if you choose, continuing our comparison.
Water is another. Oil has three, and animal flesh
four. Compounds of two elements are called 'binary
compounds'; those of three, 'ternary,' and those of
four 'quaternary.' These terms come from the Latin
words meaning respectively two, three, and four.
"Now, if four elements at the most, and commonly only
two or three, are united in combination, how is that
there can be an almost infinite variety of compounds?
To aid us in explaining this, take the word rain,
for example. For the initial letter r substitute
another, and then another, and so on, and we have the
common words, gain, lain, wain, pain, and
others, all belonging to our language. In the
 same way pin becomes tin and din and
By a simple change of one letter, the rest of the word
of a wholly different meaning. So it is with chemical
compounds: let one element be replaced by another, the
rest remaining unchanged, and behold, at once we have
new properties, a substance very different from the
"But, further than this, there is still another change
that gives an even greater variety of compounds. Just
as in a single word the same letter may be repeated
several times (note the letter i occurring four
times in the long word just cited as an example), so
the same element is, in many substances, repeated in
chemical combination. It is taken two, three, four,
five, and even more times, producing each time a
compound having its own peculiar properties. We should
hunt in vain in the dictionary for words suitable as
illustrations of this principle, for our language
refuses to repeat the same letter over and over again
in one short word. But let us imagine a series of
words such as ba, bba, bbba,
bbbba, and so
on, and let us suppose that each of these, although
containing only the letters b and a,
one of which
is repeated, has a meaning entirely different from that
of any of the others. We can thus gain a fairly good
idea of what takes place in compound substances."
"If that's the way of it," said Jules. "I can see well
enough tht the number of compounds must be very
great,—that it must be enormous, even with only the
dozen simple substances that play the chief
 part. One element changed and another repeated must
produce an almost endless variety of different groups."
"And what does Emile think about it?" asked his uncle.
"I rather agree with Jules: there's much more variety
than I thought. But I should see it better if I could
understand how bba is really different
"You would like to have an example of a compound
substance whose nature changes completely when one of
its elements is doubled?"
"Oh, Uncle, that's just what I should like to see; and
Jules would too, I'm sure."
"I can easily gratify you, my little lads."
And so saying Uncle Paul took from one of his drawers
something that he showed to his listeners. It was a
rather heavy object, of a beautiful shiny yellow, and
when exposed to the sun it gave out flashes of light.
From its brilliance it might have passed for metal.
"But that is gold!" cried Emile in astonishment at
sight of the splendid stone; "a lump of gold as big as
your two fists!"
"It is asses' gold, my boy," replied his uncle, "named
thus by miners because it deceives the ignorant, and
they take it for something precious, whereas it is
really of small value. You can find as many of these
stones as you please among the rocks in mountains; but
it wouldn't profit you a penny to pick them up. This
substance is also called, in more learned language,
iron pyrites, the
 last part of the term being taken from the Greek word
for fire; for the stone will, in fact, emit sparks when
struck with a piece of steel,—as, for example, with the
back of a knife, —and these sparks are brighter than
those obtained with flint and steel."
Here, by way of illustration, Uncle Paul made the stone
that looked like gold give out brilliant sparks by
striking it with a knife. Then he continued his talk:
"Iron pyrites or asses' gold has nothing about it of
real gold but its luster and its yellow color. It is
not a simple substance, but a compound of two elements
that are familiar to you, though you wouldn't imagine
them to be here, disguised as they are by the act of
combination. One is iron, the other sulphur."
"That shiny yellow stuff that you would take for gold
is made of iron and sulphur, like the ugly black powder
in the artificial volcano?" was Emile's incredulous
"It is made of iron and sulphur, and nothing else."
"But how different it is from either of them!"
"This difference comes from the sulphur's being
repeated in asses' gold."
"The word, instead of making ba, makes bba?"
"Exactly. To indicate this repetition of the sulphur,
they say in chemistry that iron pyrites is the
bisulphid of iron, and you know that they first
syllable of that term means twice."
"Then it's the same as if they said 'twice sulphur and
once iron.' The black powder in the artificial
 volcano is sulphid of iron, and this asses' gold is
bisulphid of iron."
"Precisely. It couldn't have been put better."
"I thank you, Uncle Paul, for showing us this splendid
stone. It will make me remember that in chemistry
ba and bba are not at all the same thing."