ET us return now to the black powder, the sulphid of iron,
that served as our starting point in this discussion.
By a process far less simple than ordinary sorting, a
process known to chemical science, this substance can
be decomposed and the sulphur and iron separated.
Subjected to the easy decomposition wrought by fire,
bread furnishes, as its most notable constituent,
carbon. Now of what, in their turn, are carbon and
sulphur and iron each composed? Let me give you the
answer made to this question by scientific
investigation as conducted ever since these substances
became the objects of man's interest and study. No
matter with what thoroughness, with what elaborate and
painstaking experiments, they are examined, no matter
how powerful the forces brought to bear on them, carbon
and sulphur and iron never give us anything but carbon
and sulphur and iron."
"But it seems to me," objected Jules, "that sulphur
does give something that isn't sulphur. When you set
fire to a little of it, there is a blue flame and some
sort of vapor that makes you cough. That vapor must
come from the sulphur, but it is
 something very different from sulphur, for it makes us
cough worse than if we had the whooping-cough, and
sulphur doesn't do that even if you hold it right under
"Let us understand each other, my boy. When I say that
sulphur never gives us anything but sulphur, I mean
that it cannot be decomposed into other substances; but
I do not by any means assert that it cannot by
combination with other substances produce not only the
vapor that makes us cough, but also many other things,
notably the black powder you now know so well, the
sulphid of iron. I told you that every substance, in
burning, combines with another which we cannot see, and
which is contained in the atmosphere about us. If
sulphur becomes enveloped in blue flames, it is a sign
that it is combining with that atmospheric substance.
The result of this combination is the vapor that makes
"Then that vapor is more complicated than sulphur?"
"It must be made of two things, sulphur and that stuff
in the air you told us about, while sulphur is made of
only one thing, sulphur itself."
"Quite right. I repeat, then, that sulphur, even when
put to every sort of test, has never been decomposed,
never been divided into different substances, as, for
example, the black powder in our medicine-bottle could
be divided into iron and sulphur, and as bread could be
resolved into several ingredients, carbon among them.
Sulphur goes to
 the making of a great many things more complicated than
itself, but can never yield anything simpler. When we
come to sulphur, decomposition stops; by no means at
our command have we yet succeeded in dividing sulphur
into two or more other substances. Hence we call
sulphur a simple substance, meaning that its further
simplification is impossible. Water, air, a pebble, a
piece of wood, a plant, an ainmal—all these may
be regarded as substances, but they are not simple
substances. Bear that in mind.
"Carbon and iron are also simple substances, for the
same reason that sulphur is a simple substance: they
cannot be made to yield anything except carbon and iron
unless they are combined with other things; but this
would not be a simplifying, it would be a complicating
process. Chemists have carefully examined all
substances to be found in nature, whether on the
earth's surface or beneath, whether in the depths of
the sea or in the air about and above us, and whether
belonging to the animal or the mineral kingdom; they
have examined all, studied all, analyzed all, and the
fruit of this immense task, prosecuted with all
possible learning and patience, is the conclusion that
the number of undecomposable or simple substances
amounts to sixty
or thereabout, including iron,
sulphur, and carbon, which we have just been
"And will you tell us about all these simple
substances?" asked Emile.
"Not all; far from it, for the greater part would not
interest us; but you shall hear about some of the more
important ones. Moreover, you already know a number of
simple substances besides the three—iron,
sulphur, and carbon—which we have just examined."
"I know other simple substances?" the boy exclaimed in
surprise. "I did not know I was so wise!"
"You knew carbon without suspecting it of obstinately
resisting all attempts to decompose it. There are more
things in your good little head than you are aware of;
my part is to put some sort of order into your jumbled
ideas. But I shall refrain as far as possible from
teaching you outright, preferring you to recall what
you already know. I will tell you at this point,
however, that all metals are simple substances."
"I see. Then copper, lead, tin, silver, gold, and
others that I forget, are simple substances, just the
same as iron."
"An expert chemist could not have put it better. They
are so many substances on which
decomposition has no hold; they are simple substances.
But there is one metal in common use that Emile has
omitted. Think! It begins with a z."
"With z? Wait—it is zinc, the same as our
watering-cans are made of."
"Right. These are not nearly all the metals, though;
there are many others, and among them some extremely
curious ones, but they are not in general use. I will
acquaint you with them as fast as we
 have occasion to handle them. One, however, might be
mentioned here. This metal runs like melted tin, but at
the same time it is cold. It has the color of silver,
and it goes up and down in a thread-like column in the
thermometer to show us the temperature of the
"Oh, that is mercury, or quicksilver!"
"Exactly. Its common name of quicksilver might deceive
you. It has the shiny appearance of silver, but none of
that metal's other qualities. It is a distinct metal,
as different from silver as are lead and copper. The
term 'quick' indicates that it runs all about, flowing
in little globules and always eluding the fingers that
try to grasp it."
"Then quicksilver is a metal, the same as iron, copper,
lead, or gold?"
"It is a metal, no more and no less, but different from
others in that the mere warmth of our climate, even in
winter, is sufficient to keep it in a molten state,
whereas to melt lead the heat of burning coal is
necessary, and for copper and especially iron it takes
the hottest kind of furnace. But were it cooled
sufficiently, it would become hard and not unlike a
piece of silver in appearance."
"Money could be made of it, then?"
"There would be nothing to prevent; but it would be a
strange kind of money, for a few minutes after putting
it in your pocket you would find it melted and running
"The color of metals does not vary much: silver and
mercury are white, tin a little less so, and lead still
less, while gold is yellow, copper red, and the
 others, notably iron and zinc, grayish white. All shine
brightly, at least when recently cleaned; or, in other
words, they all have a metallic luster. But you know
the proverb, 'All that glisters is
not gold.' In the same way, all that shines is not
metal. You would not have to hunt long in the garden to
find some insect—some beetle, for
instance—whose rich wing-sheaths have the luster
of polished metal, though in reality they are nothing
but scales of horn. Certain stones, judged by their
deceptive luster, might be mistaken, some for gold,
others for silver; and yet they contain not the
slightest particle of these two metals. The glittering
mixed with the blue sand used for
drying ink after writing have nothing in common with
gold except the glitter, and are not even made of
metal. So it is that all metals, without exception,
have the peculiar luster called metallic: but this
luster may be found, just as bright, in a great many
other things that are not metals.
"The other simple substances, sulphur and carbon among
them, are without metallic luster; some there are, too,
and very important ones, that are colorless, invisible,
of the same subtle quality as air. These non-metallic
simple substances are called by the general name of
metalloids. Carbon is a metalloid, sulphur is another.
The number of metalloids is not great, about a dozen
perhaps, but the part they play is highly important.
One might say of them what is, alas, only too true of
 beings: those that make the greatest noise are not the
ones that are the most useful. Indeed, though the
metalloids are of primary importance in the
construction of the things about us, being no less
necessary in the countless works of nature than stone
and bricks and mortar in our buildings, there are some
that many of us do not even know by name. One must at
least have read some book on chemistry to be aware of
their existence. If we were not told of them by those
more learned than ourselves, we should remain ignorant
of them to the end of our days. One of these important
substances —and it is one without which we should
speedily die—has a name that is probably
unfamiliar to your young ears; you may, in fact, never
have heard it mentioned. It is oxygen."
"Oh, what a funny name!" cried Emile. "I've never heard
"And these: hydrogen, nitrogen—do you know them?"
"No more than the other."
"I suspected as much. They are the names of two good
and useful metalloids that quietly perform their
appointed tasks without soliciting public notice, just
as a generous giver is willing to remain unknown,
provided only his gift reaches its destination. All
three—oxygen, hydrogen, and nitrogen— are
the less likely to attract popular attention, despite
the importance of their services, because they have the
invisibility, the thinness, of air. Very often, too,
they are concealed in combinations in which only the
higher science can detect their
pres-  ence. Reason enough, then, for our remaining in
ignorance about these substances that play the leading
parts in nature's never-ending drama."
"Are they, then, so very important?"
"Yes, my boy, they are extremely important."
"More so than gold?"
"You are all astray, my dear Emile, on this subject of
importance. Gold is unquestionably a very useful metal
to man; it is the sign of riches, of the savings
amassed by labor. Coined into money, it passes from
hand to hand and is good in all exchanges, in all
commercial transactions. It is a spendid part to play,
I admit; but if gold were to disappear entirely from
the earth, what would happen? Nothing very serious.
Banks might be inconvenienced, commerce upset for a
little while, but that is all. The world would soon
move on again as before. Suppose, on the other hand,
one of these three metalloids whose names you have just
learned—oxygen, for example—should
disappear. Immediately everything on earth would die,
from the biggest animal to the tiniest worm; all plant
life would perish, from the giant of the forest to the
smallest thread of moss. Life would henceforth be
impossible and this inhabited globe become a gloomy
solitude, with man, animal, and plant forever banished.
That, as you see, would be a far more serious disaster
than the inconvenience of a banker or the vexation of a
"In the general scheme of things, gold plays only an
insignificant part, almost a negligible part. If it
were lacking altogether, the order of nature would
 not be affected. Oxygen, hydrogen, and nitrogen, on the
contrary, fulfil in this world of ours functions so
important that if any one of these three were taken
away, everything would be turned topsy-turvy and life
would be rendered impossible. To these three carbon
must be added, for its part is not less important; and
thus we have our four substances indispensable to all
life, vegetable as well as animal. Now compare with
them, if you like, this gold that everybody talks
about, is familiar with, longs for, and that many wear
themselves out in trying to get. Was I not right when I
said that making the most noise in the world is a very
different thing from rendering the highest service?
Believe me, my young friends, gold is but a poor thing
when looked at from the proper point of view."
"And you will tell us about this oxygen, this hydrogen
and nitrogen, that the world cannot do without?" asked
"Certainly. I shall begin with them. Honor to whom
honor is due. To tell you what they are and what they
will do will take up more time than all the rest. To
complete the list of metalloids that you need
henceforth to know, at least by name, I will mention
one other. It is the substance you see at the tip end
of a match, overlying a layer of sulphur, and taking
fire with friction. It will give a mild glow, too, when
rubbed between the fingers in a darkened room."
"That must be phosphorus."
"Yes, phosphorus. It also is a metalloid. Let
 us sum up at this point. There are about sixty simple
substances, divided into metals and metalloids. Metals
have a peculiar sheen called metallic luster. Those
known to you are iron, copper, lead, tin, zinc,
mercury, silver, and gold. Some of the others deserve
attention as well, and I will speak of them as occasion
arises. There are, all told, about fifty
metalloids, which are much fewer in number, or about a
dozen in all, have not the so-called metallic luster.
The most important ones are oxygen, hygrogen, nitrogen,
carbon, sulphur, and phosphorus. The first three in the
list are, like air, invisible.
"Simple substances, metals as well as metalloids, are
also called elements. By this is meant that they are
the undecomposable or prime substances used by nature
in all her works."
"But, Uncle Paul," Jules here interposed, "I read in a
book that there are only four elements in nature, not
sixty, and that they are earth, air, fire and water."
"That book repeated the false notions of ancient times,
notions preserved to our day in popular speech, in
which long habit is slow to give place to the progress
of science. It was, indeed, formerly believed that
everything in nature could be traced back to earth,
air, fire and water, which were thought to be the four
undecomposable substances, the four elements, of which
all things were made.
 But it has been found after more careful study that not
one of the elements as understood by the ancients is
really a simple substance.
"In the first place, fire—or, rather,
heat—is not a material thing at all, and
consequently has no place in the list of simple
substances, which are matter even when they are
invisible. All matter can be weighed and measured. We
speak of a cubic foot of oxygen, a pound of sulphur;
but it would be the height of absurdity to speak of a
cubic foot of heat or a pound of warmth.You might just
as well pretend to weigh by the pound and measure by
the quart the notes that come from the strings of a
"A pound of F sharp or a quart of E flat would
certainly sound funny." Jules agreed, smiling at the
odd association of words.
"You smile, naturally enough, for a musical note cannot
be weighed in the scales or measured by the quart or
the bushel. And why is this impossible? Because sound
is not matter, but a movement transmitted in successive
waves from the sonorous body to our ears. The same with
heat: it is a peculiar mode of motion. To my regret, I
can but touch on this interesting subject at this time,
since to explain it properly would take so long that
chemistry would in the meantime be forgotten. I will
simply say, then, that heat cannot be classed as an
element, because it is not matter.
"When we come to air, however, we have quite another
thing. It can be measured by the quart, weighed by the
pound. It is probably new to you
 to hear air spoken of as being weighed and measured;
but nothing could be more correct. Physics could teach
us much about this if we had the time just now to give
to it. Air is matter, though, unfortunately for the
credit of the ancient theory, this matter is not a
simple substance. Instead of being made of one thing,
air is made of two very different things. I will tell
you their names before I undertake to prove to you by
experiment the truth of this assertion. Air is composed
of oxygen and nitrogen.
"Nor is water any more truly a simple substance, an
element, than air. At the proper time I will show you
that it is a compound of oxygen and hydrogen.
"As to earth, what is meant by that word? Evidently the
mixture of mineral substances—sand, clay, gravel,
pebbles, rocks, stones—that form the solid part
of the globe. Thus, instead of being an element, one
simple substance, it contains all the elements, from
the first to the last. From the earth are obtained all
the metals and various metalloids; in fact, all simple
substances could be derived from this source if we
cared to decompose those combinations in which many of
them are at present tied up. We may, then, say of the
four elements, commonly so called after the ancient
conception of the matter, that not one of them will
bear critical examination, not one will prove to be a
simple substance, an element, as the word is understood