Here, then, my dear child, we have arrived at the explanation of that
great mystery, WHY _we breathe._ Keep on the alert, for we are now
entering into a region where everything will be new to you.
Here we are at the charcoal market, I said to you just now, and no
doubt you concluded that I was beginning another comparison.
But no such thing; there is no question of comparison or simile here;
I state the fact itself, pure and simple as it stands: it is a
_market,_ for commercial intercourse and exchange are carried on
there, as I told you before, and it is a _charcoal_ market,
because _charcoal_ is, positively, the essential and chief article of
commerce.
You are astonished, I dare say, and are ready to ask me whether I can
possibly mean real charcoal, charcoal such as the cook puts into the
furnace. Surely, say you, we have nothing like _that_ in our bodies?
Surely we don't eat _that_?
But I answer yes; real, true charcoal, and you do not dislike it; you
eat of it even daily; nay, you do not swallow a single mouthful of
food which does not contain its proportion of charcoal.
You laugh; but wait a little and listen.
When you are toasting a slice of bread for breakfast, and hold it too
near the fire, what happens to it?
It turns quite black, does it not?
When mutton-chops are left too long unturned on the gridiron, what
happens to them?
They turn quite black also.
When your brother forgets the apples which he has set to roast, what
happens to them?
They turn quite black, as you have seen more than once.
It is always black, then, that these things turn, is it not? and a
fine rich _charcoaly_ black, as you may see if you please to
observe charcoal closely, for just such is the color of little burnt
cakes, over-roasted chestnuts, and potatoes in their skins, which have
been dropped into the fire.
But there is a common term by which we can express more accurately the
misfortune which has befallen all these various things--slices of
bread, mutton-chops, apples, cakes, chestnuts, potatoes, and what-not,
when "burnt," "over-toasted," "over-roasted," or "over-baked." We may
call them _carbonized_, or more simply _charred_ or _charcoaled_; though
the word _charred_ is generally used only for burnt _wood_. But _carbon_
being the principal ingredient of _charcoal_, and _charcoal_ being one
of the purer forms in which we get at _carbon_, they are almost
synonymous terms, and you may call your burnt food _carbonized_, or
_charred_, or _charcoaled_, whichever you prefer.
The next question is, how did charcoal or carbon get into the food so
as to justify our talking of its being _carbonized_ or _charred_? Even
when we use charcoal stoves for cooking, the charcoal does not jump out
and get into the mutton-chops, etc., you may be sure. Then it is clear
it must have been in them before they were brought to the fire to be
cooked; and such is indeed the case, only its black face escaped notice
because it was in such gay-looking company, and kept itself hid behind
the others like a needle lost in a match-box. Set fire to the matches,
and you will soon have nothing left but the needle, which will then
strike your eye at once. And so with our burnt food; the fire has
carried off all the other ingredients, and the charcoal is left behind
alone, exposed to everybody's view, as if on purpose to teach them that
it was always there; in the apples, i.e., the potatoes, mutton-chops,
etc., which seemed so tempting when the black rogue was hid, but from
which now, when he is there by himself, they turn away in disgust.
Charcoal is, in fact, a much more generally distributed substance than
you have been used to suppose, dear child. That which comes from burnt
wood is most easily observed, because there is a much larger proportion
of charcoal in wood than anywhere else; but there is not a morsel,
however small, of any animal or vegetable whatsoever, which does not
contain charcoal. In the sugar which you crunch, in the wine which you
drink, there is charcoal. I could even find some in the water you wash
in if I were to try hard. There is charcoal in the goose-quill which
I hold in my hand at this moment, and in the paper on which I am
writing, and in the handkerchief on my knee. If I hold them all three
in the light of my wax taper, I shall soon see them turn black and
betray the presence of our friend. It exists in the wax taper itself,
as also in the candle, as also in the oil lamp. If I were to hold a
piece of flat glass above their flame, I should collect enough of it
to blacken the tip of anybody's nose who presumed to doubt the fact.
There is a portion of it in the air; a portion of it in the earth.
Where is it not? In short, all the stones of all the buildings in the
world are filled with it from top to bottom. _Charcoal,_ under his more
scientific and important name of _carbon,_ may be called one of the
great lords of the world. His domain is so extensive that one might go
round the world without getting out of it; he is even worse than the
Marquis of Carabas.
After this you will never, I hope, want to persuade me you do not
eatcharcoal; for, indeed, you would be puzzled to escape doing so. Of
all the things you see on the dinner-table there is but one in which you
will not find it--viz., the salt-cellar; and even while saying this,
I mean only, in the _salt_ itself, for as to the salt-cellar,
clear and transparent as its glass may be, there is charcoal in it!
Our bodies, therefore, are full of charcoal. Everything that we eat
supplies them with enormous quantities of it, which take up their
quarters in every corner of our organs. It is one of the principal
materials of the vast collection of structures of which I spoke to you
in the early part of these letters, and of which the blood, the steward
of the body, is the universal master-builder. If you remember, I told
you then that these structures fell to pieces of themselves, in
proportion as the workmen went on building, and that the blood, which
brings fresh materials on its arrival from the lungs and heart, carries
away the refuse ones on its return. And, of all these refuse materials,
old charcoal is one of those which takes up the most room, as fresh
charcoal took up a great deal of room in the new materials. The blood,
as he goes back again, has his pockets quite crammed with it, and if
he did not try hard to get rid of it as fast as possible, he would be
disabled from being of any further use.
Now it is in the lungs that he clears himself of it. He gives it up
to the air, which has need of it for a very interesting operation, of
which I shall tell you more by and bye; and in return the air gives
him something which is quite indispensable to him, for without it he
would not dare to return to the organs, as his authority would no
longer be recognised.
In the same way, the charcoal-seller goes to market with his charcoal
and receives silver in exchange.
If he were to go home without money his wife would receive him with
abuse.
But what is the indispensable thing which the blood obtains in his
marketing?
Remember its name well: it is OXYGEN.
And we must speak of it with respect, for we are talking here of a
very great and powerful personage, very superior even to CARBON. If
CARBON be one of the great lords of the world, OXYGEN is its king.
There is a certain substance, my dear child, of which many people,
especially little girls, do not even know the name, but which yet
constitutes of itself alone a good half of everything we are acquainted
with in the world. And this substance is the very thing I have just
named to you. It is OXYGEN.
Ascend into the air as high as you can go, viz., to forty miles or so
from the ground, as we said before; _oxygen_ forms the fifth part
of that vast aerial ocean which surrounds the globe on every side.
There it is free--is _itself_--if I may use the expression; it
is in the condition of _gas_; that is to say, it eludes our sight,
though there is no difficulty in ascertaining its presence, when one
knows how to set about it.
Go down into the depths of the sea. People think they have good reasons
for believing this to be two and a half miles deep on an average, which
would give a pretty little sum total of tons for its whole weight, as
you will be convinced, if you take the trouble of observing the space
it covers on a map of the world;--to say nothing of lakes, rivers,
streams, the water in the clouds, the water scattered throughout the
interior or on the surface of continents, including that with which
you wash your face every morning.
Oxygen enters in the proportion of eight-ninths into the composition
of this incalculable mass. _Eight-ninths_, you understand, which
is very near being the whole nine; in every nine pounds of water there
are eight pounds of oxygen, the remainder being left for another
substance, of which we shall have occasion to speak presently, and
which is called _hydrogen_.
The earth on which you tread is full of oxygen. So far as we have
penetrated hitherto into the interior of the globe, we have found king
Oxygen everywhere: hidden under a thousand forms, connected with a
heap of substances, not one of which could exist without him; imprisoned
in a thousand combinations, and always ready to resume his natural
condition if his prison-house be destroyed. The whole surface of the
earth, plains, hills, mountains, towns, deserts, cultivated fields,
everything you would look down upon, if on a clear day you could be
carried high enough in a balloon to take in the whole earth at a
glance:--all that may be considered as an immense reservoir of oxygen,
out of which we should see it escaping in gigantic waves, if some
superhuman chemist were to take it into his head to put our poor little
globe into a retort of the same kind as chemists use among us. To give
you an example; the stones of our fine buildings, in which we have
already discovered the presence of _carbon_, are almost half made
up of _oxygen_. In a stone which weighs 100 lbs. there are 48
lbs. of oxygen, and the first chemist who passes by could make them
come out of it if he chose, if he were to use a little trouble and
skill.
I enumerated to you last time many of the substances in which _carbon_
is to be found; but as regards _oxygen_ we must give up all attempt at
making a list; it would comprehend the whole dictionary. Touch whatever
lies under your hand--in your room--in the house--wherever you may go--I
will almost defy you to put your finger upon anything--metals
excepted--which is not crammed with oxygen. Your very body, to conclude
with, would become so small a thing, were the oxygen it contains
extracted from it, that you would be perfectly amazed.
So when I told you oxygen was king of the world, I did not say too
much, did I? Between ourselves too, it is a great misfortune that
people live on so complacently in total ignorance of this all-important
material, which is connected with everything, which insinuates itself
everywhere, which we make use of every instant of our lives, which may
almost be said to be in some sort our very selves, since it constitutes
three-fourths of our body, but whose name nevertheless would, I am
certain, make many pretty little mouths pout, if one were to utter it
in a drawing-room.
This is really the case. Many young ladies who are proud to know who
Caractacus was, would be ashamed to know anything about oxygen. There
is a foolish notion that women have no business with such subjects,
probably because children are supposed not to breathe and mothers are
not required to watch over them?
This reminds me that we are on the road to explain _respiration,_
which I had almost forgotten in lifting up this corner of the veil
behind which Nature hides her most valuable secrets from the idle and
ignorant.
It is _oxygen_ then, which the blood carries off triumphantly from his
interview with the air in the cells of the lungs; and, by the way, it
is, thanks to this oxygen that it returns from the lungs to the heart,
and so from the heart to the organs, with that beautiful rosy tint which
distinguishes _arterial_ from _venous_ blood.
Now the blood gives out this oxygen on its road every time it performs
the journey, and the perpetual course it performs from the lungs to
the organs, and from the organs to the lungs, has for its chief object
the perpetual renovation of this previous provision, which is as
perpetually consumed.
Do you ask of what use it is? Does the blood leave it at random in our
organs, and is it one of the materials with which our steward is
constantly providing the little workmen of the body for their various
constructions?
No, my dear child. The proverb _"One cannot live upon air,"_ is
a very true one, although it is equally true that we cannot live without
air. Air does not nourish our organs; on the contrary, it consumes
them, and what we eat, serves to supply in precisely the same proportion
its insatiable appetite. When we leave off eating, from whatever cause,
the air does not leave off too. He goes on always just the same, and
that is the reason why people who are starved to death are so thin.
(The air has consumed the vital parts.)
You did not expect this; but now prepare yourself to go on from one
surprise to another. To begin with, I shall have to stop here and
explain to you before we go any further--can you guess what? Nay, I
am sure you cannot; FIRE.
There is not much connection, you will say, between _fire_ and
_breathing_.
But there you are mistaken. It is precisely the same thing, as I will
prove to you next time.