The Wilkinsons were having a small party,--it consisted of themselves
and Uncle Bagges--at which the younger members of the family, home
for the holidays, had been just admitted to assist after dinner. Uncle
Bagges was a gentleman from whom his affectionate relatives cherished
expectations of a testamentary nature. Hence the greatest attention
was paid by them to the wishes of Mr. Bagges, as well as to every
observation which he might be pleased to make.
"Eh! what? you sir," said Mr. Bagges, facetiously addressing himself
to his eldest nephew, Harry,--"Eh! what? I am glad to hear, sir, that
you are doing well at school. Now--eh? now, are you clever enough to
tell where was Moses when he put the candle out?"
"That depends, uncle," said the young gentleman, "on whether he had
lighted the candle to see with at night, or by daylight, to seal a
letter."
"Eh! Very good, now! 'Pon my word, very good," exclaimed Uncle Bagges.
"You must be Lord Chancellor, sir--Lord Chancellor, one of these
days."
"And now, uncle," asked Harry, who was a favorite with his uncle, "can
you tell me what you do when you put a candle out?"
"Clap an extinguisher on it, you young rogue, to be sure."
"Oh! but I mean, you cut off its supply of oxygen," said Master Harry.
"Cut off its ox's--eh? what? I shall cut off your nose, you young dog,
one of these fine days."
"He means something he heard at the Royal Institution," observed Mrs.
Wilkinson. "He reads a great deal about chemistry, and he attended
Professor Faraday's lectures there on the chemical history of a
candle, and has been full of it ever since."
"Now, you sir," said Uncle Bagges, "come you here to me, and tell
me what you have to say about this chemical, eh?--or comical:
which?--this comical chemical history of a candle."
"He'll bore you, Bagges," said Mr. Wilkinson. "Harry, don't be
troublesome to your uncle."
"Troublesome! Oh, not at all. He amuses me. I like to hear him. So let
him teach his old uncle the comicality and chemicality of a farthing
rushlight."
"A wax candle will be nicer and cleaner, uncle, and answer the same
purpose. There's one on the mantel-shelf. Let me light it.
"Take care you don't burn your fingers, Or set anything on fire," said
Mrs. Wilkinson.
"Now, uncle," commenced Harry, having drawn his chair to the side of
Mr. Bagges, "we have got our candle burning. What do you see?"
"Let me put on my spectacles," answered the uncle.
"Look down on the top of the candle around the wick. See, it is a
little cup full of melted wax. The heat of the flame has melted the
wax just round the wick. The cold air keeps the outside of it hard,
so as to make the rim of it. The melted wax in the little cup goes up
through the wick to be burnt, just as oil does in the wick of a lamp.
What do you think makes it go up, uncle?"
"Why--why, the flame draws it up, doesn't it?"
"Not exactly, uncle. It goes up through little tiny passages in the
cotton wick, because very, very small channels, or pipes, or pores,
have the power in themselves of sucking up liquids. What they do it by
is called cap--something."
"Capillary attraction, Harry," suggested Mr. Wilkinson.
"Yes, that's it; just as a sponge sucks up water, or a bit of
lump-sugar the little drop of tea or coffee left in the bottom of a
cup. But I mustn't say much more about this, or else you will tell me
I am doing something very much like teaching my grandmother to--you
know what."
"Your grandmother, eh, young sharp-shins?"
"No--I mean my uncle. Now, I'll blow the candle out, like Moses; not
to be in the dark, though, but to see into what it is. Look at the
smoke rising from the wick. I'll hold a bit of lighted paper in the
smoke, so as not to touch the wick. But see, for all that, the candle
lights again. So this shows that the melted wax sucked up through
the wick is turned into vapor; and the vapor burns. The heat of the
burning vapor keeps on melting more wax, and that is sucked up too
within the flame, and turned into vapor, and burnt, and so on till the
was is all used up, and the candle is gone. So the flame, uncle, you
see, is the last of the candle, and the candle seems to go through the
flame into nothing--although it doesn't, but goes into several things,
and isn't it curious, as Professor Faraday said, that the candle
should look so splendid and glorious in going away?"
"How well he remembers, doesn't he?" observed Mrs. Wilkinson.
"I dare say," proceeded Harry, "that the flame of the candle looks
flat to you; but if we were to put a lamp glass over it, so as
to shelter it from the draught, you would see it is round,--round
sideways and running up to a peak. It is drawn up by the hot air; you
know that hot air always rises, and that is the way smoke is taken up
the chimney. What should you think was in the middle of the flame?"
"I should say fire," replied Uncle Bagges.
"Oh, no! The flame is hollow. The bright flame we see is something
no thicker than a thin peel, or skin; and it doesn't touch the wick.
Inside of it is the vapor I told you of just now. If you put one end
of a bent pipe into the middle of the flame, and let the other end of
the pipe dip into a bottle, the vapor or gas from the candle will mix
with the air there; and if you set fire to the mixture of gas from the
candle and air in the bottle, it would go off with a bang."
"I wish you'd do that, Harry," said Master Tom, the younger brother of
the juvenile lecturer.
"I want the proper things," answered Harry. "Well, uncle, the flame
of the candle is a little shining case, with gas in the inside of it,
and air on the outside, so that the case of flame is between the air
and the gas. The gas keeps going into the flame to burn, and when the
candle burns properly, none of it ever passes out through the flame;
and none of the air ever gets in through the flame to the gas. The
greatest heat of the candle is in this skin, or peel, or case of
flame."
"Case of flame!" repeated Mr. Bagges. "Live and learn. I should have
thought a candle-flame was as thick as my poor old noddle."
"I can show you the contrary," said Harry. "I take this piece of white
paper, look, and hold it a second or two down upon the candle-flame,
keeping the flame very steady. Now I'll rub off the black of the
smoke, and--there--you find that the paper is scorched in the shape
of a ring; but inside the ring it is only dirtied, and not singed at
all."
"Seeing is believing," remarked the uncle.
"But," proceeded Harry, "there is more in the candle-flame than the
gas that comes out of the candle. You know a candle won't burn without
air. There must be always air around the gas, and touching it like, to
make it burn. If a candle hasn't got enough air, it goes out, or burns
badly, so that some of the vapor inside of the flame comes out through
it in the form of smoke, and this is the reason of a candle smoking.
So now you know why a great clumsy dip smokes more than a neat wax
candle; it is because the thick wick of the dip makes too much fuel in
proportion to the air that can get to it."
"Dear me! Well, I suppose there is a reason for everything," exclaimed
the young philosopher's mamma.
"What should you say now," continued Harry, "if I told you that the
smoke that comes out of a candle is the very thing that makes a candle
light? Yes; a candle shines by consuming its own smoke. The smoke of
a candle is a cloud of small dust, and the little grains of the dust
are bits of charcoal, or carbon, as chemists call it. They are made in
the flame, and burnt in the flame, and, while burning, make the flame
bright. They are burnt the moment they are made; but the flame goes on
making more of them as fast as it burns them: and that is how it keeps
bright. The place they are made in, is in the ease of flame itself,
where the strong heat is. The great heat separates them from the gas
which conies from the melted wax, and, as soon as they touch the air
on the outside of the thin case of flame, they burn."
"Can you tell how it is that the little bits of carbon came the
brightness of the flame?" asked Mr. Wilkinson.
"Because they are pieces of solid matter," answered Harry. "To make
a flame shine, there must always be some solid--or at least
liquid-matter in it."
"Very good." said Mr. Bagges,--"solid stuff necessary to brightness."
"Some gases and other things," resumed Harry, "that burn with a
flame you can hardly see, burn splendidly when something solid is
put into them. Oxygen and hydrogen--tell me if I use too hard words,
uncle--oxygen and hydrogen gases, if mixed together and blown through
a pipe, burn with plenty of heat but with very little light. But if
their flame is blown upon a piece of quick-lime, it gets so bright
as to be quite dazzling, Make the smoke of oil of turpentine pass
through the same flame, and it gives the flame a beautiful brightness
directly."
"I wonder," observed Uncle Bagges, "what has made you such a bright
youth."
"Taking after uncle, perhaps," retorted his nephew. "Don't put my
candle and me out. Well, carbon, or charcoal is what causes the
brightness of all lamps, and candles, and other common lights; so, of
course, there is carbon in what they are all made of."
"So carbon is smoke, eh? and light is owing to your carbon. Giving
light out of smoke, eh? as they say in the classics," observed Mr.
Bagges.
"But what becomes of the candle," pursued Harry, "as it burns away?
where does it go?"
"Nowhere," said his mamma, "I should think. It burns to nothing."
"Oh, dear, no!" said Harry, "everything--everybody goes somewhere."
"Eh!--rather an important consideration, that," Mr. Bagges moralized.
"You can see it goes into smoke, which makes soot, for one thing,"
pursued Harry. "There are other things it goes into, not to be seen
by only looking, but you can get to see them by taking the right
means,--just put your hand over the candle, uncle."
"Thank you, young gentleman, I had rather be excused."
"Not close enough down to burn you, uncle; higher up. There--you
feel a stream of hot air; so something seems to rise from the candle.
Suppose you were to put a very long slender gas-burner over the flame,
and let the flame burn just within the end of it, as if it were a
chimney,--some of the hot steam would go up and come out at the top,
but a sort of dew would be left behind in the glass chimney, if
the chimney was cold enough when you put it on. There are ways of
collecting this sort of dew, and when it is collected it turns out to
be really water. I am not joking, uncle. Water is one of the things
which the candle turns into in burning,--water coming out of fire. A
jet of oil gives above a pint of water in burning. In some lighthouses
they burn, Professor Faraday says, up to two gallons of oil in a
night, and if the windows are cold the steam from the oil clouds the
inside of the windows, and, in frosty weather, freezes into ice."
"Water out of a candle, eh?" exclaimed Mr. Bagges. "As hard to get, I
should have thought, as blood out of a post. Where does it come from?"
"Part from the wax, and part from the air, and yet not a drop of
it comes either from the air or the wax. What do you make of that,
uncle?"
"Eh? Oh! I'm no hand at riddles. Give it up."
"No riddle at all, uncle. The part that comes from the wax isn't
water, and the part that comes from the air isn't water, but when put
together they become water. Water is a mixture of two things then.
This can be shown. Put some iron wire or turnings into a gun barrel
open at both ends. Heat the middle of the barrel red-hot in a little
furnace. Keep the heat up, and send the steam of boiling water through
the red-hot gun barrel. What will come out at the other end of the
barrel won't be steam; it will be gas, which doesn't turn to water
again when it gets cold, and which burns if you put a light to it.
Take the turnings out of the gun-barrel, and you will find them
changed to rust, and heavier than when they were put in. Part of the
water is the gas that comes out of the barrel, the other part is what
mixes with the iron turnings, and changes them to rust, and makes
them heavier. You can fill a Wadder with the gas that comes out of
the gun-barrel, or you can pass bubbles of it up into a jar of water
turned upside down in a trough, and, as I said, you can make this part
of the water burn."
"Eh?" cried Mr. Bagges. "Upon my word! One of these day, we shall have
you setting the Thames on fire."
"Nothing more easy," said Harry, "than to burn part of the Thames, or
of any other water; I mean the gas that I have just told you about,
which is called hydrogen. In burning, hydrogen produces water again,
like the flame of a candle. Indeed, hydrogen is that part of the water
formed by a candle burning, that comes from the wax. All things that
have hydrogen in them produce water in burning, and the more there
is in them the more they produce. When pure hydrogen burns, nothing
comes from it but water, no smoke or soot at all. If you were to burn
one ounce of it, the water you would get would be just nine ounces.
There are many ways of making hydrogen besides out of steam by the
hot gun-barrel. I could show it you in a moment by pouring a little
sulphuric acid mixed with water into a bottle upon a few zinc or steel
filings, and putting a cork in the bottle with a little pipe through
it, and setting fire to the gas that would come from the mouth of
the pipe. We should find the flame very hot, but having scarcely
any brightness. I should like you to see the curious qualities of
hydrogen, particularly how light it is, so as to carry things up in
the air; and I wish I had a small balloon to fill with it, and make go
up to the ceiling, or a bag-pipe full of it to blow soap-bubbles with,
and show how much faster they rise than common ones, blown with the
breath."
"So do I," interposed Master Tom.
"And so," resumed Harry, "hydrogen, you know, uncle, is part of water,
and just one-ninth part."
"As hydrogen is to water, so is a tailor to an ordinary individual,
eh?" Mr. Bagges remarked.
"Well, now then, uncle, if hydrogen is the tailor's part of the
water, what are the other eight parts? The iron turnings used to make
hydrogen in the gun-barrel, and rusted, take just those eight parts
from the water in the shape of steam, and are so much the heavier.
Burn iron turnings in the air, and they make the same rust, and gain
just the same in weight. So the other eight parts must be found in the
air for one thing, and in the rusted iron turnings for another, and
they must also be in the water; and now the question is, how to get at
them?"
"Out of the water? Fish for them, I should say," suggested Mr. Bagges.
"Why, so we can," said Harry. "Only, instead of hooks and lines, we
must use wires--two wires, one from one end, the other from the other,
of a galvanic battery. Put the points of these wires into water, a
little distance apart, and they instantly take the water to pieces.
If they are of copper, or a metal that will rust easily, one of them
begins to rust, and air-bubbles come up from the other. These bubbles
are hydrogen. The other part of the water mixes with the end of the
wire and makes rust. But if the wires are of gold, or a metal that
does not rust easily, air-bubbles rise from the ends of both wires.
Collect the bubbles from both wires in a tube, and fire them, and they
turn to water again; and this water is exactly the same weight as the
quantity that has been changed into the two gases. Now then, uncle,
what should you think water was composed of?"
"Eh? well--I suppose of those very identical two gases, young
gentleman."
"Right, uncle. Recollect that the gas from one of the wires was
hydrogen, the one-ninth of water. What should you guess the gas from
the other wire to be?"
"Stop--eh?--wait a bit--eh?--oh! why, the other eight-ninths, to be
sure."
"Good again, uncle. Now this gas that is eight-ninths of water is the
gas called oxygen that I mentioned just now. This is a very curious
gas. It won't burn in air at all itself, like gas from a lamp, but it
has a wonderful power of making things burn that are lighted and put
into it. If you fill a jar with it--"
"How do you manage that?" Mr. Bagges inquired.
"You fill the jar with water," answered Harry, "and you stand it
upside down in a vessel full of water too. Then you let bubbles of the
gas up into the jar, and they turn out the water and take its place.
Put a stopper in the neck of the jar, or hold a glass plate against
the mouth of it, and you can take it out of the water and so have
bottled oxygen. A lighted candle put into a jar of oxygen blazes up
directly, and is consumed before you can say Jack Robinson. Charcoal
burns away in it as fast, with beautiful bright sparks--phosphorus
with a light that dazzles you to look at--and a piece of iron or steel
just made red-hot at the end first, is burnt in oxygen quicker than
a stick would be in common air. The experiment of burning things in
oxygen beats any fire-works."
"Oh, how jolly!" exclaimed Tom.
"Now we see, uncle," Harry continued, "that water is hydrogen and
oxygen united together, that water is got wherever hydrogen is burnt
in common air, that a candle won't burn without air, and that when a
candle burns there is hydrogen in it burning, and forming water. Now,
then, where does the hydrogen of the candle get the oxygen from, to
turn into water with it?"
"From the air, eh?"
"Just so. I can't stop to tell you of the other things which there is
oxygen in, and the many beautiful and amusing ways of getting it. But
as there is oxygen in the air, and as oxygen makes things burn at such
a rate, perhaps you wonder why air does not make things burn as fast
as oxygen. The reason is, that there is something else in the air that
mixes with the oxygen and weakens it."
"Makes a sort of gaseous grog of it, eh?" said Mr. Bagges. "But how is
that proved?"
"Why, there is a gas, called nitrous gas, which, if you mix it with
oxygen, takes all the oxygen into itself, and the mixture of the
nitrous gas and oxygen, if you put water with it, goes into the water.
Mix nitrous gas and air together in a jar over water, and the nitrous
gas takes away the oxygen, and then the water sucks up the mixed
oxygen and nitrous gas, and that part of the air which weakens the
oxygen is left behind. Burning phosphorus in confined air will also
take all the oxygen from it, and there are other ways of doing the
same thing. The portion of the air left behind is called nitrogen. You
wouldn't know it from common air by the look; it has no color, taste,
nor smell, and it won't burn. But things won't burn in it, either;
and anything on fire put into it goes out directly. It isn't fit to
breathe, and a mouse, or any animal, shut up in it, dies. It isn't
poisonous, though; creatures only die in it for want of oxygen. We
breathe it with oxygen, and then it does no harm, but good: for if
we breathed pure oxygen, we should breathe away so violently, that
we should soon breathe our life out. In the same way, if the air were
nothing but oxygen, a candle would not last above a minute.
"What a tallow-chandler's bill we should have!" remarked Mrs.
Wilkinson.
"'If a house were on fire in oxygen,' as Professor Faraday said,
'every iron bar, or rafter, or pillar, every nail and iron tool,
and the fire-place itself; all the zinc and copper roofs, and leaden
coverings, and gutters, and pipes, would consume and burn, increasing
the combustion.'"
"That would be, indeed, burning 'like a house on fire,'" observed Mr.
Bagges.
"'Think,'" said Harry, continuing his quotation, "'of the Houses
of Parliament, or a steam-engine manufactory. Think of an iron
proof-chest no proof against oxygen. Think of a locomotive and its
train,--every engine, every carriage, and even every rail would be set
on fire and burnt up.' So now, uncle, I think you see what the use of
nitrogen is, and especially how it prevents a candle from burning out
too fast."
"Eh?" said Mr. Bagges. "Well, I will say I do think we are under
considerable obligations to nitrogen."
"I have explained to you, uncle," pursued Harry, "how a candle, in
burning, turns into water. But it turns into something else. besides
that. There is a stream of hot air going up from it that won't
condense into dew; some of that is the nitrogen of the air which the
candle has taken all the oxygen from. But there is more in it than
nitrogen. Hold a long glass tube over a candle, so that the stream
of hot air from it may go up through the tube. Hold a jar over the
end of the tube to collect some of the stream of hot air. Put some
lime-water, which looks quite clear, into the jar; stop the jar,
and shake it up. The lime-water, which was quite clear before, turns
milky. Then there is something made by the burning of the candle that
changes the color of the lime-water. That is a gas, too, and you can
collect it, and examine it. It is to be got from several things,
and is a part of all chalk, marble, and the shells of eggs or of
shell-fish. The easiest way to make it is by pouring muriatic or
sulphuric acid on chalk or marble. The marble or chalk begins to hiss
or bubble, and you can collect the bubbles in the same way that you
can oxygen. The gas made by the candle in burning, and which also is
got out of the chalk and marble, is called carbonic acid. It puts out
a light in a moment; it kills any animal that breathes it, and it is
really poisonous to breathe, because it destroys life even when mixed
with a pretty large quantity of common air. The bubbles made by beer
when it ferments, are carbonic acid, so is the air that fizzes out of
soda-water, and it is good to swallow though it is deadly to breathe.
It is got from chalk by burning the chalk as well as by putting acid
to it, and burning the carbonic acid out of chalk makes the chalk
lime. This is why people are killed sometimes by getting in the way of
the wind that blows from lime-kilns."
"Of which it is advisable carefully to keep to the windward." Mr.
Wilkinson observed.
"The most curious thing about carbonic acid gas," proceeded Harry, "is
its weight. Although it is only a sort of air, it is so heavy that
you can pour it from one vessel into another. You may dip a cup of it
and pour it down upon a candle, and it will put the candle out, which
would astonish an ignorant person; because carbonic acid gas is as
invisible as the air, and the candle seems to be put out by nothing. A
soap-bubble or common air floats on it like wood on water. Its weight
is what makes it collect in brewers' vats; and also in wells, where
it is produced naturally; and owing to its collecting in such places
it causes the deaths we so often hear about of those who go down into
them without proper care. It is found in many springs of water, more
or less; and a great deal of it comes out of the earth in some places.
Carbonic acid gas is what stupefies the dogs in the Grotto del Cane.
Well, but how is carbonic acid gas made by the candle?"
"I hope with your candle you'll throw some light upon the subject,"
said Uncle Bagges.
"I hope so," answered Harry. "Recollect it is the burning of the
smoke, or soot, or carbon of the candle, that makes the candle-flame
bright. Also that the candle won't burn without air. Likewise that it
will not burn in nitrogen, or air that has been deprived of oxygen.
So the carbon of the candle mingles with oxygen, in burning, to make
carbonic acid gas; just as the hydrogen does to form water. Carbonic
acid gas, then, is carbon or charcoal dissolved in oxygen. Here is
black soot getting invisible and changing into air; and this seems
strange, uncle, doesn't it?"
"Ahem! Strange, if true," answered Mr. Bagges. "Eh? Well! I suppose
it's all right."
"Quite so, uncle. Burn carbon or charcoal either in the air or in
oxygen, and it is sure always to make carbonic acid, and nothing else,
if it is dry. No dew or mist gathers in a cold glass jar if you burn
dry charcoal in it. The charcoal goes entirely into carbonic acid gas,
and leaves nothing behind but ashes, which are only earthy stuff that
was in the charcoal, but not part of the charcoal itself. And now,
shall I tell you something about carbon?"
"With all my heart," assented Mr. Bagges.
"I said that there was carbon or charcoal in all common lights, so
there is in every common kind of fuel. If you heat coal or wood away
from the air, some gas comes away, and leaves behind coke from coal,
and charcoal from wood; both carbon, though not pure. Heat carbon
as much as you will in a close vessel, and it does not change in the
least; but let the air get to it, and then it burns and flies off in
carbonic acid gas. This makes carbon so convenient for fuel. But it is
ornamental as well as useful, uncle. The diamond is nothing else than
carbon."
"The diamond, eh! You mean the black diamond."
"No: the diamond, really and truly. The diamond is only carbon in the
shape of a crystal."
"Eh? and can't some of your clever chemists crystalize a little bit of
carbon, and make a Koh-i-noor?"
"Ah, uncle, perhaps we shall, some day. In the mean time I suppose we
must be content with making carbon so brilliant as it is in the flame
of a candle. Well; now you see that a candle-flame is vapor burning,
and the vapor, in burning, turns into water and carbonic acid gas. The
oxygen of both the carbonic acid gas and the water comes from the air,
and the hydrogen and carbon together are the vapor. They are distilled
out of the melted was by the heat. But, you know, carbon alone can't
be distilled by any heat. It can be distilled, though, when it is
joined with hydrogen, as it is in the wax, and then the mixed hydrogen
and carbon rise in gas of the same kind as the gas in the streets, and
that also is distilled by heat from coal. So a candle is a little gas
manufactory in itself, that burns the gas as fast as it makes it."
"Haven't you pretty nearly come to your candle's end'!" said Mr.
Wilkinson.
"Nearly. I only want to tell uncle, that the burning of a candle is
almost exactly like our breathing. Breathing is consuming oxygen,
only not so fast as burning. In breathing we throw out water in vapor
and carbonic acid from our lungs, and take oxygen in. Oxygen is as
necessary to support the life of the body, as it is to keep up the
flame of a candle."
"So," said Mr. Bagges, "man is a candle, eh? and Shakspeare knew that,
I suppose, (as he did most things,) when he wrote
'Out, out, brief candle!'
"Well, well; we old ones are moulds, and you young squires are dips
and rushlights, eh? Any more to tell us about the candle?"
"I could tell you a great deal more about oxygen, and hydrogen, and
carbon, and water, and breathing, that Professor Faraday said, if I
had time; but you should go and hear him yourself, uncle."
"Eh? well! I think I will. Some of us seniors may learn something from
a juvenile lecture, at any rate, if given by a Faraday. And now, my
boy. I will tell you what," added Mr. Bagges, "I am very glad to find
you so fond of study and science; and you deserve to be encouraged:
and so I'll give you a what-d'ye-call-it'?--a Galvanic Battery, on
your next birth-day; and so much for your teaching your old uncle the
chemistry of a candle."
* * * * *
[FROM A REVIEW OF GRISWOLD'S _PROSE WRITERS OF AMERICA_, IN THE
SOUTHERN LITERARY MESSENGER.]