The Chemical History of a Candle | Page 6

the other. In
fact, wicks are sometimes made of a kind of wire gauze. You will
observe that this vessel is a porous thing; for if I pour a little water on
to the top, it will run out at the bottom. You would be puzzled for a
good while if I asked you what the state of this vessel is, what is inside
it, and why it is there? The vessel is full of water, and yet you see the
water goes in and runs out as if it were empty. In order to prove this to
you, I have only to empty it. The reason is this,--the wire, being once
wetted, remains wet; the meshes are so small that the fluid is attracted
so strongly from the one side to the other, as to remain in the vessel
although it is porous. In like manner the particles of melted tallow
ascend the cotton and get to the top; other particles then follow by their
mutual attraction for each other, and as they reach the flame they are
gradually burned.
Here is another application of the same principle. You see this bit of
cane. I have seen boys about the streets, who are very anxious to appear
like men, take a piece of cane, and light it and smoke it, as an imitation
of a cigar. They are enabled to do so by the permeability of the cane in
one direction, and by its capillarity. If I place this piece of cane on a
plate containing some camphin (which is very much like paraffin in its
general character), exactly in the same manner as the blue fluid rose
through the salt will this fluid rise through the piece of cane. There
being no pores at the side, the fluid cannot go in that direction, but must
pass through its length. Already the fluid is at the top of the cane: now I
can light it and make it serve as a candle. The fluid has risen by the
capillary attraction of the piece of cane, just as it does through the
cotton in the candle.

Now, the only reason why the candle does not burn all down the side of
the wick is, that the melted tallow extinguishes the flame. You know
that a candle, if turned upside down, so as to allow the fuel to run upon
the wick, will be put out. The reason is, that the flame has not had time
to make the fuel hot enough to burn, as it does above, where it is
carried in small quantities into the wick, and has all the effect of the
heat exercised upon it.
There is another condition which you must learn as regards the candle,
without which you would not be able fully to understand the
philosophy of it, and that is the vaporous condition of the fuel. In order
that you may understand that, let me shew you a very pretty, but very
common-place experiment. If you blow a candle out cleverly, you will
see the vapour rise from it. You have, I know, often smelt the vapour of
a blown-out candle--and a very bad smell it is; but if you blow it out
cleverly, you will be able to see pretty well the vapour into which this
solid matter is transformed. I will blow out one of these candles in such
a way as not to disturb the air around it, by the continuing action of my
breath; and now, if I hold a lighted taper two or three inches from the
wick, you will observe a train of fire going through the air till it reaches
the candle. I am obliged to be quick and ready, because, if I allow the
vapour time to cool, it becomes condensed into a liquid or solid, or the
stream of combustible matter gets disturbed.
Now, as to the shape or form of the flame. It concerns us much to know
about the condition which the matter of the candle finally assumes at
the top of the wick--where you have such beauty and brightness as
nothing but combustion or flame can produce.
[Illustration: Fig. 2.]
You have the glittering beauty of gold and silver, and the still higher
lustre of jewels, like the ruby and diamond; but none of these rival the
brilliancy and beauty of flame. What diamond can shine like flame? It
owes its lustre at night-time to the very flame shining upon it. The
flame shines in darkness, but the light which the diamond has is as
nothing until the flame shine upon it, when it is brilliant again. The
candle alone shines by itself, and for itself, or for those who have

arranged the materials. Now, let us look a little at the form