The Chemical History of a Candle | Page 5

which we should not receive if they
had not occurred. We come here to be philosophers; and I hope you
will always remember that whenever a result happens, especially if it
be new, you should say, "What is the cause? Why does it occur?" and
you will in the course of time find out the reason.
Then, there is another point about these candles which will answer a
question,--that is, as to the way in which this fluid gets out of the cup,
up the wick, and into the place of combustion. You know that the
flames on these burning wicks in candles made of beeswax, stearin, or
spermaceti, do not run down to the wax or other matter, and melt it all
away, but keep to their own right place. They are fenced off from the
fluid below, and do not encroach on the cup at the sides. I cannot
imagine a more beautiful example than the condition of adjustment
under which a candle makes one part subserve to the other to the very
end of its action. A combustible thing like that, burning away gradually,
never being intruded upon by the flame, is a very beautiful sight;
especially when you come to learn what a vigorous thing flame
is--what power it has of destroying the wax itself when it gets hold of it,

and of disturbing its proper form if it come only too near.
But how does the flame get hold of the fuel? There is a beautiful point
about that--_capillary attraction_[4]. "Capillary attraction!" you
say,--"the attraction of hairs." Well, never mind the name: it was given
in old times, before we had a good understanding of what the real
power was. It is by what is called capillary attraction that the fuel is
conveyed to the part where combustion goes on, and is deposited there,
not in a careless way, but very beautifully in the very midst of the
centre of action which takes place around it. Now, I am going to give
you one or two instances of capillary attraction. It is that kind of action
or attraction which makes two things that do not dissolve in each other
still hold together. When you wash your hands, you wet them
thoroughly; you take a little soap to make the adhesion better, and you
find your hand remains wet. This is by that kind of attraction of which I
am about to speak. And, what is more, if your hands are not soiled (as
they almost always are by the usages of life), if you put your finger into
a little warm water, the water will creep a little way up the finger,
though you may not stop to examine it. I have here a substance which
is rather porous--a column of salt--and I will pour into the plate at the
bottom, not water, as it appears, but a saturated solution of salt which
cannot absorb more; so that the action which you see will not be due to
its dissolving anything. We may consider the plate to be the candle, and
the salt the wick, and this solution the melted tallow. (I have coloured
the fluid, that you may see the action better.) You observe that, now I
pour in the fluid, it rises and gradually creeps up the salt higher and
higher; and provided the column does not tumble over, it will go to the
top.
[Illustration: Fig. 1.]
If this blue solution were combustible, and we were to place a wick at
the top of the salt, it would burn as it entered into the wick. It is a most
curious thing to see this kind of action taking place, and to observe how
singular some of the circumstances are about it. When you wash your
hands, you take a towel to wipe off the water; and it is by that kind of
wetting, or that kind of attraction which makes the towel become wet

with water, that the wick is made wet with the tallow. I have known
some careless boys and girls (indeed, I have known it happen to careful
people as well) who, having washed their hands and wiped them with a
towel, have thrown the towel over the side of the basin, and before long
it has drawn all the water out of the basin and conveyed it to the floor,
because it happened to be thrown over the side in such a way as to
serve the purpose of a syphon.[5] That you may the better see the way
in which the substances act one upon another, I have here a vessel
made of wire gauze filled with water, and you may compare it in its
action to the cotton in one respect, or to a piece of calico in