Michael Faraday's The Chemical History of a Candle

Lecture One
25
before long it will draw the water out of the basin like the
wick draws the wax out of the candle. Let me show you
another application of the same principle.
You see this hollow glass tube filled with table salt. I’ll
fill the dish with some alcohol colored with red food coloring.
You see the fluid rising through the salt. There being
no pores in the glass, the fluid cannot go in that direction,
but must pass through its length. Already the fluid is at
the top of the tube: now I can light it and make it serve as
a candle. The fluid has risen by the capillary action of the
salt, just as it does through the wick in the candle.
Now, the only reason why the candle does not burn all
down the sides of the wick is that the melted wax 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 science of it, and that is the vaporous condition of the
fuel. In order that you may understand that, let me show
you a very pretty experiment.
If you blow a candle out carefully, you will see the vapor
rise from it. You have, I know, often smelled the vapor of