matter, like shells and corals, and many of the rocks and minerals in the
earth. But I have not yet told you fully and clearly the chemical history
of this substance carbonic acid as we have it from the candle, and I
must now resume that subject. We have seen the products, and the nature of
them, as they issue from the candle. We have traced the water to its
elements, and now we have to see where are the elements of the carbonic
acid supplied by the candle. A few experiments will shew this. You
remember that when a candle burns badly, it produces smoke; but if it is
burning well, there is no smoke. And you know that the brightness of the
candle is due to this smoke, which becomes ignited. Here is an experiment
to prove this: so long as the smoke remains in the flame of the candle and
becomes ignited, it gives a beautiful light, and never appears to us in
the form of black particles. I will light some fuel, which is extravagant
in its burning. This will serve our purpose a little turpentine on a
sponge. You see the smoke rising from it, and floating into the air in
large quantities; and, remember now, the carbonic acid that we have from
the candle is from such smoke as that. To make that evident to you, I will
introduce this turpentine burning on the sponge into a flask where I have
plenty of oxygen, the rich part of the atmosphere, and you now see that
the smoke is all consumed. This is the first part of our experiment; and
now, what follows? The carbon which you saw flying off from the turpentine
flame in the air is now entirely burned in this oxygen, and we shall find
that it will, by this rough and temporary experiment, give us exactly the
same conclusion and result as we had from the combustion of the candle.
The reason why I make the experiment in this manner is solely that I may
cause the steps of our demonstration to be so simple that you can never
for a moment lose the train of reasoning, if you only pay attention. All
the carbon which is burned in oxygen, or air, comes out as carbonic acid,
whilst those particles which are not so burned shew you the second
substance in the carbonic acid namely, the carbon that body which made
the flame so bright whilst there was plenty of air, but which was thrown
off in excess when there was not oxygen enough to burn it.
I have also to shew you a little more distinctly the history of carbon and
oxygen, in their union to make carbonic acid. You are now better able to
understand this than before, and I have prepared three or four experiments
by way of illustration. This jar is filled with oxygen, and here is some
carbon which has been placed in a crucible, for the purpose of being made
red-hot. I keep my jar dry, and venture to give you a result imperfect in
some degree, in order that I may make the experiment brighter. I am about
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