burning point in air, as we have a fair right to do, and as we have done
with phosphorus, you will see that it can burn in carbonic acid; and if it
burns, it will burn by taking oxygen, so that you will see what is left
behind. I am going, then, to burn this potassium in the carbonic acid, as
a proof of the existence of oxygen in the carbonic acid. [In the
preliminary process of heating, the potassium exploded.] Sometimes we get
an awkward piece of potassium that explodes, or something like it, when it
burns. I will take another piece; and now that it is heated, I introduce
it into the jar, and you perceive that it burns in the carbonic acid--not
so well as in the air, because the carbonic acid contains the oxygen
combined; but it does burn, and takes away the oxygen. If I now put this
potassium into water, I find that, besides the potash formed (which you
need not trouble about), there is a quantity of carbon produced. I have
here made the experiment in a very rough way; but I assure you that if I
were to make it carefully, devoting a day to it, instead of five minutes,
we should get all the proper amount of charcoal left in the spoon, or in
the place where the potassium was burned, so that there could be no doubt
as to the result. Here, then, is the carbon obtained from the carbonic
acid, as a common black substance; so that you have the entire proof of
the nature of carbonic acid as consisting of carbon and oxygen. And now, I
may tell you, that _whenever_ carbon burns under common circumstances, it
produces carbonic acid.

Suppose I take this piece of wood, and put it into a bottle with
lime-water. I might shake that lime-water up with wood and the atmosphere
as long as I pleased, it would still remain clear as you see it; but
suppose I burn the piece of wood in the air of that bottle. You, of
course, know I get water. Do I get carbonic acid? [The experiment was
performed.] There it is, you see--that is to say, the carbonate lime,
which results from carbonic acid, and that carbonic acid must be formed