am holding to it; and if I put the light fairly opposed to the current, it
will blow it quite out. You will say that is as it should be; and I am
supposing that you think it ought to do so, because the nitrogen does not
support combustion, and ought to put the candle out, since the candle will
not burn in nitrogen.
[Illustration: Fig. 29.]
But is there nothing else there than nitrogen? I must now anticipate that
is to say, I must use my own knowledge to supply you with the means that
we adopt for the purpose of ascertaining these things, and examining such
gases as these. I will take an empty bottle here is one and if I hold it
over this chimney, I shall get the combustion of the candle below sending
its results into the bottle above; and we shall soon find that this bottle
contains, not merely an air that is bad as regards the combustion of a
taper put into it, but having other properties.
Let me take a little quick-lime and pour some common water on to it the
commonest water will do. I will stir it a moment, then pour it upon a
piece of filtering paper in a funnel, and we shall very quickly have a
clear water proceeding to the bottle below, as I have here. I have plenty
of this water in another bottle; but, nevertheless, I should like to use
the lime-water that was prepared before you, so that you may see what its
uses are. If I take some of this beautiful clear lime-water, and pour it
into this jar, which has collected the air from the candle, you will see a
change coming about. Do you see that the water has become quite milky?
Observe, that will not happen with air merely. Here is a bottle filled
with air; and if I put a little lime-water into it, neither the oxygen nor
the nitrogen, nor anything else that is in that quantity of air, will make
any change in the lime-water. It remains perfectly clear, and no shaking
of that quantity of lime-water with that quantity of air in its common
state will cause any change; but if I take this bottle with the
lime-water, and hold it so as to get the general products of the candle in
contact with it, in a very short time we shall have it milky. There is the
chalk, consisting of the lime which we used in making the lime-water,
combined with something that came from the candle that other product
which we are in search of, and which I want to tell you about to-day. This
is a substance made visible to us by its action, which is not the action
of the lime-water either upon the oxygen or upon the nitrogen, nor upon
the water itself, but it is something new to us from the candle. And then
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