[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.
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