I am now about to shew you the combustion of another
substance phosphorus. I can do it better for you here than you can do it
at home. This is a very combustible substance; and if it be so combustible
in air, what might you expect it would be in oxygen? I am about to shew it
to you not in its fullest intensity, for if I did so we should almost blow
the apparatus up I may even now crack the jar, though I do not want to
break things carelessly. You see how it burns in the air. But what a
glorious light it gives out when I introduce it into oxygen! [Introducing
the lighted phosphorus into the jar of oxygen.] There you see the solid
particles going off which cause that combustion to be so brilliantly
luminous.
Thus far we have tested this power of oxygen, and the high combustion it
produces by means of other substances. We must now, for a little while
longer, look at it as respects the hydrogen. You know, when we allowed the
oxygen and the hydrogen derived from the water to mix and burn together,
we had a little explosion. You remember, also, that when I burnt the
oxygen and the hydrogen in a jet together, we got very little light, but
great heat. I am now about to set fire to oxygen and hydrogen, mixed in
the proportion in which they occur in water. Here is a vessel containing
one volume of oxygen and two volumes of hydrogen. This mixture is exactly
of the same nature as the gas we just now obtained from the voltaic
battery: it would be far too much to burn at once; I have therefore
arranged to blow soap-bubbles with it, and burn those bubbles, that we may
see by a general experiment or two how this oxygen supports the combustion
of the hydrogen. First of all, we will see whether we can blow a bubble.
Well, there goes the gas [causing it to issue through a tobacco-pipe into
some soap-suds]. Here I have a bubble. I am receiving them on my hand: and
you will perhaps think I am acting oddly in this experiment; but it is to
shew you that we must not always trust to noise and sounds, but rather to
real facts. [Exploding a bubble on the palm of his hand.] I am afraid to
fire a bubble from the end of the pipe, because the explosion would pass
up into the jar and blow it to pieces. This oxygen then will unite with
the hydrogen, as you see by the phenomena, and hear by the sound, with the
utmost readiness of action, and all its powers are then taken up in its
neutralisation of the qualities of the hydrogen.
So now I think you will perceive the whole history of water with reference
to oxygen and the air, from what we have before said. Why does a piece of
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