iron, I then set the wood on
fire and let them both down together into the jar. The wood is now alight,
and there it burns as wood should burn in oxygen; but it will soon
communicate its combustion to the iron. The iron is now burning
brilliantly, and will continue so for a long time. As long as we supply
oxygen, so long can we carry on the combustion of the iron, until the
latter is consumed.

We will now put that on one side, and take some other substance; but we
must limit our experiments, for we have not time to spare for all the
illustrations you would have a right to if we had more time. We will take
a piece of sulphur--you know how sulphur burns in the air--well, we put it
into the oxygen, and you will see that whatever can burn in air, can burn
with a far greater intensity in oxygen, leading you to think that perhaps
the atmosphere itself owes all its power of combustion to this gas. The
sulphur is now burning very quietly in the oxygen; but you cannot for a
moment mistake the very high and increased action which takes place when
it is so burnt, instead of being burnt merely in common air.

[Illustration: Fig. 24.]

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 oxyge