to it and into it, and therefore I make it hollow--and then take a few
iron-filings and drop them into the flame, you see how well they burn.
That combustion results from the chemical action which is going on when we
ignite those particles. And so we proceed to consider these different
effects, and ascertain what iron will do when it meets with water. It will
tell us the story so beautifully, so gradually and regularly, that I think
it will please you very much.

I have here a furnace with a pipe going through it like an iron
gun-barrel, and I have stuffed that barrel full of bright iron-turnings,
and placed it across the fire, to be made red-hot. We can either send air
through the barrel to come in contact with the iron, or we can send steam
from this little boiler at the end of the barrel. Here is a stop-cock
which shuts off the steam from the barrel until we wish to admit it. There
is some water in these glass jars, which I have coloured blue, so that you
may see what happens. Now, you know very well that any steam I might send
through that barrel, if it went through into the water, would be
condensed; for you have seen that steam cannot retain its gaseous form if
it be cooled down.

[Illustration: Fig. 14.]

You saw it here [pointing to the tin flask] crushing itself into a small
bulk, and causing the flask holding it to collapse; so that if I were to
send steam through that barrel, it would be condensed--supposing the
barrel were cold: it is, therefore, heated to perform the experiment I am
now about to shew you. I am going to send the steam through the barrel in
small quantities; and you shall judge for yourselves, when you see it
issue from the other end, whether it still remains steam. Steam is
condensible into water, and when you lower the temperature of steam, you