water; and to shew you how truly and thoroughly these changes take place,
I will take this tin flask, which is now full of steam, and close the top.
We shall see what takes place when we cause this water or steam to return
back to the fluid state by pouring some cold water on the outside. [The
Lecturer poured the cold water over the vessel, when it immediately
collapsed.] You see what has happened. If I had closed the stopper, and
still kept the heat applied to it, it would have burst the vessel; yet,
when the steam returns to the state of water, the vessel collapses, there
being a vacuum produced inside by the condensation of the steam. I shew
you these experiments for the purpose of pointing out that in all these
occurrences there is nothing that changes the water into any other
thing--it still remains water; and so the vessel is obliged to give way,
and is crushed inwards, as in the other case, by the further application
of heat, it would have been blown outwards.

[Illustration: Fig. 12.]

And what do you think the bulk of that water is when it assumes the
vaporous condition? You see that cube [pointing to a cubic foot]. There,
by its side, is a cubic inch, exactly the same shape as the cubic foot,
and that bulk of water [the cubic inch] is sufficient to expand into that
bulk [the cubic foot] of steam; and, on the contrary, the application of
cold will contract that large quantity of steam into this small quantity
of water.

[Illustration: Fig. 13.]

[One of the iron bottles burst at that moment.] Ah! There is one of our
bottles burst, and here you see is a crack down one side an eighth of an
inch in width. [The other now exploded, sending the freezing mixture in