e freezing point the fluid can no longer rise
in the neck of the flask, which is broken by the sudden expansion that
takes place at this point.

To show what an irresistible power resides in the atoms of which the
body is made, let us take an iron flask with walls one-half inch or more
in thickness; fill it with water and seal it up by screwing on the neck
an iron cap; now plunge it into the freezing mixture, and the first
effect will be to contract the water unless it is already below 39
degrees Fahrenheit, but when it reaches that point expansion sets in,
which continues to the freezing point, when a greatly increased
expansion takes place suddenly. The walls of the iron flask, although a
half-inch in thickness, are no longer able to resist the combined
efforts of the billions upon billions of the atoms of which the water is
made up, in their individual clamor for more room, hence the flask is
shivered into pieces.

There are one or two other substances which are exceptions to the
general rule, but we will mention only one, which is the metal bismuth.
If we should melt a sufficient amount to fill an iron flask, such as we
have described, and subject it to the same freezing process, the flask
will be broken the same as in the experiment made with the water.

A query arises, Why this phenomenon? Why does water follow a different
law in cooling from that of nearly all other substances?

This is a case where it is much easier to ask a question than to answer
it. When water solidifies at the moment of freezing, crystallization
sets in. But what is crystallization? Crystallization is a peculiar
arrangement of the molecules of matter, which takes place in some
substances when they pass from the liquid to the solid form. The
molecules assume definite forms and shapes, according to the nature of
the substance. When water assumes the solid form under the action of
cold the molecules arrange themselves according to certain definite and
fixed laws, the result of which is to increase the bulk to a
considerable extent over that which the same number of molecules would
occupy at a temperature of 39 degrees Fahrenheit. Hence, as has been
heretofore stated, a given block of solidified water is lighter than the
same bulk would be in the fluid state, and this is the reason why ice
floats.

What would happen in case nature did not make this exception to the laws
of expansion and contraction by heat and cold, in the case of water?
F