In gas the
particles are distant from each other, like gnats flying in the air; in
liquids, distant as men passing in a busy street; in solids, as men in
a congregation, so sparse that each can easily move about. The
congregation can easily disperse to the rarity of those walking in the
street, and the men in the street condense to the density of the
congregation. So, matter can change in going from solids to liquids
and gases, or _vice versa_. The behavior of atoms in the process is
surpassingly interesting.
Gold changes its density, and therefore its thickness, between the two
dies of the mint that make it money. How do the particles behave as
they snuggle up closer to each other?
Take a piece of iron wire and bend it. The atoms on the inner side
become nearer together, those on the outside farther apart. Twist it.
The outer particles revolve on each other; those of the middle do not
move. They assume and maintain their new relations.
Hang a weight on a wire. It does not stretch like a rubber thread, but
it stretches. Eight wires were tested as to their tensile strength.
They gave an average of forty-five pounds, and an elongation averaging
nineteen per cent of the total length. Then a wire of the same kind
was given time to adjust itself to its new and trying circumstances.
Forty pounds were hung on one day, three pounds more the next day, and
so on, increasing the weights by diminishing quantities, till in sixty
days it carried fifty-seven pounds.
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