ust and a haze of warm water.

With a deafening roar, rocks, skyscrapers, and even mountains tumble
down, fall to pieces, and sink into an inconceivably fine dust.
Nothing stands up in the world--not a tree, not an animal, not an
island. With a wild rush the oceans flood in over the dust that has
been nations and continents, and then this dust turns to a fine muddy
ooze in the bottom of a worldwide sea.

But it is an ocean utterly different from what we have in the real
world. There are no waves. Neither are there any reflections of clouds
in its surface,--first because the clouds would fly to pieces and turn
to invisible vapor, and second, because the ocean has no surface--it
simply melts away into the air and no one can tell where the water
stops and where the air begins.

Then the earth grows larger and larger. The ocean turns to a heavy,
dense, transparent steam. The fine mud that used to be rocks and
mountains and living things turns to a heavy, dense gas.

Our once beautiful, solid, warm, living earth now whirls on through
space, a swollen, gaseous globe, utterly dead.

And the only thing that prevents all this from actually happening
right now is that there is a force called _cohesion_ that holds things
together. It is the pull which one particle of anything has on another
particle of the same material. The paper in this book, the chair on
which you are sitting, and you yourself are all made of a vast number
of unthinkably small particles called _molecules_, each of which is
pulling on its neighbor with such force that all stay in their places.
Substances in which they pull the hardest, like steel, are very hard
to break in two; that is, it is difficult to pull the molecules of
these substances apart. In liquids, such as water, the molecules do
not pull nearly so hard on each other. In a gas, such as air, they are
so far apart that they have practically no pull on each other at all.
That is why everything would turn to a gas if the force of cohesion
stopped. Why things would turn cold will be explained in Chapter 4.

Cohesion, adhesion, and capillary attraction, all are the result of
the pull of molecules on each other. The difference is that capillary
attraction is the pulling of particles of liquids up into fine
spaces, as when a lamp wick draws up oil; adhesion is the pull of the
particles of one substance or thing on the particles of another when
they are very close together, as when water clings to you