The wonder of water
The sea is, of course, water—the stuff we drink, wash in, cook with,
and swim in, and the stuff that falls from the sky when it rains. Water
is so common we take it for granted. But it’s actually one of the most
amazing—and perhaps one of the most rare— materials in the whole
universe. Without it, there would be no life on earth. So far as we
know, without water there can’t be any life anywhere.
Scientists think that life on earth began in the sea. The first living
things were made mostly of water. And it is a fact that every living
thing now on earth is made mostly of water. It is also a fact that the
body fluids in people and animals are almost exactly the same as
seawater. The reason plants and animals take in water is to keep the
same amount of water in their bodies at all times. If a living creature
does not have enough water in its body, it will soon die.
But just what is water? Water is a liquid made out of two gases! Air
is made of gases, so you know that gas is dry, \”thin” stuff that you
can’t see or feel. But when two gases, oxygen and hydrogen, mix together
in a certain way, they become wet, weighty water!
Water is the only substance on earth that can be found in three
different forms. It can be a liquid, as it is in the ocean. It can be a
solid, as it is when it is ice. And it can be a gas, as it is when it is
steam or the water vapor of a cloud.
Water is a powerful chemical. You can put many kinds of strong, tough
metals into it and, in time, it will dissolve them.
Water is certainly wonderful, almost magical stuff, as well as the very
material of life itself. And scientists think that water may be quite
rare. There is none on any of the other planets that we know about.
Perhaps the great sea that covers much of our planet is a very unusual
thing.
