Waters subtle complexity manifests itself
in many ways. Unlike other liquids, it flows faster under
high pressure than under low pressure. Its solid form is lighter
than its liquid form. As a solvent, it is gentle enough to
serve as the cradle of life yet brutal enough to carve the
Grand Canyon.
This contradictory character results from an atomic arrangement
that makes waters oxygen and hydrogen atoms like to
form bonds with practically anything that crosses their pass,
even other water molecules.
We call adhesion the attractive force between the molecules
of the liquid and another substance. Cohesion is a similar
attractive force between molecules within liquid. One of the
observations is the balance between the different properties
of adhesion and cohesion. This balance gives the liquid its
degree of wetness.
For example, if you push a glass tube into a beaker full of
water, the water will rise up the tube- the narrower the tube,
the higher itll rise. This is due to the adhesion between
the water molecules and the glass tube is greater than the
cohesion within the water itself. If the same experiment is
to be carried out with mercury, the tube would cause a depression
to form in the liquid. This shows that the balance between
adhesion and cohesion is opposite. Also for the same reasons,
in the beaker of water the edge of the liquid curves upwards
along the sides, whereas in mercury it curves downwards. It
is the adhesive properties of water, which cause it to be
soaked up by sponges, blotting paper, etc.
Water is fairly adhesive but some other liquid shows more
adhesive behaviors. Therefore, wetness has a different
degree and with the above properties, water is considered
wet.