watery, more substantial. The way this is done
is to add some nonwatery substance — a
dispersed phase — to the water. This
substance may be particles of plant or animal
tissue, or various molecules, or droplets of oil,
or even bubbles of air. And how do the added
substances make the water seem more
substantial? By obstructing the free
movement of the water molecules.
Obstructing the Movement of Water
Molecules Individual water molecules are
small — just three atoms, H 2 O. Left to
themselves, they’re very mobile: so water is
runny and flows as easily as a stream. (Oil
molecules, by contrast, have three chains
stuck together, each 14 to 20 atoms long, so
they drag against each other and move more
slowly. This is why oil is more viscous than
water.) But intersperse solid particles or long,
tangly molecules, or oil droplets, or air
bubbles among the water molecules, and the