But what is water? The encyclopedia tells us that it is an oxide of hydrogen, and that it has no colour, no taste, and no smell. It is a combination of two gasses. It makes up 60-70% of our body. Roughly half of this amount is in our cells, a quarter elsewhere, and the remainder in tissues and blood. If we lose just 3 or 4 litres we start to have hallucinations, and a loss of about 10 litres means death. In a hot environment most humans without water last only 2-3 days.
About 70% of the Earth's surface is water, most of which is undrinkable, but a cycle of evaporation and condensation ensures a steady supply of fresh, clean water to much of the world's land. What does not fall as rain, comes down as snow and compacts as a storage supply of ice, which slowly melts and feeds streams and rivers through dry seasons.
As a liquid, water is almost impossible to . . .