Before the war there was a merry comedy on at the movies, called "Volga, Volga." In it a blithe water carrier sings as he whips up his lazy horses: "For water's needed everywhere: Without't you're neither here nor there . . ." The song was a great success and has now even become proverbial. But this simple ditty holds profound implications.

   For water really is substance No. 1 in life. H₂O. One atom of oxygen plus two atoms of hydrogen. Probably one of the first chemical formulas you ever learn. Now try to imagine what would become of our planet if the water suddenly disappeared from it. Dismal yawning "cavities" of sea and ocean hollows covered with a thick layer of the salt once dissolved in the water. Dry river channels, springs which will never bubble again. Rocks disintegrated to ash: water was one of their main constituents. Neither bush nor flower, not a living thing on the dead Earth. And above it a cloudless sky of a horrifying unusual colour.

   So simple a compound, and yet where there is no water, no life, intelligent or unintelligent, is possible. Why? First of all because water is the most remarkable chemical compound in the world.

   When Celsius invented his thermometer, he based his device on two values, or two constants: the boiling point and the freezing point of water. He took the former as equal to 100°, and the second to zero. Then he divided the interval between them into 100 divisions. Thus appeared the first instrument for measuring temperatures.

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