THE INGREDIENTS

Having taken readers on a guided tour of molecules (Stories of the Invisible, 2001), Nature consultant editor Ball now turns his attention to the elements.

As is so often the case in science, the story begins with the Greeks. The philosopher Empedocles postulated that matter is made up of four basic ingredients: earth, air, water, and fire. All earthly substances were understood to be mixtures of these four, hence the alchemists' conviction that with the proper procedures, base metals could be transmuted into gold. The four elements meshed so neatly with other philosophical notions that it took 2,000 years for chemists to realize that the real world didn't conform to the elegant paradigm. Even then, the notion of elemental substances was not abandoned; instead, Cavendish, Lavoisier, Dalton, and their 18th-century followers found the classical elements to be mixtures of other, more elemental substances. At that point, the focus of chemistry changed to identification of those elements: iron, oxygen, sulfur, gold, and other, far less familiar ones. The number of elements has steadily increased to well over a hundred, with new ones still being added. A second great breakthrough was the Russian chemist Mendeleyev's realization that when arranged in the right order the elements fell into clear-cut families. With this key insight, embodied in the familiar periodic table, chemistry became a more exact science. The discovery of radioactivity opened more doors, notably the understanding that elements were not eternally fixed but capable of being changed—although by processes requiring far more energy than the alchemists had at their command. Ball covers the history of his field with admirable conciseness, taking welcome detours into the colorful lore of certain members of the periodic table, notably gold, which perhaps even today remains the single most charismatic of earthly substances.

Solid scientific history, entertainingly presented.