Science and culture - Periodic table, Feb 5th 2011 P81 N3P61 周期律表
Empedocles of Acragas, a Greek philosopher, reckoned that matter consisted of four elements： earth, air, fire and water. His teachings were received wisdom for two millennia, overturned only by the birth of modern science 350 years ago. When Dmitri Mendeleev deviced his periodic table in 1869, it contained 63 elements； a similar chart in a chemistry classroom now has up to 118 entries. In his book Hugh Aldersey-Williams has deviced a cultural tour that maps most of them.
The journey is organised along five quirky themes： power, fire, craft, beauty and earth. For instance, Mr Alder-Williams groups together elements that resonate with power： economic power in the case of gold, silver and platinium； industrial might in the case iron； power in its most literal sense when it comes to elements used in nuclear reactors. He charts a meandering route. The Aztecs and Incas make way for Wagner's ゛Ring゛ cycle and Wallis Simpson, meteorites rain down from the skies and Glenn Seaborg crafts five new elements by bombarding heavy isotopes with neutrons.
The tales illustrate the frustrations that many chemists feel for their fickle field, particularly when experiments fail to work or instead produce inconsistent results. Even when the experiment is a success, its interpretation can be failure. An 18th-century English clergyman, Joseph Priestly, was the first person to isolate oxygen, but failed to recognise it as an element, the honour falling instead to a Frenchman, Antoine Lavossier. In an effort to recreate early experiments, the author collects his urine and roasts the residue for phosphorus, again without any luck.
An effort to collect a sample of every element also goes unrewarded. Staff at the Oak Ridge National Laboratory in Tennessee thwart the author's efforts to get his hands on some weapon-grade plutonium. A visit to an abandoned opencast mine on a rocky Swedish island where four rare earths were found in the 18th and 19th centuries fails to bear fruit. But he does manage to track down some elements traders who will sell him magnesium salvaged from ships and radium from the glowing hands of old wristwatches.
Ever the scientist, Mr Aldersey-Williams seeks explanation for artistic effects. He muses on how Anguste Rodin's ゛Thinker゛ leans so precariously far forward： its head rests on more than the figures' hand and knee, it transpires, because the sculpture contains a massive lead counterweight in its bottom. He goes on to recount how the allure of emeralds and rubies is provided by chromium, which not only colours the stones but also fluoresces with red light, so that the best gems appear to flicker with inner fire.
The book is not only a cultural history of the elements, it is also a lament to the loss of science as a hobby. Enterprising schoolboys no longer organise ゛stinks-and-bangs゛ extravaganzas. Mr Aldersey-Williams bemoans the decline of classroom chemistry, and the rise of a calture in which experiments performed by teachers must be timed to coincide with the length of the lesson. Children no longer have the opportunity to do hands-on works, technicians tidy away equipment that might otherwise be put to use in class and some teachers screen films of successful experiments instead of conducting their own. Few people appreciate that the natural world is a chemical one. Instead chemicals are to be feared, and kept in a locked cupboard. The author even regrets the removal from the paintbox of rich greens based on arsenic and flame-red vermilion formed from powdered mercuric sulphide. Removing risk, he suggests, enfeeble life.
