After the rise of Adolf Hitler, two of Germany's leading liberal scientists, Max von Laue and James Franck, sent their Nobel medals to the great Danish physicist Niels Bohr for safe-keeping. Everything seemed fine until 1940 when Copenhagen was overrun by the Germans. Bohr found himself in a tight spot. It was illegal to export gold from Nazi Germany and discovery of the medals, bearing Franck and Laue's names, could have led to executions.
Colleagues suggested burying the medals. Instead Bohr chose to use aqua regia, a corrosive mix of acids that was known, since the days of alchemy, to dissolve precious metals. Troops later ransacked Bohr's institute but found no gold just some uninteresting beakers containing brown liquid. These survived the war and their gold was extracted to be sent to Sweden to be cast into new medals for Franck and Laue.
Clearly alchemy can pay off, even for a quantum physicist. The authors of these two books make much of this story in their peregrinations through the periodic table while also waxing lyrical about the Nobel prize's constituent metal. For Sam Kean in The Disappearing Spoon, gold is aloof "because it doesn't bond with other elements", while Hugh Aldersey-Williams praises its incorruptibility, which inspires "a torrent of other ideals: the golden section and the golden rule"..
Empires have been built on gold, of course medieval Spain, for example. By contrast, Britain's rested on carbon (coal) and iron, while modern America relies on carbon (oil) and silicon. Ours is an elemental world, though it is only relatively recently that we have come to understand the behaviour of these basic building blocks of complex materials.
It was the 18th-century French chemist Antoine Lavoisier who first showed elements were chemically irreducible units of matter; he compiled an early list that included hydrogen, nitrogen, sulphur and oxygen. Scientists added more but could find no pattern to these additions until, in 1869, Dmitri Mendeleev produced his periodic table. In it, he categorised elements by atomic weight and chemical properties. Crucially, he left gaps for elements yet to be discovered.
These omissions made many scientists suspicious until, in 1875, they isolated gallium, whose atomic weight and chemistry had been predicted by Mendeleev. The great Russian was vindicated while chemists' lives were enriched by a substance of beguiling behaviour, as is suggested by the title of Kean's book. Gallium looks like aluminium but melts at a mere 29C. Make a spoon of it, give it to guests to stir their tea and watch it melt and form a metallic puddle at the bottom of their cups. Laugh? They have to mop it up.
The final void in the table was filled, in 1939, with francium, the last naturally occurring element to be uncovered. Physicists then started bombarding existing elements with high-energy particles to create synthetic ones. These, as Kean points out, are the first new elements to appear on Earth since the creation of the solar system billions of years ago and have found widespread use, ranging from plutonium, in nuclear bombs, to americium, which is employed in domestic smoke alarms.
Other elemental nuggets provided by Kean and Aldersey-Williams include the revelation that tellurium is the smelliest of the elements and will leave scientists reeking of a garlic-like odour for weeks should they let a piece touch their skin. By contrast, beryllium tastes like sugar while rhodium, ounce by ounce, is the most expensive to buy hence the disc made of it in 1979 for Paul McCartney after he became the bestselling songwriter and musician of all time.
Not all these periodic tales are so appealing. The 17th-century alchemist Hennig Brand boiled down gallons of his own urine to produce a residue that glowed in the dark. This was the element phosphorus. Brand carried out his work in Hamburg which, 270 years later, had 1,900 tonnes of incendiary phosphorus bombs dropped on it by Allied bombers. The resulting firestorm destroyed much of the city, including the district where Brand had discovered the element, and "melted between 40,000 and 50,000 people," according to the historian Jorg Friedrich. Sadly, phosphorus is still employed to make weapons, as Israel demonstrated during a raid in Gaza in 2009. "The smokescreen that phosphorus produces remains moral as well as literal," notes Aldersey-Williams.
Strangely, these different elements make up a very small part of the cosmos. Ninety per cent more or less of matter in the observable universe consists of hydrogen while the other 10% is helium. The other elements account for a mere 0.04% of total matter and could be dismissed by an overenthusiastic mathematician while rounding up his figures. We live in an odd part of the cosmos, it would seem.
It is provocative stuff, and both books do justice to their topic, though both struggle to forge a proper narrative from all these disjointed tales of elemental discovery. The Disappearing Spoon is cleverly conceived, easily digested but a little too glib for my liking. Periodic Tales follows a more composed, personalised approach including a quite splendid account of the author's visit to a homeopath in a bid to buy his plutonium "cures" and proves to be the more enjoyable and polished of the pair: not pure gold, perhaps, but a glistering effort.
