Periodic Tales

by Hugh Aldersey-Williams

  This was clearly the result Menghini had been expecting. But the question then arises: why did he think iron would be present? It can only be because the association of iron and Mars, blood and war, originating in Greek and Roman mythology, was so securely rooted in the alchemical orthodoxy of the time, even to the extent that those suffering from disorders of the blood were sometimes recommended to take iron salts. Further evidence that it had long been tacit knowledge that iron and blood were connected in some way comes from the name of one of the metal’s principal ores, haematite, a sixteenth-century coinage, the prefix haem-, being derived from the Greek for blood.

  Menghini too went on to make up preparations rich in iron which he fed to human and animal subjects, afterwards observing the enrichment of the red blood cells, thereby proving that the colour was linked to iron. His research made a vital contribution towards explaining–and curing–chlorosis, a disease characterized by a greenish pallor of the skin, which only then acquired its present name of anaemia, from an-plus haem-, meaning without blood.

  Iron’s association with Mars has equally confused beginnings. It was natural enough for mystics and philosophers to seek correspondences between the sun and the moon and the five observable planets and the similar number of ancient metals. But in the absence of a competent metallurgy it was impossible to decide which metals were pure and irreducible rather than mixtures. As a consequence, brass, bronze and alloys used for coins were often placed on an equal footing with gold, silver, lead and tin, while the special alchemical status of mercury meant that it was not at first linked with a planet at all. In Persia, iron was first linked with the planet Mercury. Only much later did Western alchemists reassign Mercury to its element namesake, freeing iron to pair with Mars.

  When was it first thought that Mars might have a more material connection with iron? The invention of the spectroscope in 1859 enabled scientists to analyse the light emitted by luminous bodies, leading to the discovery of several new elements identified by the signature colours of their flames. A spectrum is like a rainbow in which only a few bands of colour appear. Each element has a characteristic atomic spectrum, due to the absorption and emission of light associated with the unique energy levels of its orbiting electrons. These early spectroscopes, however, were only sensitive to emissions of light, such as from laboratory flames or from the sun. They were not able to say anything about the light reflected from non-luminous objects that gives them their colour. Scientists might speculate that the red planet was rich in iron ore, but it was no more possible to check this than it was to prove that the moon was not made of cheese. And at the time when they might profitably have begun to investigate the question, in the last years of the nineteenth century, many were in any case distracted by the planet’s white, earth-like poles and the supposed ‘canals’ crisscrossing its surface.

  It was not until spacecraft–Viking in 1976 and Pathfinder in 1997–landed on Mars that the origin of the colour could at last be explained. Rather than the dark blue expected from its thin atmosphere, they found the sky to be the colour of butterscotch owing to dust storms. The planet’s surface is covered with the same fine dust, composed of the iron oxide mineral limonite. Recent analysis of data from the Mars landers has indicated that the concentration of iron on the planet’s surface is greater than it is in the crust below, suggesting that the iron may have originated from meteorites rather than as a result of volcanic eruptions bringing mantle rock to the surface.

  It is rare that science finds itself in a position to vindicate superstitious belief, but it happened twice with the revelation of iron in blood and on Mars.

  Iron today brings to mind not venerated meteorites or magic swords, but the engineering achievements of the Industrial Revolution. The Romans had made good use of the metal for weapons, tools and construction, but it was not until 1747, when it was found how to use coal with iron to make steel, that the metal really took over. In that year, Richard Ford, who had inherited Abraham Darby’s pioneering iron foundry at Coalbrookdale in Shropshire, showed that it was possible to vary the amount of coke or coal added to the ore in order to produce iron that was either brittle or tough. The greater control of the metal’s properties achievable by the addition of small amounts of this carbon allowed iron to be manufactured for very different uses, from the structural beams of great bridges to the cogs and wheels of steam engines and spinning machines.

  The most transforming, extravagant and joyous expression of the new iron age was the railroad, an innovation whose debt to the metal is recorded in practically every language except English: chemin de fer, Eisenbahn, ferrovia, vía férrea, järnväg, tetsudou. The iron way swiftly made this element a more visible symbol of power than gold ever had been or silicon ever would be. Sentimental poets naturally read the Industrial Revolution as a destructive force and used its iron as a chief sign of its enslaving effect. As early as 1728, James Thomson, the Scot responsible for the words of ‘Rule Britannia’, bewailed the loss of the poetic golden age in ‘these iron times’. Blake’s long poem ‘Jerusalem’ positively clanks with such references, as in this sharp tirade against both science and the technology to which it gives rise:

  O Divine Spirit, sustain me on thy wings,

  That I may awake Albion from his long and cold repose;

  For Bacon and Newton, sheath’d in dismal steel, their terrors hang

  Like iron scourges over Albion.

  But it wasn’t all bad. I think Aldous Huxley struck nearer the mark, when, in Eyeless in Gaza, he comments as his central character embarks with childlike delight upon a train journey: ‘The male soul, in immaturity, is naturaliter ferrovialis.’ (That is to say: boys by nature love railways. Huxley’s typically clever allusion is to the early Christian writer Tertullian’s belief that the soul is by nature Christian, anima naturaliter christiana.) Roman iron might have been the material of shackles and chains, but Victorian steel opened up new territory, crossed oceans and brought people into contact; it literally built bridges. The magnificent cast iron bridge thrown across the Severn near Coalbrookdale in 1779 is now a UNESCO World Heritage Site. The Menai Strait suspension bridge designed by Thomas Telford in 1819 used wrought iron chains to span a channel 166 metres wide. This met the requirement of the British Admiralty that shipping be free to pass underneath, something that would have been impossible with a bridge based on stone piers. Thirty years later, Robert Stephenson completed a second iron bridge based on a tubular box design that would carry the heavier load of a steam locomotive across the strait in a rectangular tunnel. Between them, the two structures demonstrated the lightweight structural gymnastics that were possible with properly engineered iron. From Joseph Paxton’s Crystal Palace to Isambard Kingdom Brunel’s Great Eastern, we still regard these engineering achievements with real wonder. But the railway above all occasioned excitement at the time–think of Turner’s tumultuous painting of a train rattling along a viaduct, Rain, Steam, and Speed–and still occasions fondness in the memory.

  As the iron meteorites that fell to earth now show, where there is iron, rust is never far behind. Rust has its own potent symbolism, linked to its distinctive bloody colour, and proportionate to the power of iron. As the rise of the industrial age had been accompanied by images of fresh-forged iron so its decline was to be streaked with rust. The band of American states from Michigan east to New Jersey became known as the rustbelt as their steelyards and metal-bashing industries succumbed to foreign competition. The image of rust might be expected to be an entirely negative one. But not so. Just as the love of ruins stems from the vicarious thrill of imagining the collapse of our own civilization, so the corrosion of iron and steel back to the more natural form of rust appears to promise an Arcadian return. Even at the height of the Industrial Revolution, John Ruskin longed to see time and entropy do their work. In 1858, he gave a lecture at Tunbridge Wells, where the famous spring water was apt to turn rusty, commending the ‘ochreous stain’ which he said should not be seen as ‘spoil
ed iron’ but as the element in its ‘most perfect and useful state’. (He ignored an obvious tautology for the sake of his happy phrase, since ochre is simply iron oxide anyway.)

  Ruskin’s sentiment has been enthusiastically endorsed by modern sculptors whose preference is often for steel with an instant patina of rust. Antony Gormley’s Angel of the North in Gateshead embraces multitudes with its wide metal wings. The steel from which it was built recalls the heroic shipbuilding for which Tyneside was famous (ironically from around the time of Ruskin’s lecture), but the rust plainly records its demise. Richard Serra’s great arcs of rusted steel, too, strike me as salutary reminders that our feats of accomplishment are only transient. Most squat in galleries and city squares, but at the Louisiana Museum outside Copenhagen, I discover another Serra slab spanning a wooded gulch. It is a kind of inverse of the achievement of that first great iron bridge–a valley blocked, not crossed, its iron not preserved from nature but left to decompose quietly into the fallen beech leaves. I walk up to the brown wall and tap it to reassure myself that metal lies underneath. I rub my fingers along it as Ruskin must have done to some already neglected Victorian device to capture the ochreous stain. The colour tastes of blood. I wonder if the Martian meteorite I’d held would taste the same–the taste of human blood in a stone from Mars generated from celestial iron.

  The Element Traders

  The starting point for this book was my adolescent collection of the elements. I probably never got past thirty or forty out of the hundred-plus complete set, harvesting them from round the house, even with the help of one or two more elusive substances stolen from school. I am not a natural collector. But as I set to work this time, I begin to realize there is quite a community of people out there who have stuck with it and who have not only completed their set, but made it into a project, a mission and even a business.

  They are abetted in this by the internet. The periodic table provides the perfect map, a familiar visual mnemonic that leads down many rabbit-holes. Peter van der Krogt, a geographer at the University of Utrecht and a cartographic historian, clearly appreciates this. His website gives the etymology and the history of the discovery of 112 elements. (The site also includes a link to his collection of car licence plates and coins with maps on them.) On another website, Theodore Gray’s periodic table is a masterpiece of the carpenter’s art–he will even sell you a periodic table table. The story of each element lies on the other side of an engraved wooden portal. Once past this timber threshold, there are beautiful images of the element and its minerals and details of where and how he obtained them. The sources are sometimes exotic, but more often very ordinary: his cerium comes from a camp-fire starter bought from Walmart, his bromine in the form of sodium bromide used to salt the water in hot-tubs. He also accepts donations. ‘A lot of people seem to have an element or two in their attic,’ he notes laconically on the site. ‘By the way, if you have any depleted Uranium from Afghanistan, I could use it.’

  Max Whitby and Fiona Barclay have made more than a hobby of the elements. They are element traders, supplying fellow enthusiasts like Gray with specimens of the pure elements from their mews studio-cum-laboratory in a former chocolate factory in West London. Whitby is a former director of the BBC’s Tomorrow’s World programme. He set up a business publishing multimedia before going back to school and rediscovering his scientific roots. He has recently been awarded a doctoral degree for research in carbon ‘nanopipes’, the tiny rolls of graphite that are currently one of the hottest fields of chemical investigation. Fiona manages a company called Bird-Guides, which produces exactly what its name suggests. Together the two have combined their interests to produce lavish natural history DVDs, and, on the side, run their trade in the elements.

  We meet for lunch at a local greasy spoon serving improbably authentic Thai food. Max and Fiona have come prepared. Out on to the table come samples of various metallic elements, solid lumps the size and shape of thirty-five-millimetre film canisters. I am invited to guess what they are. Magnesium and tungsten are easy enough to tell apart, but others have me stumped. So many are similar at first glance, with the same grey sheen. However, closer inspection reveals slight differences. The light they reflect is subtly different in colour–some metals have the barest tinge of pink, or yellow, or blue. The surfaces have all been polished smooth, but according to the way the metals naturally solidify, they vary in appearance, some being almost mirror-like while others are slightly grainy, hinting at a distinctive crystalline microstructure.

  It is when you pick up the specimens that they really start to separate themselves. You start out with a fairly clear idea of what you think a lump of metal that size should weigh–information you’ve gathered over a lifetime from shuffling coins or handling kitchen utensils. But these more unusual specimens soon confound those expectations. Some, like the tungsten, are astonishingly heavy, and a few are so improbably light that you doubt they can be metal at all and wonder if they are cunningly disguised plastic. Lifting them in turn, you unlearn what you think substances ought to weigh and learn to be surprised each time by how heavy or light each sample is compared with the last. They feel different against the skin. Some are warm to hold, others seem to suck the heat from your hand. They smell different too, some metals tainted by the grease of previous touchings, others maintaining a citrus cleanness. As I pick up one sample after another, I am disappointed at how many I get wrong. I take some consolation from the fact that the bar is set pretty high. One specimen is a block of hafnium, an element mainly used to make control rods in nuclear reactors. What on earth are they doing with it? ‘Contemplating it,’ says Max.

  Why the elements, I ask. ‘I like the way the table explains our world. Each allocation is a little bit of our civilization,’ Max suggests. For Fiona, it’s about collectible sets–‘birds, butterflies and elements’.

  The trick is to buy the elements in bulk, as they are typically supplied for industry, and then to melt them down and remake them into more attractive forms. Most enthusiasts prefer their metal elements prepared as shiny beads that show their lustre to good effect. Others, German collectors especially, for some reason, want more natural-looking specimens, and creating these may involve heating and cooling pieces of the element in such a way that they form large crystals.

  Perhaps thirty of the elements can be bought over the counter, if you know the right counter. Magnesium, for example, is sold by ships’ chandlers for use as ‘sacrificial anodes’ placed below the waterline where they corrode in preference to other metal parts of the vessel. Max’s raw magnesium is the sacrificial anode of an oil tanker, a whopping lump the size of a hip bath. Rarer metals used as catalysts are sold in the form of powder. Max and Fiona chop and mould these raw materials into the prettier forms that customers appreciate as ‘elements as they truly are’. Whether this is as they truly are is a moot point, of course. But diced, sautéed and served up in these ways, the elements are certainly deliciously transformed. The inert gases come in discharge tubes bent into the shape of the letters of their respective chemical formulae. The most reactive or poisonous elements come in sealed ampoules–subject to shipping restrictions. Even radioactive rarities such as radium and promethium are offered for sale, in the form of glowing hands salvaged from old wristwatches and safely encased in resin.

  Their clients include schools and chemical companies, for whom they construct beautiful displays of elements and their compounds pigeonholed into illuminated boxes. But another significant portion of their business comes from obsessive individuals. Radiologists are prominent among their customers: perhaps the dependence for their work on the ability of radioactive forms of certain elements to decay into other elements leaves them craving the apparent fixity of the periodic table. For others it is undoubtedly the finitude that appeals. A complete set of the elements is after all the ultimate collection: from it you could in principle make anything found in any collection anywhere.

  They show me beads of rare metals
: rhodium, ruthenium, palladium and osmium. All these elements are closely related to platinum and share its serious grey lustre. They look extremely similiar, although detailed examination reveals slight variations among them. I can see that osmium, for example, has a distinctly blue tinge compared with its precious neighbours. I heft the pieces in my hand–the densest of all the elements and therefore the densest substance known to exist. I cautiously sniff them too. Although osmium metal is benign, its volatile oxide is one of the smelliest and most poisonous substances known. I am relieved to find I can smell nothing. In 2004, osmium tetroxide was at the centre of a terrorist alarm in London. I ask if innocent element-trading isn’t made difficult because of such things. Max admits he has been visited once or twice by the ‘nuclear police’. ‘They were very nice. They gave us some advice on how to improve our inventory.’

  Max and Fiona’s task for the day is to prettify some industrial molybdenum. Molybdenum is a good example of the many elements we tend to hear little about even though they are not rare and are often quietly useful, this one being employed mainly in specialist steel alloys. They start with a few pieces of dull grey metal in powder form pressed into cake rather than cast ingots or forged bars. Molybdenum has one of the highest melting points of all the elements, and so the next stage is quite a palaver, requiring a powerful electric furnace. The floor of the furnace is a copper plate which will itself be prevented from melting under the extreme heat by cold water running underneath it. Around this is what looks like a glass bell jar, but is in fact a protective screen of quartz, which makes a transparent circular wall. The whole contraption is no bigger than a pressure cooker, but seems able, like an Elizabethan theatre, to contain worlds.