Periodic Tales

by Hugh Aldersey-Williams

  It was not until 1831 that the element was rediscovered half a world away in a quite different kind of mineral by the Swede Nils Sefström and given the name by which we know it today. Sefström was the director of mines at Falun, 200 kilometres north-west of Stockholm. He had formerly worked as an assistant to Jöns Jacob Berzelius, one of the greatest figures in the history of science, who, as we shall see later, played his own disproportionate role in the discovery of the elements. It was Berzelius who chose the name vanadium, after Vanadis, an alternative name for the goddess Freyja, who appears in some of the Norse eddas. Vanadis (the dis of the Vanir, or ‘lady of the beautiful people’) is the goddess of love, beauty and fertility. Except when engaged in some naked seduction, which is often, she appears robed in colour and glittering with jewels. Her prize possession is Brisingamen, the necklace of the Brisings, which is represented with the most elaborate gold craftsmanship and frequently studded with flaming gemstones. When she weeps, her tears are of red gold if they fall on solid ground and amber if they fall at sea.

  The vanadium mineral–an ore with an unpredictable yield of iron that sometimes proved strong but sometimes brittle–had been a puzzle to Berzelius for some time. In 1823, it was examined by the German Friedrich Wöhler, the most famous of the many chemists who beat a path to Berzelius’s laboratory. Wöhler later became the first person to synthesize a substance found in living organisms (urea, a simple end product of protein decomposition) from exclusively mineral precursors, thereby proving that chemistry was universal across the animate and inanimate realms. But on this occasion there was no revelation. When Sefström duly made his breakthrough, Berzelius wrote to Wöhler with his own little prose edda:

  Long ago there lived in the far North the goddess Vanadis, beautiful and alluring. One day there came a knock at her door. The goddess sat quietly and thought, ‘I will let him knock once more’, but the second knock failed to come, and the man who had knocked merely walked away. The goddess was curious to know who was so indifferent to being admitted, and she sprang to the window to view the departing guest. ‘Ah-ha!’, she said to herself, ‘it’s that rogue Wöhler. It serves him right; had he been a little more persistent I would have let him in. But he doesn’t even look up at the window in passing.’ A few days later there was another knock at the door. Sefström stepped in, and from this meeting Vanadium was born.

  The name of an element can confer a kind of immortality. For a start, the unfortunate Del Río might be better known today if a rival proposal to name his discovery rionium had won more support. But even deities stand to gain by chemical association. ‘In his naming of the elements Berzelius gave new life to the figures of Scandinavian mythology,’ according to one of his biographers. ‘Thorium and vanadium will remain in the periodic table long after Thor and Vanadis and the other gods and goddesses of the Vikings have been forgotten.’

  Preserved in the collection of the Berzelius Museum in Stockholm are some three dozen test tubes filled with the various vanadium salts that the Swede had been able to make. The colours include bright turquoise and pale sky blue, orange, maroon, chestnut and tan, various ochres, a sludgy green and black–many of the shades found in the tunicates.

  Crushing Emeralds

  Beauty comes out of necessity. For though we may dress up the truth with fancy aesthetic theories, we are biologically programmed to appreciate colour and the reflected glare of the sun for our survival. These things are signals of ripe fruit in the trees and the sparkle of fresh water. No wonder that Vanadis named her daughters–with wince-making new-age trendiness, it seems to us now–Hnoss (Jewel) and Gersemi (Treasure), reflecting these two properties so coveted in the dull, dark north: the colourful and the gleaming.

  Prized above all are finds or artefacts that unite the two qualities, such as polished gemstones and of course the shining yellow metal gold. These conjoint desires are reflected in our language. The word gleam stems from an Indo-European root, ghlei-, ghlo- or ghel-, meaning ‘to shine, glitter or glow’, which is also the origin of the word yellow. An astonishing number of words that describe light coming in bright flashes share this root (glint, glitter, glimmer, glisten, glitz, glance and gloss among them, as well as cognates such as glad and gloat, which reveal our emotional investment in objects possessing this property). Glass as well as glare comes from the Anglo-Saxon glær, meaning amber, another shining yellow substance found in nature and one of the customary ornaments of the goddess Vanadis.

  The Viking goldsmith unites metallic gleam and crystal colour when he sets a stone–Brisingamen is described as ‘gem-figured filigree’ in Beowulf. But what the smith cannot know is that both metal and jewel may have the same elemental origin. Vauquelin had discovered bright chromium by accident in a humble if rare specimen of red lead carbonate from Siberia. Along with other scientists of the age he was greatly preoccupied with the question of what gave precious stones their signal colours. In the vast chemical encyclopedia that he produced with his mentor Antoine-François de Fourcroy between 1786 and 1815, Vauquelin agreed that the ruby was ‘the most esteemed of precious stones’, and noted that the beryls, a class of gem-stone that he recognized to include emeralds, came in colours ranging all the way from blue-green to the ‘russet yellow of honey’ ‘the best emeralds come from Peru,’ he added.

  Shortly after his discovery of chromium, Vauquelin, newly promoted as an official assayer of precious metals, was to be found pounding a Peruvian emerald in a pestle and mortar and dissolving its powder in nitric acid in an attempt to unweave the rainbow of the jewel box. He was able to convert the residue into the same substance he had obtained from the Siberian ore, thereby proving that the colouring agent in emerald was chromium. He went on to show that the red of ruby was also due to chromium. More comprehensive analysis only possible more than a century later finally explained why these gems have been prized for so long. The deep red of rubies and limpid green of emeralds is only the half of it: the chromium in both stones also fluoresces with red light, so that the stones appear to flicker with inner fire.

  If the same contaminating metal, chromium, could be responsible for two such brilliantly contrasting colours, it suggested that there was something worth investigating about the basic matrix of the ruby and beryl crystals into which the chromium was locked which might explain this dramatic difference. Vauquelin returned to analyse the beryls in more detail, discovering that they were comprised of a number of basic ores. The main constituent was silica, or silicon dioxide, as in sand, quartz and amethyst. Alumina made up much of the remainder. This crystalline form of aluminium oxide is the principal ingredient of corundum, of which rubies and sapphires are made. But there was also, Vauquelin now realized, a new oxide which had escaped detection earlier because of its unremarkable similarity to the others. Isolated and purified, however, this oxide did possess one exceptional property. It was sweet to the taste, and for this reason Vauquelin named it ‘glucina’. The new metallic element that he knew it must contain he called ‘glucinum’, although nobody would be able to produce it for another thirty years. (Zirconium, another new element, discovered in rather similar fashion in stones of jargon, or zircon, by Vauquelin’s German friend Martin Klaproth in 1789, also went through a long purdah, only being isolated by Berzelius in 1824.) Later, it emerged that glucina was not the only sweet-tasting metal compound, and it was renamed beryllia and its associated element, beryllium.

  For those seeking riches, news of these experiments must have come as a disappointment. Even the most precious gemstones were shown to contain no precious essence, as the more alchemically minded investigators had surely hoped they would. Unlike the dirty ores, from which gleaming metal could be extracted, these crystals lost all their value when they were processed in the laboratory. Just two years before Vauquelin’s experiments with emerald and ruby, the English chemist Smithson Tennant even burnt a diamond away to nothing, proving that it was made of nothing more exotic than carbon.

  The modern chemists had thei
r reward though–Vauquelin had his chromium and beryllium, Sefström and Berzelius their vanadium, Klaproth his zirconium. Their work cleared away much confusion in the jewel trade. Tales of precious artefacts seen by excitable explorers in remote lands could now be subjected to more sceptical examination. It became obvious, for example, that many stones claimed to be emeralds were too large to be true gems, and that the term was being employed simply as an admiring simile for all manner of green objects that were actually made of jade or even glass. Today, when much progress has been made in the manufacture of artificial stones, the word ‘gem’ is generally reserved for natural specimens. Classification according to colour is more of a problem. Because the colour of gemstones arises from impurities in them, there is no rigorous definition of what makes an emerald or a ruby. A beryl is therefore simply a stone too pale to be called an emerald on an arbitrary scale of greenness.

  Increasing colonial trade with countries rich in these minerals, such as Burma and Colombia, together with machine cutting techniques, saw to it that coloured jewels grew in popularity through the nineteenth century. Jewels were fascinatingly ambivalent in an age when strictness of morals was matched by sumptuousness of ornament. Only virtuous women and wisdom are rarer than rubies, according to the Bible. Wearing jewellery was an indication of virtue, yet also an enticement. The stones themselves are naturally beautiful, but there is devilment in the art with which they are cut, and it is no great surprise to find Mephistopheles giving Margareta a tempting casket of jewels in Goethe’s Faust. The famous ‘jewel song’ of Gounod’s opera version of the story amplifies this transaction as the chaste heroine laughingly imagines herself transformed into a worldly princess–in Bernstein’s wicked parody of the aria in Candide, Cunégonde mordantly reflects that if she’s not pure, at least her jewels are.

  The imputation of purity is doubtless one reason why Ruby and Beryl became popular Christian names in Victorian times, only falling from favour in the 1930s. Today, Ruby may be undergoing a revival, but you have to search a little harder for other names inspired by gemstones: Esmeralda is now fashionable for girls, Jasper for boys.

  The spread of precious stones as luxury consumer goods has prompted more knowledgeable allusions in literature. The emeralds Edmund Spenser refers to in The Faerie Queene or those in Milton’s Paradise Lost might be any green gem, their precise hue less important than their general rarity. But we imagine that the Emerald City in L. Frank Baum’s 1900 fable The Wonderful Wizard of Oz is truly built of that stone. And here the colour may be significant. Easily distracted academic economists have interpreted the story as an allegory of United States monetary policy at the end of the nineteenth century: the yellow brick road represents the gold standard leading the way to the Emerald City, the colour of the greenback dollar, governed by the ineffectual wizard, who is President Grover Cleveland. The allegory depends for its message on the fact that Dorothy wears silver slippers, which become the symbol of the populist ‘free silver’ movement that was pressing the United States mint to make silver tradeable for coin (in the same way that gold was already) following the discovery of new deposits in the American West. Having escaped notice when the book was first published and the issue was topical, this amusing undercurrent was then completely buried in the legendary film version of the story made in 1939. By this time, the subtext was technological rather than economic: Dorothy was famously given ruby slippers to celebrate the Technicolor process in which the part of the film is shot. The ‘silver screen’ was dead.

  The Crimson Light of Neon

  Imagine finding the proverbial painting in the attic. You take it to be examined and are assured that it is an original, indeed a masterpiece, and, what’s more, that it’s by a painter completely unknown to the art world. Naturally, you return to the attic to see what else you can find. And in the dust, you uncover another painting, and then several more–a complete oeuvre, in fact, of a great master whom nobody knew existed.

  This is what happened to William Ramsay, the professor of chemistry at University College London, who discovered five new chemical elements during the 1890s. These new elements bear a strong family resemblance: all are gases, all colourless and odourless, all remarkably unreactive. They earned the name of the inert or noble gases, and most chemists found them boring. Today, however, it is their laziness that makes them useful to us, primarily for lighting: when subjected to electrical excitation they glow brightly while remaining chemically unchanged.

  Ramsay made the first of these discoveries in 1894, working with Lord Rayleigh at the Cavendish Laboratory in Cambridge. Rayleigh had found that nitrogen obtained from minerals by chemical means was mysteriously lighter than nitrogen that remained in the air after burning all the oxygen. Ramsay solved the puzzle by burning shavings of magnesium in atmospheric nitrogen. Most of the gas combined with the reactive metal. But a little was left over, and its spectral light when excited to a glow did not correspond to any known substance. Rayleigh and Ramsay announced their discovery of a new element which they named argon; ‘a most astonishingly indifferent body’, they wrote. Because argon is heavier than nitrogen, its one per cent presence in air had made the atmospheric nitrogen seem a fraction heavier than the chemically made nitrogen. At a college dinner, the poet A. E. Housman proposed the toast ‘argon’ and called on those assembled to ‘Drink to the gas.’

  Ramsay became excited that argon might be the first of a group of elements that would form a new column in the periodic table. In 1895, an American geochemist wrote to Ramsay with news that he had obtained an inert gas by heating a mineral sample. Ramsay wanted to see whether this was argon, too. He scrabbled around for comparable samples, even begging specimens of a likely-looking uranium mineral from the British Museum (he was rebuffed). Soon Ramsay had repeated the American’s experiment and examined the spectrum of the gas that came off. But the spectral lines did not correspond to argon. They indicated something still more unexpected, matching lines previously observed in the light of the sun. This time, Ramsay had confirmed the terrestrial existence of the gaseous element helium.

  Ramsay spent the next three years trying to obtain further gaseous elements from minerals. The day when the new element might turn up became a laboratory joke, but the day never came. In May 1898, he and his assistant, Morris Travers, tried a new tack, taking advantage of new technological developments that enabled gases to be liquefied in large quantities. Since argon is relatively abundant in the air, they reasoned that other equally unreactive gases might be all around us too. They obtained a gallon of liquefied air and carefully boiled it off until just a small residue remained. Analysis of this residue once again revealed new spectral lines. They turned out to be due to a dense gas that Ramsay and Travers called krypton, a name they had first considered for argon. (Krypton means ‘hidden’, argon means ‘lazy’, so as far as the gases’ chemistry goes the names are much of a muchness, but since krypton is rarer than argon it was a good call.) Ramsay telegraphed his wife, who was in Scotland, with news of the discovery. ‘You get a new element every time I come away,’ she wrote back, her faith in her husband’s abilities clearly rather greater than his colleagues’.

  Their basic hunch confirmed, Ramsay and Travers scaled up the same experiment by a factor of a thousand, starting not with liquefied air but with liquid argon. Despite the jibes of rivals and sceptics, Ramsay was confident of success. Anybody who wanted to overtake them would first have to make several bucketfuls of argon, which in itself was no small matter. In a series of careful evaporations, the men this time detected a light gas which boiled off ahead of the argon. In June, Ramsay announced this latest discovery. Ramsay’s thirteen-year-old son Willie, astutely suggested the name novum for the new element, an idea that his father immediately accepted, at least in essence: ‘neon’ merely reflects the convention of using Greek rather than Latin roots when naming elements.

  Once again, Ramsay and Travers confirmed their find using a spectrometer. Placing an electrical potential a
cross a volume of the gas, they were delighted to see a distinctive new glow. Travers was not only an able laboratory hand; he also became Ramsay’s biographer, and was not too modest to include himself as a third-person character in the narrative. His account of the day surely ranks as one of the best accounts of the dramatic moment of discovery:

  As Ramsay pressed down the commutator of the induction coil he and Travers each picked up one of the direct-vision prisms, which always lay at hand on the bench, hoping to see in the spectrum of the gas in the tube some very distinctive lines, or groups of lines. But they did not need to use prisms, for the blaze of crimson light from the tube, quite unexpected, held them for some moments spell-bound.

  Beginning again with liquid neon and krypton, they found one further noble gas, xenon, ‘the stranger’. With evidence of these elements’ uniqueness resting solely on their spectra–there were no measured physical properties and no observed chemical reactions–it is unsurprising that Ramsay had his detractors, especially as he had got into the habit of occasionally announcing his discoveries before actually making them. Not least among the doubters was Dmitrii Mendeleev, who had declared in 1895 that argon did not fit in his periodic table, and so must be a heavy form of nitrogen. The British scientists spent the next two years purifying samples of their new elements in order to prove their existence once and for all. In 1900, the sceptics were finally persuaded. Towards the end of that year, Ramsay gave a major lecture summarizing his experiments, which was then published in the Philosophical Transactions of the Royal Society with a quotation from Sir Thomas Browne’s Religio Medici at its head: ‘Natura nihil agit frustra, is the only indisputed Axiome in Philosophy. There are no Grotesques in Nature; not anything framed to fill up the empty Canons, and unnecessary Spaces.’ Ramsay had filled up five spaces in the periodic table, and a few years later was awarded the Nobel Prize for Chemistry, by which time others had discovered the radioactive gas radon that completed the tally of the noble gases.