Uncle Tungsten: Memories of a Chemical Boyhood (2001) (25 page)

The wonder of spectral analysis, analysis at a distance, had literary resonances as well. I had read
Our Mutual Friend
(written in 1864, just four years after Bunsen and Kirchhoff had launched spectroscopy), and here Dickens imagined a ‘moral spectroscopy’ whereby the inhabitants of remote galaxies and stars might analyze the light from the Earth to gauge its good and evil, the moral spectrum of its inhabitants.

‘I have little doubt,’ Lockyer wrote at the end of his book, ‘that, as time rolls on…the spectroscope [will] become…the pocket companion of everyone amongst us.’ A small spectroscope became my own constant companion, my instant analyzer of the world, whipped out on all sorts of occasions: to look at the new fluorescent lights that were beginning to appear in London Tube stations, to look at solutions and flames in my lab, or at coal fires and gas flames in the house.

I also explored the absorption spectra of compounds of all sorts, from simple inorganic solutions to blood, leaves, urine, and wine. I was fascinated to find out how characteristic the spectrum of blood was even when dried and how small a quantity was needed to analyze in this fashion – one could identify a faint bloodstain more than fifty years old and distinguish it from a rust stain. The forensic possibilities of this intrigued me; I wondered if Sherlock Holmes, along with his chemical explorations, had used a spectroscope too. (I was especially fond of the Sherlock Holmes stories, and even more of the Professor Challenger ones which Conan Doyle had written later – I identified with Challenger; I could not identify with Holmes. In
The Poison Belt
, spectroscopy plays a crucial role, for it is a change in the Fraunhofer lines of the sun’s spectrum that alerts Challenger to the presence of an approaching poison cloud.)

But it was the bright lines, the brilliant colors, the emission spectra I always came back to. I remember going to Piccadilly Circus and Leicester Square with my pocket spectroscope, and looking at the new sodium lights that were being used for street lighting, at the scarlet neon advertisements, and at the other gas-discharge tubes – yellow, blue, green, according to the gas used – which now turned the West End into a glory of colored lights after the long blackout of the war. Each gas, each substance, had its own unique spectrum, its own signature.

Bunsen and Kirchhoff had felt that the position of the spectral lines was not only a unique signature of each element, but a manifestation of its ultimate nature. They seemed to be ‘a property of a similar unchangeable and fundamental nature as the atomic weight,’ indeed a manifestation – as yet hieroglyphic and indecipherable – of their very constitution.

The complexity of spectra (that of iron, for example, contained several hundred lines) in itself suggested that atoms could hardly be the small, dense masses which Dalton had imagined, distinguished by their atomic weights and little else.

One chemist, W.K. Clifford, writing in 1870, expressed this complexity in terms of a musical metaphor:

…a grand piano must be a very simple mechanism compared with an atom of iron. For in the spectrum of iron there is an almost innumerable wealth of separate bright lines, each one of which corresponds to a sharp definite period of vibration of the iron atom. Instead of the hundred-odd sound vibrations which a grand piano can emit, the single iron atom appears to emit thousands of definite light vibrations.

There were a variety of such musical images and metaphors at the time, all concerned with the ratios, the harmonics, which seemed to lurk in the spectra, and the possibility of expressing them in a formula. The nature of these ‘harmonics’ remained unclear until 1885, when Balmer was able to find a formula relating the position of the four lines in the visible spectrum of hydrogen, a formula that enabled him to predict correctly the existence and position of further lines in the ultraviolet and infrared. Balmer, too, thought in musical terms, and wondered whether it might be ‘possible to interpret the vibrations of the individual spectral lines as overtones of, so to say, one specific keynote.’ That Balmer was on to something of fundamental importance, and not some numerological mumbo jumbo, was immediately recognized, but the implications of his formula were wholly enigmatic – as enigmatic as Kirchhoff’s discovery that the emission and absorption lines of elements were the same.

Cold Fire

M
y many uncles and aunts and cousins served as a sort of archive or reference library, and I would be referred to different ones for specific problems: most often to Auntie Len, my botanical aunt, who had played such a lifesaving role in the grim days of Braefield, or Uncle Dave, my chemical and mineralogical uncle, but there was also Uncle Abe, my physics uncle, who had started me on spectroscopy. Uncle Abe was consulted rather rarely at first, because he was one of the senior uncles, six years Uncle Dave’s senior and fifteen years my mother’s. He was regarded as the most brilliant of his father’s eighteen children. He was intellectually formidable, although his knowledge had come through a sort of osmosis, not formal training. Like Dave, he had grown up with a taste for physical science, and like Dave, he had gone geologizing to South Africa as a young man.

The great discoveries of X-rays, radioactivity, the electron, and quantum theory had all occurred in his formative years and were to remain central interests for the rest of his life; he had a passion for astronomy and for number theory as well. But he was also perfectly capable of turning his mind to practical and commercial ends too. He played a part in developing Marmite, the widely used vitamin-rich yeast extract developed early in the century (my mother adored this; I hated it), and, in the Second World War, when normal soap was difficult to get, he helped develop an effective fat-free soap.

Though Abe and Dave were alike in some ways (both had the broad Landau face, with wide-set eyes, and the unmistakable, resonant Landau voice – characteristics still marked in the great-great-grandchildren of my grandfather), they were very different in others. Dave was tall and strong, with a military posture (he had served in the Great War and in the Boer War before that), always carefully dressed. He would wear a wing collar and highly polished shoes even when he worked at his lab bench. Abe was smaller, somewhat gnarled and bent (in the years that I knew him), brown and grizzled, like an old shikari, with a hoarse voice and chronic cough; he cared little what he wore, and usually had on a sort of rumpled lab smock.

The two were associated formally as codirectors of Tungstalite, though Abe left the business end to Dave and spent all his time in research. It was he who developed a safe and effective way of ‘pearling’ lightbulbs with hydrofluoric acid in the early 1920
s
 – he had designed the machines to do this in the Hoxton factory. He also worked on the use of ‘getters’ in vacuum tubes – highly reactive, oxygen-hungry metals like cesium and barium which could remove the last traces of air from a tube – and, earlier, he had patented the use of Hertzite, his synthetic crystal, for crystal radios.

He had developed and patented a luminous paint, and this was used in military gunsights in the First World War (it may have been decisive, he told me, in the Battle of Jutland). His paints were also used to illuminate the dials of Ingersoll watches and clocks. He had, like Uncle Dave, big, capable hands, but where Uncle Dave’s were seamed with tungsten, Uncle Abe’s were covered with radium burns and malignant warts from his long, careless handling of radioactive materials.

Both Uncle Dave and Uncle Abe were intensely interested in light and lighting, as was their father; but with Dave it was ‘hot’ light, and with Abe ‘cold’ light. Uncle Dave had drawn me into the history of incandescence, of the rare earths and metallic filaments which glowed and incandesced brilliantly when heated. He had inducted me into the energetics of chemical reactions – how heat was absorbed or emitted during the course of these; heat that sometimes became visible as fire and flame.

Through Uncle Abe, I was drawn into the history of ‘cold’ light – luminescence – which started perhaps before there was any language to record things, with observations of fireflies and glowworms and phosphorescent seas; of will-o’ – the-wisps, those strange, wandering, faint globes of light that would, in legend, lure travelers to their doom. And of Saint Elmo’s fire, the eerie luminous discharges that could stream in stormy weather from a ship’s masts, giving its sailors a feeling of bewitchment. There were the auroras, the Northern and Southern Lights, with their curtains of color shimmering high in the sky. A sense of the uncanny, the mysterious, seemed to inhere in these phenomena of cold light – as opposed to the comforting familiarity of fire and warm light.

There was even an element, phosphorus, which glowed spontaneously. Phosphorus attracted me strangely, dangerously, because of its luminosity – I would sometimes slip down to my lab at night to experiment with it. As soon as I had my fume cupboard set up, I put a piece of white phosphorus in water and boiled it, dimming the lights so that I could see the steam coming out of the flask, glowing a soft greenish blue. Another, rather beautiful experiment was boiling phosphorus with caustic potash in a retort – I was remarkably nonchalant about boiling up such virulent substances – and this produced phosphoretted hydrogen (the old term), or phosphine. As the bubbles of phosphine escaped, they took fire spontaneously, forming beautiful rings of white smoke.

I could ignite phosphorus in a bell jar (using a magnifying glass), and the jar would fill with a ‘snow’ of phosphorus pentoxide. If one did this over water, the pentoxide would hiss, like red-hot iron, as it hit the water and dissolved, making phosphoric acid. Or by heating white phosphorus, I could transform it into its allotrope, red phosphorus, the phosphorus of matchboxes.«52» I had learned as a small child that diamond and graphite were different forms, allotropes, of the same element. Now, in the lab, I could effect some of these changes for myself, turning white phosphorus into red phosphorus, and then (by condensing its vapor) back again. These transformations made me feel like a magician.«53»

But it was especially the luminosity of phosphorus that drew me again and again. One could easily dissolve some of it in clove oil or cinnamon oil, or in alcohol (as Boyle had done) – this not only overcame its garlicky smell, but allowed one to experiment with its luminosity safely, for such a solution might contain only one part of phosphorus in a million, and yet still glow. One could rub a bit of this solution on one’s face or hands, and they would glow, ghostlike, in the dark. This glow was not uniform, but seemed (as Boyle had put it) ‘to tremble much, and sometimes…to blaze out with sudden flashes.’

Hennig Brandt of Hamburg had been the first to obtain this marvelous element, in 1669. He distilled it from urine (apparently with some alchemical ambition in mind), and he adored the strange, luminous substance he had isolated, and called it cold fire (
kaltes Feuer
), or, in a more affectionate mood,
mein Feuer
.

Brandt handled his new element rather carelessly, and was apparently surprised to discover its lethal powers, as he wrote in a letter to Leibniz on April 30, 1679:

When in these days I had some of that very fire in my hand and did nothing more than blow on it with my breath, the fire ignited itself as God is my witness; the skin on my hand was burned truly into a hardened stone such that my children cried and declared that it was horrible to witness.

But though all the early researchers burned themselves severely with phosphorus, they also saw it as a magical substance that seemed to carry within itself the radiance of glowworms, perhaps of the moon, a secret, inexplicable radiance of its own. Leibniz, corresponding with Brandt, wondered whether the glowing light of phosphorus could be used for lighting rooms at night (this, Abe told me, was perhaps the first suggestion of using cold light for illumination).

No one was more intrigued by this than Boyle, who made detailed observations of its luminescence – how it, too, required the presence of air, how it fluctuated strangely. Boyle had already made extensive investigations of ‘luciferous’ phenomena, from glowworms to luminous wood and tainted meat, and had made careful comparisons of such ‘cold’ light with that of glowing coals (both, he found, needed air to sustain them).

On one occasion Boyle was called down from his bedchamber by his frightened and astonished servant, who reported that some meat was glowing brightly in the dark pantry. Boyle, fascinated, got up at once and commenced an investigation, which culminated in his charming paper ‘Some Observations about Shining Flesh, both of Veal and Pullet, and that without any sensible Putrefaction in those Bodies.’ (The shining was probably due to luminescent bacteria, but no such organism was known or suspected in Boyle’s time.)

Uncle Abe, too, was fascinated by such chemical luminescence, and had experimented a great deal with it as a young man, and with luciferins, the light-producing chemicals of luminous animals. He had wondered whether they could be turned to practical use, to make a really brilliant luminous paint. Chemical luminosity could indeed be dazzlingly brilliant; the only problem was that it was ephemeral, transient, by nature, disappearing as soon as the reactants were consumed – unless there could be (as with fireflies) a continued production of the luciferous chemicals. If chemistry was not the answer, then one needed some other form of energy, something that could be transformed into visible light.

Abe’s interest in luminescence had been stimulated, when he was growing up, by a luminous paint used in their old house in Leman Street – Balmain’s Luminous Paint, it was called – for painting keyholes, gas and electric fixtures, anything that had to be located in the dark. Abe found these glowing keyholes and switches wonderful, the way they glowed softly for hours after being exposed to light. This sort of phosphorescence had been discovered in the seventeenth century, by a shoemaker in Bologna who had gathered some pebbles, roasted them with charcoal, and then observed that they glowed in the dark for hours after they had been exposed to daylight. This ‘phosphorus of Bologna,’ as it was called, was barium sulphide, produced by the reduction of the mineral barytes. Calcium sulphide was easier to procure – it could be made by heating oyster shells with sulphur – and this, ‘doped’ with various metals, was the basis of Balmain’s Luminous Paint. (These metals, Abe told me, added in minute amounts, ‘activated’ the calcium sulphide, and lent it different colors as well. Perfectly pure calcium sulphide, paradoxically, did not glow.)