Uncle Tungsten: Memories of a Chemical Boyhood (2001) (6 page)

Scheele, Uncle Dave would say, was wholly dedicated to his work, caring nothing for fame or money and sharing his knowledge, whatever he had, with anyone and everyone. I was impressed by Scheele’s generosity, no less than his resourcefulness, by the way in which (in effect) he gave the actual discovery of elements to his students and friends – the discovery of manganese to Johan Gahn, the discovery of molybdenum to Peter Hjelm, and the discovery of tungsten itself to the d’Elhuyar brothers.

Scheele, it was said, never forgot anything if it had to do with chemistry. He never forgot the look, the feel, the smell of a substance, or the way it was transformed in chemical reactions, never forgot anything he read, or was told, about the phenomena of chemistry. He seemed indifferent, or inattentive, to most things else, being wholly dedicated to his single passion, chemistry. It was this pure and passionate absorption in phenomena – noticing everything, forgetting nothing – that constituted Scheele’s special strength.

Scheele epitomized for me the romance of science. There seemed to me an integrity, an essential goodness, about a life in science, a lifelong love affair. I had never given much thought to what I might be when I was ‘grown up’ – growing up was hardly imaginable – but now I knew: I wanted to be a chemist. A chemist like Scheele, an eighteenth-century chemist coming fresh to the field, looking at the whole undiscovered world of natural substances and minerals, analyzing them, plumbing their secrets, finding the wonder of unknown and new metals.

Light for the Masses

U
ncle Tungsten was a complex mixture, at once intellectual and practical, as were most of his brothers and sisters, and the man who fathered them all. He loved chemistry, but he was not a ‘pure’ chemist, like his younger brother Mick; Uncle Dave was an entrepreneur, a businessman, as well. He was a manufacturer who made a moderately good living – there was always a ready sale for his bulbs and vacuum tubes, and this was enough. He knew everyone who worked for him in friendly, personal detail. He had no desire to expand, to become huge, as he could easily have done. He remained, as he had first been, a lover of metals and materials, endlessly fascinated by their properties. He would spend hundreds of hours watching all the processes in his factories: the sintering and drawing of the tungsten, the making of the coiled coils and molybdenum supports for the filaments, the filling of the bulbs with argon in the old factory in Farringdon, and the blowing of the glass bulbs and their pearling with hydrofluoric acid at his new factory in Hoxton. He did not need to do this – his staff was competent, and the machinery worked perfectly – but he loved it, and he would sometimes think of further refinements, new processes, as he did so. He did not really need the compact but finely equipped laboratories in his factories, but he was curious and addicted to experiment, some of it with immediate application to his manufacturing, though much of it, as far as I could judge, for the pure pleasure of it, for fun. Nor did he need to know, as he did in encyclopedic detail, the history of incandescent lamps, of lighting generally, and of the basic chemistry and physics behind them. But he loved to feel that he was part of a tradition – a tradition at once of pure science, applied science, artisanry, and industry.

Edison’s vision, Uncle liked to say, of light for the masses, had finally come true in the incandescent bulb. If someone could look at the earth from outer space, see how it rotated every twenty-four hours into the shadow of night, they would see millions, hundreds of millions, of incandescent bulbs light up nightly, glowing with white-hot tungsten, in the folds of that shadow – and know that man had finally conquered the darkness. The incandescent bulb had done more to alter social habits, human lives, Uncle would say, than any other invention he could think of.

And in many ways, Uncle Dave told me, the history of chemical discovery was inseparable from the quest for light. Before 1800, one had only candles or simple oil lamps such as had been used for thousands of years. Their light was feeble, and the streets were dark and dangerous, so one could hardly go out at night without a lantern or a full moon. There was a tremendous need for an efficient form of lighting that could be used safely and easily in the home and in streetlamps.

At the beginning of the nineteenth century gas lighting was introduced, and people experimented with many forms of this. Different nozzles produced gas flames of different shapes: there was the bat’s-wing and the fish-tail and the cock-spur and the cock’s-comb – I loved these names, as he said them, just as I loved the beautiful shapes of the flames.

But gas flames, with their glowing carbon particles, were scarcely brighter than candle flames. One needed something additional, a material that would shine with special brilliance when heated in a gas flame. Such a substance was calcia – calcium oxide, or lime – which shone with an intense greenish white light when heated. This ‘limelight,’ Uncle Dave said, was discovered in the 1820
s
and used to illuminate the stages in theaters for many decades – that was why we still talked about ‘the limelight,’ even though we no longer used lime for incandescence. One could get a similar brilliant light by heating several other earths – zirconia, thoria, magnesia, alumina, zinc oxide. (‘Do they call that zincia?’ I asked. ‘No,’ said Uncle, smiling – ’I never heard it called that.’)

It became clear by the 1870
s
, after many oxides had been tried, that there were some mixtures that glowed more brilliantly than any of the individual oxides. Auer von Welsbach, in Germany, experimented with innumerable such combinations and finally, in 1891, hit on the ideal: a 99-to-l mixture of thoria and ceria.This ratio was critical: a 100-to-l or 98-to-l ratio, Auer found, was far less effective.

Up to this point, bars or pencils of oxide had been used, but Auer found that ‘a fabric of suitable shape,’ a ramie mantle, could provide a far greater surface area to be impregnated with his mixture and thus a brighter light. These mantles would revolutionize the whole industry of gas lighting, allowing it to seriously compete with the infant electric light industry.

My Uncle Abe, a few years older than Uncle Dave, had a vivid memory of this discovery, and of how their somewhat dimly lit house in Leman Street was suddenly transformed by the new incandescent mantles. He remembered too how there had been a great thorium rush: in the course of a few weeks thorium rose to ten times its previous price and a desperate search began for new sources of the element.

Edison, in America, was also a pioneer experimenter on the incandescence of various rare earths, but had failed to make the breakthrough that Auer did, and had turned his attention in the late 1870
s
to perfecting a different sort of light, an electric light. Swan, in England, and several others, had started experimenting with platinum bulbs in the 1860
s
(Uncle had one of these early Swan bulbs in his cabinet); and Edison, intensely competitive, now joined the race, but found, like Swan, that there were major difficulties: platinum’s melting point, though high, was not high enough.

Edison experimented with many other metals with higher melting points to get a workable filament, but none proved suitable. Then in 1879 he had a brainwave. Carbon had a much higher melting point than any metal – no one had ever been able to melt it – and though it conducted electricity, it had a high resistance, which would make it heat up and incandesce more easily. Edison tried making spirals of elemental carbon, akin to the metal spirals in earlier filaments, but these carbon spirals fell apart. His solution – almost absurdly simple, though it took an act of genius on his part to see it – was to take an organic fiber (paper, wood, bamboo, linen or cotton thread) and burn it, leaving a skeleton of carbon sufficiently strong to hold together and conduct a current. If these filaments were inserted into evacuated bulbs, they could provide a steady light for hundreds of hours.

Edison’s bulbs opened up the possibility of a real revolution – though, of course, they had to be tied to a whole new system of dynamos and power lines. ‘The first central electrical system in the world was constructed by Edison right here in 1882,’ Uncle said, taking me to the window and motioning toward the streets below. ‘Big steam dynamos were installed on Holborn Viaduct, over there, and they supplied three thousand electric lightbulbs along the Viaduct, and on Farringdon Bridge Road.’

The 1880
s
, then, were dominated by electric bulbs and the setting up of a whole network of power stations and power lines. But then in 1891, Auer’s perfected gas mantles, which were highly efficient and moderately priced (and could use existing gas lines), mounted a serious challenge to the young industry of electric light. My uncles had told me about the fight between electric and gas lighting when they were young, and how the balance kept shifting in favor of one or the other. Many houses built in this era – including ours – had been equipped for both, as it was unclear which would win out in the end. (Even fifty years later, in my boyhood, there were many streets in London, especially in the City, that were still lit by gas mantles, and sometimes at dusk one could see the lamplighter with his tall pole, going from one streetlamp to another, lighting them one by one. I loved to watch this.)

But for all their virtues, the carbon bulbs had problems. They were fragile and became more so with use, and they could only be run at a relatively low temperature, so one had a dullish yellow light, not a brilliant white one.

Was there any way out of this? One needed a material with a melting point almost as high as carbon’s, or at least around 3,000°C, but with a toughness a thread of carbon could never have – and only three such metals were known: osmium, tantalum, and tungsten. Uncle Dave seemed to become more animated at this point. He admired Edison and his ingenuity enormously, but carbon filaments, it was obvious, were not to his taste. A respectable filament, he seemed to feel, had to be made of metal, for only metals could be drawn to form proper wires. A wire of soot, he sniffed, was a contradiction in terms, and it was astounding that they held up as well as they did.

The first osmium bulbs were made in 1897 by Auer, and Uncle Dave had one of these in his cabinet. But osmium was very rare – the total world production was only fifteen pounds a year – and very costly. It was almost impossible then to draw osmium into wire, so the osmium powder had to be mixed with a binder and squirted into a mold, the binder being subsequently burned off. These osmium filaments, moreover, were very fragile and would break if the bulbs were turned upside down.

Tantalum had been known for a century or more, though there had always been great difficulties in purifying and working it. By 1905 it became possible to purify the metal enough to draw it into wires, and with tantalum filaments, incandescent bulbs could be mass-produced cheaply and compete with carbon bulbs in a way never possible with osmium bulbs. But to get the requisite resistance, one had to use a great length of spidery-thin wire, zigzagging it inside the bulb to make a complex cagelike filament. Though tantalum softened a little when heated, these filaments were nonetheless highly successful, and finally challenged the hegemony of the gas mantle. ‘Suddenly,’ Uncle said, ‘tantalum bulbs were all the rage.’

Tantalum bulbs continued to be the rage until the First World War, but even at the height of their popularity, another filament metal, tungsten, was being explored. The first viable tungsten lamps were made in 1911, and could operate briefly at very high temperatures, though they would soon blacken with the evaporation of tungsten and its deposition on the inner surface of the glass. This challenged the ingenuity of Irving Langmuir, an American chemist who suggested the use of an unreactive gas to exert a positive pressure on the filament, and thus reduce its evaporation. An absolutely inert gas was called for, and an obvious candidate was argon, which had been isolated fifteen years before. But the use of gas filling in turn led to another problem: massive heat loss from convection through the gas. The answer to this, Langmuir realized, was to have as compact a filament as possible, a tightly coiled helix of wire, not a spread-out spiderweb. Such a tight coil could be made with tungsten, and in 1913, all this was put together: finely drawn tungsten wire, tightly coiled helices, in a bulb filled with argon. It was evident, at this point, that the days of the tantalum bulb were numbered, and that tungsten – tougher, cheaper, more efficient – would soon replace it (although this could not happen until after the war, when argon became available in commercial quantities). It was at this point that many manufacturers turned to making tungsten bulbs, and that Uncle Dave, with several of his brothers (and three of his wife’s brothers, the Wechslers, also chemists), pooled their resources and founded their firm, Turigstalite.

Uncle Dave loved telling me this saga, much of which he had lived through himself, and its pioneers were heroes to him, not least because they had been able to combine a passion for pure science with strong practical and business sense (Langmuir, he told me, was the first industrial chemist ever to get a Nobel prize).

Uncle Dave’s bulbs were larger than Osram, or GE, or other electric bulbs on the market – larger, heavier, and almost absurdly robust, and they seemed to last forever. Sometimes I longed for them to expire, so I could then smash them (not easy) and pull out the tungsten filaments and their molybdenum supports, and then have the pleasure of going to the triangular cupboard under the stairs to get a new, mint bulb, wrapped in its crinkled cardboard cylinder. Other people bought their electric bulbs one at a time, but we were sent cartons straight from the factory, a few dozen bulbs at a time – 60-watt and 100-watt bulbs for the most part, though we used little 15-watt bulbs for cupboards and night-lights, and a blazing 300-watt bulb as a beacon on the front porch. Uncle Tungsten made lightbulbs of all sorts and sizes, from dinky 1½-volt bulbs designed for little penlights to immense bulbs used for football fields or search-lights. There were also bulbs of special shapes, designed for instrument dials, ophthalmoscopes, and other medical instruments; and (despite Uncle’s attachment to tungsten) bulbs with filaments of tantalum for use in cinema projectors and on trains. Such filaments were less efficient, less capable of higher temperatures than tungsten, but more resistant to vibration. These, too, I liked to break open when they went pfft!, so I could extract the tantalum wire inside and add it to my growing stock of metals and chemicals.