11. Humphry Davy: A Poet-Chemist
I first heard Humphry Davy’s name, I think, a little before the war, when my mother took me to the Science Museum, up to the top floor, where there was a model of a coal mine, its dusty galleries lit by feeble lamps. There she showed me the Davy safety lamp – there were several models of this – and explained to me how it worked, and how it had saved innumerable lives. And then she showed me, next to it, the Landau lamp, invented in the 1870s by her father – basically an ingenious modification of the Davy one. Davy was thus identified in my mind as an ancestor of sorts, almost part of the family.
Born in 1778, Davy grew up at the beginning of Lavoisier’s revolution. It was an age of discovery, the coming-of-age of chemistry – a time, too, when great theoretical clarifications were emerging. Davy, an artisan’s son, was apprenticed to a local apothecary-surgeon in Penzance, but soon aspired to something larger. Chemistry, above all, started to attract him. He read and mastered Lavoisier’s Elements of Chemistry – a remarkable achievement for an eighteen-year-old with little formal education. Grand (perhaps grandiose) visions started revolving in his mind: Could he be the new Lavoisier, perhaps the new Newton? (One of his notebooks from this time was labeled ‘Newton and Davy.’)
Lavoisier had left a ghost of phlogiston in his conception of heat or ‘caloric’ as an element, and in his first, seminal experiment, Davy melted ice by friction, thus showing that heat was motion, a form of energy, and not a material substance, as Lavoisier had thought. ‘The non-existence of caloric, or the fluid of heat, has been proved’, Davy exulted. He set forth the results of his experiments in a long ‘Essay on Heat and Light’, a critique of Lavoisier as well as a vision of a new chemistry that he hoped to found, one finally purged of all the remnants of alchemy and metaphysics.
When news of the young man, of his intellect and perhaps revolutionary new thoughts about matter and energy, reached the chemist Thomas Beddoes, he published Davy’s essay, and invited him to his laboratory, the Pneumatic Institute in Bristol. Here Davy analyzed the oxides of nitrogen (which had first been isolated by Priestley) – nitrous oxide (N2), nitric oxide (NO), and the poisonous, brown ‘peroxide’ of nitrogen (N02) – made a detailed comparison of their properties, and wrote a wonderful account of the effects of inhaling the fumes of nitrous oxide, ‘laughing gas.’ Davy’s description of inhaling nitrous oxide, in its psychological perspicacity, is reminiscent of William James’s own account of the same experience a century later, and it is perhaps the first description of a psychedelic experience in Western literature:
A thrilling extending from the chest to the extremities was almost immediately produced… my visible impressions were dazzling and apparently magnified, I heard distinctly every sound in the room… As the pleasurable sensations increased, I lost all connection with external things; trains of vivid visible images passed through my mind and were connected with words in such a manner, as to produce perceptions perfectly novel. I existed in a world of newly connected and newly modified ideas. I theorised; I imagined that I made discoveries.
Davy also discovered that nitrous oxide was an anesthetic, and suggested its use in surgical operations. (He never followed up on this, and general anesthesia was only introduced in the 1840s, after his death.)
In 1800 Davy read Alessandro Volta’s paper describing the first battery, his ‘pile’ – a sandwich of two different metals with brine-dampened cardboard in between – which generated a steady electric current. Although static electricity, as lightning or sparks, had been explored in the previous century, no sustained electrical current was obtainable until now. Volta’s paper, Davy was later to write, acted like an alarm bell among the experimenters of Europe, and, for Davy, suddenly gave form to what he now saw as his life’s work.
He persuaded Beddoes to build a massive electric battery – it consisted of a hundred six-inch-square double plates of copper and zinc, and occupied an entire room – and started his first experiments with it a few months after Volta’s paper. He suspected almost at once that the electric current was generated by chemical changes in the metal plates and wondered if the reverse was also true – whether one might induce chemical changes by the passage of an electric current.
Water could be created (as Cavendish had shown) by sparking hydrogen and oxygen together.[20] Could one now, with the new power of electric current, do the opposite? In his very first electrochemical experiment, passing an electric current through water (he had to add a little acid to render it conducting), Davy showed that it could be decomposed into its constituent elements, hydrogen appearing at one pole or electrode of the battery, and oxygen at the other – though it was only several years later that he was able to show that they appeared in fixed and exact proportions.
With his battery, Davy found, he could not only electrolyze water, but heat metallic wires: a platinum wire, for example, could be heated to incandescence; and if the current was passed into rods of carbon, and these were then separated by a short distance, a dazzling electric ‘arc’ would leap out and bridge them (‘an arc so vivid’, he wrote, ‘that even the sunlight compared with it appeared feeble’). Thus, almost casually, Davy hit upon what were to become two major forms of electrical illumination, incandescence and arc lighting – though he did not develop these, but went on to other things.[21]
Lavoisier, making his list of elements in 1789, had included the ‘alkaline earths’ (magnesia, lime, and baryta) because he felt they contained new elements – and to these Davy added the alkalis (soda and potash), for these, he suspected, contained new elements too. But there were as yet no chemical means sufficient to isolate them. Could the radically new power of electricity, Davy wondered, succeed here where ordinary chemistry had failed? First he attacked the alkalis, and early in 1807 performed the famous experiments that isolated metallic potassium and sodium by electric current. When this occurred, Davy was so ecstatic, his lab assistant recorded, that he danced with joy around the lab.[22]
One of my greatest delights was to repeat Davy’s original experiments in my own lab, and I so identified with him that I could almost feel I was discovering these elements myself. Having read how he first discovered potassium, and how it reacted with water, I diced a little pellet of it (it cut like butter, and the cut surface glittered a brilliant silver-white – but only for an instant; it tarnished at once). I lowered it gently into a trough full of water and stood back – hardly fast enough, for the potassium caught fire instantly, melted, and as a frenzied molten blob rushed round and round in the trough, with a violet flame above it, spitting and crackling loudly as it threw off incandescent fragments in all directions. In a few seconds the little globule had burned itself out, and tranquillity settled again over the water in the trough. But now the water felt warm, and soapy; it had become a solution of caustic potash, and being alkaline, it turned a piece of litmus paper blue.
20
While Cavendish was the first to observe that hydrogen and oxygen, when exploded together, created water, he interpreted their reaction in terms of phlogiston theory. Lavoisier, hearing of Cavendish’s work, repeated the experiment, reinterpreting the results correctly, and claimed the discovery for himself, making no acknowledgment of Cavendish. Cavendish was unmoved by this, being wholly indifferent to matters of priority and, indeed, to all matters merely human or emotional.
While Boyle and Priestley and Davy were all eminently human and engaging, as well as scientifically brilliant, Cavendish was quite a different figure. The range of his achievements was astounding, from his discovery of hydrogen and his beautiful researches on heat and electricity to his famous (and remarkably accurate) weighing of the earth. No less astounding, and even in his lifetime the stuff of legend, was his virtual isolation (he rarely spoke to anyone, and insisted his servants communicate with him in writing), his indifference to fame and fortune (though he was the grandson of a duke, and for much of his life the richest man in England), and his ingenuousness and incomprehension in regard to all human relationships. I was deeply moved, but if anything more mystified, when I read more about him.
He did not love; he did not hate; he did not hope; he did not fear; he did not worship as others do [wrote his biographer George Wilson in 1851]. He separated himself from his fellow men, and apparently from God. There was nothing earnest, enthusiastic, heroic, or chivalrous in his nature, and as little was there anything mean, grovelling, or ignoble. He was almost passionless. All that needed for its apprehension more than the pure intellect, or required the exercise of fancy, imagination, affection, or faith, was distasteful to Cavendish. An intellectual head thinking, a pair of wonderfully acute eyes observing, and a pair of very skilful hands experimenting or recording, are all that I realise in reading his memorials. His brain seems to have been but a calculating engine; his eyes inlets of vision, not fountains of tears; his hands instruments of manipulation which never trembled with emotion, or were clasped together in adoration, thanksgiving or despair; his heart only an anatomical organ, necessary for the circulation of the blood…
Yet, Wilson continued,
Cavendish did not stand aloof from other men in a proud or supercilious spirit, refusing to count them his fellows. He felt himself separated from them by a great gulf, which neither they nor he could bridge over, and across which it was vain to stretch hands or exchange greetings. A sense of isolation from his brethren, made him shrink from their society and avoid their presence, but he did so as one conscious of an infirmity, not boasting of an excellence. He was like a deaf mute sitting apart from a circle, whose looks and gestures show that they are uttering and listening to music and eloquence, in producing or welcoming which he can be no sharer. Wisely, therefore, he dwelt apart, and bidding the world farewell, took the self-imposed vows of a Scientific Anchorite, and, like the Monks of old, shut himself up within his cell. It was a kingdom sufficient for him, and from its narrow window he saw as much of the Universe as he cared to see. It had a throne also, and from it he dispensed royal gifts to his brethren. He was one of the unthanked benefactors of his race, who was patiently teaching and serving mankind, whilst they were shrinking from his coldness, or mocking his peculiarities… He was not a Poet, a Priest, or a Prophet, but only a cold, clear Intelligence, raying down pure white light, which brightened everything on which it felt, but warmed nothing – a Star of at least the second, if not of the first magnitude, in the Intellectual Firmament. Many years later, I reread Wilson’s astonishing biography and wondered what (in clinical terms) Cavendish ‘had.’ Newton’s emotional singularities – his jealously and suspiciousness, his intense enmities and rivalries – suggested a profound neurosis; but Cavendish’s remoteness and ingenuousness were much more suggestive of autism or Asperger’s syndrome. I now think Wilson’s biography may be the fullest account we are ever likely to have of the life and mind of a unique autistic genius.
21
The ease of obtaining hydrogen and oxygen by electrolysis, in ideally inflammable proportions, led at once to the invention of the oxy-hydrogen blowpipe, which produced higher temperatures than had ever been obtained before. This allowed, for example, the melting of platinum, and the raising of lime to a temperature at which it gave out the most brilliant sustained light ever seen.
22
Mendeleev, sixty years later, was to speak of Davy’s isolation of sodium and potassium as ‘one of the greatest discoveries in science’ – great in its bringing a new and powerful approach to chemistry, in its defining of the essential qualities of a metal, and in its exhibition of the elements’ twinship and analogy, the implication of a fundamental chemical group.