by Oliver Sacks
14 In his biography of Lavoisier, Douglas McKie includes an exhaustive list of Lavoisier’s scientific activities which paints a vivid picture of his times, no less than his own remarkable range of mind: ‘Lavoisier took part,’ McKie writes,
…in the preparation of reports on the water supply of Paris, prisons, mesmerism, the adulteration of cider, the site of the public abattoirs, the newly-invented ‘aerostatic machines of Montgolfier’ (balloons), bleaching, tables of specific gravity, hydrometers, the theory of colors, lamps, meteorites, smokeless grates, tapestry making, the engraving of coats-of-arms, paper, fossils, an invalid chair, a water-driven bellows, tartar, sulphur springs, the cultivation of cabbage and rape seed and the oils extracted thence, a tobacco grater, the working of coal mines, white soap, the decomposition of nitre, the manufacture of starch…the storage of fresh water on ships, fixed air, a reported occurrence of oil in spring water…the removal of oil and grease from silks and woollens, the preparation of nitrous ether by distillation, ethers, a reverberatory hearth, a new ink and inkpot to which it was only necessary to add water in order to maintain the supply of ink…, the estimation of alkali in mineral waters, a powder magazine for the Paris Arsenal, the mineralogy of the Pyrenees, wheat and flour, cesspools and the air arising from them, the alleged occurrence of gold in the ashes of plants, arsenic acid, the parting of gold and silver, the base of Epsom salt, the winding of silk, the solution of tin used in dyeing, volcanoes, putrefaction, fire-extinguishing liquids, alloys, the rusting of iron, a proposal to use ‘inflammable air’ in a public firework display (this at the request of the police), coal measures, dephlogisticated marine acid, lamp wicks, the natural history of Corsica, the mephitis of the Paris wells, the alleged solution of gold in nitric acid, the hygrometric properties of soda, the iron and salt works of the Pyrenees, argentiferous lead mines, a new kind of barrel, the manufacture of plate glass, fuels, the conversion of peat into charcoal, the construction of corn mills, the manufacture of sugar, the extraordinary effects of a thunder bolt, the retting of flax, the mineral deposits of France, plated cooking vessels, the formation of water, the coinage, barometers, the respiration of insects, the nutrition of vegetables, the proportion of the components in chemical compounds, vegetation, and many other subjects, far too many to be described here, even in the briefest terms.
15 Boyle had experimented with the burning of metals a hundred years before, and was well aware that these increased in weight when burned, forming a calx or ash that was heavier than the original. But his explanations of the increase of weight were mechanical, not chemical: he saw it as the absorption of ‘particles of fire.’ Similarly, he saw air itself not in chemical terms, but rather as an elastic fluid of a peculiar sort, used in a sort of mechanical ventilation, to wash the impurities out of the lungs. Findings were not consistent in the century that followed Boyle, partly because the gigantic ‘burning glasses’ used were of such power as to cause some metallic oxides to partly vaporize or sublime, causing losses rather than increases in weight. But even more frequently there was no weighing at all, for analytical chemistry, at this point, was still largely qualitative.
16 In this same month, Lavoisier got a letter from Scheele describing the preparation of what Scheele called Fire Air (oxygen) admixed with Fixed Air (carbon dioxide), from heating silver carbonate; Scheele had obtained pure Fire Air from mercuric oxide, even before Priestley had. But in the event, Lavoisier claimed the discovery of oxygen for himself and scarcely acknowledged the discoveries of his predecessors, feeling that they did not realize what it was that they had observed.
All this, and the question of what constitutes ‘discovery,’ is explored in the play Oxygen, by Roald Hoffmann and Carl Djerassi.
17 Replacing the concept of phlogiston with that of oxidation had immediate practical effects. It was now clear, for example, that a burning fuel needed as much air as possible for complete combustion. François-Pierre Argand, a contemporary of Lavoisier’s, was quick to exploit the new theory of combustion, designing a lamp with a flat ribbon wick, bent to fit inside a cylinder, so that air could reach it from both the inside and the outside, and a chimney which produced an updraft. The Argand burner was well established by 1783; there had been no lamp so efficient or so brilliant before.
18 Lavoisier’s list of elements included the three gases he had named (oxygen, azote [nitrogen], and hydrogen), three nonmetals (sulphur, phosphorus, and carbon), and seventeen metals. It also included muriatic, fluoric, and boracic ‘radicals’ and five ‘earths’: chalk, magnesia, baryta, alumina, and silica. These radicals and earths, he divined, were compounds containing new elements, which he thought would soon be obtained (all of them were indeed obtained by 1825, except fluorine, which defeated isolation for another sixty years). His final two ‘elements’ were Light and Heat – as if he had not been wholly able to free himself from the specter of phlogiston.
19 More than fifty years later (for my sixty-fifth birthday), I was able to gratify this boyhood fantasy, and had, besides the normal helium balloons, a few xenon balloons of astonishing density – as near to ‘lead balloons’ as could be (tungsten hexafluoride, though denser, would have been too dangerous to use – it is hydrolyzed by moist air, producing hydrofluoric acid). If one twirled these xenon balloons in one’s hand, then stopped, the heavy gas, by its own momentum, would continue rotating for a minute, almost as if it were a liquid.
Chapter Eleven: Humphrey Davy: A Poet-Chemist
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.
23 The enormous chemical reactivity of potassium made it a powerful new instrument in isolating other elements. Davy used it himself, only a year after he discovered it, to obtain the element boron from boric acid, and he tried to obtain silicon by the same method (Berzelius succeeded here, in 1824). Aluminium and beryllium, a few years later, were also isolated through the use of potassium.
24 Mary Shelley, as a child, was enthralled by Davy’s inaugural lecture at the Royal Institution, and years later, in Frankenstein, she was to model Professor Waldman’s lecture on chemistry rather closely on some of Davy’s words when, speaking of galvanic electricity, he said, ‘a new influence has been discovered, which has enabled man to produce from combinations of dead matter effects which were formerly occasioned only by animal organs.’
25 David Knight, in his brilliant biography of Davy, speaks of the passionate parallelism, the almost mystical sense of affinity and rapport, that Coleridge and Davy felt, and how the two planned, at one point, to set up a chemical laboratory together. In his book The Friend, Coleridge wrote:
Water and flame, the diamond, the charcoal…are convoked and fraternized by the theory of the chemist…It is the sense of a principle of connection given by the mind, and sanctioned by the correspondency of nature…If in a Shakespeare we find nature idealized into poetry, through the creative power of a profound yet observant meditation, so through the meditative observation of a Davy…we find poetry, as it were, substantiated and realized in nature: yea, nature itself disclosed to us…as at once the poet and the poem!
Coleridge was not the only writer to ‘renew his stock of metaphors’ with images from chemistry. The chemical term elective affinities was given an erotic connotation by Goethe; Keats, trained in medicine, reveled in chemical metaphors. Eliot, in ‘Tradition and the Individual Talent,’ employs chemical metaphors, from beginning to end, culminating in a grand, Davyan metaphor for the poet’s mind: ‘The analogy is that of the catalyst…The mind of the poet is the shred of platinum.’
26 The great chemist Justus von Liebig wrote powerfully about this feeling in his autobiography:
[Chemistry] developed in me the faculty, which is peculiar to chemists more than to other natural philosophers, of thinking in terms of phenomena; it is not very easy to give a clear idea of phenomena to anyone who cannot recall in his imagination a mental picture of what he sees and hears, like the poet and artist, for example…There is in the chemist a form of thought by which all ideas become visible in the mind as the strains of an imagined piece of music…
The faculty of thinking in phenomena can only be cultivated if the mind is constantly trained, and this was effected in my case by my endeavouring to perform, so far as my means would allow me, all the experiments whose description I read in the books…I repeated such experiments…a countless number of times,…till I knew thoroughly every aspect of the phenomenon which presented itself…a memory of the sense, that is to say of the sight, a clear perception of the resemblance or differences of things or of phenomena, which afterwards stood me in good stead.
27 Davy went on with his investigations of flame, and, a year after the safety lamp, published Some Philosophical Researches on Flame. More than forty years later, Faraday would return to the subject, in his famous Royal Institution lectures on The Chemical History of a Candle.
28 Enlarging on Davy’s observation of catalysis, Dobereiner found in 1822 that platinum, if finely divided, would not only become white-hot, but would ignite a stream of hydrogen passing over it. On this basis he made a lamp consisting basically of a tightly sealed bottle containing a piece of zinc which could be lowered into sulphuric acid, generating hydrogen. When the stopcock of the bottle was opened, hydrogen gushed out into a small container holding a bit of platinum sponge, and instantly burst into flame (a slightly dangerous flame, because it was virtually invisible, and one had to be cautious to avoid being burned). Within five years, there were twenty thousand Dobereiner lamps in use in Germany and England, so Davy had the satisfaction of seeing catalysis at work, indispensable in thousands of homes.
Chapter Twelve: Images
291 was intrigued, too (though I never practiced it), by cine-photography. Here again it was Walter who made me realize that there was no actual movement in the film, only a succession of still images which the brain synthesized to give an impression of movement. He demonstrated this to me with his film projector, slowing it down to show me only the still images, and then speeding it up until the illusion of motion suddenly occurred. He had a zoetrope, with images painted on the inside of a wheel, and a thaumatrope, with drawings on a stack of cards, which when rotated, or rapidly flicked, would give the same illusion. So I had the sense that movement, too, was constructed by the brain, in a manner analogous to that of color and depth.
30 Wells’s reference to the Martians’ unknown element also intrigued me later when I learned about spectra, for he described it, early in the book, as ‘giving a group of four lines in the blue of the spectrum,’ though subsequently – did he reread what he had written? – as giving ‘a brilliant group of three lines in the green.’
Chapter Thirteen: Mr Dalton’s Round Bits of Wood
31 Yet Proust’s view was challenged by Claude-Louis Berthollet. A senior chemist of great eminence, an ardent supporter of Lavoisier (and a collaborator with him on the Nomenclature), Berthollet had discovered chemical bleaching and accompanied Napoleon as a scientist on his 1798 expedition to Egypt. He had observed that various alloys and glasses manifestly had quite varied chemical compositions; therefore, he maintained, compounds could have a continuously variable composition. He also remarked, when roasting lead in his laboratory, a striking, continuous color change – did this not imply a continuous absorption of oxygen with an infinite number of stages? It was true, Proust argued, that heated lea
d took up oxygen continuously and changed color as it did so, but this was due, he thought, to the formation of three distinctly colored oxides: a yellow monoxide, then red lead, then a chocolate-colored dioxide – admixed like paints, in varying proportions, depending on the state of oxidation. The oxides themselves might be mixed together in any proportion, he felt, but each was itself of fixed composition.
Berthollet also wondered about such compounds as ferrous sulphide, which never contained exactly the same proportions of iron and sulphur. Proust was unable to give a clear answer here (and indeed the answer only became clear with a subsequent understanding of crystal lattices and their defects and substitutions – thus sulphur can substitute for iron in the iron sulphide lattice to a variable extent, so that its effective formula varies from Fe7 S8 to Fe8 S9. Such nonstoichiometric compounds came to be called berthollides).
Thus both Proust and Berthollet were right in a way, but the vast majority of compounds were Proustian, with a fixed composition. (And it was perhaps necessary that Proust’s view became the favored one, for it was Proust’s law which was to inspire the profound insights of Dalton.)
32 Though Newton hinted, in his final Quaerie, at something that almost seems to prefigure a Daltonian concept:
God is able to create particles of matter of several sizes and figures, and in several proportions to the space they occupy, and perhaps of different densities and forces.
33 Dalton represented the atoms of elements as circles with internal designs, sometimes reminiscent of the symbols of alchemy, or the planets; while the compound atoms (which we would now call ‘molecules’) had increasingly intricate geometric configurations – the first premonition of a structural chemistry that was not to be developed for another fifty years.