Every element echoed the properties of the one above, was a slightly heavier member of the same family. The same melody, so to speak, was played in each period – first an alkali metal, then an alkaline earth metal, then six more elements, each with its own valency or tone – but played in a different register (it was impossible to avoid thinking of octaves and scales here, for I lived in a musical house, and scales were the periodicity I heard daily).
It was eightness which dominated the periodic table before me, though one could also see, in the lower part of the table, that extra elements were interposed within the basic octets: ten extra elements apiece in Periods 4 and 5, and ten plus fourteen in Period 6.
So one went up, each period completing itself and leading to the next one in a series of dizzying loops – at least this is the form my imagination took, so that the sober, rectangular table before me was transformed, mentally, into spirals or loops. The table was a sort of cosmic staircase or a Jacob’s ladder, going up to, coming down from, a Pythagorean heaven.
I got a sudden, overwhelming sense of how startling the periodic table must have seemed to those who first saw it – chemists profoundly familiar with seven or eight chemical families, but who had never realized the basis of these families (valency), nor how all of them might be brought together into a single over-arching scheme. I wondered if they had reacted as I did to this first revelation: ‘Of course! How obvious! Why didn’t I think of it myself?’
Whether one thought in terms of the verticals or in terms of the horizontals – either way one arrived at the same grid. It was like a crossword puzzle that could be approached by either the ‘down’ or the ‘across’ clues, except that a crossword was arbitrary, a purely human construct, while the periodic table reflected a deep order in nature, for it showed all the elements arrayed in a fundamental relationship. I had the sense that it harbored a marvelous secret, but it was a cryptogram without a key – why was this relationship so?
I could scarcely sleep for excitement the night after seeing the periodic table – it seemed to me an incredible achievement to have brought the whole, vast, and seemingly chaotic universe of chemistry to an all-embracing order. The first great intellectual clarifications had occurred with Lavoisier’s defining of elements, with Proust’s finding that elements combined in discrete proportions only, and with Dalton’s notion that elements had atoms with unique atomic weights. With these, chemistry had come of age, and had become the chemistry of the elements. But the elements themselves were not seen to come in any order; they could only be listed alphabetically (as Pepper did in his Playbook of Metals) or in terms of isolated local families or groups. Nothing beyond this was possible until Mendeleev’s achievement. To have perceived an overall organization, a superarching principle uniting and relating all the elements, had a quality of the miraculous, of genius. And this gave me, for the first time, a sense of the transcendent power of the human mind, and the fact that it might be equipped to discover or decipher the deepest secrets of nature, to read the mind of God.
I kept dreaming of the periodic table in the excited half-sleep of that night – I dreamed of it as a flashing, revolving pinwheel or Catherine wheel, and then as a great nebula, going from the first element to the last, and whirling beyond uranium, out to infinity. The next day I could hardly wait for the museum to open, and dashed up to the top floor, where the table was, as soon as the doors were opened.
On this second visit I found myself looking at the table in almost geographic terms, as a realm, a kingdom, with different territories and boundaries. Seeing the table as a geographic realm allowed me to rise above the individual elements, and see certain general gradients and trends. Metals had long been recognized as a special category of elements, and now one could see, in a single synoptic glance, how they occupied three-quarters of the realm – all of the west side, most of the south – leaving only a smallish area, mostly in the northeast, for the nonmetals. A jagged line, like Hadrian’s Wall, separated the metals from the rest, with a few ‘semimetals’, metalloids – arsenic, selenium – straddling the wall. One could see the gradients of acid and base, how the oxides of the ‘western’ elements reacted with water to form alkalis, the oxides of the ‘eastern’ elements, mostly nonmetals, to form acids. One could see, again at a glance, how the elements on either border of the realm – the alkali metals and halogens, like sodium and chlorine, for example – showed the greatest avidity for each other and combined with explosive force, forming crystalline salts with high melting points which dissolved to form electrolytes; while those in the middle formed a very different sort of compound – volatile liquids or gases which resisted electric currents. One could see, remembering how Volta and Davy and Berzelius ranked the elements into an electrical series, how the most strongly electropositive elements were all to the left, the most strongly electronegative to the right. Thus it was not just the placement of the individual elements, but trends of every sort that hit the eye when one looked at the table.
Seeing the table, ‘getting’ it, altered my life. I took to visiting it as often as I could. I copied it into my exercise book and carried it everywhere; I got to know it so well – visually and conceptually – that I could mentally trace its paths in every direction, going up a group, then turning right on a period, stopping, going down one, yet always knowing where I was. It was like a garden, the garden of numbers I had loved as a child – but unlike this, it was real, a key to the universe. I spent hours now, enchanted, totally absorbed, wandering, making discoveries, in the enchanted garden of Mendeleev.[40]
There was a photograph of Mendeleev next to the periodic table in the museum; he looked like a cross between Fagin and Svengali, with a huge mass of hair and beard and piercing, hypnotic eyes. A wild, extravagant, barbaric figure – but as romantic, in his way, as the Byronic Humphry Davy. I needed to know more of him, and to read his famous Principles, in which he had first published his periodic table.
His book, his life, did not disappoint me. He was a man of encyclopedic interests. He was also a music lover and a close friend of Borodin (who was also a chemist). And he was the author of the most delightful and vivid chemistry text ever published, The Principles of Chemistry.[41]
Like my own parents, Mendeleev had come from a huge family – he was the youngest, I read, of fourteen children. His mother must have recognized his precocious intelligence, and when he reached fourteen, feeling that he would be lost without a proper education, she walked thousands of miles from Siberia with him – first to the University of Moscow (from which, as a Siberian, he was barred) and then to St. Petersburg, where he got a grant to train as a teacher.
(She herself, apparently, nearing sixty at the time, died from exhaustion after this prodigious effort. Mendeleev, profoundly attached to her, was later to dedicate the Principles to her memory.)
Even as a student in St. Petersburg, Mendeleev showed not only an insatiable curiosity, but a hunger for organizing principles of all kinds. Linnaeus, in the eighteenth century, had classified animals and plants, and (much less successfully) minerals, too. Dana, in the 1830s, had replaced the old physical classification of minerals with a chemical classification of a dozen or so main categories (native elements, oxides, sulphides, and so on). But there was no such classification for the elements themselves, and there were now some sixty elements known. Some elements, indeed, seemed almost impossible to categorize. Where did uranium go, or that puzzling, ultralight metal, beryllium? Some of the most recently discovered elements were particularly difficult – thallium, for example, discovered in 1862, was in some ways similar to lead, in others to silver, in others to aluminium, and in yet others to potassium.
40
Years later, when I read C.P. Snow, I found that his reaction to first seeing the periodic table was very similar to mine:
For the first time I saw a medley of haphazard facts fall into line and order. All the jumbles and recipes and hotchpotch of the inorganic chemistry of my boyhood seemed to fit themselves into the scheme before my eyes – as though one were standing beside a jungle and it suddenly transformed itself into a Dutch garden.
41
In his very first footnote, in the preface, Mendeleev spoke of ‘how contented, free, and joyous is life in the realm of science’ – and one could see, in every sentence, how true this was for him. The