Mendeleyev鈥檚 Dream by Paul Strathern, Hamish Hamilton, 拢12.99, ISBN
024114065X
ON A visit to a remote part of Ethiopia, I glanced inside a small, ramshackle
shop and was surprised to see on the wall a periodic table, lovingly drawn by
hand. I shouldn鈥檛 have been amazed. People everywhere understand that matter is
composed of elements. The periodic table sorts them all out by atomic weight and
shared behaviour鈥攁nd shows a periodic pattern emerging that鈥檚 linked to
the number of electrons. But how did this idea achieve global dominance? Well,
taking a nap played an important part.
On a cold Friday morning in St Petersburg in 1869, Dmitri Ivanovich
Mendeleyev set himself the task of discovering how to bring order to the
numerous elements that had recently been discovered. Late the following Monday,
he fell asleep, frustrated but convinced he was on the verge of a great
discovery. The solution came to him in a dream. He awoke and immediately wrote
down his 鈥淧eriodic Table of the Elements鈥�, from which we derive our modern
table, instantly recognisable wherever it鈥檚 found.
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In Mendeleyev鈥檚 Dream, Paul Strathern reveals the historical springs
that fed the Russian academic鈥檚 tour de force. A lecturer at Kingston University
in Surrey, Strathern studied science before turning to philosophy, making him
well qualified for this: the roots of modern chemistry lie in the ideas of the
ancient Greek philosophers. Strathern is an entertaining guide, too, capably
marshalling a colourful cast of thinkers and experimentalists.
Two and a half thousand years ago, Thales of Miletus found fossil seashells
on a walk in the hills. Grasping that the hills must once have been a sea, he
concluded that one element, water, was the source of all matter. His critics
declared that a single element could not explain the diversity they observed,
and added another three: air, fire and earth. Everything in the world was a
mixture of these four.
Around that time, Leucippus and his pupil Democritus plugged the idea that
matter is made up of a far greater variety of elements in different
combinations. They called them atoms. Sadly, Aristotle, an authority in matters
scientific for hundreds of years after his death, favoured the four elements,
although he tinkered with the model a bit by adding a fifth (aether) to account
for the behaviour of heavenly bodies. Lacking the backing of Aristotle, atomic
theory languished for 2000 years.
But as Strathern points out in this beguiling book, even Aristotle鈥檚 heavy
hand couldn鈥檛 stop progress of sorts. Alchemy was born in Alexandria, the
ancient world鈥檚 largest city, when Greek thinking met the ancient Egyptian
practice of khemeia, the manufacture of a magical black powder that
transformed metals. The metals gold, silver, copper, iron, tin, lead and mercury
were known, but not understood to be elements: practitioners of alchemy believed
that one metal could be changed into another: the ignoble could become noble.
Alchemy, a murky practice obscured by mysticism, did eventually evolve into
orderly chemistry. Geniuses and charlatans spent centuries seeking the secret of
making gold from base metal鈥攁nd they repeated experiments and noted
results, a foretaste of the scientific method.
What we would all recognise as modern chemistry arguably began with the
publication, in 1661, of Robert Boyle鈥檚 The Sceptical Chymist. He
defined an element as a substance that cannot be broken down into simpler
substances. But, says Strathern, Boyle himself secretly continued the search for
the philosopher鈥檚 stone, aiding repeal of a 400-year-old anti-alchemy law.
Strathern also introduces Manchester鈥檚 own chemical brother John Dalton. Born
in 1766, he set atomic theory on its quantitative foundation by proving that
different elements had different atomic weights. Notation followed from Sweden.
J枚ns Berzelius had the idea of representing elements by the first letter of
their name鈥擧 for hydrogen and so on鈥攋ust in time, Strathern says, to
deal with the host of new elements discovered in the first half of the 19th
century.
Suddenly there were almost too many elements. Chemistry seemed little more
than a swarm of facts. No one could discern an underlying structure to harvest
this mass of knowledge. Some made a brave stab at it. First was a French
inspector general of mines, Alexandre Beguyer de Chancourtois, who in 1862
described a 鈥渢elluric screw鈥� that demonstrated some sort of pattern to the
elements. Sadly, says Strathern, his poor presentation completely obscured its
significance.
Two years later, John Newlands independently proposed a 鈥渓aw of octaves鈥�,
suggesting that if the elements were arranged in order of increasing atomic
weight, there was a repeating pattern. The worthy members of Britain鈥檚 Chemical
Society ridiculed the idea. Then our temperamental and wild-haired Russian hit
the jackpot.
Mendeleyev did have gaps in his table, but he suggested these were
undiscovered elements and predicted their properties. A few years later the
first gap was filled鈥攁nd the discovery of gallium matched Mendeleyev鈥檚
prediction. The periodic law had proved its worth. Mendeleyev鈥檚 dream had become
reality.
It鈥檚 a pleasure to find a popular book about chemistry. We need a few more
like this to inspire the non-chemists with the joys of the discipline. But I
don鈥檛 recommend announcing that your latest discovery came to you in a dream
when you apply for funding. Save that for the Nobel acceptance speech.