Molecules Of Murder, by John Emsley

Drops of death from Cleopatra to the KGB

Death by poison holds a lurid fascination, and history is replete with examples of how toxins brought a deliberately premature end to life. Cleopatra is said to have killed herself with the bite of an asp but she also experimented with the juice of deadly nightshade – belladonna. Or rather, she had a slave experiment, but the death was not as quick and as painless as Cleopatra desired, which is why she ended up committing suicide with the help of the snake.

Belladonna juice was widely known in ancient Rome as a deadly poison. It was a favourite of wives wishing to get rid of unwanted husbands – which is perhaps how Livia murdered her husband, the Emperor Augustus. The active ingredient of deadly nightshade is a chemical called atropine, and a single berry of the plant contains enough to kill a young child.

Atropine works on the central nervous system, causing a paralysis at the nerve endings. It can save lives as well as end them, and has been extensively used in medicine. The name belladonna (beautiful lady) refers to the use of extracts in eye-drops in the 16th century to dilate a woman's pupils to make her look more attractive.

This particular trick was used by Dr Robert Buchanan, who murdered his second wife Anna in New York City in 1892 with a dose of morphine. An overdose of this drug was known to cause pinpoint pupils at death. Buchanan knew that drops of atropine placed in the eyes of his wife would divert attention away from morphine.

John Emsley has crafted this clever book about murder by poisoning with the intention of serving two audiences – those fascinated by crime and by science. He deals with each poison with a detailed description of its properties, and as such it sometimes reads like a chemistry textbook. However, this heaviness of scientific description is alleviated by the detail about the precise use of the poisons in real life.

He divides poisons into those found naturally, such as belladonna, and those man-made, such as carbon monoxide and polonium-210, the radioactive substance that killed the ex-KGB officer Alexander Litvinenko in 2006. Emsley summarises the incriminating evidence that led the British authorities to demand the extradition of another former KGB officer, Andrei Lugovoy, who left a radioactive trail wherever he went.

The mistake of those who poisoned Litvinenko was not to use enough polonium-210 to kill him quickly. It was his lingering death that allowed his doctors to discount thallium poisoning. The case was similar to that of Georgi Markov, the Bulgarian defector who died in London in 1978 after being stabbed with an umbrella tip armed with a tiny pellet loaded with deadly ricin toxin. Like Litvinenko's, Markov's demise was eventually solved. Emsley says there are, thankfully, few poisons available to the assassins and murderers of the 21st century that are not fully understood. So perhaps the days of murder by poisoning are coming to a close.