The Elements of Murder: A History of Poison

Natural History, July, 2005 by Laurence A. Marschall

The Elements of Murder: A History of Poison by John Emsley Oxford University Press, 2005; $30.00

My idea of bliss in the dog days of summer is a comfortable lawn chair, a cool drink, and a stack of murder mysteries. For those with similar criminal fixations, here's a thick book of nonfiction that might also fill the bill: a natural and social history of poisons, by the former Science Writer in Residence at the chemistry department of the University of Cambridge. John Emsley's book includes more than anyone but a fiend would want to know about the uses and abuses of antimony, arsenic, lead, mercury, and thallium, along with information about a host of elements less commonly ingested but, under the proper circumstances, no less deadly: barium, chromium, selenium, and tellurium among them.

The danger of these poisons, well known to pathologists, is that their effects can be both cumulative and insidious. When such toxic elements are environmental, particularly when they occur in one's everyday surroundings, one can be slowly poisoned without ever becoming aware that something is wrong. Substances now considered highly poisonous were once even prescribed as home remedies, simply because they had no apparent negative effect and their medicinal effect was beneficial. Calomel, a chloride of mercury, was used well into the 1950s as a so-called teething powder for babies, since it was known to soften the gums. The babies' relief, unfortunately, was a mild case of mercury poisoning. At its most severe, mercury poisoning causes teeth to fall out. Because mercury also attacks the nervous system, even the low doses in the teething powder no doubt affected the mental development of millions of smiling babies. And smiling adults, too: President Lincoln supposedly ingested mercury in the pills he took as a laxative, which may have led to his reported propensity to mood swings.

That same treacherous subtlety makes poison the weapon of choice for many murderers, especially the ones who want to conceal the very existence of a crime. Has the skin on your palms and the soles of your feet been thickening lately? Have you been weary, overly irritable, losing appetite and weight? Are your eyes red and watery? Check that elderberry wine your maiden aunts have been serving you, or those bonbons that keep coming from a secret admirer. You have all the signs of chronic arsenic poisoning.

Then again, if you're losing your hair, watch out! It may be more than bad genes--especially if your body has that tingling feeling, or your hands and feet feel numb from time to time, or you're having trouble sleeping. Someone who would profit from your demise may have read The Pale Horse, a classic Agatha Christie, whose villain used thallium salts to knock off his victims.

Thallium ions are dead ringers for potassium ions, one of the metals essential to health. Thallium, however, does not function quite the same way potassium does. When too much thallium circulates in the blood, it invades all the organs of the body, impairing their operation, destroying hair follicles, muscles, and nerves. Because it takes time for thallium to get into the ceils, large doses may produce no immediate effect. But because it is not readily excreted, thallium continues to build up long after the fatal flagon has been drained. By the time the victim begins hallucinating, turns gray-skinned, becomes paralyzed, and dies, it may be impossible to identify who did the dastardly deed, or when.

The list of the famous who may have been poisoned by one of these devious toxins is a long one, from Pope Clement II to Mozart. Emsley has dug up the dirt on these and a rogue's gallery of lesser-known cases. Today, with analytical techniques that can routinely sniff out minute amounts of toxins, villains can no longer count on getting away with the perfect murder. But if the golden age of poisoning is gone (replaced, to be sure, by other forms of mayhem), in Emsley's book it's still very much alive.

LAURENCE A. MARSCHALL, author of The Supernova Story, is W.K.T. Sahm Professor of Physics at Gettysburg College in Pennsylvania, and director of Project CLEA, which produces widely used simulation software for education in astronomy. He is the 2005 winner of the Education prize of the American Astronomical Society.