A is for Arsenic (25 page)

Post-mortem results for nicotine may be complicated by the presence of nicotine from other sources. If the victim was a heavy smoker, as was the case with Sir Bartholomew, nicotine would already be present in the body. Nicotine is also rapidly metabolised into cotinine in the body, with a half-life of only one to two hours. Cotinine has a half-life of approximately twenty hours and is used as an indicator of exposure to tobacco, as it can still be detected days or even weeks later. Cotinine will also interact with nicotinic receptors but with a much lower potency than nicotine. Blood serum levels of nicotine or cotinine above 2mg/litre are associated with serious toxicity.

Even though Sir Bartholomew was a heavy smoker, nicotine poisoning is confirmed as the cause of death. It is virtually
impossible to smoke enough cigarettes or cigars in one go to be at risk from nicotine poisoning.
⁶⁵
Nicotine is a fast-acting poison, so a large dose must have been administered to Sir Bartholomew very shortly before he died, but no one can explain how. Poirot suggests that a clear colourless liquid such as nicotine, added to the port Sir Bartholomew had drunk, might dilute its colour. However, the traditional volume of a port glass is 190ml, and an enormous quantity of nicotine, well above the lethal dose, could have been added to a glass of port before the colour was sufficiently diluted to notice. As Poirot points out, even if the colour had been diluted, the cut of the port glass would help hide the presence of nicotine.

In the light of events at Sir Bartholomew's dinner party, the death of the Reverend Babbington looks even more suspicious, and the vicar's body is exhumed. A post-mortem reveals the presence of nicotine, even though the Reverend wasn't a smoker. Any nicotine in his body from passive smoking would have been only in very low quantities, so it was easier in this case to attribute death to deliberate poisoning. Metabolic processes in the body stop at the point of death, and nicotine is remarkably stable with regard to decomposition post-mortem; it has been detected in human remains months after burial. The presence of nicotine in Babbington's remains, and whether there was enough for a fatal dose, should, therefore, have been easy to determine.

As the title of the book suggests, there had to be a third murder, and this time there was no doubt as to how the poison was administered. The final victim is Mrs de Rushbridger, a patient at the sanatorium that Sir Bartholomew ran; and her dose of nicotine is delivered in a box of liqueur chocolates. Only one chocolate is eaten and death occurs very rapidly, just two minutes later. There must have been a very large dose contained inside that single chocolate. The space inside a liqueur chocolate is quite small, so almost all of it must have
been taken up with nicotine, leaving little space for liqueur to help disguise the flavour. Mrs de Rushbridger was either taken by surprise by the unusual flavour or was too polite to spit out the chocolate.

There is no doubt about the cause of death in any of the three murders in
Three Act Tragedy,
but how easy would it have been for the murderer to obtain nicotine? There was a range of options open to the 1930s would-be nicotine-poisoner. One method would be grow-your-own, but the amount of nicotine in a plant varies with species and age, and this is perhaps the least reliable method. Another method would be to extract nicotine from tobacco products like cigars or cigarettes. The amount of tobacco per 1,000 cigarettes in 1960 was 1kg, giving an average of 1g tobacco per cigarette; as few as 35 cigarettes could be used to obtain a lethal oral dose. The amount of tobacco in cigarettes has dropped considerably since the 1930s because of the use of reconstituted tobacco and additives. However, since 1999 the average amount of
nicotine
has been increasing, year on year by approximately 1.3 per cent. The overall result is that today, you would need around 60 cigarettes to extract the same amount of nicotine. However, the easiest method in 1935 would have been to purify nicotine from a nicotine-based insecticide, and this was the method chosen by the murderer in
Three Act Tragedy
. In 1935 the concentration of nicotine in insecticides would have been very high, perhaps as much as 43 per cent.

There have been mutterings about the implausibility of the motive behind the three murders in
Three Act Tragedy
. For the American publication of the book, the motive was changed significantly. But, as usual for Christie, there is little to complain about in the science. From a practical point of view, the means and methods of murder are credible and accurate.

Notes

⁶⁰
All parts of the plants contain nicotine, but the highest concentration is in the leaves.

⁶¹
Though their legacy lives on in the form of neonicotinoids, a group of chemicals very similar to nicotine that kill insects but have fewer side effects in vertebrates. Although they were originally designed to act on pests, these compounds also have a devastating effect on insects that are beneficial to plants, bees in particular.

⁶²
Fans of the TV series
Sherlock
may remember Holmes using nicotine patches to help him with particularly difficult problems. This is not recommended.

⁶³
And, by the time of his death, he was recovering from a leg amputation.

⁶⁴
Picric acid is also known as trinitrophenol, which is chemically very similar to trinitrotoluene, or TNT. Consequently picric acid is also explosive.

⁶⁵
There is, however, at least one historical example of death occurring during an ill-advised pipe-smoking contest.

Sad Cypress

I do by no means deny that some truths have been delivered to the world in regard to opium: thus, it has been repeatedly affirmed by the learned that opium is a tawny brown in colour – and this, take notice, I grant; secondly, that it is rather dear, which I also grant – for, in my time, East Indian opium has been three guineas a pound, and Turkey eight; and, thirdly, that, if you eat a good deal of it, most probably you must do what is disagreeable to any man of regular habits – viz., die.

Thomas de Quincey,
Confessions of an English Opium Eater

OPIUM has been with us for millennia. Poppies and their extracts are mentioned in the Ebers papyrus of 1500BC but descriptions of their effects on people have been found in Sumerian records dating back 6,000 years or more. Opium is perhaps the oldest medicine, and its astonishing efficacy means
it is still in use in various refined forms today.
⁶⁶
It has brought relief from pain and suffering to millions, as well as serving as an inspiration for poets and painters, but it has also brought about untold misery. Opium, its constituents and several of its derivatives are highly addictive. The overpowering desire or need for these drugs overrides every other thought, and the demand for them has brought about crimes from petty thefts to international wars.

In nineteenth-century England, opium, in the form of laudanum, was a part of everyday life in the way that cigarettes, alcohol and paracetamol are today. Opium could be purchased at almost any pharmacy or grocer's, without question. Today, despite strict laws and, in many places, severe punishments, it is estimated that 9.2 million people across the world use one of opium's most powerful and destructive derivatives – heroin.

Agatha Christie was well aware of the many sides of opium's character. Opium and its derivatives are mentioned in more than a dozen of her books; Christie had her characters relieved from pain, sedated, addicted and murdered by this class of drug. Two of the nine victims that Agatha killed using opium compounds appear in the novel
Sad Cypress
, written in 1940, and the plot has some similarities with real-life cases. Both victims, Laura Welman and Mary Gerrard, are killed with morphine, the most commonplace of the biologically active compounds found in opium. Elinor Carlisle stands accused of both murders, and the case against her appears to be conclusive. That is until Hercule Poirot is called upon to use his little grey cells and save her from the gallows.

The opium story

Opium is the name given to the crude extract obtained from poppy plants. There are many species of poppy, several of which contain useful amounts of opium, but
Papaver somniferum
is the species cultivated specifically for the opium it contains. This species has been grown in the Middle East since at least 3400BC, though the plant originated in Turkey. The poppy in its many varieties now grows throughout the world, both wild and in legal and illegal cultivations (for food, medicines and street drugs), as well as in gardens as ornamental flowers. Opium for illegal use is obtained from poppy plants by slicing the green seed head with a razor blade, allowing a milky sap to ooze out. After a day the dried sap will have turned brown, and the gummy mass is scraped off, pressed into cakes of raw opium and allowed to dry. For legal supplies to the pharmaceutical industry, farmers first remove the seed pods (with the seeds sold for use in bread and cakes). Morphine is then extracted from the remaining stems and leaves, using solvents.

Throughout the centuries of its use, opium has been the medication of choice for a huge array of pain-causing conditions. The drug is ineffective in treating the underlying causes of disease, but it is a powerful analgesic (pain-relieving drug) that gives the patient a feeling of well-being; all things considered, opium was, until relatively recently, one of the very few drugs that would have been of any real benefit to a patient. Many herbs, extracts, tinctures and products of the chemist's laboratory were used as medicines, some of which were innocuous, but at worst they were potentially lethal. Almost any compound seen to produce an effect on an individual's constitution was thought to be beneficial in some way, even if the person initially appeared to get worse. Until science determined the root cause of diseases, doctors were effectively working blind, and effective treatments were discovered more by luck than judgement. Medicine in the mid-nineteenth century was neatly summed up by Oliver Wendell Holmes Jr, in his address to the annual meeting of the Massachusetts Medical Association in 1860: ‘Throw out opium, which the
Creator himself seems to prescribe … and the vapours which produce the miracle of anaesthesia, and I firmly believe that if the whole
materia medica
as now used could be sunk to the bottom of the sea, it would be all the better for mankind – and all the worse for the fishes.'

In addition to its analgesic properties, opium in higher doses also acts as a sedative. An early form of anaesthesia was the
spongia somnifera,
or sleep-inducing sponge, which was used to lessen the pain and horror of medieval surgery. The sponge was soaked in a solution of water and wine, mixed with opium, lettuce, hemlock, hyoscyamus (henbane), mulberry juice, mandragora (mandrake) and ivy.
⁶⁷
Once prepared, the sponge was dried out and stored until it was needed; it was then moistened so the juice could be drunk. The same sponge could be used a number of times.

Up until the middle of the nineteenth century, opium was mixed with a staggering variety of other ingredients to produce a range of remedies for almost every conceivable ailment. These other ingredients were usually inactive, sometimes lethal and occasionally very strange; combinations included powdered pearls, chloroform, wine, belladonna and amber. The mixture of opium with alcohol, now commonly referred to as laudanum, was discovered by Paracelsus (1493–1541), a Swiss-born alchemist, who realised opium was more soluble in alcohol than water, and that it was more effective in this form. Two depressant drugs taken together, such as alcohol and opium, enhance the effects of each other, making laudanum a potent pain-reliever, but also enhancing the depressant effects, thereby increasing the risk of coma and death. In the nineteenth century ‘tincture of opium' consisted of the powdered drug dissolved in alcohol in a 10 per cent mixture, though in reality the concentrations of both opium and alcohol varied
enormously. Its use became widespread and prices plummeted; tincture of opium became cheaper than gin or wine, and there were no restrictions on its sale. By around 1850, the annual consumption of opium averaged 5g per person. It was even spooned into the mouths of infants to relieve teething troubles. The result was that many people became addicted, including the poet Samuel Taylor Coleridge, Abraham Lincoln's wife, Mary, and even Queen Victoria herself.