A is for Arsenic (12 page)

Christie and cyanide

The two deaths in
Sparkling Cyanide
are very similar. Both Rosemary and George Barton had lethal doses of potassium cyanide added to their champagne glasses. Potassium and sodium cyanide salts are white crystalline solids much like sugar or table salt in appearance. These salts can have a faint but characteristic smell of almonds, due to a reaction between the salt and moisture in the air producing small amounts of hydrogen cyanide. A small amount of white crystals that looked like sugar certainly would not have seemed out of place in a restaurant, and could easily be slipped into a drink without anyone suspecting. Champagne is mostly water and would have easily dissolved the potassium cyanide; champagne is slightly acidic (around pH4) and the acidity could have made the reaction to produce hydrogen cyanide faster, and made the smell and taste of bitter almonds stronger.

However, between 20 and 60 per cent of people
cannot smell cyanide
. The research done in this area is not huge – asking people to sniff cyanide, even in safe amounts, does not have volunteers queuing out of the door. Experimentation was mostly carried out in the 1950s and 1960s, though the phenomenon had been known about long before then. The conclusions of these studies vary, but the general consensus is that while there is a genetic component involved, previous exposure to cyanide in the environment seems to be the more important factor in determining an individual's ability to detect cyanide. Rosemary and George may not have been able to notice that their champagne had an unusual smell and flavour, and Christie made no comment on the characteristic cyanide smell on this occasion.

The effects of the poison took hold immediately after the champagne had been swallowed. Symptoms of cyanide
poisoning generally appear between one and fifteen minutes after exposure; the quickest way to get the poison to take effect would be to introduce it directly into the bloodstream by injection. Inhalation of hydrogen cyanide gas would not take much longer. Ingested cyanide compounds would be expected to act a little more slowly, as there is a slight time-lag while the cyanide is absorbed through the walls of the gastrointestinal tract and makes its way into the bloodstream. Cyanide ingested on a full stomach would take even longer; Christie does not mention at what stage of the meal the poisoning takes place in
Sparkling Cyanide
.

The symptoms Rosemary and George displayed, gasping for breath and convulsions, are an accurate description of what you might expect to see in a cyanide victim. Christie makes a point of the blue colour of the victims, and it is suggested that this is a symptom of the poisoning. Unfortunately, and very unusually for Christie, she got this wrong. The blue colour, or ‘cyanosed face' as Christie describes it, is a condition called cyanosis.

The word ‘cyanosis' is also derived from the Greek word
kyanos.
It is caused by a lack of oxygen circulating in the body. When an oxygen molecule binds to the iron atom in haemoglobin, forming oxyhaemoglobin, it becomes bright red. Deoxyhaemoglobin is formed after the oxygen has been released; its colour is closer to the blue end of the spectrum.
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An excess of blue-coloured deoxyhaemoglobin causes a noticeable blue colour in the skin. The condition can be localised owing to the cold (think of blue fingertips in winter), or because of a blocked artery, but it can also give a general blue colour to the whole body because of problems absorbing oxygen from the lungs. There are a variety of root causes for this condition, but none of them involve cyanide.

Cyanide victims sometimes actually seem flushed in appearance, with a pink coloration to their skin. Cyanide-haemoglobin complexes are pink in colour, but this is not the only cause of the flushed appearance. Because oxygen is blocked from binding to cytochrome c oxidase, it is not consumed in the normal respiration process and its concentration in the blood builds up. With high levels of oxygen present the oxyhaemoglobin fails to release its oxygen, and red oxygenated blood returns to the heart and lungs through the veins. Hence the red flushing.
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Both victims in
Sparkling Cyanide
die very quickly; George takes one and a half minutes to die, and this would be plausible if he had been given a large dose of potassium cyanide. The potassium cyanide was supposedly contained within a ‘cachet faivre'; aspirin and other remedies in powdered form were often folded inside slips of paper, a common form of packaging in the 1940s, and headache powders are still sometimes sold like this today. The powders are dissolved in water before swallowing; a normal dose of aspirin would be approximately 600mg, so a lethal (200–300mg) dose of potassium cyanide would easily fit in the cachet, and even leave room for more than was strictly needed.

The cause of Rosemary and George Barton's deaths was never in doubt. Few poisons act as quickly as cyanide, and traces of potassium cyanide were found in the champagne glasses as well as in an empty Cachet Faivre paper found under the table. A post-mortem examination would probably show indications of cyanide poisoning. Potassium and sodium cyanide are slightly corrosive, and may leave traces of burning on the lips and tongue. In the stomach the corrosive properties may have shown themselves by eroding the stomach wall, leaving behind a characteristic blackened discoloration for the pathologist to find. Hydrogen cyanide doesn't corrode the
stomach in the same way, but there are other signs to look for. There may have been an aroma of bitter almonds emanating from the viscera for the pathologist to smell, if he was able to, to confirm the presence of cyanide (inhaling cyanide fumes from cadavers can be a considerable hazard for mortuary staff). The cherry-red appearance of the blood would also indicate cyanide, although carbon monoxide poisoning can cause a similar coloration. But while detecting cyanide poisoning is relatively straightforward, determining the quantity ingested is much more difficult, even today.

Levels of both cyanide and thiocyanate in the body can be determined accurately, but there may be several natural or environmental sources of cyanide to complicate things. Cyanide is a common chemical unit, and cyanide compounds can be introduced into the body through the food we eat. Agatha Christie helpfully describes what was on the menu at the Luxembourg the night that Rosemary dies – Oysters, Clear Soup, Sole Luxembourg, Grouse, Poires Hélène (pears in a sugar syrup) and Chicken Livers in Bacon. George, in his attempt to expose the murderer at his recreation of the scene one year on, even replicates the food served to the guests. But there are no dishes on the menu that would deliver particularly high doses of cyanide.

However, there may have been a possible antidote amongst the comestibles, in the form of sugar. Champagne contains a little sugar, but the most sugary champagne contains only 50g of sugar per litre, compared to 150g per litre in the Madeira wine that Rasputin drank on his final night. But there were other sources of glucose at the Luxembourg. The sugar syrup in the Poires Hélène dish could have protected Rosemary and George against the worst effects of cyanide poisoning. Perhaps they died before they got to the dessert course.

Yet another source of cyanide, one that could have affected post-mortem analysis, is in cigarette smoke. Smoking was much more common in 1945 than it is today, and though Christie doesn't mention whether Rosemary or George were smokers, it would have been quite likely that they were.
Hydrogen cyanide is a common by-product of the combustion of natural materials such as tobacco, silk or wool, and some plastics also release hydrogen cyanide when they burn. Cyanide poisoning is thought to contribute to a significant proportion of deaths from smoke inhalation in fires, though cyanide levels are not always specifically tested in the remains of these victims, but it is an important consideration for fire-fighters.

In addition to all of these sources, cyanide compounds can also be produced in the body by the normal decay processes that occur after death. So the post-mortem picture can be complicated by many potential sources of cyanide, some of which may have been metabolised into thiocyanate before death, and the addition of new cyanide compounds afterwards.

The best thing the pathologist in
Sparkling Cyanide
could have done would have been to analyse the residues left in the champagne glass. If there was enough left in the glass, the concentration of cyanide, and therefore the total dose, could have been determined. This is still the best way of determining the dose in cyanide poisoning cases today, as unpicking the amount of cyanide from environmental sources and working out the dose from post-mortem blood levels of cyanide and thiocyanate is a task full of potential errors.

Little seems to have been done for Rosemary or George to try to save or revive them. There is no mention of emergency treatment, or even of calling an ambulance to rush them to hospital. Antidotes were available in 1945 – but that would not have made for a good murder-mystery novel.

Notes

³⁴
Though still not good to drink or wash in.

³⁵
Books on poisons and toxicology often state that the ancient Egyptians used cyanide from peach stones as a poison. A paper published in 1938 traced these statements back to an alleged translation by Duteil of a passage in ‘an extremely ancient papyrus in the Louvre', which is as follows:
Ne prononcez pas le nom de IAO, sous la peine du pecher
(‘Speak not the name of IAO [Hebrew shorthand for the name of God] under the penalty of the peach-tree'). This first appeared in an 1842 book on the history of chemistry by F. Hoefer. He claimed to be quoting Duteil but the quote has not been found in Duteil's writing. In 1938 the Louvre had four documents that might be expected to contain such a quote, the ‘demotic magical papyrus' and three ‘Greek magical papyri' but they contain no such reference to the penalty of the peach. The source of the quote remains a mystery.

³⁶
Tawell lived in London but kept his mistress in a cottage in Salt Hill, near Slough, Berkshire.

³⁷
‘Cyanogenic' simply means something capable of generating hydrogen cyanide.

³⁸
The tough seed coating will also prevent the release of much of the poison.

³⁹
Hence we see blue veins under our skin where deoxygenated blood is being transported back to the lungs to collect more oxygen.

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To be fair to Christie, I have read many different descriptions of the colour of corpses in cyanide poisonings. These range from flushed to ashen, though not blue.

Appointment with Death

‘Winston, if you were my husband, I would flavour your tea with poison.'

‘Madam, if I were your husband, I would drink it.'

Lady Nancy Astor and Winston Churchill

The quote above is typical of the acid-tongued exchanges between Lady Nancy Astor, the first female Member of Parliament, and Winston Churchill. Agatha Christie may have been thinking of Lady Astor when she created the character Lady Mary Westholme for her 1938 novel
Appointment with Death
. The two certainly bear a striking resemblance; Christie claimed, however, that her inspiration for this loud and opinionated character came from two women she had met in the Far East. Another character in the novel, Dr Gerard, comments thus on Lady Westholme: ‘that woman should be poisoned … It is incredible to me that she has had a husband
for many years and that he has not already done so.' But it turns out not to be Lady Westholme who is poisoned; the victim is another domineering woman, Mrs Boynton.

Appointment with Death
is set in Jordan, where a tourist group visits the abandoned city of Petra. The tourist party is made up of the Boynton family, under the control of malicious Mrs Boynton; Miss Pierce, a timid former nursery governess; Dr Gerard, a psychologist;
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the outspoken lady politician Lady Westholme; and Sarah King, a young doctor. On the first afternoon at Petra the group takes the opportunity to explore the site, leaving Mrs Boynton alone in the hot sun. When the party returns to camp Mrs Boynton is dead. The death would have been attributed to natural causes were it not for a mark left by a hypodermic syringe on Mrs Boynton's wrist, and some missing heart medicine. Fortunately for all concerned (though maybe not for Mrs Boynton), Hercule Poirot is holidaying nearby, and he is asked to investigate the true cause of death.

The suspected poison in the case of Mrs Boynton is digitalis, an extract of the foxglove plant, which is often prescribed to treat certain heart conditions. Digitalis is an effective medium of murder, with the added benefit that symptoms of an overdose resemble those of the disease the drug is prescribed for. Plus it is readily available, and lethal in very small quantities. Incredibly, very few murderers have used this toxic substance, or perhaps many have but they got away with it. But before you rush to take out hefty life-insurance policies on your closest and wealthiest relatives, or start growing foxgloves in your garden, remember that the drug is detectable even in minute quantities.