The Science of Mysteries: Instructions for A Deadly Dinner

One day on Twitter, some science bloggers who began life on the dark side, in the humanities, happily discovered a shared taste for classic mystery writers.  We thought we might write a series of posts, all on the same day, about the science in mystery books and so …

You’ll find me here talking about toxicology, one of the great writers from the golden age of detective fiction, Dorothy L. Sayers, and her 1930 book Strong Poison. But you’ll also find Jennifer Ouellette exploring physics in Sayer’s masterpiece, The Nine Tailors, at Cocktail Party Physics and also in Jane Langton’s Dark Nantucket Noon for Discovery News. Not to mention Ann Finkbeiner at The Last Word on Nothing looking at geology, rivers and the great Josephine Tey’s book, To Love and Be Wise. It’s made for a great week of reading  very smart writers of the past and consulting with very smart writers today.


When people ask why I would choose to write a book about poisons (The Poisoner’s Handbook) I usually start with my brief stint as a chemistry major, my continuing affection for using poisons as a way to think about our chemical planet. But I always end up admitting that – and, yes, this will make me sound a little twisted –  I’ve been thinking about poison murders since I was in high school.

That was when I started reading my way through my mother’s collection of early 20th century murder mysteries – Sayers, Agatha Christie,  Georgette Heyer, Mignon Eberhart, Patricia Wentworth – women who spun the most intricate plots around the most evil chemistry. Of these, only Christie is really famous today, more for her brilliant plotting and  quirky detectives like Hercule Poirot or Miss Marple than for her savvy toxicology. But she knew her chemistry; she’d worked as a nurse and in a hospital pharmacy.

In her debut novel, The Mysterious Affair at Styles (1920), the killers deftly use bromine to precipitate strychnine into the bottom of  victim’s tonic bottle, carefully timing that last lethal dose. It was this that caught my attention and imagination – the elegant use of a lethal substances, the way the peculiarities of a poison could literally carry a plot. A much later Christie novel, The Pale Horse (1961), uses the unnerving symptoms of  poisoning by thallium to produce both a puzzle and a ominous sense of disaster.

But none of these writers, I think, did more justice to that most famous of homicidal poisons, arsenic, than did Sayers in Strong Poison. The title comes from the lyrics of a 17th century ballad, The Poisoned Man: “O that was strong poison, my handsome young man/O yes, I am poisoned mother; make my bed soon/For I’m sick to the heart, and I fain wad lie down.”

But the chemistry is absolutely up-to-date for 1930, the year the book was published. In fact, Sayers for all her literary background (she was an Oxford University educated scholar of classical languages and considered her translation of Dante’s Divine Comedy to be her best work) performs as an outstandingly good science writer in the course of the story. Consider this description:

And presently, definitely, magically, a thin silver stain began to form in the tube where the flame impinged on it. Second by second it spread and darkened to a deep brownish-black ring with a shining metallic centre.

“Holy blank,” I said to myself. “She’s talking about the Marsh test.” I was at the moment rereading Strong Poison, and I was exactly 29 pages from the end but I put the book down so that I could run downstairs and inform my husband that Sayers really knew her arsenic.

I don’t know why I bother to tell him these things. He always looks so hunted.

Source: Wikipedia commons

But about the Marsh test. It was developed by a British chemist, James Marsh, during the 1830s. At the time, there was no good test for detecting arsenic (or really any poison) in a corpse. Marsh himself had been involved in the prosecution of one accused murderer who was found not guilty partly because the science was so inconclusive. After the verdict, the man admitted that he had indeed killed his grandfather with arsenic. Infuriated, Marsh dedicated his spare hours to looking for a better test. The technique he developed would eventually revolutionize toxicology – it worked, it led to convictions, and it was credited for a reduction in 19th century arsenic murders, as would-be poisoners for first time worried about scientific evidence.

The Marsh test used a mixture of zinc, acid, and heat applied to suspect tissue to generate a fine vapor. If the tissue contained arsenic, the vapor would include arsine gas which, when cooled, formed a dark silvery “arsenic mirror”. In fact, that shining metallic formation so beautifully described by Sayers above.

That revealing Marsh test, as you might imagine, appears fairly late in the story. Sayers begins the book at the murder trial of a mystery writer, Harriet Vane, accused of killing her former lover with arsenic. Vane had purchased arsenic shortly before the death although she claimed to have done so has part of research for a novel.  The detective who starred in most of Sayer’s mysteries, Lord Peter Wimsey, attends the trial and becomes convinced of Vane’s innocence. He’s also smitten by Vane’s intelligence and fierce independence – setting the stage for a courtship than runs through several following novels.

But the judge in the trial isn’t smitten at all. As he instructs the jury, he details Vane’s promiscuous behavior with the dead man (she lived with him) and dwells on her unnerving knowledge of arsenic, noting that Vane “evidently gave considerable thought to the subject, for there were a number of books on her shelves dealing with forensic medicine and toxicology, and also the reports of several famous poison trials..”

I had a moment in which I realized – is this why my husband occasionally looks so hunted? – that this fictional character might be describing my literal library. The rows of books about  forensic medicine and toxicology books, the specific case studies of murderous events. Like Sayers’  Harriet Vane, I even possess a book on “the Armstrong case.”

But in our mutual defense, this was a famous murder; Herbert Rowse Armstrong, executed in 1922,  poisoned his wife with so much arsenic that even after death it was found oozing out of her hair. Armstrong is still famed as the only solicitor in the history of the United Kingdom to have been hanged for murder.

In Sayer’s story, Vane is saved by a hung jury (the holdout is a friend of Wimsey’s) and before the new trial is set, the detective is able to discover the real killer. There’s never a doubt that Vane’s lover, Philip Boyes, was killed by arsenic. His death is a catalog of classic arsenic symptoms – from severe nausea and vomiting, to tremors and chilling of his hands and feet. Arsenic’s effects are well known, thanks to its long homicidal – and industrial –  history and the fact that it’s a naturally occurring element, known to contaminate water supplies around the planet.

So the problem in solving Boyes’ murder is mostly figuring out how he ingested that last lethal dose of the poison. The evening that the victim died, he’d shared a dinner with his cousin in which they both ate from the same dishes. The cousin, as the judge noted, remained perfectly healthy. Boyes had then gone to visit Vane who might, or might not, have served him a poisoned cup of coffee. But if not at her hands, then whose?

“You’ve got to have some plausible pretext for giving a bloke arsenic,” complains Wimsey to an associate. “You can’t just catching him standing on a doorstep and say ‘Here, have a drink of this,’ can you?”.

Eventually, Wimsey discovers that someone besides Vane (and no, I won’t tell you who) has a secret supply of packets of a mysterious white powder. At this point it’s clear that Sayers has also been reading up on Herbert Rowse Armstrong, who put arsenic weedkiller into paper packets and kept them in his pockets.

Armstrong claimed that he needed the poison on him in case he stumbled upon an unexpected weed.He had, in fact, been tipping it into his wife’s tea. One of the reasons that poisoners liked arsenic so much – before scientists like Marsh made it so detectable – is that it tends to be bland in taste, difficult for a victim to detect in food or drink. In some of my favorite 19th century tests by forensic chemists, they mixed it into everything from pudding to wine to prove that point. (In case you wondered, that fact also comes from my personal library.)

Anyway, it’s that neatly discovered white powder that Wimsey puts so successfully through the Marsh test. Once he’s found the poison, he is able to reconstruct the crime and to trick the murderer into a confession. I won’t give it all away here but it involves the idea of building up an arsenic immunity before serving a particularly deadly dinner.

When I arrived at the solution to the mystery, I thought to myself, “Holy blank, she’s talking about the arsenic eaters of Styria.” These were 19th century Austrian peasants who supposedly became resistant to arsenic toxicity by eating it in small regular doses. One report had them smearing a poisonous paste on their morning toast. At Sayer’s time, arsenic-eating was prominently featured in toxicology books and her description is, again, textbook perfect.

Or at least 1930s textbook perfect. It was a hot theory in her time but today it appears less convincing,  based on mythology as much as science. Modern science tells us  that chronic exposure to arsenic is likely to bring on a host of health problems, ranging from skin discoloration to malignancy, that Sayer’s villain would not have enjoyed unblemished good health.

But her ending holds up perfectly in terms of the science of 80 years ago. And the other details – the shimmering results of a Marsh test, for instance? They’re as good today as they were when Sayers plotted out her story of arsenic and murder by a very strong poison.

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28 Responses to The Science of Mysteries: Instructions for A Deadly Dinner

  1. Pingback: The Science of Mysteries: For Whom the Bells Toll | | USEFUL DOCUMENTUSEFUL DOCUMENT

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  4. Richard Francis says:

    Thanks for this post. I’ve been a Sayers fan for as long as I can remember and it’s great to know the science behind the story.

  5. Deborah Blum says:

    Me too. She’s so smart and there’s a wonderful sense of humor that runs through it. I hope the post encourages people who don’t know Sayers to take a look.

  6. Andy Beaton says:

    Very cool, but I must confess I never pictured Harriet Vane as she appeared on the book cover at the top.

  7. Great story, and I loved your book. I am a practicing medical toxicologist and and lived this sort of thing in real life over the past 30 years. What amazes me is how so often no one suspects anything malicious, and even when they do, they don’t act upon it. I am working on a collection of my real life experiences.

  8. Dr Aust says:

    Nice post. As a long-ago chemistry undergraduate I always enjoy reading about a good literary poisoning.

    Isn’t there another of Sayers’ novels where digitalis features as a poison? My memory is that the deceased is taking digitalis as a medicine, so the fiendishness of the murderer (the dead man’s relatives who inherit his estate are suspected) is to make it look as if the death was accidental, with the dead man taking too many of his own tablets by mistake.

    Of course, this one also makes a good scientific story, as the cardiac glycosides (like digitalis) have a famously low therapeutic index (that is, the difference between the therapeutic dose, and a dose that produces adverse effects, is very small). In fact I often mention the ‘digitalis murder mystery’ to the medical students when we discuss cardiac glycosides as a way of introducing the therapeutic index idea.

  9. Joan says:

    Nice post. I love Dorothy Sayers in particular and the Golden Age of detective novels in general. Sayers was very careful with her science.

    Have you read anything by John Rhode? Some of the Dr. Priestly novels are entertaining. The Claverton Mystery has a death that must be murder by arsenic — but isn’t. The solution is clever and all about chemistry. The Corpse in the Car is another one with an apparently natural death that Dr. Priestly nails down as murder by chemistry.

  10. Laura Dodd says:

    I also have a modest collection of poison and poisonous plant books. I love chemistry and herbology, and have a penchant for thinking about the dark side of matters as well as beneficial. My interest made my last husband (no, not late) a little nervous too. I assured him that if I ever became murderous, I wouldn’t dare turn to poison. I don’t think he was comforted by that.

  11. Joanne says:

    Hi Deborah,

    After reading the Poisoner’s Handbook, I can clearly see how these mystery type novels were influential in your writing style.

    I plan to read the series that includes the book “The Sweetness at the Bottom of the Pie”
    I think the young ladies I influence will find that series intriguing and hopefully draw them into science.

    It was great meeting you last February in Chicago! I look forward to seeing you at @Scio12 this year!

  12. Marcoscan says:

    Thanks for the post, very nice!

  13. Cousin Matthew says:

    A grand exposition of Strong Poison, which is definitely one of my favorite detective stories. But then, I also like the undignified Murder Must Advertise.

    (You mean, Marsh’s test releases arsine? Ack!)

    Sayers had a lot of fun with current science; who else would have a police inspector saying to his friend, “Don’t go all Eddington”? Try that in a modern work, perhaps with Hawking instead. Not likely.

    However, it’s the sport to see the engineer Homer nod. In The Documents in the Case there is a need for monochromatic light, and “[Sir James] snapped off the lights, and we were left with only the sodium flame. In that green, sick glare…” That what sick glare?

    But the book is well worth reading, I think, as the most science-laden of her books, even if it lacks Lord Peter. His place is taken, more or less, by an artistic, poetic y0ung man who lacks a number of Wimseyan superhuman qualities, among them a familiarity with current science. He has to find the key to the poisoning case by talking at dinner with three scientists and a Church of England vicar of modern tastes, plus an obligatory Pale Young Curate. Does that sound too Sayers to be true? Believe it.

    BTW there happens to be a set of notes on the book, footnotes that make sense only in conjunction with the text; but the end is an appendix about the science in the dinner discussion, both the state of the science in the 1920s and its state in 2003. Pleasantly enough, the latter is already noticeably out of date.

    Apologies for the blogwhoring.

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  15. Thanks for that post: I love the way that fiction and science come together.

    Incidentally, I ran across some comments on ‘arsenic eating’ while researching my forthcoming book on an inter-war British murder trial.

    Details here:

  16. Ed Whitney says:

    The Unpleasantness at the Bellona Club features an old man who dies in his chair and sits unnoticed for several hours during the Armistice Remembrance soon after the Great War. He proves to have died of digitalis poisoning.

  17. Deborah Blum says:

    No, haven’t read John Rhode but now I’m totally intrigued. We’re going to do more mystery posts so this could definitely go into the line up. Will start with The Claverton Mystery.

  18. Deborah Blum says:

    I’ll bet your story will make a great book!

  19. Deborah Blum says:

    No, the image is all wrong. But I love those old lurid paperback covers so couldn’t resist.

  20. Porlock Junior says:

    That’s nothing — the cover of one paperback edition features the solution to the mystery. Pfaugh.

  21. Deborah Blum says:

    No! That’s a total cover sin.

  22. Great blog, hope to see it continue.

  23. Dr. Aust, I was intimately involved in the prosecution of Charles Cullen, an infamous muderous nurse in New Jersey and other places who got away with murder for many years until killing 2 patients with digoxin and 2 with insulin in the same ICU over about a month period of time and our poison center picked up the trend. I have been the medical director fr nearly 30 years and have a treasure trove of interesting poisoning experiences. If I ever get to really write my book, it will be one of the featured chapters.

  24. Deborah Blum says:

    Sincerely hope you will write that book, Dr. Marcus.

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