Spontaneous Human Combustion: The Myth That Refused to Burn Out

What happened?

Reeser’s case wasn’t the first of its kind, and it wouldn’t be the last. Reports of people supposedly bursting into flame from the inside out go back at least to the 1700s, when a French physician named Jonas Dupont collected dozens of accounts into a book on the phenomenon. The pattern was always similar: an elderly person, usually alone, found reduced mostly to ash, while the surrounding furniture, walls, and belongings were barely singed. For much of the 18th and 19th centuries, doctors and the public blamed excessive drinking — the theory being that a lifetime of alcohol had turned a person’s tissues into something flammable enough to ignite on their own.

That theory got a public airing in 1853, when Charles Dickens killed off a character, the rag-and-bottle shop owner Mr. Krook, by spontaneous combustion in his novel Bleak House. His friend and fellow writer George Henry Lewes objected in print, calling the scene “a vulgar error” with no scientific basis. Dickens defended himself in the book’s preface, insisting he’d researched the subject and citing around thirty supposed historical cases, including one investigated in Italy in 1731. The two men argued the point publicly for weeks and never fully resolved it.

Science, however, was already closing in on an answer. In 1850, the German chemist Justus von Liebig — one of the founders of modern organic chemistry — tested the alcohol theory directly. He soaked animal tissue in concentrated ethanol and tried to ignite it; the alcohol on the surface burned off and the tissue itself, being mostly water, wouldn’t catch. He also dosed live mice with enough ethanol to intoxicate them and found they were no more flammable than sober ones. Liebig later testified as an expert witness in a French murder trial, arguing in court that spontaneous combustion of a human body was, chemically speaking, impossible.

Reeser’s death in 1951 revived the debate on a national stage. St. Petersburg’s police chief was stumped enough to mail evidence — including carpet fragments and what were thought to be fragments of teeth — to FBI Director J. Edgar Hoover. The FBI’s lab concluded that Reeser, a user of sleeping pills, had likely fallen asleep while smoking. Her nightclothes caught fire, and her body then burned slowly for hours, fueled by her own body fat. Newspapers at the time also reported that her skull had somehow “shrunk” to the size of a teacup — a detail that made the story feel even more uncanny, but which was never confirmed in the police or FBI reports and doesn’t hold up forensically: heat causes skulls to fracture or rupture, not shrink. It’s best treated as a lurid embellishment rather than a fact.

The real forensic explanation is called the wick effect, and it works something like a candle turned inside out. In a candle, a wick draws up melted wax and burns it. In a body, clothing or upholstery can act as the wick, soaking up fat that liquefies as skin and tissue burn, and feeding a slow, sustained flame. In 1989, forensic fire investigator John DeHaan demonstrated this for the BBC science program QED: he wrapped a dead pig, chosen for its human-like fat content, in a blanket, used a small amount of fuel as a stand-in for a dropped cigarette, and let it burn. Over roughly five hours, the pig smoldered down to bone at temperatures reaching close to 800°C (1,472°F) at the wick site, while the surrounding room stayed relatively cool and undamaged.

Why was it strange?

The wick effect explains the two things that made these deaths look impossible: a body reduced almost entirely to ash, in a room that barely burned. It’s not that fire behaved strangely — it’s that a slow, low, well-fed flame concentrated almost all its heat in one spot for hours, rather than spreading. Without an eyewitness, an unattended fire that burns for that long, in one place, looks like nothing anyone has seen a normal house fire do.

What did scientists learn?

Every confirmed case attributed to “spontaneous” combustion has involved an identifiable external ignition source — a cigarette, a candle, a spark — plus a body positioned near a fuel source like upholstered furniture, and enough time undisturbed for the wick effect to run its slow course. No verified case has ever shown a body igniting without an outside spark. The myth persisted less because of missing evidence and more because investigators rarely find that spark: it burns away along with everything else near it.

How does it affect us today?

The wick effect is now standard material in fire investigation and forensic pathology, helping investigators correctly identify accidental fire deaths — often involving elderly, ill, or intoxicated people who couldn’t escape a small, slow-starting fire — rather than misattributing them to something inexplicable. It’s also a good working example of how forensic science operates generally: instead of asking “what mysterious force could explain this?”, investigators ask “what mundane process, given enough time, could produce this?”

Fun fact

Liebig wasn’t just debunking a myth for fun — he was also the chemist who invented the bouillon cube and helped develop the first infant formula. The same rigor he brought to proving people couldn’t spontaneously combust, he brought to figuring out how to concentrate meat extract into a shelf-stable product.

Sources

• Death of Mary Reeser — Wikipedia
• Wick effect — Wikipedia
• The FBI Investigates a Case of “Spontaneous Human Combustion” — Wonders & Marvels
• Hotter Than the Dickens — Science History Institute
• Justus von Liebig — Wikipedia

A note: this article discusses real deaths, including one involving smoking and sedative use. If you or someone you know is struggling with substance use or needs support, resources like SAMHSA’s National Helpline (1-800-662-4357) are available.