Classically, three elements of combustion are recognized as necessary: suitable fuel, an oxidizing agent, and an appropriate source of spark or fire. The concept of spontaneity requires only fuel and usually oxidizer are present. Any source of ignition remains mysterious and unknown.
The Typical SHC Scenario
Typically, the individual who supposedly succumbs from spontaneous human combustion (SHC) is immobile and obese. The victim is likely to be female, though by no means is that always the case.
The individual meeting the above specifications is likely to be seated in a chair or lying in bed. Parts of the extremities escape the flames, especially the feet and often the clothing, along with the immediate surroundings.
Historical Concepts – Spontaneous Human Combustion
Some have tried to link SHC with alcoholism. Novelist Charles Dickens is one of them. His “bad guy” character, rag and bottle merchant Krook in Bleak House (1853) (a heavy user of alcohol) is so consumed. After all, alcohol is quite flammable.
Some suggest internal imbalances are the cause of SHC, such as methane buildup in the digestive tract. The difficulty is that in general, it is the outer portions of the body that experience the greatest degree of combustion, rather than the internal organs.
Avoiding the Black-and-White
It has been pointed out: it is important to avoid over-categorization. Mysterious fires not easily explained shouldn’t automatically be labeled SHC. They should be handled on an individual basis for what they are – fires of unknown origin. On the other hand, it shouldn’t automatically be assumed there is no such thing. Rather, a better approach is, if SHC does exist, how is it to be explained in scientific terms?
Stop and Think
Recall SHC’s typical characteristics – the trunk is consumed, but the extremities, and the clothing often remain intact. The fire is small and with little effect on the surroundings.
Is there no source of ignition? Tales of SHC are often portrayed as mysterious, otherworldly. Truth be told, sources of ignition actually do exist. One source is a lit cigarette. The victim may be alcoholic. He or she falls asleep while drunk and smoking.
What explanation fits these facts? Well what that we are already familiar with bears a flame, yet is slow to be consumed? A candle. Liquefied wax climbs the wick and is burned, causing little immediate damage to the wick. But, you say, the wick is eventually consumed. But that is because the wick lies at the highest point of a candle.
How can it be explained why the hands and especially the feet are not inevitably consumed? It is because of all the parts of the human body, it is the feet that are lowest in fat, followed by the hands.
Now think back to the inebriated, unconscious, potential SHC victim… The cigarette slips from between his lips. A small fire starts, on the chest or abdomen. The skin is penetrated. Body fat liquefies like the wax of a candle. The clothing is the wick. The obese victim has much fat, enabling the fire to progress. Before long, death ensues.
Other Sources of Ignition
There are, of course, other ways a fire can be initiated. But the molten fat and wick theory seems the likely candidate for some of the cases of SHC. It provides a basis for the conjecture that SHC can exist is not to be viewed as inherently impossible.
Note: You might also enjoy Mysterious St. Elmo’s Fire