Spontaneous human combustion

Spontaneous human combustion (SHC) is the burning of a person's body without the apparent presence of an external source of ignition. While the cause of such combustion remained for many years a complete mystery it is now generally accepted that the most probable cause of SHC seems to be a Wick Effect fire. The Wick Effect is discussed below.

Table of contents

1 Characteristics
2 Complications
3 Theories

3.1 The 'Wick' Effect
3.2 Experiment

4 See also
5 External links

Characteristics

There are many characteristics that together distinguish SHC from other forms of fire.

In spite of the name, the fire is never started spontaneously (i.e. the fire is never started by itself). There is always some form of ignition present around the fire.
The fire is usually localized to the body of the victim. Furniture and appliances near the victim are usually left untouched by the fire. Little or no damage is done to the vicinity of the victim.
The body of the victim is usually more severely burnt than in a normal house fire. The burns are, however, not distributed evenly across the body. The torso of the victim is usually very severely damaged, sometimes reduced to ashes, but the extremities of the victims are usually left untouched by the fire
Most cases of SHC occur indoors
Appliances (e.g. televisions) located on top of cupboards can be damaged
Victims are often female
Victims are often overweight
Most victims are also said to be alcoholic

Complications

Being more than 75% water, the human body does not burn very well. However, in many cases of SHC, victims' bodies were reduced to cinders. To render the body to such a state requires temperatures of more than 1700° C (3000° F). Even in modern crematoria, which have temperatures around 1100° C (2000° F), the bones cannot be broken down completely and have to be ground into smaller pieces.

Many murderers have tried to burn their victims (in fact, many have attempted to cover up their crimes by SHC). However, once the accelerant is burnt up, the victim will stop burning. This is true in the case of Adolf Hitler, whose body was burnt after he committed suicide. However, his body was still easily identifiable even though more than 20 litres of fuel was used. Moreover, forensic investigation reveals no use of accelerants in suspected SHC cases.

Theories

Of course, as with any apparently anomalous phenomenon, there are a number of theories that attempt to explain how SHC happens. Most have a scientific basis; some do not.

The victim was smoking and inadvertently caused ignited some flammable object (e.g. clothing) and the resulting fire killed him/her.
The victim was drinking and the excessive alcohol content in the body cause the fire to be large enough to kill. Obesity, age and other factors also cited by proponents of this theory.
"Wick" effect (see below)

The 'Wick' Effect

The wick effect essentially says that a person is burned through his own fats after being ignited, accidentally or otherwise. The clothed human body is like an 'inside-out' candle: the human fat (the fuel source) is inside and the clothes of the victim (the wick) is outside. Hence there was a continuous supply of fuel, in the form of fat that melted and dripped to the victims' clothing.

Experiment

Using a dead pig wrapped in a blanket and placed in a mocked-up room, BBC set out to prove the 'wick' theory in its science television show QED. A small amount of petrol was poured on the blanket as an accelerant. After igniting the petrol, the researchers left it to burn by itself. The temperature of the fire was regularly recorded and it was only around 800° C (1472° F). As the fire burned through the pig's skin, it melted its subcutaneous fats, which flowed onto the blanket. Bone marrow, which also contains a high amount of fats, also contributed to the burning. The surrounding furniture was not burnt although a television placed above a cupboard had its plastic cover melted. The fire had to be manually extinguished after seven hours. The majority of the pig's body had been burnt to ashes.

From the experiment, the BBC researchers explained the following characteristics of SHC:

The fires were highly localized: the flames of the fire were less than 50 centimetres high, therefore the fire usually did not spread to furniture in the vicinity.
The body is very severely burnt: the fire, although not very hot comparatively, can burn for a long period of time, as shown by the experiment. It is further fuelled by the body fat of the victim, which explains why the body can burn for such a long time.
Furniture located above cupboards burnt: the fire continuously heated the air and produced a convection current. Hot air rose and caused the plastics in television set to melt.

Charles Dickens used spontaneous human combustion as a plot device in his novel Bleak House (1853), which added considerably to interest in the subject.