Scrolling through my feed this week, I got intrigued by a phenomenon shared by a comment in which the mention was on the mystery surrounding the spontaneous human combustion (SHC). This is the case of some unexplained and unnatural burning of dead bodies by fire.
Spontaneous combustion is the act of having a fire burn without corresponding intense heat applied on the object. In chemistry, some few chemical elements like the phosphorus, a very reactive metal easily experience spontaneous combustion at temperatures of around 30-degree Celsius when exposed to moist air.
A recontruction of sponteneous human combustion. Image credits: By CC-BY-SA-4.0 from Link]
The idea that a dead body can naturally ignite and burn up to the point of only ashes left while leaving the surrounding areas intact looks like something out of a horror movie based on a book written by the American horror story writer, Mr Stephen King. However, the occurrences of this phenomenon is not a work of fiction. And how it came to happen has being a subject which intrigues, fascinates, and one with conflicting explanations by many people for many centuries. There are many sceptics as well as believers as to the true nature of how a human body can completely self-incinerate without outside influence.
The SHC has been a subject which spans centuries after it was first mentioned in the year 1641 Thomas Bartholin, a Danish mathematician and physician, brought the issue to public attention when he wrote that a lady "went up in ashes and smoke" leaving the straw bed she was sleeping on unscathed.
While many believe that SHC is a real thing, others think its nothing more than an urban legend or an old wife tale. The scientific community is torn between these two camps of those who believe and those who think it is just a myth.
So far, recorded victims of this SHC all exhibit similar characteristics; the upper bodies are majorly incinerated leaving the lower part of the body untouched especially the leg. First responders to the scene of this phenomenon perceive some smoky sweet smell.
There have been many conflicting theories to the real cause of the unexplained burning of the human body. Popular amongst the assumption is that the victims may have been alcoholics who must have consumed copious amounts of alcohol making them inflammable. But this theory was dead on arrival as the human body is made up of 60% of the human body is made up of water with the lungs leading by having up to 83% of it made of water. Even the human bones are not spared as they are 31% water.
Alcohol is flammable, but the truth the alcohol out on the shelf in various bars is never 100% alcohol. 100% alcohol can easily lead to faster alcohol poisoning as the liver will be unable to break up the alcohol fast enough. Alcohol burning is even a way American tavern owners of the 1800s test the authenticity of their newly arrived liquor by lighting it up with a match.
The German chemist, Justus von Liebig who investigated numerous cases of SHC concluded that alcohol consumption was not the cause of the fire as even anatomical specimens preserved in 70% ethanol was not ignitable. This laid to rest the thinking that the victims might have drank a little too much.
If the mysterious fire was not as a result of alcohol, what then could it be?
Some school of thoughts started looking in the direction of natural fuel. For there to be a fire, there must something to act as fuel.
The Wick Effect
The candle is common in most homes and used for a variety of functions such as religious events, romantic hangout such as candle-lit dinner, in commemoration of the dead, etc. A candle simply has two major parts, the wick and the wax. The wick is that ropelike element we light and the wax may be either made from a mixture of paraffin and insect wax (mostly bees) to provide the fuel with which it burns.
The now-retired University of Leeds professor of forensic medicine, Dr David Gee experimented to show the human body fact can act as a wax on the wick. Hence the term wick effect, to burn when ignited. The truth is, the skin, tissue and bone will burn when exposed to fire. This, Dr David Gee demonstrated by acquiring some quantity of human fat in a test-tube, wrapping it with skin and covering the whole object with clothing and subsequently igniting it. This test is as much replication of a human body as the Dr can get, as getting a real body to burn in this experiment is not possible. The model successfully continued to burn without any additional aid thereby proving that there is nothing mysterious in all the deaths that the human body fat can indeed act as fuel to sustain burning. Or is it?
Many alleged cases of SHC follows a pattern that laid credence to the claims of the result of the wick effect experiment. Men and women have the amount of massive fat distribution in their bodies. Most of which points around the upper body and torso, e.g. the hips, thighs, and breasts. These areas are often the part most likely to be burnt entirely in the events of the reported SHC cases.
Modern crematorium operates in temperature range of between 1650 degrees Fahrenheit °F (898.889°C) to 1800 Fahrenheit (982.222°C). The process usually lasts between 1 to 3 hours depending on age, body type and weight of the remains.
Below these temperatures, combustions of osteological material(bones and skeletal elements like teeth) are not complete.
Estimated heat output from bodies discovered in an SHC incident can be calculated using the Heskestad equation which calculates the intensity of flames going by its height and area burnt which is
H = 0.235Q2/5- 1.02D
H= flame height measured in meters
Q= heat output measured in kilowatts (KW)
and D= Diameter of fuel spread or burnt area measured in meters
When this was calculated, the heat output was found to be in the value of between 11 and 23 kW.
But burning fat without outside influence is difficult to attain temperatures hot enough to burn into ashes as in the case of most SHC incidents.
Despite previous research results regarding the effects of heat on human remains, the most common criticism leveled against the "wick effect" hypothesis by advocates of SHC is the inability of researchers to replicate (and therefore account for)the unusual degree of bone incineration often seen in alleged cases of SHC. Indeed, the reduction of bones remains perhaps the most difficult factor of fire cremation deaths to explain.
While the above studies suggest that burning pork fat reaches temperatures sufficient to calcine bones, DeHaan' s pig failed to bum to ashes as hoped. I would like to suggest that previous attempts such as these have failed not because the "wick effect" hypothesis is lacking, but because a fully appropriate research design with appropriate subjects has never been used. P20: Debunking the Spontaneous Human Combustion Myth: Experiments in the Combustibility of the Human Body
In conclusion, it is safe to assume while human bodies are flammable, they do not spontaneously combust. However, SHC advocates, are not likely to agree to this the conclusion.
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