One of the largest problems in the study of Spontaneous Human Combustion is the constant inability (or unwillingness) of most researchers to look at the phenomena on a case-by-case basis. There is a tendency for so-called SHC 'experts' to shoot down theories that explain one case because it cannot explain another; using this method, any grouping of events can be argued as unexplainable as long as at least one of the events is not explained. This is neither scientific nor logical.
The plain truth is that some cases of SHC are explainable when looked at carefully. The number one thing to notice when studying the cases given is that in the majority of these events the actual 'combustion' is not witnessed; and that further, in a majority of this subset of cases, the time between when the victim was last seen alive and when they were found immolated is several hours. This begs the question: Just how spontaneous does 'spontaneous combustion' have to be if it has several hours in which to do its work?
There are three main arguments for a spontaneous combustion explanation in these cases. The first has been the assertion that the flames had to have caught the victim by surprise and been very fast about their work, or the victim could have found some way to avoid being consumed. This is a valid argument, and it must be accounted for; the obvious answer is that the victim must have been either incapacitated or dead previous to the burning... and, in a majority of these cases, we find evidence for the possibility of one or the other of these two states. Ironically, as Joe Nickell points out in his book Secrets of the Supernatural, the old theory that alcoholics are more liable to this form of death may be true -- because the drunker a person gets, the more likely they'll be unable to respond properly or in time if they do to catch on fire.
The second argument put forward in defense of the spontaneous combustion explanation in these cases is the assertion that there was no outside source of ignition (lighters, heaters, candles, etc). However, when the full facts of these cases are reviewed, again a majority are found to have had an ignition source available that has been traditionally ignored in the retellings of the legends.
The third and last argument for the spontaneous combustion explanation is that the flames must have burned at an anomalously high temperature to have reduced the body so quickly. This argument is supported by asserting two 'facts'. The first is that, since the human body is composed a great deal of water, human bodies are just plain difficult to burn. The second assertion is that crematoriums have to run at temperatures of 2,500 or more degrees Fahrenheit to reduce a body in just 3 hours; so, logically, if the body is consumed by SHC in a shorter time, then the temperature must be exponentially higher.
Unfortunately for these arguments, neither are true. Though the human body does contain a large quantity of water, it boils off just ahead of advancing fire and so forms no impedement to burning. As for the second assertion -- about 2,500 degree temperatures being needed to consume a body -- according to Joe Nickell in his book Secrets of the Supernatural, Werner Spitz and Russell Fischer's book Medicolegal Investigation of Death (1980) states that a body can be reduced in just an hour and a half at temperatures of 1600-1800 degrees; and the longer the body has to burn, the lower the temperature required. Many of the cases in the subset we are looking at had several hours each wherein just such a prolonged consumption of the bodies could occur; additionally, if there was additional 'fuel' besides the body's own fat, a higher temperature could be reached and the consumption could happen faster. In many more of this subset of cases, additional objects burned with the victims (wood floors, chairs, rugs, etc.). So, in these cases, there is nothing to support a claim of either "spontaneous combustion" or "preternatural combustibility."
This slow consumption of a body by a lower temperature flame using the clothing as a wick and the body fats as fuel, dubbed "the candle effect" by D.J. Gee in 1965, also explains other effects associated with this kind of "spontaneous combustion." In a room with poor ventilation, oxygen is quickly used up by open flames which then level out to a slow smolder, producing a heavy smoke; in the case of a human body, this smoke would contain grease from the burning body fats and soot from the clothing and body tissues. Because heat rises, the greasy, sooty smoke would coat the room starting from the ceiling and working its way down, stopping at any level that it could escape. This creates an orange greasy film that covers the walls and ceiling starting at a point several feet above the floor; and this is an effect often noticed in rooms where this form of "spontaneous combustion" has occurred.
The actual burn damage is also limited to just the area that the fuel source (the body) occupies, because there is not enough oxygen in the room to sustain the burning when the fuel is gone. Above the burning, in the area occupied by the hot smoke, the ambient temperature becomes high enough to melt plastic and heat up metal; but no objects can combust in the smoke due to the low amount of oxygen. So clocks melt, and doorknobs heat up, but paper remains undamaged; and when the door is opened, the inrush of oxygen causes a dramatic flare up in any smoldering remains left.
Thus a large number of cases attributed to Spontaneous Human Combustion are explainable by this "candle effect". Of the remaining cases, some more undoubtably would fall into this same category of explainability if we only knew more about each one. And even though this is not proof that this explanation is necessarily correct in these cases, it does show that they have not been properly proven to be of a paranormal nature; and without proof of paranormality, science is compelled to accept the easier explanation.
But don't take this as disheartening; as ever, my goal is to separate the truly anomalous from the merely unusual. The strangest and most unique cases of SHC remain unexplained, and will undoubtably be unexplainable for some time to come... if they are explainable.
