Spontaneous human combustion

While we're on the subject of arms and legs, I've been meaning to do a post about spontaneous human combustion (SHC), in which a person is almost completely destroyed by a fire that has no external source of ignition and does not consume flammable things in the immediate vicinity. Many theories have been put forth to explain the mysterious phenomenon, including high blood alcohol level and the wick effect. SHC is the cause of death of a character in Bleak House by Charles Dickens (1812-1870), who researched the known cases, which now extend into the early 21st c. The lower leg in the photo is that of retired doctor John Bentley (1874-1966), who died in the bathroom of his Pennsylvania home. Most of Bentley's body was reduced to ash between 9pm on Dec. 4th, when friends looked in on him, and the following morning, when a meter reader - alerted by a strange smell and a light blue smoke - found his remains. A 2 1/2' x 4' hole was burned in the floor, and yet the rubber tips on Bentley's walker, which can be seen in the photo, did not melt. Bentley smoked a pipe, but it was still in its stand on a bedside table. The perplexed coroner ruled that death was caused by asphyxiation and burning of 90% of the body.