COMBUSTION WITHOUT FLAME. 365 



When the phenomena of spontaneous combustion take 

 place near the surface of the earth, its effects are of a less 

 dangerous character, though they frequently give birth to 

 permanent conflagrations, which no power can extinguish. 

 An example of this milder species of spontaneous combus- 

 tion has been recently exhibited in the burning cliff at 

 Weymouth ; and a still more interesting one exists at this 

 moment near the village of Bradley, in Staffordshire. 

 The earth is here on fire, and this fire has continued for 

 nearly sixty years, and has resisted every attempt that has 

 been made to extinguish it. This fire, which has reduced 

 many acres of land to a mere calx, arises from a burning 

 stratum of coal about four feet thick and eight or ten 

 yards deep, to which the air has free access, in conse- 

 quence of the main coal having been dug from beneath it. 

 The surface of the ground is sometimes covered for many 

 yards with such quantities of sulphur that it can be easily 

 gathered. The calx has been found to be an excellent 

 material for the roads, and the workmen who collect it 

 often find large beds of alum of an excellent quality. 



A singular species of invisible combustion, or of com- 

 bustion without flame, has been frequently noticed. I 

 have observed this phenomenon in the small green wax 

 tapers in common use. When the flame is blown out, the 

 wick will continue red hot for many hours, and if the 

 taper were regularly and carefully uncoiled, and the room 

 kept free from currents of air, the wick would burn on in 

 this way till the whole of the taper was consumed. The 

 same effects are not produced when the colour of the wax 

 is red. In this experiment the wick, after the flame is 

 blown out, has sufficient heat to convert the wax into 

 vapour, and this vapour, being consumed without flame, 

 keeps the wick at its red heat. A very disagreeable 

 vapour is produced during this imperfect combustion of 

 the wax. 



