130 THE CHEMISTRY OF COLLIERY EXPLOSIONS. 



A colliery explosion in which coal-dust is the principal 

 agent is originated by the heat in the products of an 

 exploded blasting agent, or ignited inflammable gas, insti- 

 tuting a series of chemical changes in the coal-dust, 

 commencing with distillation, followed by chemical and 

 physical changes in the educts which liberate heat, place 

 free hydrogen at disposal, and re-establish the series in 

 the adjacent coal. This series of actions is of constant 

 sequence or reproduction along the path of coal-dust until a 

 place is reached where the supply of atmospheric oxygen is 

 increased and the accumulated hydrogen is exploded, causing 

 disruptive effects, but leaving sufficient heat to repeat the 

 phenomena beyond. 



In conclusion, this theory accounts for the coked residues 

 of coal and the positions in which they were found ; ex- 

 plains the presence of amorphous carbon in suspension in 

 the atmosphere, and its characteristic dejjosition upon the 

 side walls throughout the fields of disaster ; accounts for the 

 comparative absence of the oxides of carbon in the gaseous 

 products ; supplies the heat for distillation, dissociation, and 

 other demands ; allows time for the distillation of coal and 

 the chemical changes in the educts; provides explosive gas 

 for disruptive purposes ; explains the occurrence of dis- 

 ruptions at intervals, the intervening periods of rest from 

 disruptive action, the conditions under which propagation 

 proceeds or is arrested, and excludes no coal except that 

 which yields no combustible gases when subjected to the 

 temperature of dry distillation. 



