DUE TO GAS DERIVED FROM COAL-DUST. 



123 



When the blasting charge was fired, products of com- 

 bustion holding 140,000 gramme units of heat were projected 

 through the planes of rupture in fan -like sheets into the 

 coal-dust. The products would suffer diminution of tem- 

 perature in expansion through the planes of rupture and 

 through the air ; but the velocity of projection through the 

 distances of 4 to 8 feet between the shot and the coal-dust 

 would not permit any important surrender of heat to the 

 faces of rock or the air, and the products would be at an 

 exalted temperature when they struck the coal. 



The temperature of distillation of coal in the gas retort is 

 under 1000° C, and the educts are {London Gas, Frank- 

 land) : — 



100-00 



The first educts from the coal-dust would be represented 

 by this composition with the addition of some impurities, 

 and the point to note is that hydrogen not in combination 

 with carbon, forms over 50 per cent., and gaseous hydro- 

 carbons over 38 per cent., of the gases. 



These educts would be ignited and burn immediately upon 

 their liberation from the coal if adequate oxygen were 

 present, and distillation and combustion would continue 

 along the path of coal-dust so long as oxygen was available, 

 and sufficient heat was disengaged to sustain the actions ; 

 but, as already observed, such combustion has no disruptive 



