xiv Proceedings. \January 21st, 191 j. 



the conclusions arrived at by the late Sir Frederick Abel, viz., 

 that the presence of such incombustible dusts in a mine may 

 bring about the explosion of small percentages of fire-damp in 

 air which would not otherwise be inflammable. 



While the experiments on which Abel founded these con- 

 clusions have been repeated on a similar scale at the Home 

 Office Experimental Station at Eskmeals during the past year 

 with negative results, the explanation advanced by Abel has also 

 been examined experimentally in the chemical laboratories of 

 the Manchester University. 



Abel's explanation is that the finely divided dust, heated up 

 by the lamp flame, allows chemical action to take place on its 

 surface — just as platinum brings about the combination of 

 hydrogen and oxygen— and that the oxidation of the fire-damp 

 proceeds with increased rapidity as the dust becomes more 

 highly heated. The dust particles are thus raised to incan- 

 descence and fire the gas mixture round them. 



This explanation involves the assumption that an amount of 

 combustible gas, which is insufficient to propagate flame in the 

 mixture, can by suffering partial combustion bring the remainder 

 into an explosive state. The heating up of a gas mixture by an 

 external source of heat increases its explosive power ; but this is 

 not found to be true if the heat is derived from the burning of 

 the gas itself. 



The authors have heated up mixtures of coal gas and air and 

 mixtures of methane and air by means of a long platinum spiral 

 through which an electric current was passed. After chemical 

 combustion is started the mixtures become less and not more 

 explosive, although only a portion of the heat is derived from 

 combustion of the gas itself. Even if the incombustible dusts 

 acted like platinum it would be difficult to explain Abel's results 

 as being due to a catalytic action. 



Experiments carried out at Eskmeals show that the presence 

 of fine incombustible dusts do not increase, but retard, the rate 

 of explosion of gaseous mixtures. 



