Manchester Memoirs, Vol. hit. (191 3), No. 15. 5 



dust heated by the flame was carried upwards a few inches. 

 Such an ignition was seen to occur several times, and the 

 flame then travelled along the gallery, both forwards and 

 backwards, as described by Abel, " with feeble explosive 

 effect." On the other hand, the admission of an incom- 

 bustible dust to the current when the mixture of gas and 

 air was complete had no effect on the cap or flare of the 

 lamp-flame except to make it more luminous. 



While these experiments were being carried out at 

 the Home Office Experimental Station at Eskmeals, we 

 thought it worth while to test the theoretical explanation 

 offered by Abel of the influence of finely divided dusts on 

 explosions. 



According to Abel's explanation, the warmed dust 

 acts catalytically like platinum to bring about the oxida- 

 tion of the firedamp that surrounds each particle, and 

 this oxidation proceeds more rapidly as the particles get 

 heated up by the chemical action, until finally the dust 

 particles become incandescent. So far the explanation 

 does not appear improbable or inconsistent with known 

 facts. But Abel supposes that the dust particles when 

 they have reached incandescence, owing to the heat of 

 combustion of a portion of the firedamp mixture in which 

 they are floating, can ignite the residual firedamp, and, 

 moreover, the flame so produced can then propagate 

 itself into regions where this initial catalytic combustion 

 has not taken place. This catalytic action of the dust is 

 similar, he says, to that possessed by platinum : and just 

 as platinum brought into contact with mixtures of oxygen 

 with hydrogen or hydrocarbons sets up a chemical action 

 which raises the temperature of the metal until it causes 

 the mixture to explode, so heated magnesia acts on fire- 

 damp and air. 



If will be observed that the analogy with the action 



