182 COALFIELDS AND COLLIERIES OF AUSTRALIA. 



men and horses are constantly trampling- coal underfoot. In 

 the main haulage-ways the dust is not so disturbed. Then again r 

 the top dust, which is very fine, and settles on the top of 

 timbers, is purer than that lying on the ground, which is more 

 or less mixed up with rock dust it is not so readily watered, 

 but is easily reached by flame. Also porous dust is more 

 dangerous than dense dust. The enormous surface pre- 

 sented by coal in a minute state of division, to the action of 

 flame, induces instantaneous combustion, and distils oft' gas. 

 But beside chemical properties, it would seem that coal dust, 

 anyhow at the inception of a coal mine explosion in which 

 it takes part, may act catalytically. The reason for catalytic 

 phenomena is somewhat obscure, for certain effects are 

 bi ought about by the mere presence of a substance which it- 

 self undergoes no perceptible change. It has been shown 

 by experiment that an inert substance, such as magnesia, when 

 finely pulverised and suspended in air will assist the explosion 

 of an admixture of fire-damp and air. With regard to 

 watering coal dust, it is necessary that the dust be properly 

 moistened to be effective. We all know how a drop of water 

 falling on dust gets coated with the fine particles and rolls 

 about on the top of it, also if just sprinkled on the top of the 

 dust a moist crust may be formed, but the first footstep stirs 

 up the dust below it again. Very little dampness is necessary 

 to prevent dust from igniting so long as the whole of the 

 available dust is damp. In this mine we had the two main 

 sources of colliery explosions fire-damp and coal dust 

 moreover, the atmosphere was warm and dry. The heading 

 in which the explosion occurred rose as the miners advanced, 

 yet bratticing was not used in the space between the last 

 stenton and the face of the headway to drive out foul air, con- 

 sequently the lighter gas would tend to accumulate at the 

 face, where the air being stagnant would serve as a reservoir 

 for gas. One would naturally expect under the circum- 

 stances that extra precautions would have been taken to avoid 

 accidents, but instead there appears to have been carelessness, 

 and a total disregard of the most ordinary precautions by those 

 chiefly concerned. Safety-lamps were used in the danger 

 zone, presumably as a talisman, for it was the old-fashioned 

 Davy, with an insecure lock that was not always fastened, and 

 shots were sometimes fired by lighting touch-paper by tilting 

 the safety lamp so that the flame could ignite the touch-paper 

 through the gauze; not only this, but the fuse was sometimes 

 lit by the flame of a lucifer match. That men were allowed 

 to carry lucifer matches, and use tobacco in a district where 

 fire-damp was given off, shows lax discipline, and the wonder 

 is that an accident did not occur from causes other than an 

 overcharged shot. It is strange how some people will not 

 use a little forethought, but insist on experiencing everything 



