ACCEPTING Mr. Galloway's view that in many mines the extent and destructiveness of colliery explosions are due to the distribution of coal-dust in the air, may I suggest the possibility of preventing the explosion from spreading beyond the sphere of the fire-damp by sprinkling the floors throughout, at certain regular interval, with mineral oil? A shady road, with one such sprinkling, may be kept free from dust for several weeks during the summer, and the corridors of a mine, not being open to wind and rain, would of course remain wet for a longer period. A saucer filled with dust and treated with mineral oil will retain the oil for months even when exposed to sun and rain. The mixture of coal-dust and oil is quite uninflammable. The experiment may perhaps be worth trying in one of the drier coal-mines.