WE have in Great Britain large accumulations of blast furnace slag, of cinders, and clinker, and in the neighbourhood of Edinburgh of burnt shale, the residue from the stills of the oil industry.

Clinkers, as any Wisconsin boy who ever cleaned out his grandma's coal furnace can tell you, are stony, unburned chunks of impurities that settle in the furnace. When you hit a clinker, instead of ash ...