CAN you guess this riddle?
There is something that ordinary householders store away in their cellars by the ton. Yet it is worth more than all the world's gold and silver. Poor people buy it-- and great nations fight for it. Terrible explosives-- and healing medicines-- are made from it. It may be the source of ill-smelling gases-- or of delicious perfumes. Much of it is rocklike-- but it burns.
The answer, or course, is coal.
Does your stove or furnace burn hard or soft coal? Then, no doubt, you know something about one of the many different kinds of coal.
Soft coal-- its long name is "bituminous coal"-- is not really soft; it is merely not so hard as hard coal. It is black and rather dusty.