第139章 第二册(56)

"Cast-iron is just the metal to use for all sorts of articles, where beauty of shape is wanted. We can mold it into any shape we please.""But," Willie joined in, "these cast-iron things won"t stand much hard wear and tear, for cast-iron is very brittle, and breaks very easily.""Cast-iron is used for making fenders, fire-grates, railings, iron bedsteads, brackets, saucepans, andkettles," said Fred. "These things will last a long time if fairly used.""Teacher showed us too," said Willie, "that cast- iron will bear almost any amount of downward pressure. It will neither twist out of shape nor break. This is why the great pillars to support bridges and arches are always made of cast-iron. The stands for our desks at school are made of cast-iron. They willbear any amount of pressure, but they would snap in two with a blow, because they are so brittle.""Can you tell us, Norah," asked Fred, "something we can"t do with cast-iron?""Well," said Norah, " as the cast-iron is so brittle,it could not be beaten out into thin sheets. It would break with the blows of the hammer.""Quite right," said Fred, "cast-iron is not malleable." "And as it will not hold together, it could not be drawn out into wire. It would break apart with thepulling."