书城教材教辅科学读本(英文原版)(套装1-6册)
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第161章 第二册(78)

"Ah," she said, "it would have been rusted all over, wouldn"t it, Fred?""Yes, it would," replied Fred. "But I say, Norah, what will you say when I tell you that your tin mug is not a tin mug at all. It is really made of iron. Very few of the things which we call tin-ware are reallymade of tin. They are made of sheet iron, covered with a coating of tin on both sides. It would be better to call them "tinned ware.""Let us see why the tin is put over the iron. The iron would rust very quickly, but the tin, although it will tarnish, does not rust. When it gets dull and tarnished, a rub will make it clean and bright again." "But how do they put the tin coat on the sheetiron?" said Norah.

"Teacher melted some tin in the old iron spoon," said Fred, " to show us how easily it melts. It is the most fusible of all the metals. To make the "tinned ware" the sheet of iron is dipped into melted tin, and when it is taken out the tin forms a coat all over it.

"The tinman uses solder to join the pieces of tin together when he makes vessels for use. Solder is a mixture of lead and tin.