书城教材教辅科学读本(英文原版)(套装1-6册)
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第127章 第二册(44)

Metals have a bright, shining surface, which we call their lustre. We say they are lustrous-that is, full of lustre. Metals sometimes rust and lose their lustre. Gold and silver do not rust. We call them precious metals. Malleable means " able to be hammered out."Some More about Metals

"I say, Fred," said Willie, "we didn"t finish with the metals last night. Norah would like to hear all about wire, I daresay.""Oh yes," said Norah, "I should, and can you tell me how they make wire, Fred? Father was using some wire today no thicker than sewing thread. I should like to know how they make it.""Well," said Fred, "teacher showed us some coils of wire of all sorts in our lesson, and told us how it is made.

"Let us take this piece of iron wire. This was made from a thick round bar of iron a few inches in length. It was first made red-hot in the fire. As it got red- hot it became soft. In this state it was taken out with tongs and forced through a hole in a strong steel plate. The hole was smaller than the iron bar itself, and it is easy to see that it squeezed the iron as it went through.""Of course," said Willie, joining in, "this made the iron bar thinner, and at the same time longer.""Yes, I understand." said Norah.