书城教材教辅科学读本(英文原版)(套装1-6册)
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第122章 第二册(39)

"Yes, it has melted," said Fred. "Teacher gave us a new name today for this melting. We may say we melt the lead or fuse it. Fuse and melt mean the same.""Yes, and the things that we can fuse," said Will, joining in, "are fusible. Some things, such as wood, brick, slate, and stone, do not melt with heat. They are said to be infusible-that is, not fusible. Teacher pointed out to us that some of our minerals are useful to us entirely because they are fusible. Like lead, they can all be melted or fused with heat. We call them metals.""Can you tell any of the metals, Norah?" said Fred. "Iron and copper are metals as well as lead," saidNorah.

"Yes," said Will, "and so are gold, and silver, and tin, and zinc."SUMMARY

Wax melts in a spoon over the fire-the solid becomes a liquid, and ?ows about. Lead, too, melts in the same way. We say it is fusible. Iron, copper, tin, zinc, silver, and gold will all melt or fuse, like the lead. They are metals.

Lesson 19

Maize