书城教材教辅科学读本(英文原版)(套装1-6册)
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第242章 第三册(67)

"Remember, however, that in some very cold parts of the world mercury always becomes solid in the winter. In its solid state it is malleable, and can be beaten and rolled out like other metals.""I thought it was very curious to see teacher boil the mercury in the tube, as if it were water," said Will. "We saw the liquid metal boil, and we saw the vapor from it condense into tiny little silvery balls, on the cool sides of the tube."SUMMARY

Mercury is a liquid metal. It ?ows about, and readily breaks up into tiny drops. It is silvery-white, and has a bright metallic lustre. It is nearly fourteen times as heavy as water.

Lesson 22

The Poisonous Snakes

"I see you have your Natural History book under your arm, Fred," said Norah. "Have you got something more to tell us about animals?""We have had another lesson about snakes to- day," said Will, "so I suppose Fred wants to have a chat about them now."The three were soon seated round the table, and then Fred began.

"Teacher explained to us that there are two kinds of snakes, which we may call the poisonous and the non-poisonous snakes. Suppose we talk about the poisonous snakes first. Here is a picture of one of them.