英文科學(xué)讀本 第二冊(cè)·Lesson 40 Gold

Lesson 40 Gold

Come here, Norah, and see how rich I am, said Fred.

Just look, Willie, cried Norah. "Fred has got a bright, new sovereign. How beautiful it looks. Where did you get it, Fred? Did you find it?"

No, said Fred, "I did not find it. It is not mine. Father lent it me. We are going to have a chat about gold tonight. We must take care of it, though.

Now suppose we begin. You shall tell us what you can find out about gold, by looking at the sovereign, Norah.

Well, said his sister, "the first thing I can see is that gold is a yellow metal, with a very bright polish or lustre."

Yes, said Fred, "and we might say that it is the only yellow metal we have."

But, said Norah, "isn't brass a yellow metal too?"

It is yellow, dear, but, if you remember, brass is not a pure metal. It is a mixture of copper and zinc. Then too," he added, "polished brass has a very high lustre, but just look at this brass candlestick. It was left out in the toolhouse and forgotten. See, it is covered with patches of green rust."

Yes, but gold never rusts, said Willie. "It does not even tarnish. It remains quite unchanged by air or damp.

Now take the sovereign in one hand and this shilling in the other, Norah.

I know what you mean, said she. "The gold sovereign is heavier than the silver shilling."

Yes, dear, it is, said Fred. "Gold is the heaviest of all the metals I have shown you."

I suppose, said Willie, "you remember those thin leaves of silver, we talked about the other night?"

Yes, said Norah. "It takes ten thousand of them to make a pile one inch high."

What would you think, then, of gold leaves so thin that twenty-eight of them, one above the other, would not be thicker than the one leaf of silver? It is true, though, and teacher says it takes 282,000 leaves of gold to make a pile an inch in height. How very thin the gold must be beaten.

That tells us that gold is much more malleable than silver, said Norah.

It is the most malleable of all the metals, said Fred. "It can be beaten, rolled, cut, and twisted, or worked up into any shape the workman wishes.

It is for all these reasons, and also because gold is scarce, and therefore valuable, that people like to use it for rings, chains, bracelets, watches, and other beautiful ornaments to wear. You should remember that gold, like silver, is too soft to be used alone. Some copper is mixed with it to make it harder."

Teacher told us too, said Willie, "that gold is mostly found not as an ore, but in little round grains, called nuggets. The nuggets are pure gold."

SUMMARY

Gold is a yellow metal, with a very high lustre. It is a precious metal; it never rusts, or even tarnishes. It is the most malleable and ductile of all the metals. As it is scarce, it is used for money, and beautiful articles for use and ornament.