英文科學(xué)讀本 第二冊(cè)·Lesson 31 Copper

Lesson 31 Copper

Look, Norah, said Fred, "here is mother's copper coal scuttle. Suppose we have a talk about copper. What is the first thing you notice about it?"

Its colour is bright red, and it has a shining surface, said Norah.

Quite right, said Fred. "Remember that copper is the only red metal, and that it has a bright lustre.

Now look at the scuttle again, he added. "You will see that it is made of thin sheet copper. How was this made?"

It was beaten out, or rolled out, said Norah.

What does that tell us? asked Fred.

It tells us that copper is malleable.

It is, said Fred, "one of the most malleable of all the metals.

Now I will hold the scuttle up, he went on, "and you shall strike it with this stick. What do you notice?"

It gives out a loud ringing sound, said Norah.

Yes, said her brother, "it does, and we say that copper is sonorous, which means loud-sounding.

This is copper wire—some thick, some very thin. What can you tell me by looking at this wire?

The copper must be ductile, said Norah, "or it could not be drawn out."

Quite right again, said Fred, "and it is very tough or tenacious, for we may pull, bend, or twist the wire about almost as we please, and it will not break."

I want now to show Norah this rusty copper nail, said Willie. "See, it is covered with bright green patches. These patches are the rust of copper. Copper rusts very easily, and the rust of copper is poison. It is called verdigris.

Copper is dug out of the earth as an ore, said Fred, "like most other metals. Like iron-ore, it has to be smelted to remove the useless matter, and then it is made into many useful things, such as kettles, saucepans, scuttles, and other articles used in the house."

Does Norah know, asked Willie, "that brass is made by melting copper and zinc together? What a beautiful useful metal brass is!"

Our pennies, half-pennies, and farthings are made of bronze, said Fred, "and bronze is made by melting copper, tin, and zinc together."

Yes, and bells are made of bell-metal, added Willie. "Bell-metal is a mixture made by melting copper and tin together."

SUMMARY

Copper is a red metal, with a bright lustre. It is very tough, malleable, and ductile. It rusts easily, and the rust of copper is poison. Copper gives out a ringing sound when it is struck. Brass is made from copper and zinc. Bronze is made from copper, tin, and zinc. Pennies, half-pennies, and farthings are made of bronze.