What is the black-lead in your pencil made of? If you take a bit of the metal which we call lead, you will find that it is grey in colour, very heavy, and not at all like the black-lead in your pencil. But the lead will make a mark on paper just as your pencil does.,
We call the stuff black-lead, because it makes marks like lead; but there is really no lead in it at all. Black-lead is not a metal. It is made of carbon, which is also found in coal and in many other things. It is the carbon in coal which makes it burn so well.,
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如果把石墨弄得特别热,石墨就会燃烧起来,但是燃烧得特别慢,不能用它生火。,
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If we make black-lead very hot, it will burn. But it will burn very slowly-so slowly that it would be of no use for making a fire.,
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有一些石头里面会有大块的石墨。人们把这些大块石墨,先磨成细粉,又压成硬块儿。,
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Black-lead is found in some kinds of rocks in big lumps. These lumps are ground into very fine powder, and then the powder is pressed into hard blocks.,
These blocks are next cut up into thin strips. Each strip of black-lead is made of just the right size to fit into the hollow that has been cut for it in the wood of the pencil.,
Your mother will tell you that black-lead is very useful to her in the house. She rubs it on stoves and grates, and many other things that are made of iron, to cover the iron and keep it from rusting.,
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潮湿的空气会让铁生锈,但是只要用石墨盖住,铁就接触不到空气,会一直亮闪闪的。,
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The damp air makes the iron rust; but when we cover it with black-lead, the air cannot reach it, and it keeps bright.,
Have you ever seen a diamond? It is a very bright, hard kind of stone, and very dear. Diamonds are sometimes set in gold rings, and they are very pretty. Yet the diamond is made of pure carbon, just as black-lead is.,
Is it not strange that the dull black-lead, which costs so little, and the sparkling diamond, which costs so much, are both made of the same stuff that burns in the grate to keep us warm?,