英文科學(xué)讀本 第一冊·Lesson 08 Porous Bodies

Lesson 08 Porous Bodies

I wish, said Fred, "every fellow in my class had a jolly little sister, like I've got, to play school in the evenings.

We had a fine lesson on a sponge today. Would you like us to tell you all about it, Norah?

That I should, said his sister.

Come along then, said Fred. "I've got the sponge ready. I will stand it in a saucer of water, just as teacher did."

Now Norah shall take it out of the saucer and put it on the table.

What have you done with the water in the saucer, Norah? It is all gone; the saucer is empty.

Bring me the sponge. Now squeeze it over the saucer.

Oh, I see, said Norah. "The water all went up into the sponge."

Yes, little girl, said Fred. "And now we will see how it got there."

If you look at the sponge, you will find that there are little holes all over it.

I will cut a piece of it away, and we shall see that the holes are not on the outside only, but all through the sponge. The sponge is full of holes. Will knows the proper name for these little holes.

Oh yes, said Willie, "teacher told us to call them pores; and as the sponge is full of pores, we say it is porous."

Then I suppose, said Norah, "the sponge sucks up the water because it is porous; the water fills up the holes in it."

Right, said Fred. "Here is a piece of bread. If I stand it in the saucer with only a little water in the bottom, the bread will soon be wet all through."

The bread, like the sponge, is porous, said Norah. "I can see the holes in it."

Yes, said Willie, "but teacher showed us that some things may be porous although we cannot see the pores."

How did he do that? said Norah.

He put a piece of lump sugar and a piece of chalk into a plate, with a little red water in the bottom, said Willie. "We couldn't see any pores in the sugar or the chalk, but we saw the red water go up. That proves that there must be pores in them, and that sugar and chalk are both porous bodies."

Teacher gave us a long word to think about. said Fred. "The word is absorb, and it means to suck up."

He says all porous bodies absorb or suck up liquids through their pores.

SUMMARY

Sponge is full of holes. These holes are called pores. Porous means full of holes. Sponge is a porous body. All things that are full of holes are porous. Bread, chalk, lump-sugar, and salt are porous bodies.