英文科学读本 第一册·Lesson 22 Salt

Lesson 22 Salt

The boys came running home a day or two later, as fast as their legs would carry them.

Oh, Norah, they both shouted, as soon as they got their breath, "we've got something fine to show you tonight."

I'll go and see what I can find, said Fred.

After tea Fred said, "Now, I'm teacher tonight, so sit down in your places."

I've got some salt and a tumbler of water, just as we had the other night, he began. "Now we will put the salt into the water and stir it up."

What happens to the salt, Norah?

The salt dissolves in the water. said his sister. "It is there, but we cannot see it."

Quite right, said Fred. "Teacher says we can call this salt water brine. Brine means salt water."

Now, little girl, he went on, "suppose I told you that you must get the salt out of the water. That would be a puzzle for you, wouldn't it?" Norah looked puzzled."

See me do it, then, said clever Fred. He had found an old tin lid. He filled this with the brine, and stood it over the fire. Soon the water began to boil, and a cloud of steam rose from it.

They watched it for a long time, till all the water had boiled away.

There, cried both boys with a shout and a laugh, "that's just what teacher did. We'll soon get the salt back now."

Give me a bit of rag, added Fred, "so that I can lift the lid off the fire without burning my fingers. There, now we will let it get cold."

As soon as it was cold enough to handle, Fred showed them that there was something left behind in the tin.

See, said he, "I will scrape it up in a little heap."

Now dip your finger into it, Norah, and taste it. Norah did so, and found that it was real salt.

Fred had got the salt back by boiling the brine.

SUMMARY

Brine is salt water. The salt is in the water, but we cannot see it. If we boil the brine, the water will fly away in steam, and we can get the salt back.