' said Harry.

Joe laughed.

'No; it comes out of the ground.'

'This is like the slate story,' said Dora.

Harry nodded.

9. 'But, Joe, I want to know how the chalk makes the ground good.'

'I don't know how, but it does. If it lies here for a year or more, the
earth will turn brown, and we can grow wheat in it. Besides, chalk holds
water, and so it will keep the ground moist up here.'

10. 'How?'

'Well, when it rains, the water will not run away through the earth, but
will stay in the lumps of chalk. Are you going? Good-bye, then.'

CHALK.

PART 2.

[Illustration: 'Fizz and bubble, bubble and fizz.']

eve'-ning
brought
vin'-e-gar
bub'-ble
air
stirred
poured
grains
hun'-dreds
smiled
crowds
threads
catch
died
dropped
mixed

1. The children had much to say that evening about Joe and the field.
They had brought home a lump of chalk.

2. 'I will show you something,' said father, and he got a cup of
vinegar, crushed a little of the chalk, and dropped it into the cup.

Fizz and bubble, bubble and fizz!

3. What was going on?

When the stir came to an end, the chalk was not there!

'Part of it has gone off in gas,' their father said. 'The rest is lime,
and it is mixed with the vinegar.'

4. 'We did not see any gas,' said Harry.

'You can't see gas. It is like air. All those bubbles were made by the
gas. It went out of the cup into the air.

'Now, get a cup of water. Come along! Where is your chalk?'

5. Father rubbed some of it into the water, and stirred it up. The water
now looked like milk.

Father poured it into the sink, and showed Harry and Dora, at the bottom
of the cup, a great many tiny grains.

6. 'Those little round things,' he said, 'are shells.'

'Shells!' said Dora, trying to see them better.

'Were live things ever in them?' asked Harry, and put a finger into the
cup to fish some out.

7. 'Yes, long, long ago. That bit of chalk had hundreds and hundreds of
shells in it. Now, mother, it is your turn! I have had mine. What do you
know about chalk?'

8. Mother smiled and began: 'There was once a very deep sea, full of
live things, little and big. And on the top of the water were crowds of
tiny things in shells, that put out long arms like threads to catch
their food.

9. 'When they died they all dropped to the bottom of the sea, and lay
there. The shells were so very little that they made a