Part 2

Never mind, we will try. First, there is the stalk, or woody part. When you put a piece of stick in the fire, what becomes of it?

Oh, it smokes and blazes, and then nothing is left but some ashes.

What is it which burns away?

That I cannot tell.

It is the gaseous part which burns in a flame, like what you have seen come out of coal. But what do you call woody matter that will not blaze?

Charcoal, father. Then I understand now that wood is nothing but charcoal and the gases. What are these gases?

The gas which blazes so readily, my dear, is hydrogen: and it has a very strong smell too. The air we breathe is a mixture of two gases--oxygen and nitrogen. It is only the oxygen that we take into our lungs.

Well, that is curious.

I shall puzzle you more, Willie, when I tell you that water is nothing but a mixture of oxygen gas and hydrogen gas.

It certainly is funny that water, which puts out flame, should be partly composed of the burning gas.

You must also know, my lad, that hydrogen would not burn without oxygen. You blow air into a fire to give food for flame.

But however could the plants get hold of the gases, father?

Did it never strike you why God formed leaves?

It never did, except that I thought he did it to make the trees look pretty.

That is quite true, Willie. The good God loves beauty, and he has surrounded us with beauty of all kinds. But he made things for use as well as to be looked at. The leaves absorb or suck in gases from air and water.

Then I suppose the veins like that we see in leaves conduct these gases away into the plant.

Quite right, my boy. Where now shall we get the charcoal, or carbon, as the learned men call it?

That I cannot find out at all.

You told me, Willie, that smoke came out of burning wood. What becomes of it?

When I was a very little boy, I thought it went up to form clouds; but now I know part of it turns into soot in the chimney, and that looks like our charcoal or carbon.

It really is. As to that which comes out of the chimney, it passes upward, and gets gradually mixed with the air. The little particles of carbon join the oxygen, and become a sort of gas called carbonic acid gas, which is absorbed into the plant.

How wonderful that the solid part of a tree should once have been floating about in the air!

Do you think the leaves of a plant to be the same as the stem?

Yes, I do; for when they are thrown in a fire, they smoke, blaze, and leave an ash like the wood does.

Just so. You know the smoke to be carbon passing into the air; but we must examine the ash a little more carefully. If you take some ash from the fireplace, and put it into hot water, the solid part will of course fall to the bottom.

Will no part mix with the water?

There will be something; for if we pour off the water, and allow it to evaporate in a dish, there will be found to be a sediment left, and that is potash or pearl ash.

I have heard of people in the bush doing that when they could not get soap, for they said that the potash got the dirt out of clothes.