They breathe it into their lungs, and it supports life in them, the same as the air which we breathe supports life in us.

Do solids contain air?

Yes; solids contain more or less air.

Where is the air in fur and in wool?

It is among the hairs of the fur and the wool.

Where is the air in cotton and linen goods?

It is among the fibres of the cotton and the linen.

Where is the air in fruit?

It is among the particles composing the fruit.

Where is the air in wood?