5. The smoke goes back to the blood, and is carried to the lungs and given off by the breath. The ashes go back to the blood and pass off through the skin and the kidneys.
6. The burning in the cells makes heat.
7. Some of the heat is changed to power, as it is in a steam engine.
8. The heat also warms the body. It keeps it at the same warmth on a cold day as on a hot day.
9. We wear clothes to keep the heat in, and so to keep us warm.
10. The air of a room needs to be changed often. It is made stuffy by our breath.
11. The voice is made by the breath in a box in the neck.
12. Alcohol uses air belonging to the cells of the body.
13. Tobacco smoke has the same poisons as tobacco. It can poison the whole body through the lungs.