Chapter 40

most necessary to preserve life? Name some of the ways in which the blood becomes impure. Why is bad-smelling air dangerous to health? What are germs? Why are some diseases "catching"? Name some such diseases. What should be done with a person who has a "catching" disease? What is the effect of the breath upon the air? How much air is poisoned and made unfit to breathe by each breath? How much air do we spoil every minute? every hour? How much pure air does each person need every minute? every hour? How do we get fresh air into our houses? Why are windows and doors not good means of ventilating in cold weather? How should a room be ventilated? How should we use the lungs in breathing? What about the clothing in reference to the lungs? Why is it injurious to breathe habitually through the mouth? What is the effect of alcohol upon the lungs? What is the effect of tobacco-using upon the throat and nose?