How is the air expelled from the lungs?--"The chest contracts and sends the impure air through the tubes and windpipe, the nose and mouth, into the atmosphere." What do you mean by contracts?--"Becomes smaller." What do you mean by atmosphere?--"The air." Of what use is the air when it is in the lungs?--"It makes the blood pure." Why can you not live without breathing?--"Because, if I do not breathe, pure air cannot get into the lungs to make the bad blood pure, and I cannot live if the dark, impure blood is sent back again through my body." Why must you live in the sunlight?--"Because the sunlight helps to purify the blood and strengthen the body." Why must you wear loose clothing?--"Because tight clothing stops the circulation of the blood." Why must you avoid tight-lacing?--"Because tight-lacing crowds the ribs against the lungs, so that the lungs cannot move freely." Why should you wear clean clothing?--"That nothing impure may pass into the body through the pores of the skin." Why should you keep the body clean?--"That the pores of the skin may not be closed, but remain open to let the perspiration pass through." What has the cleanliness of the body to do with the health of the lungs?--"If the body is not kept clean, the perspiratory pores become clogged." What happens when the perspiratory pores are clogged?--"The impure particles which should pass through them stay in the body, and cause disease in the lungs or other parts." Why should you sit and stand erect?--"Because, if I am in the habit of stooping, my lungs will be crowded, and will not have enough room to move freely." Why should you keep all parts of the body warm?--"Because chilling any part of the body causes the blood to chill in that part, and thus hinders its circulation." Why should you not change your winter clothing too early in the spring of the year?--"I may take cold if not warmly clothed during the cool days of early spring." Why should you avoid draughts of cool air?--"Because the cool air blows upon some parts of the body and closes the pores of the skin, checking the perspiration, and hindering the circulation of the blood." Why should you not rush suddenly from a warm to a cool place?--"Because when warm the pores of the skin are open; if I rush suddenly into the cool air, these pores are closed too quickly." Why does stopping the perspiration hurt the lungs more or less?--"The impurities it ought to carry away remain in the body, make the blood impure, and produce disease in some part; very often that part is the lungs." What harm does alcohol do in the lungs?--"It fills the lungs with impure blood." What harm does it do to the air-cells?--"It hardens the walls of the air-cells of the lungs." What harm is done by the hardening of these air-cells?--"1. The lungs cannot take in enough of the gas called oxygen to purify the blood perfectly. 2. The gases or vapors in the lungs cannot pass freely through the hardened air-cells."