AND PHYSIOLOGY. 



267 



all combustible substances. And it is safe to say, that the 

 greater the care we take to ventilate our rooms, and in every 

 way to breathe pure air, the longer shall we live and with 

 the least amount of pain and disease. Breathing impure air 

 is one of the greatest natural evils to which civilized society 

 is subject, and destroys more lives than almost any other. 



471. — 5. We need Pure Air by Night as well as by 

 Day. — Hence we see that the lungs need pure air all the time, 

 by night as w T ell as by day — in the sitting-room, the eating- 

 room, and the bed-chamber, the school-house, the meeting- 

 house, rail-car, and steamboat, if we would do our utmost to 

 ward off disease and death. 



472. — 6. Capacity of the Lungs Affected by Posture.— 

 The capacity of the chest is greatly influenced by our posi- 

 tion in sitting or standing, and the amount of use to which 

 it is subject. If the shoulders are thrown forward or the 

 body is bent in the same way, the lungs are compressed, and 

 can not be filled to their full capacity. Hence special pains 

 should be taken to maintain the body in an erect posture, and 

 to keep the chest thrown forward. 



473. — 7. Pure Air is often a Medicine —In most diseases 

 the breathing of pure air is important for restoration to per- 

 fect health, since there are often some impurities in the blood 

 or system which are removed mainly by pure air. So that 

 the rule of supplying pure and warm air to the sick room 

 should be rigidly observed. 



474. — 8. Warm and Moist Air the Best for a Ileal thy 

 Person. — The air best adapted for breathing should contain 

 but a small amount of moisture, nor should it be perfectly 

 dry, especially that which comes from intensely heated iron 

 surfaces. Cold and damp air is apt to bring on irritation of 

 the mucous membrane, producing coughs and colds. 



475. — 9. Capacity of the Lungs may be Increased.— 



471. When and where do we need pure air ? 472. How is the capacity of the lungs 

 modified ? What of the necessity of an erect posture in sitting or standing ? 473. Why is 

 pure air so important in sickness? 474. What is the best quality of air for bieathing? 



