THE ATMOSPHERE 91 



always places a contestant for athletic honors at a great 

 disadvantage. 



Adenoids. Occasionally small bulbous growths par- 

 tially fill the nasal passages leading to the throat. These 

 growths are called adenoids. A good surgeon can readily 

 remove them. This should always be done, since mouth 

 breathing is such a serious menace to health. 



Colds are inflammations of the membranes lining the 

 air passages. If the area affected is limited to the nasal 

 cavities, we call the inflammation a cold in the head ; 

 if the pharynx is affected, a sore throat is the result ; if 

 the trachea and bronchial tubes are affected, we call it a 

 chest cold. When the inflammation extends to the lining 

 of the air sacs, pneumonia results. 



Diphtheria, croup, and tuberculosis are all germ diseases 

 which are produced by special kinds of bacteria. 



QUESTIONS 



1. Who was Torricelli? 



2. Why is the air less dense on the top of a mountain than 

 that at its base? 



3. What would be some of the effects of increasing the amount 

 of oxygen in the air? 



4. How can you show that exhaled breath contains carbon 

 dioxide? 



5. How does painl prevent iron from rusting? 



6. What is the working principle of the ordinary commercial 

 fire extinguisher? 



7. Why does a good draft make a fire burn better? 



8. Why do we use kindling in starting a coal fire ? 



9. Why does a blanket thrown over a fire put it out? 



10. What causes wood to rot? 



11. What is the value of nitrogen in the air? 



12. Give some proofs that air has " inertia." 



13. Of what value are breathing exercises? 



