MECHANICAL ACTION. 95 



Q. Why is a DEAD BODY COLD ? 



A. Air is no longer conveyed to the 

 lungs after respiration has ceased ; and, 

 therefore, animal heat is no longer evolved 

 by combustion. 



CHAPTER VII. 



MECHANICAL ACTION. 



1. PERCUSSION. 



Q. How is heat produced by MECHANICAL 



ACTION ? 



A. 1.- By Percussion. 2. By Fric- 

 tion. 3. By Condensation. 



Q. What is meant by PEBCUSSION ? 



A. The act of striking ; as when a 

 blacksmith strikes a piece of iron on his 

 anvil with his hammer. 



Q. Why does BEATING IRON make it RED- 



