SCIENCE OF COMMON THINGS. 



How a friction match ignites. Temperature of living animals. 



were, by the compression of its parts, and the button 

 receives most of the caloric, owing to a stronger attrac- 

 tion for it, than is possessed by the wood. 



9O1 Why does a friction match, drawn over sandpaper or other rough 

 tubstance, ignite 1 



When the match is drawn over sand paper, or other 

 rough substance, certain phosphoric particles are rub- 

 bed off, and being compressed between the match and 

 the paper, their heat is raised sufficiently high to ignite 

 them, and fire the match. If the match be drawn over 

 a smooth surface, the compression must be increased, for 

 the temperature of the whole phosphoric mass must be 

 raised in order to cause ignition. 



0O3 What singular property have most living animal bodies f 



The property of maintaining in themselves an equable 

 temperature, whether surrounded by bodies that are 

 hotter or colder than they are themselves. 



9O3 Illustrate this fact. 



The sailors of the Arctic exploring expedition during 

 the polar winter, while breathing air that froze mer- 

 cury, still had in them the natural warmth of 98 Fah- 

 renheit above zero ; and the inhabitants of India, where 

 the same thermometer sometimes stands 115 in the 

 shade, have their blood at no higher temperature. 



SO 4 Do vegetables possess in any degree this property of maintaiitkiy 

 a constant temperature within their structure ? 



Growing or fresh vegetables have this property to a 

 certain extent. 



9O5 What, then, is vital heat? 



^ The heat generated or excited by the organs of a 

 living structure. 



O6 What is the cause of vital or animal heat? 



The cause of animal heat is not certainly known or 

 determined; it is supposed to be due to chemical 

 action, the result of respiration and nervous excitation. 



907 Has {he, power of animals to preserve a peculiar temperature any 

 limits ? 



Yes ; intense cold suddenly coming upon a man 

 7 



