90 EXPERIMENTAL GENERAL SCIENCE 



Practical Exercises 



1. When a hot flat-iron cools in ironing, does it lose its heat by 

 conduction or by radiation? 



2. Savages used to boil water by putting hot stones in it. Was the 

 water warmed by conduction or by radiation? 



3. By what method does a coal stove warm a room? 



4. Is a steam-heated flat warmed by conduction or by radiation? 



5. Which is a better conductor of heat, copper or iron? (Find out 

 by heating six-inch sections of copper and iron wire in the bunsen 

 burner.) 



6. Would a flat-iron be as useful if made of copper? 



7. Why are steam pipes usually covered with asbestos or other 

 porous material? 



8. Why does frost remain longer on the boards of a walk than it does 

 on the heads of the nails in the boards? 



9. Fill a test-tube with water and by means of a bunsen burner apply 

 heat near the open end. When the water begins to boil there, feel of the 

 bottom of the tube. What do you learn from this experiment as to 

 whether or not liquids are good conductors of heat? 



10. Why can one touch a hot iron with a wet finger and not be 

 burned? (Note that the moisture turns to gas.) (78.) 



11. Why will a flask filled with hot water cool off more slowly if 

 wrapped with cotton batting ? 



