33 



9. How does the chipmunk differ in appearance from the red squir- 

 rel ? Sketch. 



10. Compare the habits of the squirrels. 



LVII. Water, Steam, and Ice. 



1. Determine the physical properties of water, such as color, taste, 

 shape, surface, and cohesion, bv simple experiments. In what respects 

 does water differ from steam or ice ? 



2. Describe the effects of heat on water in a glass flask. What is 

 the cause of " singing "' just before boiling ? Is steam visible? What 

 is a cloud ? 



3. \\'hat happens when a jet of steam strikes a cold surface ? 



4. What is evaporation ? W^hy is evaporation more rapid some 

 days than others ? 



5. Why do wet clothes dry more rapidly some days than others ? 



6. Explain the "sweating of pitchers containing ice-water." 



7. Explain the formation of clouds. Why are some clouds white, 

 others black ? Why do clouds move ? 



9. How is rain formed ? When clouds rapidly disappear what is the 

 probable reason ? 



10. Determine the conditions of formation of ice and snow. 



11. Examine snow-flakes and observe their structure. 



12. How could you show that water expands on being heated? 

 That water expands on freezing ? 



13. What is a thermometer ? What is its use ? 



14. Show that heat is required to melt ice. 



LVIII. The Air. 



1. What are the proofs for the existence of air ? Make experi- 

 ments. 



2. Show that air exerts pressure, is elastic, has weight, expands 

 when warmed, and contracts when cooled (use an air-thermometer to 

 show expansion and contraction). 



3. Air is a gas. Name other gases which are also colorless and 

 odorless. 



4. Make some carbonic-acid gas and determine its properties. How 

 do its properties differ from those of air ? 



5. Why water rises when the piston is drawn up in a " squirt-gun " 

 or syringe. 



6. The barometer. W^hy is mercury used ? \\'hat is the use of the 

 barometer ? 



7. Winds : Their cause, direction, importance, kinds. 



3 BULL. U2 



