32 LABORATORY MANUAL 



1. Place the projecting end of the glass tube into the 

 beaker of colored liquid. Heat the tube gently with a 

 Bunsen flame. Observe carefully all changes. Without 

 changing the apparatus allow the gas in the test tube 

 to cool. What change do you now observe? How do 

 you account for the change ? 



B. Tightly cork a test tube filled with air. Gently 

 heat the tube over the Bunsen flame. Explain the 

 result. Does this change indicate an increase in the 

 amount of gas in the test tube or in its volume ? From 

 the last three exercises what is the effect of the increase 

 of temperature upon the intermolecular spaces ? Upon 

 the molecules? The effect of the decrease of tempera- 

 ture upon the intermolecular spaces? Upon the mole- 

 cules ? 



Exercise 12. Cohesion, Adhesion, and Gravity. 

 Object: A study of forces acting between molecules 

 and between masses. 



Apparatus 



Spring balance Battery jar 



Circular glass plate Sealing wax 



Directions: By means of sealing wax, attach three 

 strings at equidistant points near the margin of the 

 glass plate. Tie the ends of the strings together and 

 suspend the plate from the hook of the spring balance. 

 (The glass plate must hang horizontally.) Record the 

 weight of the glass plate. Then lower the apparatus 

 over the battery jar filled with water, until the plate 

 touches the water. Slowly lift the balance, at the 



