10 LABORATORY EXERCISES. 



phosphorus after a time cease to 

 burn? 



What change do you see in the level 

 of the water within the glass jar? 

 How do you explain this? (See 

 Exp. 4.) 



FIG. 2. 



e. What change do you see in the com- 

 pound that was formed within the 

 glass jar? Explain. 



2. Slide a piece of glass beneath the mouth of 

 the bottle, turn the latter right side up, 

 taking care not to lose any of the water 

 that has risen in the jar. The ingredient 

 of the air left in the bottle is nitrogen. 

 Keep the bottle covered and shake the 

 water about to wash the nitrogen as 

 much as possible. 



a. Drop a piece of blue litmus paper 

 (see experiment 7) into the water. 

 What change do you see? (This 

 proves that oxid of phosphorus 

 makes water acid.) 

 B. Properties of nitrogen. 



i. What are the physical properties of the 

 nitrogen in the bottle? What are the 



