EXERCISE 21 

 DO GASES MIX WITH ONE ANOTHER? 



Materials. The air of the schoolroom ; any other gas, as illuminating gas or ammonia gas 

 escaping from ammonia water. 



Directions. With pupils seated at their desks, open the gas jet, noting the exact time of doing 

 so. Allow each pupil to record the time when he first detects the illuminating gas. Does the illumi- 

 nating gas reach all parts of the room ? Have you any idea as to how it passed through the air ? 

 Open the windows, and after a few minutes see if you can detect the illuminating gas. What 

 has occurred ? 



NOTE. Ammonia gas may be used instead of illuminating gas in the above experiment. 



Additional problems. Is it a good plan to use a lighted match in hunting for a supposed leak in a gas 

 pipe? Why? 



If sufficient illuminating gas has escaped into a room so that the odor of the gas may readily be 

 detected in all parts of the room, it is sometimes said, " The room is full of gas." Is there no air present ? 



[26] 



