EXERCISE 22 



WILL GASES MIX WITH ONE ANOTHER IF THE LIGHTER GAS IS PLACED ABOVE 



THE HEAVIER ONE? 



Materials. Two wide-mouthed bottles (about 6- or 8-ounce bottles); illuminating gas; air. 



Directions. Fill a wide-mouthed bottle with illuminating gas by collecting over water. Close the 

 mouth of the bottle with a card and place the gas-filled bottle, mouth downward, upon a similar bottle 

 filled with air. Withdraw the card. The air and the illuminating gas will thus be in contact in the 

 necks of the bottles with the lighter of the two gases above. 



After fifteen or twenty minutes test each bottle with a flame to discover whether the illumi- 

 nating gas has gone down into the lower bottle, or air from the lower bottle has gone up. How do 

 you explain the results ? 



Additional problem. Why are not the gases of the air in separate layers ? Would they be if there were 

 no winds ? 



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