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Common Science 



FIG. 51. In a minute the cork will fly out. 



test tube turned to steam, the steam had to get out and 

 pushed the cork out ahead of it. 



Experiment 37. Pour about half an inch of water into 

 the bottom of a flask. Bring it to a vigorous boil over the 

 burner and let it boil half a minute. Now take the flask 

 off the flame and quickly slip the mouth of a toy balloon 

 over the mouth of the flask. Watch what happens. If 

 things go too slowly, you can speed them up by stroking 

 the outside of the flask with a cold, wet cloth. 



When the balloon has been drawn into the flask as far as 

 it will go, you can put the flask back on the burner and heat 

 the water till it boils. When the balloon has been forced 

 out of the flask again and begins to grow large, take the 

 flask off the burner. Do this before the balloon explodes. 



The reason the balloon was drawn into the flask was 

 that the steam in the flask turned back to water as 



