FREEZING AND FORCE. 



cool it sufficiently, again we burst the vessel 

 through the formation of ice. 



The expansive force of freezing water plays 

 an active part in the destruction of mountains. 

 Water from rain or melted snow lodges in the 

 crevices, and then on exposure to severe cold 

 freezes with an expansive force which splits 

 the rock as thousands of wedges might. 



On a smaller scale the bursting of our water 

 pipes is an instance of the same force. When 

 a column of water is securely held between 

 two taps, if the pipes are strong enough to pre- 

 vent it from expanding, it cannot freeze. But 

 if the expanding force be the stronger, the pipes 

 will either stretch or burst. Water does not 

 leak until a thaw comes, so it is not till then 

 that the bursting is discovered, though it 

 occurred during the frost. 



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