STRANGE BEHAVIOR OF WATER 41 



temperature, it could not be molded in this way. Iron acts 

 in a similar manner, and because of this property the black- 

 smith can shape his horseshoes, and the machinist can make 

 his engines and other articles of daily service to man. 



FIG. 20. Molten glass being rolled into a form suitable for window panes. 



33. Strange Behavior of Water. One has but to remember 

 that bottles of water burst when they freeze, and that 

 ice floats on water like wood, to know that water expands 

 on freezing or on solidifying. A quantity of water which 

 occupies 100 cubic feet of space will, on becoming ice, need 

 109 cubic feet of space. On a cold winter night the water 

 sometimes freezes in the water pipes, and the pipes burst. 

 Water is very peculiar in expanding on solidification, be- 

 cause most substances contract on solidifying ; gelatin and 

 jelly, for example, contract so much that they shrink from the 

 sides of the dish which contains them. 



If water contracted in freezing, ice would be heavier than 



