WATER. 103 



that will occur when the ice is pushed under the water. 

 Add the weight of the overflow to the weight of the ice to 

 get the weight of water displaced. 



A lump of ice weighed 34 J ounces ; the overflow of water 

 weighed 3 ounces. The specific gravity of the ice was 34 J 

 divided by 34 \ + 3, which gives 69 seventy-fifths or -92. Using 

 the specific gravity, find the weight in ounces of a cubic 

 foot of ice. 



What if Water Shrunk in Freezing ? — Water expands in 

 volume as it freezes, hence ice floats. 



If water continued contracting so that its bulk in ice were 

 less than in the liquid form would it float 1 



If the ice in the ponds and rivers and lakes kept sinking as 

 it formed what would happen to the fish? If the pond or 

 lake were frozen from the bottom to the top how would its 

 thawing be affected. 



Convection. — Water at or above 39° F. is expanded by the 

 application of heat. Expansion makes it lighter, and hence 

 the water touching the bottom of a pot on a hot stove ascends 

 as it warms and thus allows colder water to take its place. 

 Apply this to warming an upstairs room with water heated in 

 the basement and to boiling the water in a tank by means of 

 a pipe passing through the stove. 



Heat Expands Solids and Liquids. — Insert a small-bore 

 glass tube through a perforated cork. Push the cork into a 

 bottle filled with water colored with dye or potassium perman- 

 ganate. The water will rise in the tube as the cork enters 

 the bottle. Warm the bottle and observe the consequent 

 rising of the liquid in the tube ; cool it and observe it descend. 

 Compare with the movement of mercury or spirit in a 

 thermometer. 



Make a ring on the end of a wire that will almost let a 

 marble drop through. Hold the marble supported in the ring 



