242 NATURE STUDY AND AGRICULTURE 



heat ? When the tube is almost full of water set the flask 

 in a cool place. Does the water contract? When fruit 

 jars are filled to the top with the hot fruit, why is it that 

 there is a space left at the top of the jar when the fruit has 

 cooled ? 



Will gases expand with heat? Use the same flask, as 

 in the preceding experiment. Pour out the water and dry 

 the flask thoroughly. What is in the flask now that the 

 water is out ? Insert the stopper as before, but place over 

 the end of the glass tube a rubber tube at least a foot long. 

 Hold the end of the rubber tube under water. Now slowly 

 heat the flask. What happens? As you heat the air in 

 the flask it expands and flows out through the rubber tube 

 as indicated by the bubbles. Heat a bottle (a round 

 listerine bottle is a good kind), by rolling it over and over 

 on a hot stove. When hot turn it upside down in a tumbler 

 one fourth full of water. Why does the water rise up in 

 the bottle? Heating the air expanded it so that some of 

 the air flowed out of the bottle. As it cooled, the air in the 

 bottle contracted and the pressure of air on the surface of 

 the water pushed the water up into the bottle. 



We are now ready to conclude that heat expands solids, 

 liquids, and gases, and that cold contracts them. What is 

 the effect of heat on solids and liquids as they ' change 

 from one of these states to the other ? 



Fill a cup level full of melted tallow or paraffin. Set 

 it in a cool place. Examine the next day. Is it still level 

 full? What happened to the paraffin as it cooled and 

 solidified? Which occupies the greater space, liquid or 

 solid paraffin? Melted lard, or solid lard? Which is 

 heavier, a cup level full of solid paraffin or the same size 



