loo Common Science 



142. Automobile tires tighten upon a sudden change from cold 



weather to hot. 



143. When paper has been rolled, it tends to curl up again after 



being unrolled. 



144. Seats running across a car are much more comfortable when 



a car starts and stops, than are seats running along the 

 sides. 



145. You cannot siphon water from a low place to a higher one. 



146. Candles get soft in hot weather. 



147. Meteorites fall to the earth from the sky. 



148. When you preserve fruit and pour the hot fruit into the jars, 



you fill the jars brim full and screw on the cap air-tight ; 

 yet a few hours later the fruit does not fill the jars ; there 

 is some empty space between the top of the fruit and the 

 cover. 



149. Water pipes burst in the winter when it is very cold. 



150. When people want to make iron castings, they first melt the 



iron, then pour it into molds. They leave it in the molds 

 until cold. After that the iron holds the shape of the 

 molds. Explain why the iron changes from a liquid to a 

 solid. 



SECTION 18. Evaporation. 



Why is it that when ink is spilled it dries up, but when it 

 is in the bottle it does not dry up ? 

 What put the salt into the ocean? 

 Why do you feel cold when you get out of the bathtub ? 



Wet clothes get dry when they are hung on the clothes- 

 line. The water in them evaporates. It turns to in- 

 visible vapor and disappears into the air. Water 

 and all liquids evaporate when they are long exposed 

 to the air. If they didn't well, let us imagine what 

 the world would be like if all evaporation should sud- 

 denly stop : 



You find that your face is perspiring and your 

 hands as well. You wipe them on your handkerchief, 



