EVAPORATION. 163 



Q. Why is MOULD HARDENED by the SUN ? 



A . Because (when the moisture of the 

 mould has been evaporated by the sun) 

 the earthy particles come into closer 

 contact, and the mass becomes more 

 solid. 



Q,. Show the WISDOM of GOD in this arrange- 

 ment. 



A. If the soil did not become crusty 

 and hard in dry weather, the heat and 

 drought would penetrate the soil, and kill 

 both seeds and roots. 



Q. Why is TEA cooled FASTER in a SAUCER 

 than, in a cup ? 



A. Because evaporation is increased 

 by increasing the surface ; and as tea in a 

 saucer presents a much larger surface to 

 the air, its heat is more rapidly carried 

 off by evaporation. 



(The subject of " convection" will be treated of in a 

 future chapter, and would scarcely be understood iu 

 this place.) 



Q. Why is not the VAPOUR of the SEA SALT? 

 A. Because the salt is always left 

 behind, by the process of evaporation. 



Q. Why does a WHITE CRUST appear fin hot 

 weather) upon CLOTHES wetted by sea water. 



