EVAPORATION. 159 



A. The salt of the sea retards evap- 

 oration ; and (as the heat of the body is 

 drawn off very gradually) the sensation 

 of cold is prevented. 



Q. Why does SPRINKLING a HOT ROOM with 

 water COOL IT ? 



A. The heat of the room causes a 

 rapid evaporation of the sprinkled water ; 

 and as the water evaporates, it absorbs 

 heat from the room, and cools it. 



Q. Why does WATERING the STREETS and 

 roads COOL THEM ? 



A. The hot streets and roads part 

 with their heat to promote the evaporation 

 of the water sprinkled on them. 



Q. Why does a SHOWER of RAIN seem to COOL 

 the AIR in summer-time ? 



A. The earth (being wet with the 

 rain) parts with its heat to promote 

 evaporation ; and as the eavth is cooled, 

 it cools the air also. 



Q. Why is LINEN DRIED by being exposed to 

 the WIND ? 



A. The air (blowing over the linen) 

 promotes evaporation, by removing the 

 vapour from the surface of the wet linen, 

 as soon as it is formed. p 2 



