472 NATURE STUDY. 







current. The little pieces of paper looked as if they were playing tag. 

 The water nearest the flame got warm first. Then it rose. It took 

 the little pieces of paper up with it. As soon as the hot water went 

 up, the cold water took its place. Cold water is heavier than warm 

 water.'* AGNES TAYLOR. 



SLOW EVAPORATION OB DRYING. 



Step I. What slow evaporation is. Put vessel contain- 

 ing a very little water near stove or radiator, but not over 

 fire. Place wet handkerchief or sponge, or paper or slate, 

 in a warm place in a vessel, or under such conditions that 

 pupils can easily observe and prove that water dust comes 

 from them. Impress thought that drying is a slow evapo- 

 ration. Get from children many illustrations of slow evapo- 

 ration in schoolroom, at home, out-doors. 



Step II. What helps slow evaporation or drying. Place 

 a measured quantity of water in vessel in warm part of 

 room and in similar vessel in place not so warm. After 

 an hour or two, or on the following day, measure. Place 

 water in sunlight and in shade, and measure as before. 

 Why the difference ? After children have told as well as 

 they can, what we did and what we saw, they can " think 

 out " one answer to the question, What helps slow evapora- 

 tion ? Cannot they be helped to tell a story, and follow an 

 order somewhat like this : " John put a cupful of water 

 near the stove. Harry put a cupful of water near the door. 

 It was warmer near the stove. We left them there all 

 night. This morning John's cup was empty. Harry's cup 

 was almost full. The water near the stove had all evapo- 

 r^ted. Mary thought the warm stove made the water 

 evaporate faster. We all thought so. James put some 

 water in the sun, and some where the sun did not shine. 

 The water in the sun evaporated faster. The warm sun 

 helped it. So we think that water evaporates fastest where 

 it is warmest. Heat helps slow evaporation." 



