Heat 



105 



FIG. 50. A view of the Dead Sea. 



Great Salt Lake and the Dead Sea, unlike most lakes, 

 have no rivers flowing out of them to carry the salt and 

 water away, but rivers flow into them and bring along 

 small amounts of salt all the time. Then the water evap- 

 orates from Great Salt Lake and the Dead Sea, leaving 

 the salt behind ; and that is why they are so very salty. 



When people want to get the salt out of sea water, 

 they put the sea water in shallow open tanks and let 

 the water evaporate. The salt is left behind. 



Experiment 35. Dissolve some salt in warm water until 

 no more will dissolve. Pour the clear liquid off into an 

 evaporating dish, being careful not to let any solid particles 

 of the salt go over. Either set the dish aside uncovered, for 

 several days, or heat it almost to boiling and let it evaporate 

 to dryness. What is left in the dish? 



Application 28. Some girls were heating water for tea, 

 and were in a hurry. They had only an open stew pan to 

 heat the water in. 



