WATER, AND ITS USES 45 



is the salt now ? Get a drop of water from any part of the 

 vessel that does not have salt in it. By what are the particles 

 of salt and water held together ? What apparently must be 

 true of the size of the salt particles ? How is it that every 

 drop of water has apparently come into contact with a 

 particle of salt without the liquid having been stirred or 

 heated? 



6. Evaporate some of the salt solution to dryness. Taste 

 any solid left. What is it ? Let the rest of the liquid stand 

 in a covered dish till next day and see if any of the salt 

 settles to the bottom. If not, why not? Try to filter out 

 the salt. What is here taught of the size of the particles? 



7. Stir a little earth into a tumbler of water and let it 

 stand. Explain what happens. Repeat with kerosene and 

 water, and explain the result. Why does cream rise on milk ? 



8. Heat gently some water in a test tube. Where does 

 the air that collects on the sides of the tube come from? 

 (Bubbles of steam if formed could not persist in the water 

 below boiling temperature.) Explain how this air was kept 

 in the water. 



9. Lay a blotter down upon a drop of ink. What is 

 done to the ink by the blotter ? How can this be ? Since 

 we say that water dissolves air, why not say that the ink 

 dissolved the blotter, or the blotter dissolved the ink? 



Give a good definition for solution. 



10. Note very carefully the results as the teacher follows 

 out these directions : 



Wet the inside of a clean bottle with .a little strong hy- 

 drochloric acid, and set the bottle to drain, bottom up. In 

 like manner (perhaps in another part of the room) wet 



