44 LABORATORY LESSONS IN GENERAL SCIENCE 



Tie one thickness of cotton cloth about the thermometer 

 bulb, wet it with alcohol, and repeat the test. 



What becomes of the alcohol in both cases? Recall by 

 what means the vaporization of liquids has been accom- 

 plished before. Give an explanation of the thermometer 

 changes. When vapors are condensed and changed to 

 liquids what is true of this heat of vaporization? 



3. Into a hot iron spoon put water a little at a time, 

 and observe what changes occur in the water and in the tem- 

 perature of the spoon. What becomes of the heat that was 

 in the metal? 



What part does vaporization play in the temperature 

 of any region intensely heated by the sun during the day, as 

 during our summer time ? What is true of the temperature 

 of land surfaces largely destitute of water when under a 

 summer's sun? 



SOLUTION, ABSORPTION, DIFFUSION 



1. Make crayon marks on the blackboard, or lead 

 pencil marks on paper. Why does an attempt to jar or 

 shake these off not succeed? 



2. Dip a finger into water. Explain why it comes out wet. 



3. Let a stream of water from some height fall into a 

 jar of water. Account for the bubbles of air in the jar. 



4. Lower into water a rough stone. Why do not all 

 the air bubbles on the surface of the stone rise to the liquid 

 surface ? 



6. Drop a lump of salt into some water. State what 

 change occurs in it. What force that previously held the 

 parts of the lump together has now been overcome ? Where 



