A YEAK IN SCIENCE 



45 



in temperature do you note? How do you account for 

 this change? See Exercise 18. 



Water, ether, or alcohol may be used in place of the 

 chloroform. Place a drop of chloroform on the back 

 of the hand. What is the sensation produced as the 

 chloroform evaporates? What is the principle used 

 in the manufacture of ice by the use of ammonia? 



CHAPTER VI 



PHYSICAL AND CHEMICAL CHANGES 



Exercise 22. Physical Change. 

 Object: To determine the nature of a physical 

 change. 



Apparatus 



Salt 



Distilled water 

 Evaporating dish 

 Wire gauze 

 Bunsen burner 

 Glass stirring rod 

 Ring stand 



Directions: Place some 

 salt in an evaporating 

 dish. Cover it with dis- 

 tilled water. Stir it with, 

 the glass rod. What 

 happens to the salt ? Place Fi s. n. 



the evaporating dish with the solution on the wire 

 gauze over the flame. Heat the solution slowly until 



