c. Heat from chemical cliang-es. 



Experiment 33. Heat due to chemical 

 changes. 



27. Cooking. 



a. An example of one kind of chemical change, 



b. Aids digestion and prevents disease. 



28. The difference between heat and temperature. 



Experiment 34. Heat and temperature 

 distinguished. 



29. Destructive distillation. 



a. The making of charcoal. 



b. The making of illuminating gas. (See Sec- 

 tion 88.) 



Experiment 35. Destructive distillation. 

 (This subject, Heat, is continued in the work 

 for the eighth grade.) 



AIR, VII. 



30. A brief summary of the facts stated under the 

 same topic in the work for the fifth and sixth grades. 



31. The buoyancy of the air. 



a. The hot-air and gas balloons. 



Experiment 36. Blowing soap-bubbles 

 with gas. 



b. Bodies heavier than air. 



Experiment 37. How to make a toy 

 boomerang and a toy glider. 



32. "Suction" vacuum. (See Section 89.) 



Experiment 38. To show what suction 

 is. The "sucker." 



33. Pumps. 



a. The lift pump. 



Experiment 39. How to make a suction 

 pump. 



