75. Preservation of food. 



a. Cleanliness. 



b. Coolness. 



c. By sealing. 



d. By heating. 



Experiment 62. Preserving food by 

 heating. 



e. By chemical means/ Some of the dangers. 



Experiment 63. Preserving eggs. 



76. The teeth. 



a. Care of the teeth. 



b. Cause of decay. 



(This subject, Food, is continued in the work 

 for the seventh grade.) 



MECHANICS. VI. 



77. A brief summary of the facts stated under the 



same topic in the work for the fifth grade. 



78. Altitude measurement. 



Experiment 64. How to make and use 

 altitude measurer. 



79. The wheel and axle. 



Experiment 65. The wheel and axle a 

 lever. 



80. The pulley. 



a. Fixed. 



b. Movable. 



Experiment 66. The pulley a lever. 



81. The screw. 



Experiment 67. The screw a circular in- 

 clined plane. 



82. Inertia. 



