LIST OF EXPERIMENTS XIII 



16. Expt. 19. Ordinary Sources of Light . .33 

 Expt. 20. Cold Light : .. ' . . . . 36 



17. Expt. 21. The Varying Heat from the Sun . 40 

 Expt. 22. The Amount of Heat Received by 



Different Colors .... 42 



Expt. 23. The "Burning Glass" ... 43 



18. Expt. 24. Heat Causes Expansion . . 44 

 Expt. 25. The Result of Unequal Expansion 46 



19. Expt. 26. How to Read a Thermometer . 50 

 Expt. 27. Hot or Cold? .;' ... 52 



21. Expt. 28. Primitive Fire-making ... 55 

 Expt. 29. The Flint and Steel Gaslighter . 56 



22. Expt. 30. Complete and Incomplete Combus- 



tion ... . . .59 



23. Expt. 31. The Combustion of Different Mate- 



rials . . . . . . 61 



24. Expt. 32. The Cause of Flames . . . 62 



25. Expt. 33. Drill for Extinguishing.. Burning 



Clothing . . . . . . .64 



26. Expt. 34. Good and Poor Conductors of Heat 67 



27. Expt. 35. Holding the Breath and Deep 



Breathing / . . . . 71 

 Expt. 36. The Effect of Depriving a Plant of 



Air . ... . . 71 



28. Expt. 37. To Show the Presence of Air in 



Soil and Water . . . ." 73 



29. Expt. 38. The Amount of Oxygen in the Air 76 

 Expt. 39. The Amount of Carbon Dioxide In 



the Air . . . .- 77 



30. Expt. 40. To Prepare and Use Oxygen . 78 

 32. Expt. 41. Carbon Dioxide from Combustion 



and the Breath 82 



