iv CONTENTS 



EXERCISE PAGE 



30. Water Tests 32 



31. Filtering and Precipitating ; 33 



32. Crystals 34 



33. Does the Temperature Change During Solution? 35 



34. Hydrogen 35 



35. Hydrochloric Acid and Ammonia Water 36 



36. Chlorine 37 



37. Sulphur 38 



38. Charring of Carbon Compounds 39 



39. How Ores are Reduced to Metals 40 



40. Carbon Dioxide and Fermentation 41 



41. Lime 42 



42. Magnets 43 



43. Electric Charges 44 



44. A Simple Electric Cell 45 



45. The Sal Ammoniac Cell 46 



46. Electromagnets 47 



47. Shadows 48 



48. Brightness Changes with Distance 49 



49. Candle Power 50 



50. Mirrors 51 



51. Refraction of Light 52 



52. Of What is White Light Composed? 53 



53. How Color is Affected by the Kind of Light 55 



54. How Sound is Made and Carried 56 



55. How Sounds are Strengthened 57 



56. Levers 57 



57. Tools Based on the Lever 59 



58. Pulleys 60 



59. The Inclined Plane 61 



60. The Screw , 63 



61. Wheel and Axle 64 



62. Friction 65 



63. Applied Forms of Simple Machines 65 



64. Acids 66 



65. Bases, or Alkalies 67 



