QUESTIONS. 275 



contain ? How soon will the air in a close room of that size be ren 

 dered unfit to breathe ? 43. What is meant by ventilated ? How 

 important is ventilation ? 44. Do plants breathe ? Is air necessary to 

 them ? 45. By daylight what do growing plants do ? What is done 

 with it ? How do plants purify the atmosphere ? What relation do we 

 see in this ? State it distinctly. 46. What action do plants Have in 

 the night ? When is wood formed ? 47. An oxide ? [See 22.] Bases ? 

 What do they do ? Why are the compounds of acids and bases called 

 salts ? 48. What docs carbonic acid and lime form ? Sulphuric acid 

 and lime ? Nitric acid and potash ? 49. Oxygen combining with ? 

 Decay of fallen leaves ? What are favorable ? How is humus formed ? 

 Nearly all decay ? What are formed during decay ? 50. Humus ? 

 Ulmin ? Ulmic acid ? Humin ? Humic acid ? 51. Geic acid ? Crenic 

 acid ? Apocrenic acid ? 52. Action of nitrogen ? 



CHAPTER III. 53. What is meant by atmosphere ? How high ? 

 54. The atmosphere ? What are acting in it ? 55. What operations 

 are going on in it ? What are rising into it ? What are all striving to 

 do ? 56. What is the sun doing ? Every star ? Oxygen ? Water ? 

 57. By what force does water penetrate ? Capillary attraction ? 58. 

 Osmotic action? How? 59. How does -oxygen act? 60. Each gas 

 do ? Give proof. 61. How does heat act ? Conduction ? Radiation ? 

 What effect does heat produce in solids ? In liquids ? In gases ? 63. 

 Attraction of gravitation ? Attraction of cohesion ? Force of adhe 

 sion ? 64. Force of vegetable life ? Force of animal life ? A third 

 force ? A fourth ? 65. Under what influence is woody fibre formed ? 

 What other effects has the sun s light? 66. What facts prove the 

 influence of the sun s light ? 67. What experiment shows that light 

 gives wood its strength ? * 68. Why is this ? What is the difference 

 in the growth by day and by night ? 69. What power has the sun s 

 light upon animals ? 70. How important is sunshine to human beings ? 

 Point out the difference between two children, otherwise like each 

 other, one kept much in the sunshine, the other much in the shade. 

 71. How does the sun act upon the soil ? What precaution is desirable 

 when trees are to be ^planted ? 72. What other effects are produced by 

 the atmosphere? 73. What appearance does amber or wax exhibit 

 when rubbed ? What is the cause ? How is glass excited ? 74. 

 Explain what the opposite electricities are ? 75. Meant by discharged ? 



* This is also strikingly shown in the growth of forests. Trees standing near 

 an opening in the woods make the greatest growth of foliage and limbs, on the 

 side towards the light. 



24* 



