CHAPTER II 

 COMPOSITION OF LIFELESS AND LIVING THINGS 



8. Introduction. For a great many years scientists 

 have been studying plants and animals, and from this 

 study they have learned that the bodies of all living organ- 

 isms, including human beings, are made from substances 

 found in the water, soil, and air, and that when plants and 

 animals cease to live, their bodies are changed into the 

 chemical substances of which soil, air, and water are com- 

 posed. We are now to learn by experiments the charac- 

 teristics of some of these materials found in lifeless things, 

 and some of the combinations of these materials in plants 

 and animals. 



I. ELEMENTS, COMPOUNDS, AND OXIDATION 



Materials: Splinters of wood and pieces of carbon; starch, 

 sugar, egg, meat; potassium chlorate, oxid of manganese, pieces of 

 marble, zinc, hydrochloric acid, lime water (see below) ; elements for 

 demonstration (e.g. phosphorus, sulphur, iron, magnesium) ; com- 

 pounds for demonstration (e.g. magnesium sulphate, sodium nitrate, 

 potassium nitrate, calcium phosphate, calcium carbonate); test 

 tubes, thistle tube, apparatus stand, tray for collecting gases, de- 

 livery tube, cylindrical graduate or glass jar. (All of the materials 

 named above will be found in the chemical or physical laboratory 

 of almost every high school.) 



Preparation of lime water : Put into a large bottle a good handful 

 of lime (freshly slaked in water, if possible ; air-slaked lime may be 

 used, however). Fill the bottle with water, shake the mixture, and 



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