THE NATURE AND NEEDS OF LIVING 

 MATTER 



PROBLEM I 



A study of the common elements in the environment 

 of living things- 



a. Nitrogen (N) and the Composition of the Air 



Note. The most abundant elements in living matter are 

 carbon, hydrogen, oxygen, and nitrogen. 



Apparatus. Large deep dish of water, bell jar or large 

 wide-mouth bottle, large cork, and phosphorus. 



Method. Cut off a bit of phosphorus as large as a pea, and 

 float it on the large piece of cork. 

 Ignite it, and cover it quickly 

 with the bell jar. 



Observations. 1. Does the 

 water rise in the bell jar? If so, 

 how high ? 



2. What was in the bell jar as it 

 was inverted over the phosphorus ? 



Note. The phosphorus unites 



in burning with an element in the FlG " r T Gettillg ^percent- 



age of nitrogen in the air. 



air called oxygen, and forms a sub- 

 stance (fumes) which dissolves in the water present. 



Conclusions. 1. What formerly occupied the space now 

 filled with water ? What part of the original contents of the 

 jar was oxygen ? 



2. If the phosphorus used all the oxygen in burning, about 

 what part of the air must be oxygen ? (The rest is mostly 

 nitrogen.) 



SHARPE'S LAB. MAN. 2 17 



