BIOLOGY 



ber of elements, nine chemical elements being ordinarily pr< 

 ent in living things, four of which predominate, while the oth 

 four are present only in small quantities. They are as follows : - 



Oxygen, a colorless, odorless gas, forming about one-fif 

 of the atmosphere. 



Carbon, a solid at ordinary temperatures. Charcoal, graphi 

 lampblack, and diamond are examples of almost pure carbc 



Hydrogen, a gas, the lightest of all known substances a: 

 highly inflammable. 



Nitrogen, a colorless, odorless gas which comprises abo 

 four-fifths of the atmosphere. 



Sulphur, phosphorus, calcium, iron, and potassium cons 

 tute the other chemical elements that are found in livi 



Carben 



Oxt/yen 



V 



Xydroyen. 



FIG. 1. DIAGRAM SHOWING THE RELATIVE PROPORTIONS 

 OF THE CHIEF ELEMENTS MAKING UP A LIVING BODY 



things. Only very small amounts of these elements are presei 

 although calcium is found in animals in considerable quantit: 

 in the bone. Figure 1 shows diagrammatically the relati 



