HIGH SCHOOL AGRICULTURE 



CHAPTER I 



Elements. All substances in the universe are com- 

 posed of certain elements. About eighty of the ele- 

 ments 1 are familiar to chemists. Of this number there 

 are ten which are of chief importance in explaining the 

 composition of the soil and the growth of plant and 

 animal life. 



The Most Important Ten Elements. - 



Oxygen O Potassium, K (L. Kalium) 



Hydrogen H Iron . . Fe (L. Ferrum) 



Nitrogen N Calcium .... Ca 



Carbon C Magnesium . . . Mg 



Phosphorus P Sulphur S 



To these may be added four others that are of 

 less importance: (i) Chlorine, Cl; (2) Sodium, Na; 

 (3) Aluminium, Al; and (4) Silicon, Si. 



Compounds. A substance formed by the union of 

 two or more elements is called a compound. Most of 

 the substances that we see and handle are compounds. 

 Water is a compound made by the union of the element 

 hydrogen and the element oxygen. Sugar and starch 



1 A list of known elements with their symbols will be found in the 

 Appendix. 



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