DEFINITIONS 



any understanding of statements of analyses 

 upon which purchase should be made. 



An Element is a substance that cannot be 

 divided into simpler substances. The num- 

 ber of elements necessary to the growth of 

 plants is small, and of this number calcium 

 is one and magnesium is another. 



Compounds. We do not find these ele- 

 ments merely mixed with other elements to 

 form a soil. They unite in definite propor- 

 tions by weight to form chemical com- 

 pounds. As conditions change, many of 

 these compounds undergo change, giving 

 up one element, or group of elements, and 

 uniting with another element or group 

 from a different compound. Heat, moist- 

 ure and the action of bacteria are factors in 

 promoting the changes. There is no more 

 restless activity than may be found among 

 the elements composing a productive soil. 



Calcium is an element which will unite 

 with oxygen and carbon dioxide to form a 

 compound known as calcium carbonate. 

 The chemist's symbol for calcium is Ca. 



Calcium Oxide is a compound left after 

 the burning of limestone, and is known as 

 fresh burned lime, or quick lime. Its 

 formula is CaO. It contains, when pure, 



29 



