1024 



SUCCESSFUL FARMING 



Oxygen about 65 



Carbon " 18 



Hydrogen " 10 



Nitrogen " 3 



Calcium " 2 



Phosphorus 



Potassium about . 35 



Sulphur .... 

 Sodium .... 

 Chlorine . . . 

 Magnesium . 

 Iron 



.25 

 .15 

 .15 

 .05 

 .004 



Iodine 



Fluorine 



Silicon 



Very minute quantities. 



These percentages mean that the body of an adult weighing 154 

 pounds contains about — 



100 pounds of oxygen \ pound of potassium. 



27 

 15 



3 

 U 



carbon . 



" hydrogen 



" nitrogen \ " 



" calcium 1 ounce 



" phosphorus -fg 



. sulphur, 

 sodium, 

 chlorine, 

 magnesium, 

 iron. 



Description of Body Elements. — Let us familiarize ourselves a little 

 with these body elements. 



As every one knows, the air we breathe is made up mainly of a mix- 

 ture (not compound) of oxygen and nitrogen, each of which is a colorless, 

 odorless gas. About one-fifth the air by volume is oxygen.* 



Water is a chemical combination of oxygen and hydrogen, another 

 colorless, odorless gas. In water both oxygen and hydrogen have lost 

 their identity and have formed a compound. 



Carbon is familiar in its elemental form as soot, lampblack, coal, 

 charcoal. We realize its presence in our foods by the blackening that 

 occurs when we scorch or burn them. 



Calcium, Potassium and Sodium never occur in nature in their ele- 

 mental forms. When freed from their compounds they are soft, silvery- 

 white metals that are dangerous to handle. 



Phosphorus, also, is never in nature in its elemental form. When 

 pure it may be a yellow solid that burns spontaneously in the air. 



Sulphur, a yellow solid, is well known. When set on fire it burns 

 with the familiar blue flame of the sulphur match. 



Chlorine is a heavy, yellow, suffocating gas. Our common table salt 

 is composed of chlorine and sodium chemically combined. Chlorine so 

 combined with hydrogen forms hydrochloric acid, the essential acid, of 

 the gastric juice of the stomach. 



Magnesium is a silvery-white metal that burns with a brilliant white 

 flame. 



Iron we are all familiar with. 



Body Compounds. — From the foregoing it is needless to add that no 

 one of the elements that make up the human body occurs in the body in its 

 elemental form. These elements are chemically combined with each other in 



*The carbon dioxide found in the air is very important in plant life. It occurs to the extent of about 

 3 parts per 10,000. 



