16 AGRICULTURAL CHEMISTRY. 



one, oftener of two, very often of three, less frequently 

 of four, and rarely of more than four. 



14. The names of the 15 elements, mentioned above, 

 as constituting more than 99 hundredths of all known 

 matter, are 1. Oxygen ; 2. Chlorine ; 3. Sulphur ; 4. 

 Phosphorus ; 5. Carbon ; 6. Silicon ; 7 ; Nitrogen ; 8. 

 Hydrogen ; 9. Iron ; 10. Manganese ; 11. Potassium ; 

 12. Sodium ; 13. Calcium ; 14. Magnesium ; 15 Alu- 

 minum. 



15. Oxygen is a gas, colorless, tasteless, inodorous; 

 not distinguishable by any of the senses from common 

 atmosphere. It constitutes, as mixed with nitrogen, 

 1-5 of the air ; as combined with hydrogen, 8-9 of 

 water; enters largely into all plants and animals; 

 forms a part of rocks and soils; and is supposed to 

 constitute not far from one half of all known matter. 

 It is the great supporter of combustion ; and it con- 

 stitutes the respirable portion of the atmosphere. No 

 fire can burn without it, nor animal breathe in its ab- 

 sence. It enters into combination with all other ele- 

 ments. We seldom see anything, unless it be the pre- 

 cious metals, which is not compose*d in part of this 

 substance. 



16. Chlorine is a yellowish green gas, 2^ times 

 heavier than air, existing largely in sea-water, consti- 

 tuting more than half of common salt, and entering in 

 a slight degree into all soils, and forming a part of all 

 plants. On soils found by analysis to be deficient in 

 chlorine, it should be supplied in the form of common 



