SCIENTIFIC AGRICULTURE. 1G1 



common salt, of which great quantities are found in Poland, 

 England and elsewhere. It is the principal saline ingredient 

 in the waters of salt lakes and the ocean. It is found in many 

 minerals, most plants, and in all the animal fluids. Sodium is 

 found in vast quantities in South America in the form of a 

 nitrate. 



The pure metal -sodium is lighter than water, its specific 

 gravity being 0.972; its equivalent number is 23.3. It is a 

 silvery white metal, resembling potassium closely in its appear- 

 ance. The compounds of sodium are numerous and important 

 This metal is soft at common temperatures, melts at 194 F., 

 and oxidizes rapidly in the open air. 



As soda exists in most soils, and is found in some form in 

 most if not all plants, it is probably a necessaay ingredient in 

 soils ; many of its salts, particularly the nitrate, sulphate, chlo- 

 ride and phosphate, are valuable fertilizers. 



POTASSIUM. 



This is the metallic basis of potash : it is bluish white when 

 not exposed to the air, but by the contact of ajr it instantly 

 oxidizes and becomes covered by a crust of the alkali, potash: 

 when thrown in water, it takes fire and burns, with a violet 

 flame. At common temperatures it is soft and may be 

 molded into any form, like wax: "at 32 it is quite brittle, 

 and crytalizes in cubes;, at 70 it is pasty, and at 150, per- 

 fectly liquid. At a dull, red heat, it boils, forming a green 

 vapor, and may be distilled." 



Like sodium, it is lighter than water; its specific gravity 

 being 0.655. Potassium has a remarkable affinity for oxygen, 

 which it abstracts from almost all other bodies. Its equiva- 

 lent number is 39.3. Potash is a strong fixed alkali: it neu- 

 tralizes the strongest acids, and its salts are numerous and 

 important Potassium is not found in an uncombincd and 

 pure state in nature, but in the form of an oxide : it exists in 



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