50 AMERICAN MANURES. 



the amount of fertilizing elements they may 

 contain 



PHOSPHORUS. 



Phosphorus as commonly met with is yellow 

 and transparent, resembling wax in consistency. 

 Having a powerful affinity for oxygen, it never 

 occurs free in nature. It is spontaneously in- 

 flammable, and for this reason is preserved under 

 water. Phosphorus was originally prepared from 

 urine by a tedious and disagreeable process ; but 

 Gahn, a Swedish chemist, having discovered that 

 it enters largely into the composition of bones, it 

 is now prepared from this class of bodies. When 

 burnt in air or oxygen, it is converted into snow- 

 like flocks, which are called anliydrous phos- 

 phoric acid. 



Phosphoric Acid contains, in 100 parts, phos- 

 phorus 43.66, oxygen 56.34. This acid has a 

 great affinity for water, and by exposure to a 

 moist atmosphere is converted into lujdrated 

 phosphoric acid. There are several hydrates of 

 this acid ; but only one of these enters into the 

 composition of manures, viz : tri-basic phosphoric 

 acid. A tri-basic acid is one that requires three 

 equivalents of the same or of different bases to 

 form a salt; for example : 



Bone-Phosphate of Lime, known as Basic 

 Phosphate of Lime, is composed of one equivalent 



