CHEMISTRY. 



67 



it takes fire and burns with a brilliant flame and intense light, 

 with the evolution of dense white fumes. 



It is not found in nature in an uncombined state, "and is 

 not known [says Johnston,] to be susceptible of any useful 

 application in practical agriculture." Phosphoric acid results 

 from the combination of 'the fumes of burning phosphorus 

 with the oxygen of the atmosphere. It has the characteristic 

 properties of acids, and unites with lime, soda and potash, to 

 form phosphates. This acid is not found in nature in a free 

 state, but the compounds of phosphorus are extensively dif- 

 fused throughout nature, and are essential to the growth of 

 all cultivated plants. 



CATALOGUE OF THE COMPOUNDS DERIVED FROM THE INORGANIC 

 ELEMENTS OF PLANTS. 



Sulphurous acid, 



Sulphuric " 



Phosphoric " 



Potash, 



Soda, 



Lime, 



Magnesia, 



Chloride of Potassium, 

 " Sodium, 



" Calcium, 



" Magnesium, 



First Chloride of Iron, 



Second " " " 



Carbonate of Soda, 



Bi-carbonate " 



Nitrate " 



Sulphate 



Phosphate " 



Bi-phosphate " 



Alumina, 

 Silica, 



Protoxide of Iron, 

 Peroxide " 

 Protoxide of Magnesia, 

 Sesquioxide " 



Peroxide " 



Sulphuret of Potassium, 

 Sodium, 

 Calcium, 

 Iron, 



Bi-sulphuret " 

 Carbonate of Potash, 

 Bi-carbonate " 

 Sulphate " 



Nitrate " 



Binoxalate " 



Bitartrate " 



Phosphate 



