Mineral Phosphates 



Mineral Phosphates. 



Mineral phosphates or phosphorites are found in 

 many places all over the surface of the globe — in 

 France, Belgium, Germany, Spain, Russia, England, 

 America, and Africa. In England they are chiefly 

 encountered in the form of phosphatic chalk at 

 Taplow in Buckinghamshire, or in accumulations 

 surrounding fossils in the Cambridge greensand, and 

 in Bedfordshire in the same form. Deposits of 

 coproliths, which we shall presently describe, are 

 foimd in the lias, and also in the black phosphorites 

 of North Wales. 



The phosphoric acid is present in a form of in- 

 soluble tribasic phosphate of lime [Ca3(P04)2], asso- 

 ciated with various impurities, such as carbonate of 

 lime [CaCOs], sulphate of lime [CaSOJ, magnesia 

 [MgO], iron, aluminium, etc. 



Mineral phosphates, especially the rich phos- 

 phates of Florida and of North Africa, are employed 

 chiefly in the manufacture of superphosphates. 

 Transformed into superphosphate they are extremely 

 valuable and have been and continue to be of 

 signal services to agriculture. 



On account of the results of lucky trials, made 

 under favourable circumstances, they have been 

 used, ground more or less finely, without under- 

 going any process of transformation. Needless to 

 say the results in general agriculture have often 

 been contradictory and often negative, but in every 

 case their value eventually has been in proportion 

 to their fmeness. Finely ground they may be used 

 in very acid soil, but in neutral soil they will give 



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