Phosphates 



assimilable. The output of this country, although 

 great — 60,000 tons — does not meet the demand, so 

 they were imported from India and very largely 

 from the Argentine, but also from Brazil, Morocco, 

 Egypt, and the Continent, and within recent years 

 the total importation had mounted up to about 

 50,000 tons per annum. 



The Importance of Fineness. — This is a matter 

 of the very first importance, far more so than is 

 generally imagined ; and it is astounding that the 

 demand for coarsely ground bones is still so great. 

 A difference of i per cent, nitrogen and 5 per cent, 

 phosphoric acid can easily be sacrificed to fineness 

 of material, and in spite of this fineness bone will 

 never be assimilated in a single year. It will 

 generally take from two to three years. For this 

 reason it is not a manure to be recommended. 



There are cases where finely ground bones have 

 given very good results — in acid soils for example ; 

 but these cases are the exception and cannot be in 

 any way regarded as a general rule. 



Green Bodies. — It is not economical to use ground 

 bones green. They contain too much fat and are 

 not easily assimilable, either as regards phosphates 

 or nitrogenous organic matter. The phosphate is 

 in the tricalcic form, often called bone phosphate. 

 They are more or less unevenly ground, but are 

 always of slow and incomplete action, and con- 

 sequently are poor value. 



Green bones when dried and cleaned of their 

 fat contain about 4 per cent, organic nitrogen and 

 50 per cent, tricalcic phosphate. They are con- 

 verted into — 



54 



