PHOSPHO-NITROGENOUS MANURES 



239 



Composition of Bones. The ash of bones consists 

 almost entirely of tricalcic phosphate, but contains also 

 a small proportion of magnesia and fluorine. It can be 

 removed by the action of dilute hydrochloric acid which 

 dissolves out the phosphate and leaves behind the organic 

 matter or combustible part of the bones. The latter 

 contains two principal ingredients fat and ossein. The 

 fat can be extracted by solvents or by heat. The ossein 

 is an albuminoid substance, and in the dry state con- 

 tains about 17 per cent, of nitrogen. On prolonged 

 boiling with water it is converted into the familiar sub- 

 stance known as glue or gelatine. 



The following analysis shows the average composition 

 of mammalian bones in the fresh or green state : 



PER CENT. 



Water .' 

 Organic matter . 



Ash 



6-7 

 40-0 



[fat 

 I ossein 



( P 2 5 ! 

 53-3 CaO 



( Mg. F., etc. 



100-0 



6-7 

 14-6 



25'4 = 4'0 nitrogen. 

 22-3 = 48'7 Ca 3 (P0 4 ) 2 . 

 29-2 



1-8 



100-0 



The proportions of these constituents, however, vary 

 considerably in the bones of animals of different age, and 

 species, and in bones taken from different parts of the 

 skeleton. 



