62 Fertilizers 



with organic substances, or with minerals, or both, the 

 content of phosphoric acid and its combination with 

 other substances determining the usefulness of the phos- 

 phate to the manure-maker. 



The phosphoric acid in these materials is soluble with 

 difficulty in the soil water; and hence in their original 

 condition, or in the crude raw forms, they give up this 

 element in proportion as they decompose or decay in the 

 soil. Those in combination with organic substances, 

 either animal or vegetable, are, as a rule, more quickly 

 useful as a source of phosphoric acid than those composed 

 entirely of mineral constituents. 



PHOSPHATE OF LIME, OR BONE PHOSPHATE ANIMAL 



BONE 



The bones of animals are the chief source of phos- 

 phates that exist in combination with organic matter, 

 and were for a long time the main source for manurial 

 purposes. 



Bone consists chiefly of three classes of substances; 

 viz., moisture, organic matter, containing nitrogenous 

 and fatty matter, and phosphate of lime, or bone phos- 

 phate the proportion, particularly of the nitrogen 

 and phosphoric acid, depending upon the kind of bone 

 and the method of its treatment. 



Bone from the same kind of animal differs in com- 

 position according to the age of the animal and its loca- 

 tion in the body. In a general way, the younger the 

 animal the softer the bone, the poorer in phosphate of 

 lime and the richer in nitrogen; the older the animal, 

 the richer in phosphate of lime and the poorer in nitrogen. 

 The large and hard thigh bones of an ox, for instance, 



