ARTIFICIAL AND CONCENTRATED MANURES. 81 



ganic 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, the proportion, 

 particularly of the nitrogen and phosphoric acid, depend- 

 ing upon the kind of bone, and the method of its treat- 

 ment. 



Bone from the same kind of animal differs in compo- 

 sition according to the age of the animal, and according 

 to its location 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 nitro- 

 gen. The large and hard thigh bones of an ox, for in- 

 stance, differ in composition from the softer and more 

 porous bones of other parts of the body. 



Treat a bone with dilute hydrochloric acid, and you 

 dissolve the phosphate of lime, and leave the soft pulpy 

 animal matter, which retains its original shape. Burn 

 the bone, and you drive off the organic matter, and leave 

 the porous phosphate of lime in the original shape, show- 

 ing the structure of the bone. The phosphate of lime 

 of the harder bones is dense and compact ; that from 

 the softer bone is more open and porous. The chief cause 

 of variation in the composition of bones used as manure, 

 however, is due to the treatment they receive. This is 

 recognized by manufacturers and dealers, and different 

 names of brands are used to indicate the method of 

 manufacture or treatment; as applied, however, they do 

 not always correspond to the methods of treatment. 



