82 FIRST PRINCIPLES OF AGRICULTURE. 



Raw Bone. — The term "raw bone" is properly ap- 

 plied to bone that has not suffered any loss of its origi- 

 nal constituents in the processes of its manufacturp ; and 

 is for this reason highly regarded by farmers, who be- 

 lieve that it is purer than any other form. This is 

 true in a large measure, though the fact that it is raw 

 bone is not altogether an advantage from the standpoint 

 of usefulness. Kaw bone too often contains consider- 

 able fatty matter, which makes it a difficult process to 

 grind it fine, and which also has a tendency to retard the 

 decay of the bone in the soil. A considerable amount of 

 fat also reduces proportionately the percentage of the val- 

 uable constituents, phosphoric acid and nitrogen. Good 

 raw bone, free from meat and excess of fat, should con- 

 tain on the average twenty-two per cent of phosphoric 

 acid, and four per cent of nitrogen. 



Fine Bone. — The trade terms "bone meal," "bone 

 dust," and "fine bone" are used to indicate mechanical 

 condition, or fineness of division, and do not refer es- 

 pecially to composition. These names should not be 

 taken as indicating the fineness without personal exami- 

 nation, since frequently the products do not, in this 

 respect, correspond to the name. Fineness is an impor- 

 tant consideration, since, the finer the bone, the quicker it 

 will decay, and its constituents become available to plants. 



Boiled and Steamed Bone. — The larger portion of 

 the bone used as manure has been boiled or steamed for 

 the purpose of freeing it from fat and nitrogenous matter, 

 both of which are products valuable for other purposes. 

 The fat is, of course, of no value as a manure, and its 

 absence is an advantage. The nitrogen, while useful 



