68 Report of the Acting Director and Chemist op the 



Bones. — Bones consist of two quite different kinds of material. 

 The hard portion consists mostly of calcium phosphate or phosphate 

 of lime, and constitutes from one-half to three-fifths of the weight 

 of the bone. The remaining portion consists largely of a soft, flesh- 

 like substance called ossein, or, more commonly, gelatin. It is dis- 

 tributed throughout the entire mass of bone and is rich in nitrogen. 

 When bones are burned, the nitrogenous matter is driven off and 

 only the mineral portion or phosphate of lime remains. Bones, 

 such as are used in making commercial fertilizers, contain 4 to 5 per 

 cent, of nitrogen and from 20 to 25 per cent, of phosphoric acid, 

 equivalent to 45 to 55 per cent, of phosphate of lime. 



Bone-Ash. — As the name implies, bone-ash is made simply by 

 burning bones in the open air. The nitrogen is, of course, driven 

 ofE and lost in burning, and the chief constituent is insoluble cal- 

 cium phosphate, equivalent to 30 to 35 or more per cent, of phos- 

 phoric acid. 



Bone-Black, known also as bone-charcoal, is extensively used 

 in refining sugar. After it has been used several times, portions 

 become useless for refining purposes and are then sold as fertilizer. 

 Bone-black is made by heating bones in closed vessels, the air 

 being excluded. By heating bones in this manner, the fat, water, 

 and nitrogen are removed from the bones ; and the bone-black 

 remaining consists mainly of insoluble calcium phosphate and 

 carbon or charcoal. The presence of the carbon hinders the 

 decomposition of the phosphate, so that it is, in this form, not 

 readily available as food for plants. Good bone-black may contain 

 30 or more per cent, of phosphoric acid. 



Bone-Meal goes under various names, such as ground bone, bone- 

 flour, bone-dust, etc. We find in the market raw bone-meal and 

 steained bone-meal. Raw bone-meal contains the fat naturally 

 present in bones. The presence of the fat is objectionable, because 

 it makes the grinding more difficult and retards the decomposition 

 of the bone in the soil, while fat itself has no value as plant food. 

 When bones are steamed, the fat is removed and the bone is more 

 easily ground. Moreover, the chemical nature of the nitrogen com- 

 pounds appears to be changed in such a manner that the meal 

 undergoes decomposition in the soil more rapidly than in case of 

 raw bone. The presence of easily decaying nitrogen compounds in 

 bone hastens, in the process of decomposition, to dissolve more or 

 less of the insoluble phosphate. Bone meal should contain from 3 



