BONES. 253 



De ground to meal, bone meal ; the finer ground, the better. 

 In this state, a pile of meal, if moistened, soon heats, fer- 

 mentation sets in, and the gelatine evolves from 4 to 6 per 

 cent, of its weight as pure ammonia. 



Doubtless this fermentation has its value, if excited in 

 bone meal before using it as a manure. If ammonia es- 

 capes, which is easily known by the smell, this valuable 

 element can be retained by sprinkling the pile with a few 

 pounds of plaster, or with half a pint of oil of vitriol 

 stirred into two gallons of water for every 100 lbs. of bone 

 meal. 



If it were easy to reduce bones, in their entire state, to 

 powder, its animal part could be easily retained. But the 

 practical difficulty of grinding raw bones is just beginning to 

 be overcome, and however perfectly this process may be 

 hereafter effected, still the amount of raw, or entire bones, 

 will be always very small compared with bones from which 

 a portion of the animal matter has been removed. This 

 leads to the second head of the subject, bone as deprived of 

 a portion of its gelatine. 



This is effected by a continued and long boiling in the 

 open air, skimming off the fat and gelatine as they arise to 

 the surface of the water ; or better, by steaming, under a 

 pressure of 4 or 5 pounds on the inch, by which the gelatine 

 is removed, and may be extracted as glue. This leaves the 

 bone porous, and as the water immediately fills the pores, 

 the bone weighs as much nearly as it did before boiling. 

 By long boiling, or steam.ing and separating the fat and glue, 

 bone becomes soft and pliable while warm, but hard and 

 brittle when cold. In this state bone readily breaks, easily 

 grinds. 



The following is the composition of bone partly deprived 

 of its gelatine : 



