BONES. 201 



most part, some fat. Both these substances, how- 

 ever, may be disregarded in forming a decision upon 

 the manuring properties of bones. 



Whoever desires a more precise acquaintance with 

 the constituents of bones may institute the following 

 simple experiments. 



1. Place a beef-bone, previously dried and weighed, 

 in a stove-fire, and take it out again when it has 

 completely recovered its white color, which in heat- 

 ing at first passes into black ; the gelatine burns up, 

 the bone-earth, on the contrary, remains behind. The 

 bone thus burnt to whiteness^ and now a third part 

 lighter than at first, consists of about nine tenths 

 phosphate of lime and one tenth carbonate of lime. 

 This proportion between gelatine {\) and bone-earth 

 (I) is, however, not unchangeable, but varies in dif- 

 ferent animals, and indeed even in one and the same 

 animal, according to its age and the nature of the 

 bones. 



2. Place a bone in a glass or stone vessel, and 

 pour over it some diluted muriatic acid ; the bone 

 will by degrees become soft and transparent, and 

 finally pass into a cartilaginous, semi-transparent 

 mass. The muriatic acid dissolves the bone-earth, 

 and the gelatine remains behind, since it is as insol- 

 uble in muriatic acid as in water. If the gelatine is 

 withdrawn from the acid and boiled, after a previous 

 washing with water, it is transformed into glue, and 

 a solution is obtained that coagulates on cooling. If 

 the muriatic acid, when poured off", is mixed with 



