CHEMICAL COMPOSITION OF THE BONES. 23 



of earthy matter than any other bones in the body. From 

 these causes, arises considerable discrepancy in the analysis 

 given by different chemists. In early life the relative propor- 

 tion of earthy matter is at its minimum, the animal at ijs max- 

 imum. In advanced age, the reverse holds good, when the 

 bones are notoriously brittle and liable to fracture. Diseased 

 conditions of the system are known to still further modify these 

 proportions : in childhood the earthy matter may be so much 

 diminished that the bones become plastic and yielding, as in 

 rickets ; and at later periods of life, it preponderates occasion- 

 ally so much over the animal as to render them liable to break 

 at the slightest shock, as in cases of fragilitas ossium ; and 

 in some of the venereal affections, the bones are rendered nearly 

 as solid and heavy as a piece of ebony. 



The earthy matter of the bones of the higher animals con- 

 sists chiefly of phosphate of lime, with carbonate of lime, and 

 a small quantity of phosphate of magnesia, and fluate of lime. 

 The phosphate of lime of the bones is a subsalt, according to 

 Miiller, in which the base and acid are combined in peculiar 

 proportions, and which is always obtained when biphosphate 

 of lime is precipitated by an excess of ammonia. The phos- 

 phate of lime of the urine is a super-salt, held in solution ; in 

 the disease called mollities ossium, it seems to be excreted in 

 this state in the urine in larger quantity than natural. The 

 following is the result of Berzelius' analysis of the bones in man 

 and the ox : 



Man. Ox. 



Cartilage* completely soluble in water 32.17 



VI 1 1Q < * 3 " 30 



Vessels - ... 1.13 



Neutral phosphate of lime - - 51.04 55.45 



Carbonate of lime 11.30 3.85 



Fluate of lime - 2.00 2.90 



Phosphate of magnesia 1.16 2.05 



Soda with a small proportion of cloride of } 1 04* 



sodium - - 



100.00 100.00 



* i. e. Gelatine. 



