BONE. 



387 



entire matrix. In addition, we find magnesium phosphate and 

 small amounts of calcium chloride, calcium fluoride, potassium and 

 sodium salts, and a little iron. Of the manner in which the differ- 

 ent salts are combined with each other, nothing definite is known, 

 but we may possibly assume, with Gabriel, that the composition of 

 the bone-ash, as well as the tooth-ash, can be represented by the 

 formula [Ca ? (PO 4 ) 2 -f- Ca 5 HP 3 O 13 + H 2 O], in which 2 to 3 per cent. 

 of calcium is replaced by magnesium, potassium, and sodium, and 

 4 to 6 per cent, of the phosphoric acid by carbonic acid, chlorine, 

 and fluorine. 



Whether or not the mineral constituents of the bone exist in com- 

 bination with the organic components of the tissue has not as yet 

 been definitely ascertained, but does not appear improbable. 



An idea of the quantitative distribution of the different salts in 

 different animals and bones may be formed from the accompanying 

 analyses. The figures have reference to 100 parts of bone-ash 

 (Zalefsky) : 



Calcium phosphate (Ca 3 (PO 4 ) 2 ) . . 

 Magnesium phosphate (Mg 3 (PO 4 ) 2 ) . 

 Calcium in combination with carbon 



Human. 



83.89 

 1.04 



Ox. 



86.09 

 1.02 



Turtle. 



85.98 

 1.36 



Guinea- 

 pig- 

 87.38 

 1.05 



dioxide, chlorine, and fluorine . . 7.65 7.36 6.32 7.03 



Carbon dioxide 1 5.73 6.20 5.27 . . 



Chlorine 1.80 2.00 



Fluorine 2 ............ 2.30 3.00 2.00 . . 



Calcium Phosphoric Magnesium 

 oxide acid oxide 



(CaO). (P 2 5 ). (MgO). 



Small flounder (ash in general) . . 53.13 42.72 0.91 



Man (ash in general) 52.83 38.73 0.48 



Man (humerus) 51.31 36.65 0.77 



Ox (femur) 51.28 37.46 1.05 



Goose (ash in general) 51.01 38.19 1.27 



Rabbits, varying in age between 



one day and four years (general 



ash) 51.91-52.89 39.78-42.20 0.83-1.38 



The variations in the amount of bone-ash, as a whole, in different 

 bones of the same animal, are seen in the following table (Fr6my) : 



Per cent. 



Femur 



Humerus 



Tibia 1*64.1-64.6 



Occipital bone 



Cranium 



Scapula ' 63.3 



Vertebrae , 54.2 



The amount of water which is found in bones varies between 13.8 

 and 44.3 per cent. It is greater in the spongy bones than in those 

 of the compact variety, and gradually diminishes with age. 



1 These figures are somewhat too low, as a certain amount of carbon dioxide escapes 

 during the incineration of the bone. 



2 According to (Tabriel, the amount of fluorine does not exceed 0.1 per cent., and is usually 

 less than 0.5 per cent. 



