276 THE MINERAL MATTERS OF BONE. [BOOK I. 



The following exhibits the probable composition of the mineral 

 matters of bone calculated from the analyses of Zalesky. 



Calcium phosphate (Ca 3 2PO 4 ) 83'889 



Calcium carbonate (CaC0 3 ) 13'032 



Calcium in combination with fluorine, 



chlorine and organic acids 0'350 



Fluorine 0'229 



Chlorine 0183 



98722 



The occurrence of considerable quantities of a fluoride in bone 

 has, since it was first discovered, attracted the attention of many in- 

 vestigators (Chevenix, Morichini 1 , Gay Lussac, Berzelius 2 , G. Wilson 

 and others). The presence of this element is readily proved by 

 heating powdered bone with strong sulphuric acid in a leaden 

 or platinum capsule, when hydrofluoric acid is given off, as can be 

 proved by its etching glass. 



Constitu- ^ ^ as been surmised that a combination of calcium 



tion of the phosphate and calcium fluoride having the same consti- 

 minerai mat- tution as the mineral Apatite exists in bone ; the 

 ters of bone. composition of this mineral is shewn by the formula 

 Ca 10 M 2( 6(P0 4 ). 



In bone, however, the fluorine is present in very minute 

 quantities, the main compound having probably the composition 

 Ca 10 CO 3 , 6(P0 4 ). This matter is discussed again in connection 

 with dentine and enamel (see p. 291). 



Zalesky has shewn that chlorides exist in bone in two conditions, 

 a portion being soluble in water, and another portion being only 

 dissolved by acids. 



influence of The influence of food, rich or poor in earthy salts, 



food on mine- upon the composition of bone has been studied by 

 rai matters of various writers with entirely different results. Thus 

 Forster 3 observed a diminution in the proportion of 

 calcium in the bones of dogs fed upon a diet in which calcium salts 

 were deficient. In similar experiments performed on dogs, Zalesky 4 

 obtained altogether negative results. Weiske 5 came to similar con- 



1 An account of Morichini's discovery of fluorine in fossil teeth was given in a 

 letter addressed by Gay Lussac to Berthelot in the Annales de Chimie of 30 Fructidor, 

 an 13 (1805). 



2 Berzelius, "Extrait d'une lettre a M. Vauquelin sur le fluate calcaire contenu 

 dans les os et dans 1'urine." Ann. de Chim. t Vol. LXI. (1807) p. 256. 



3 J. Forster, "Ueber die Verarmung des Korpers speciell der Knochen an Kalk bei 

 ungeniigender Kalkzufuhr." Zeitschrift f. Biolog., Vol. xn. p. 464. 



4 Zalesky, Op. cit., p. 44 et seq. 



5 Weiske, "Einfluss verschiedener der Nahrung beigemengter Erdphosphate auf 

 die Zusamrnensetzung der Knochen." Zeitschr. f. Biolog., Vol. vm. p. 239. "Ueber 

 Knochenzusammensetzung bei verschiedenartiger Ernahrung." Zeitschr. f. Biol., Vol. 

 x. p. 410. 



