BONE. 527 



acid, but also contain carbonic acid and, in smaller amounts, magnesium, 

 chlorine, and fluorine. Alkali sulphate and iron, which have been found 

 in bone-ash, do not seem to belong exactly to the bony substance, but 

 to the nutritive fluids or to the other constituents of bones. The traces 

 of sulphate occurring in the bone-ash are derived, according to MOR- 

 NER, 1 from the chondroitin-sulphuric acid. According to GABRIEL, 

 potassium and sodium are essential constituents of bone-earth, and this 

 has been substantiated by ARON. 2 



The opinions of investigators differ slightly as to the manner in 

 which the mineral bodies of the bony structure are combined with each 

 other. Chlorine is present in the same form as in apatite (CaCl2,3Ca3P 2 O 8 ) . 

 If we eliminate the magnesium, the chlorine, and the fluorine, the 

 last, GABRIEL claims, occurring only as traces, the remaining mineral 

 bodies form the combination 3(Ca 3 P 2 O8)CaCO3. In his opinion the 

 simplest expression for the composition of the ash of bones and teeth 

 is (Ca 3 (PO4)2 + Ca 5 HP3Oi3 + Aq), in which 2-3 per cent of the lime is 

 replaced by magnesia, potash, and soda, and 4-6 per cent of the phos- 

 phoric acid by carbonic acid, chlorine, and fluorine. 



Analyses of bone-earths have shown that the mineral constituents 

 exist in rather constant proportions, which are nearly the same in dif- 

 ferent animals. As an example of the composition of bone-earth we here 

 give the analyses of ZALESKY. S The figures represent parts per thousand : 



Man. Ox. Tortoise. Guinea-pig. 



Calcium phosphate, Ca 3 P 2 O 8 838 . 9 860 . 9 859 . 8 873 . 8 



Magnesium phosphate, Mg 3 P 2 O 8 10.4 10.2 13.6 10.5 



Calcium combined with CO 2 , Fl, and Cl. .. 76.5 73.6 63.2 70.3 



CO 2 57.3 62.0 52.7 



Chlorine 1.8 2.0 1.3 



Fluorine 4 2.3 3.0 2.0 



Some of the CO 2 is always lost on calcining, so that the bone-ash does not 

 contain the entire CO 2 of the bony substance. 



AD. CARNOT 5 found the following composition for the bone-ash of 

 man, ox, and elephant: 



1 Zeitschr. f. physiol. Chem., 23. 



2 Gabriel, ibid., 18, which also contains the pertinent literature; Aron, Pfluger's 

 Arch., 106. 



3 Hoppe-Seyler, Med.-chem. Untersuch., p. 19. 



4 The reports as to the quantity of fluorine disagree; see Harms, Zeitschr. f. 

 Biologic, 38; Jodlbauer, ibid., 41. 



5 Compt. rend., 114. 



