QUALITIES OF IVORY 227 



contains from 40 to 43 per cent, of organic matter, while 

 human dentine has only about 25 per cent.* 



The following analyses of dentine are published in Tomes's 

 "Manual of Dental Anatomy." I is by Von Bibra of per- 

 fectly dried dentine, II is another by Von Bibra, and III 

 is by Berzeliusif 



I II 



Organic matter 27 . 61 20 . 42 



Fat 40 .58 



Phosphate and fluoride of lime 66.72 67.54 



Carbonate of lime 3 . 36 7 . 97 



Phosphate of magnesia 1.18 2.49 



Other salts 83 1 . 00 



100.10 100.00 



Gelatine and water 28 . 00 



Sodium salts 1.50 



Phosphate of magnesia 1 . 00 



Phosphate of lime 62 . 00 



Fluoride of lime . . . , _ 2 . 00 



Carbonate of lime 5.50 



In fossil ivory a much larger proportion of fluoride of lime 

 appears than in that taken from animals of our day. This 

 is believed by Monsieur Carnot to be due to metamorphosis, 

 the fluorine having replaced to a certain extent the lime 

 phosphate. 



The density of ivory varies in specimens from different 

 places ; the specific gravity as given in Landholt's Tabellen| 

 is from 1.83 to 1.92; the Annuaire of the French Bureau des 

 Longitudes** gives a slightly higher figure — ^namely, 1.93. 



*Tomes, op. cit., p. 373. 



fTomes, Charles S., "A Manual of Dental Anatomy," 3d ed., London, 1889, p. 63. 



JLandholt's physikalisch-chemische TabeUen, Berlin, 1894, p. 67. 



** Annuaire pour I'an 1906. Publiee par le Bureau des Longitudes, Paris, 1906, p. 439, 



