in Recent as well as in Fossil Bones. 28^ 



being crystallized, it is somewhat variable in its composition, yet, 

 when selected as pure as possible, contains as much as 81 per cent, 

 of phospate of lime, and 14 per cent, of fluoride of calcium, the re- 

 mainder appearing to consist of silica and peroxide of iron. 



The conclusion arrived at, with respect to the compact form of 

 mineral phosphate of lime occurring in the above locality, coupled 

 with the reports of other chemists to the same effect relative to the 

 crystallized apatite, naturally led me to speculate as to the final 

 causes of the apparently constant association of fluoride of calcium 

 with earthy phosphates, amongst the older materials of the globe, 

 and to ask myself, whether it might not bo possible, that fluorine, 

 as well as phosphorous, fulfilled some hitherto unexplained ofl^ice, 

 in the economy of those organic beings, for the sake of which such 

 mineral matters may be conjectured to have been treasured up in 

 the rock formations from the beginning of time. 



These reflections brought to my mind the researches of Morichini 

 and of Berzelius, with respect to the existence of fluorine in bones, 

 seeing that the latter, according to the concurrent testimony of botli 

 these philosophers, appear to contain, as a constant ingredient, a 

 minute quantity of fluoride of calcium, inasmuch as its presence is 

 vouched for by them, in recent as well as in fossil bones, and in the 

 teeth of mammalia, as well as in other parts of their osseous struc- 

 ture. 



Here, however, I was compelled to pause, by observing the con- 

 trary statements put forth by other able chemists relative to this 

 point. Fourcroy and Vauquelin having, previously to the re- 

 searches of Berzelius, denied the existence of fluorine in recent 

 bones ; and Dr Rees having, subsequently to them, in a memoir 

 drawn up under a full knowledge by what had been done before, 

 arrived at a conclusion equally opposed to that of the Swedish phi- 

 losopher.* One too, which has been since corroborated in a com- 

 munication relative to the composition of bones, made to the French 

 Institute, by Messrs. Girardin and Preisser of Rouen, and lately 

 published in the Comptes Hendus.jf 



As, however, none of these gentlemen appear to dispute that 

 fluorine does occur iri fossil bones generally, the conclusion they have 

 arrived at leaves the subject, it must be confessed, encumbered with 

 greater difficulties than before ; for as all sound chemical analogies 

 stand opposed to the admission of the idea, that fluorine can have 

 been generated from the other constituents, during any process of 

 decay or alteration that might have occurred in it during the ages 

 that had elapsed since it formed a part of the living structure, we 

 should be driven to the belief, that the fluoride of calcium contained 

 in bone had filtered in from w^ithout ; a conjecture which, although 



* See Phil. Mag. S. 3, vol. xv. p. 55S. Ed. 

 1 Ibid. S. 3, vol. xxiv. p. 154. Ed. 



