SOURCE OF FLUORINE IN FOSSIL BONES. 





The analyses of fossil bones communicated by MM. Grirardin 

 and Preisser to the Academie des Sciences, October, 1842, afford 

 the only well-detailed numerical results of the composition of 

 this class of bones that we possess. The authors appear to 

 have bestowed considerable care upon their research, and their 

 estimate of the proportion of fluoride of calcium present was 

 as follows : 



Per cent. 



A metacarpal bone of a bear from the cavern of Mialet... 1.09 



Tusk of an elephant 2.64 



Vertebra of a plesiosaurus 2.11 



The great bone of the pcekilopleuron bucklandii 1.50 



Eib of an ichthyosaurus 1.02 



Head of the same ichthyosaurus 1.65 



Bone of the lamentin from the tertiary formation in the 



environs of Valognes 9.12 



This fluoride would appear to form a distinguishing mark 

 between fossil and recent bones, although Berzelius has found 

 it to exist in these latter, and Marchand, in some recent experi- 

 ments, mentions the same fact; still many other chemists have 

 not succeeded in detecting it. MM. Grirardin and Priesser sup- 

 pose that it was owing to some accidental circumstances that 

 Berzelius was enabled to discover it in the cases that he ex- 

 amined, they having in no instance found it, although care- 

 fully sought for. My experience tends to confirm Berzelius in 

 his statement, having in several cases obtained most decided 

 evidence of its presence in recent bones, but in very minute 

 quantity. In many instances I failed to detect it, and attribute 

 the failure more to the minuteness of the quantity than to the 

 total absence of it. 



I would here remark that in examining for fluorine in the 

 ordinary way, by testing the effects of the hydrofluoric acid 

 (liberated by the action of sulphuric acid) upon waxed glass 

 with characters traced out, the process requires some precau- 

 tion when the quantity present is supposed to be very small ; 



