Source of Fluorine in Fossil Bones. 235 



axis of rotation. In consequence of that event, the North 

 Pole, which had originally been very near to Hudson's Bay, 

 was changed to a more easterly position ; but the countries 

 which it abandoned had been so long a time, and so deeply 

 frozen, that evident vestiges still remain of its ancient polar 

 rigour. A long series of years would be required for the 

 solar action to impart to the northern parts of the new con- 

 tinent the climate of their present geographical position." 



Fortunately, our knowledge of meteorology is now suffi- 

 ciently advanced to enable us to laugh at this crude explana- 

 tion of a change in the position of the terrestrial axis, result- 

 ing from the concussion of a comet. — American Journal of 

 Science and Arts, vol. xlvii., No. 2, p. 221. 



Source of Fluorine in Fossil Bones* 



The analysis of fossil bones, communicated by MM. 

 Girardin and Preisser to the Academic des Sciences, Octo- 

 ber 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 fluo- 

 ride 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, . . . 2Q'i: 



Vertebra of a Plesiosaurus, . . . 2'11 



The great bone of the Pcekilopleuron Bucklandii, . 1*50 



Rib of an Ichthyosaurus, .... 1'02 



Head of the same Ichthyosaurus, . . . 1'65 



Bone of the Lamantin, 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 



* Extract from a communication made to the Association of American 

 Geologists and Naturalists, at Washington, May 1844. 



