100 Dr. J. L. Smith on Fluorine in Fossil Bones. 



chloric acid upon certain kinds of glass that contain a large quan- 

 tity of metallic oxides, or upon glass the surface of which has 

 been altered by the action of the air ; there is however no appa- 

 rent corrosion in these cases. 



The existence of fluorine in fossil bones, and its doubtful, or 

 as some say absolute, non-existence in those of recent animals, 

 have induced MM. Girardin and Preisser to conclude that it did 

 not belong originally to the bones of fossil animals, but has found 

 its way there by infiltration after their death, and they appear to 

 have come to this conclusion without having examined the chem- 

 ical character of the formations from which the various bones 

 were taken. 



I have had an opportunity of throwing some light upon this 

 subject, from the examination of two bones taken from the same 

 calcareous deposit and within two feet of each other, the one cel- 

 lular and the other compact. The cells of one of these bones 

 were filled with small concretions of calcareous matter, evidently 

 arising from the infiltration of some of the material forming the 

 bed in which they lay ; these concretions it would seem ought 

 certainly to contain a portion of whatsoever matter had been in- 

 filtrated, as all infiltrations must have passed in together. These 

 concretions, carefully detached from the bone, were examined 

 especially for fluorine, but not the slightest trace was found, 

 while on the contrary a very small quantity of the compact part 

 of the same bone, gave decided indications of the presence of this 

 substance. This fact must certainly lead to the conclusion that 

 the fluoride of calcium in the body of the bone was not infiltra- 

 ted, for had it been otherwise, it would have been associated with 

 matter known to be infiltrated, as the calcareous nodules. 



The same cellular bone was examined as a whole, that is to 

 say, without detaching the calcareous matter, in comparison with 

 the compact bone from the same locality ; and in the former there 

 was found less fluoride of calcium than in the latter, contrary to 

 what would have been the case had this fluoride been infiltrated. 

 Compact bone, . . 2-45 per cent, fluoride of calcium. 

 Cellular bone, . . 2-00 " " " 



The deposit from which these bones were taken was analyzed, 

 and fluoride of calcium detected, but in very small quantity; and 

 whether it arises from disintegrated osseous matter, or belonged 

 originally to the calcareous remains forming this bed, is of no 



