236 Sou7-ce of Fluorine in Fossil Bones. 



experiments, mentions the same fact ; still many other che- 

 mists have not succeeded in detecting it. MM. Girardin 

 and Preisser suppose that it was owing to some accidental 

 circumstances that Berzelius was enabled to discover it in 

 the cases that he examined, they having, in no instance, 

 found it, although carefully sought for. My experience tends 

 to confirm Berzelius in his statement, having, in several 

 cases, obtained most decided evidence of its presence in re- 

 cent 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 the total absence of it. 



I would here remark, that in examining for fluorine in the 

 ordinary way, by testing the effects of the hydro-fluoric acid 

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

 with characters traced out, the process requires some pre- 

 caution when the quantity present is supposed to be very 

 small ; for I have been able, in several instances, to obtain a 

 permanent delineation of the characters traced, without the 

 presence of fluorine. In these cases it is caused by the 

 action of the vapours of either sulphuric or hydrochloric 

 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 

 apparent 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. Girai'din and Preisser to con- 

 clude that it did not belong originally to the bones of fossil 

 animals, but has found its way there by infiltration after 

 death ; and they appear to have come to this conclusion 

 without having examined the chemical character of the for- 

 mations from which the various bones were taken. 



I had an opportunity of throwing some light upon this sub- 

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

 calcareous deposit, and within two feet of each other, the 

 one cellular, 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 concre- 



