SOURCE OP FLUORINE IN FOSSIL BONES. 177 



Per cent. 



Compact bone, fluoride of calcium 2.45 



Cellular bone, " " 2.00 



The deposit from which these bones were taken was ana- 

 lyzed, and fluoride of calcium detected, pertaining to mollusca 

 or vertebrated animals; and were it necessary to suppose that 

 it could have existed in only one of these, I should unhesita- 

 tingly attribute its origin to the vertebrated animals, particu- 

 larly on account of their abundant provision of phosphates. 

 Bones were also examined that contained fluorine when the 

 deposit from which they were taken showed no traces of this 

 element. 



Dr. Daubeny has lately examined the question of the ex- 

 istence of fluorine in recent bones, and decided it in the 

 affirmative. 



It is not surprising that we should find the phosphates and 

 fluorides associated in the animal kingdom; for in the mineral 

 kingdom fluorine is a very common attendant upon the phos- 

 phates, as for instance in the apatites, wagnerite, wavellite, 

 uranite, etc.; and I think if we search the mineral kingdom 

 we shall not find so constant an association of any two elements 

 as fluorine and phosphorus. All the phosphates of the alkalies 

 and earths contain fluorine. 



If then this element is associated with the phosphates, they 

 must exist together in the soils arising from the disintegration 

 of the rocks containing these minerals, and the plants grow- 

 ing upon these soils would upon taking up the phosphates 

 naturally appropriate the accompanying fluorides, which two 

 classes of salts would subsequently pass to the same portion of 

 the animal feeding upon these plants — namely, to the bones. 



The reason why the existence of fluorine in recent bones is 

 doubtful may be owing to the fact that the great mass of the 

 phosphate of lime originally in the soil has from various causes 

 disappeared, and with it the fluoride of calcium ; and that the 

 portion of this latter still remaining is so small that notwith- 

 standing the double condensation that it undergoes through 

 the agency of plants and animals, it is not in sufficient quantity 

 to come readily within the reach of our tests. 



