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III. Comparative Analysis of Recent a?id Fossil Bones. 

 By J. MiDDLETON, Esq., F.G.S. 



To Richard Phillips, Esq. 

 Dear Sir, 

 XJAVING lately devoted some time and attention to the 

 analyses of bones, both recent and fossil, I trust some 

 of the results at which I have arrived may not be unacceptable 

 to the readers of the Philosophical Magazine. I took up the 

 subject with the view of ascertaining, if possible, the law by 

 which fluoride of calcium becomes augmented or developed 

 in fossil bones, as, should this be established, an important 

 step would, I conceived, be thereby made towards the ascer- 

 tainment of geological time. 



That fossil bones contain fluoride of calcium in greater 

 quantity than recent ones is a fact which has long been known, 

 though heretofore not adequately explained. One theory pro- 

 posed to account for it on the hypothesis that the source of 

 fluorine in animals is their food, and that that in former times 

 must have contained a greater quantity of the substance than 

 it now does, and thus the bones of animals then living came to 

 possess it in a higher proportion. To this theory, however, 

 I felt unable to consent, as, in order to entitle it to credence, 

 its supporters should, in my opinion, be prepared to show that 

 fluoride of calcium is capable from its nature of occupying 

 the place and discharging the functions of phosphate of lime 

 in living bones, without detriment to their health and strength ; 

 as also that if a greater quantity of fluoride of calcium were 

 present in the food of animals, a greater proportion would be 

 absorbed. To assume these is to assume too much, the more 

 especially as the general constancy and uniformity of nature 

 is thereby opposed, who, having her own materials to select 

 from and to work with from the beginning, is as little likely 

 to deviate in the constituent elements of things as in the laws 

 by which the things themselves are governed. 



It is perhaps unnecessary to examine other explanations 

 less generally received, though all equally exceptionable; 

 suffice it to say that unsatisfied with them I was induced to 

 seek for another. In this search it occurred to me that fluorine 

 might exist in common water, and if so, that its accumulation 

 in fossil bones would be found to be the result of infiltration, 

 as with carbonate of lime, peroxide of iron, &c. In order to 

 ascertain whether there was any foundation for this view, I 

 examined the following substances and found them to contain 

 fluorine, some in greater some in less proportion : — 



1. Deposit in a chloride of lime vat. 



2. >•• water-conduit pipe of a coal mine. 



