Comparative Analysis of Becent and Fossil Bones. 285 



ments, in which the prism may be used with great advantage ; and the 

 Committee have no hesitation in asserting, that this is a most ingenious 

 and useful mode of throwing light, either natural or artificial, in all casee 

 in which " Specula" are employed. 



The Committee unanimously recommend it to the fiavGurable consi- 

 deration of the Royal Scottish Society of Arts. 

 Signed in name of the Committee. 



(Signed) Charles Ransfokd, M.D., F.R.S.S.A., 

 Convener, 

 Edinbubgh, May 22. 1844. 



Comparative Analysis of Becent and Fossil Bones. 



By J. MiDDLETON, F.G.S. 

 TO RICHARD PHILIPS, ESQ. 



Dear Sir, — Having 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 conceive, be thereby 

 made towards the ascertainment 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 here- 

 tofore not adequately explained. One theory proposed to account 

 for it on the hypothesis, that the source of fluorine in animals is 

 their food, and that in former times it must have contained a greater 

 quantity of the substance than it does now ; 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 

 shew that fluoride of calcium is capable, from its nature, of occupying 

 the place, and discharging the functions of phosphate of lime in liv- 

 ing 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 as- 

 sume these is to assume too much, the more especially as the gene- 

 ral 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. 



