Fluorine in Recent as ijoell as in Fossil Bones. 1 27 



permit me to carry further the present investigation, if, in 

 order to give my results in a state of greater completeness, I 

 neglected the present opportunity of communicating them*. 

 The only criterion, therefore, I am at present enabled to offer 

 as to the proportion of fluorine in the bones examined, is a 

 comparison of the depth and distinctness of the marks pro- 

 duced by the latter, with those caused by a certain known 

 amount of fluor spar, mixed with a weight of phosphate of lime 

 or other earthy material equal to that present in the bones 

 ppernted upon. Judging by this rough mode of measurement, 

 it would appear, that in several instances the faintness of the 

 marks shows a smaller quantity of fluorine to have been pre- 

 sent in the specimen, than would have been contained in a 

 mixture of one-tenth of a grain of fluor spar added to 100 

 grains of phosphate of lime. 



The existence of fluoric acid, as a constant, or at least a 

 common ingredient in bones of all ages, would seem a priori 

 to be much more probable, than its absence in recent bones 

 would be, if its normal presence in fossil ones be admitted, 

 for we can readily understand its finding its way into the ani- 

 mal structure through the medium of plants, which may im- 

 bibe it along with those phosphates with which it is so generally 

 associated. Indeed it seems so likely, that those vegetables 

 at least that contain much phosphate of lime should possess a 

 trace of it, that I am at this very time examining the ashes of 

 barley with reference to the latter pointf. 



The greater distinctness of the marks produced by the fos- 

 sil bones acted upon than by the recent ones may be more 

 difficult of explanation; but before it is urged as an objection 

 against the view taken, it should be determined, whether the 

 difference may not arise from the removal of the greater part 

 of the animal matter from the fossil bone, owing to its long 

 interment in the earth. Of the six specimens of fossil and 

 recent bones of which I made a rough analysis, that from 

 Stonesfield, which was the oldest of any, having been im- 



* I have since, by the aid of the apparatus described in the former note, 

 attempted to estimate the amount of fluorine in the fossil bone from Stones- 

 field, and in the recent human bone from an anatomical cabinet. The 

 former afforded 8*7 grains per cent, of fluoride ot calcium, the latter only 

 20, results which will at least indicate the relative, if not the absolute 

 quantity of fluorine present. 



■f- I have since ascertained that no sensible action is exerted on glass by 

 heating with sulphuric acid the earthy phosphates present in 12 lbs. of 

 barley. Sprengel, I find, had already suggested the probable occurrence 

 of fluorine in plants, but conceives that it exists in such a state of combi- 

 nation, as causes it to be dissipated by the heat necessary for expelling the 

 carbonaceous matter, and therefore cannot be detected in the ordinary 

 method. 



