292 Dr Daubeny on the Occurrence of Fluorine 



stated the proportion of fluorine in these samples of bones and teeth, 

 as well as the fact of its actual presence, and likewise if I had ex- 

 tended my examination over a larger number of specimens ; but I 

 have been compelled to postpone the former part of the inquiry until 

 I could obtain an apparatus suitable for the purpose, and doubted 

 when my time would permit me to carry further the present inves- 

 tigation, if, in order to give my results in a state of greater com- 

 pleteness, 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 produced by 

 the latter, vvdth those caused by a certain amount of fluor spar, 

 mixed with a weight of phosphate of lime, or other earthy material, 

 equal to that present in the bones operated upon. Judging by this 

 rough mode of measurement, it would appear, that in several in- 

 stances the faintness of the marks shews a smaller quantity of fluo- 

 rine to have been present 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 nor- 

 mal presence in fossil ones be admitted, for we can readily under- 

 stand its finding its way into the animal structure through the 

 medium of plants, which may imbibe 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 point, t 



Th6 greater distinctness of the marks produced by the fossil bones 

 acted upon than by the recent ones, may be more difficult of expla- 

 nation ; 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 mterment in the earth. Of the six speci- 



* 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 Stonesfield, and in the recent human bone from an anatomical 

 cabinet. The former afforded 8*7 grains per cent, of fluoride of calcium, 

 the latter only 2*0, results which will at least indicate the relative, if not 

 the absolute quantity of fluorine present. 



t 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 occur- 

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

 combination, as causes it to be dissipated by the heat necessary for ex- 

 pelling the carbonaceous matter, and therefore cannot be detected in 

 the ordinary method. 



