560 Intelligence and Miscellaneous Articles. 



and all the animal substances in which fluorine has been said to 

 exist, ai"e particularly rich in phosphoric acid; — thus the ashes of 

 ivor5% of human bone, and the enamel of teeth, as also the precipi- 

 tate obtained from urine by means of lime-water, are all of them 

 composed, in very great part, of phosphate of lime. Mr. Richard 

 Phillips has mentioned (in the Annals of Philosoph)-, vol. v.), that 

 when the water contained in uranite is driven off from the powdered 

 mineral, a portion of the phosphoric acid is volatilized with it ; the 

 heat used being that of a common spirit-lamp. This is the only 

 fact with which I am acquainted (with the exception of my own 

 observation), to show that phosphoric acid will volatilize with 

 water. The heat used in Mr. Phillips's experiment was, most pro- 

 bably, considerably higher than any which I applied. There seems 

 no doubt that phosphoric acid is much more volatile than it has 

 heretofore been supposed. 



Having failed in detecting fluoric acid in human bones, I deter- 

 mined on testing for its presence in the enamel of teeth, in recent 

 ivory, and in the precipitate obtained from urine by the addition of 

 lime-water. Two difl^erent specimens of ivory (tusks of the ele- 

 phant) gave no evidence of the presence of fluoric acid, when care- 

 fully tested, either before or after calcination ; and I was equally 

 unsuccessful with the enamel of human teeth and the precipitate 

 from the urine *. .. "Z", 



In these experiments, when I had failed in acting on the glass, 

 I always found that the_ addition of 0'3 grains of fluoride of calcium to 

 the experiment produced a strong and indelible mark on the surface 

 of the glass test-plate. I mention 0"3 grains, because it will always 

 be found sufficient to produce a most unequivocal corrosion ; though I 

 obtained satisfactory results by the addition of a much less quantity. 

 I have had only one opportunity of examining fossil ivory ; and in 

 that instance I could not ascertain its locality : on submitting it, 

 however, to the tests used for recent ivory, bone, &c., I obtained 

 immediate action on the glass. 



In conclusion, I must express my firm conviction, that fluoride of 

 calcium, as an ingredient in fossil ivory, must be regarded as an 

 extraneous matter, introduced by the partial mineralization of the 

 animal substance ; — that no such constituent exists in recent ivory, 

 the enamel of teeth, human bone, or urine ; — in fact, that fluoride 

 of calcium should be expunged from the list of the constituents of 

 animal substances. — Guy's Hospital Reports, Aug. 1839. 



* I was much pleased to observe, that Mr. Pepys, in an analysis of ena- 

 mel published in Mr. Fox's work on the Teetli, does not mention fluoride 

 of calcium as an ingredient of that substance. This analysis was made by 

 Mr. Pepys in 1833, several years after the fluoride had been declared a 

 constituent of the enamel. 



INDEX 



