in Animal Substances. og^ 



Rjadnra, and the earth of Mnmarosch, may have arisen 

 from the decomposilion of the skeletons of large terrestrial 

 animals. 



Upon learning that the fluoric acid existed in the enamel 

 of teeth, 1 immediately recollected that Rouelle had for- 

 merly annomiced that he was unable to procure phosphorus 

 from ivory ; and I suspected that it might he similar in its 

 composition te enamel. I therefore calcined a quantity of 

 ivory, and poured upon it concentrated sulphuric acid : va- 

 pours were now distngaged, which I readily recoonised to 

 be those of the fluoric acid. The tusks of th'e boai^aftorded 

 the same results. When I say that the3e two substances 

 contain fluale of lime^ I would not be understood to assert 

 that they are wholly composed of it, because I had no means 

 of niakmg an accurate analysis ; the vapours of the fluoric 

 acid, however, are so abundant, that we should be led to 

 believe its combination with lime forms a very large part of 

 their composition. 



A few days after these experunents I examined, along 

 •with M. Morichini, a portion of fossil ivory which had been 

 found in the neighbourhood of Rome. It's concentric lay- 

 ers, both external and internal, yielded the fluoric acid in 

 great abundance. I attempted also to analyse the bones of 

 fish; but I have made only a single experiment on those of 

 the tench; and from this I confess 1 dare not say any thing 

 decisive. 



You perceive then, my friend, that it is highly probi-ble 

 the enamel of the teeth of all animals is formed,' in a great 

 measure, of the fluate of lime : and it mav be remarked, 

 that their canine teeth are either entirely composed of the 

 enamel, or contain a much larger proportion of it than the 

 others. As we have hitherto found in the urine all the dif- 

 ferent substances composing the bones, have we not ground 

 for believing that it also contains the fluoric acid ? If at a 

 certain period of life the fluate of lime can be deposited upon 

 the teeth, it appears necessary that wlieu these have acquired 

 their fuM growth this substance should find some outlet from 

 the body. 



What is tlic origin of this fluate of lime in animal sub- 

 stances ? Although the presence of fluate of lime in the 

 phosphate of lime of Kstramadura has occasioned a sus- 

 picion that one of the acids forming these salts may be a 

 modiiication of the other, this opinion appears to me to 

 have but little foundation ; for the co-existence of the two 

 substances proves nothing as to tlieir intimate nature : and 

 vc may readily convince ourselves, by «niiplv in-pecting'a 



fossil 



