260 On the Presence of Fluoric Acid 



tion, a small quantity of gelatine, and then drying it. The 

 vapours which these tliree substances yield by the sulphuric 

 acid, exhibit equally the property of corroding glass, and 

 depositing siliceous concretions in water, or on a moist 

 sponge. They present also other characters which it would 

 be useless here to mention, but which, taken in conjunc- 

 tion with the above, will not permit us to doubt their 

 identity. 



According to the cx',.crimcnts of M. Morichini, 100 parts 

 of the cnimel of human teeth contain thirty of animal sub- 

 stance, a little magnesia, alumine, and carbonic acid ; and 

 twentv-two of the iiuoric and phosphoric acids, in combina- 

 tion with hme. He has been unable to separate accurately 

 the fluoric from the phosphoric acid, but conceives that this 

 last exists only in verv small quantity. 



The enamei of the teeth of the fossil elephant is likewise 

 composed of the same elements, but in different proportions: 

 thus it contains less phosphoric acid than that of the human 

 leeth, and much less animal substance. M. Morichini, 

 however, believes that this difference in the quantity -of 

 phosphoric acid in the two enamels very probably arises 

 from a portion of the bony matter of human teeth, which 

 it is very difficult to separate completely from the enamel. 

 The most interesting result, and that which we least sus- 

 pected, is the existence of fluoric acid in animal substances; 

 a discovery of very great value., and one from which we 

 mav justly expect the most important cons(K^uences. 



These conclusions respecting the presence of fluate- of 

 lime in the enamel of the teeth, are no doubt contrary to 

 our former ideas upon this subject ; for M. Josse, who has 

 analysed the enamel of human teeth*, and Mr. Hatchettf, 

 who examined ihat of a fossil elephant's tooth, have both 

 discovered tio other substance besides the phosphate of lime. 

 The opinion of these two chemists induced M. Morichini 

 to submit his own to rigorous examination : but his expe- 

 riments have been so multiplied that there can now be en- 

 tertained hardly any doubt upon this subject. 



Pclletier has proved that the phosphate of lime of Estra- 

 madura contains a portion of fluate of lime, and that the 

 earth of Mamarosch consists of a larc;e proportion of this 

 last, with a small quantity of phosphate. M. Morichini, 

 reasoning from his own experiments, which prove that these 

 two salts may be found united in animal substances, con- 

 ceives it very possible that the phosphate of lime of Estra- 



• Aimales de Chimie. f ^'^'l- I'fans. 179f». 



madura. 



