^IQ ENAMEJL OF TEETH. 



from a portion of Uie bony part from which the enamel is fe- 

 parated with great difficulty. But (he nioft interefting and 

 unexpefted refult is, that fluoric acid exifts in animal fub- 

 flances : a difcovery of the greateft importance. Thefe ex- 

 periments oppoCe theprefent opinion concerning the compofi- 

 lion of enamel, for Mr. Hatchett in his analyfis of this fub- 

 fiance has only deteded phofphate of lime. 

 Morichini pro- The refult of Mr. Hatchett's experiments, together with 

 feffcs to have thofe which were fubfequently publiQied by Mr. Jofle, in the 

 by repeated Annales de Chimie, Tom XLIII. rendered it neceflary for 

 experiments. M, Morichini to fubmit his opinion to accurate inveftigation, 

 and after having made a numerous feries of experiments on the 

 fubjeft, he obferves, that he cannot entertain a doubt, that 

 the enamel of human teeth confjfts chiefly of fluat of lime. 

 General remarks After fome obfervations on the compofition of ivory, M. 

 py Gay-Luflac. Gay-Luflac concludes tliis part of his letter, by obferving that 

 there is an immenfe field laid open in that part of chemiftry 

 which relates to animal fubftances, if it were merely to fearch 

 for fluoric acid. Morichini has undertaken an inveftigation 

 of the fubjed : but fo much remains to be done, that the ex- 

 ertions of many chemifts will be requilite." 

 The iuthor's ^ '^^'^ ""^ relate fome experiments, which will fliew that 



experiments fluoric acid does not exift in the enamel of human teeth, but 

 ftewthecon. ^j^^^ ^j^j^ fubflance conlifls chiefly of phofphate of lime, as 



originally ftated by Mr. Hatchett.* 

 Enamel of his- 0"6 hundred grains of the enamel of human teeth, detached 

 man teeth was from vvhat is ufually termed the bony part, but which appears 

 Ized ^and^fiib-' ^° confift of a fubflance of the nature of ivory, were kept for 

 jefted to fui- a few minutes in a red heat, and then pulverifed. The en^ 

 The"fumes*did ^'"^^'j *^'^"* reduced to powder, was put into a platina crucible, 

 not corrode in wiiicha piece of a glafs rod was placed horizontally in fuch 

 9'*^' a manner as to be about an inch and a half above the enamel. 



Half an ounce of fuiphuric acid was then added, and the 

 crucible being covered with a clean plafe of glafs, the heat of 

 a lamp was applied, and diflillation carried on for half an 

 hour. During theprocefs, white fufFucating fumes were ex- 

 tricated; but on removing the glafs which clofed the top of 

 tlie crucible, neither this, nor the rod below it were in the 

 lead aded upon ; which certainly would have happened, had 



* Vide Phil. Tranf. 1799, p. 358. 



any 



