EXAMINATION OF THE TEETH. 37 



mical chara&ers, and to point out the error of confidering it 



as a common offeous body, having no other difference but the 



denfity arifing from the compa&nefs of its conftituent parts. 



I (hall firft concifely point out the pbyfical characters of the Phyfical charac 



enamel of the teeth, and then proceed to the chemical invef-^j° f ^ J^. 



ligation. This analyfls rauft more fully elucidate the phyfio- 



logical inferences I lhall then offer, to prove that nature has 



affigned particular functions to this fubftance, which differs 



abfolutely from the bones. 



When examined on the fur face of the teeth, the enamel is It appears chryf- 

 ,.,.,,., r 1-1 i r talhzed in its 



white, lmooth, pohfned, tranlparent, very brittle, and or f ra & ure . 



extreme hardnefs : its fracture lliews a very diflinct, regular 



chryflallization, formed of an affemblage of fmall brilliant 



cryflals, very compact, and inclining to the fliape of needles. 



On all the furfaces which it covers, as well as in the interior 



of certain teeth where it is found, it is difpofed in radii, a 



little oblique and horizontal, alinofl perpendicular to the body 



of the bone, forming at the point of contact, with it two 



angles, the upper one re-entering and acute, the other infe- 



ferior, re-entering and obtufe. This fubftance is found in 



this manner, in all animated beings which have teeth. 



From this fliort fketch of the phyfical characters of the Its characters 

 teeth, it will be feen, that it is impoifible to avoid concluding, Q l f ^ c £££} ° 

 that the enamel is very different from the offeous body to teeth, 

 which it adheres ; for which reafon I have often propofed to 

 •niyfelf, to make a fcrupulous examination of it, A favour- 

 able circumftance offered itfelf, and furnifhed me with an 

 opportunity of making the experiments I had long intended : 

 an opportunity which I (hould not eafily have found any 

 where but at Paris. Before recounting the means I have 

 employed, I ought to fay that thefe experiments have been 

 performed in the laboratory of the medical fchool. 



The analogy of the work I wifhed to undertake, with the 

 interefling researches on animal fubflances, which continually 

 occupy the profeffors of chemiflry of the medical fchool : the 

 flattering approbation and eagernefs expreffed by profeffor 

 £)ei/eux, in affi fling me with his advice ; the zeal manifefted 

 by the pupils of this laboratory, to whom the care of per- 

 forming the operations is confided : in fhort, a, multitude of 

 facilities left me no doubt that my hopes would be crowned 

 with fuccefs. 



One 



