EXAMINATION OF THE TEETH. 39 



concentration, their combined or infenfible caloric, and on 

 that caloric which, being only interpofed between their con- 

 stituent particles, is the caufe of their various temperature. 

 Hence arife varieties in the affinities, wliich change the at- 

 tractions, and produce different variations in the refults, of 

 which I fhall have occafion to fpeak. 



Having plunged human teeth and thofe of feveral animals Nitric acid adtf 

 into nitric acid, I obferved that it aded rapidly on the enamel, [f^I^Jd 

 and flowly on the bone. The firft wasfoon entirely diffolved, flowly on the 

 and I could only perceive the offeous part, which in its turn* bone * 

 but in a much longer time, difappeared in an excefs of acid. 

 When the folution was compleated, I tafted it ; it appeared 

 to me ftill ftrongly acid, and I found that its tafte differed 

 from that of nitric acid. To judge of the nature of this li-The nitric folu- 

 quor, I filtered it, and fubmitted it to fome experiments, tl ™J^ r ** acid. 

 which mowed that it contained phofphoric acid, difengaged, 

 without doubt, by the nitric acid. 



Teeth digefted with muriatic acid, gave fimilar refults to Muriatic acid. 

 the former. 



But the fame effects were not produced when I employed Sulphuric acid 

 fulphuric acid : whether concentrated or diluted with water, enamel S and 

 hot or cold, the effervefcence with the enamel, which I no- more on the 

 ticed in the other acids, did not take place with this. Itap-^ 6, 

 peared at firft to refufe to diffolve this fubftance, but I foon 

 faw it act on the bony part. In a little time I obferved it 

 precipitate a whitifh fait, which I knew to be a true fulpjiate. 

 of lime. This folution alfo preferved its acid tafte, of which 

 I could not deprive it, notwithstanding the pains I took by 

 adding frefh teeth. This acidity was owing to the phofphorip 

 acid which had been difengaged. 



The experiments which I have juft 'defcribed with the The enamel fe« 

 three acids, did not fatisfy me ; they had been performed on P* rat . ed ty f u (- 

 teeth furnifhed with their enamel. The refults were there- 

 fore confufed, and it was neceffary to examine them in a 

 direct manner. I refolved, therefore, to operate upon the 

 enamel perfectly freed from the offeous part : I endeavoured 

 to fcparate it with a file, but this method appeared too labo- 

 rious and too tedious to fumifli me with a fufficient quantity. 

 I had recourfe to the fulphuric acid : the preference I gave to 

 it, was pointed out by the laft experiment I have noticed, 

 ^hove* which had left me confiderable portions of the ename^ 



undiffolved* 



