40 



SXAMINATK5N OF THE TEETH. 



Ignition left a 

 white powder j 



inicfiffblved, and perfectly deprived of the ofleous fiibfianc©„ 

 This method (ucceeded beyond my hopes, by weakening the 

 acid a little, which I made warm to haflen the effect. Thus 

 I foon procured detached enamel in fuflkient quantity, amply 

 to fupply the experiments I propofed to make, 

 Ita appearance. The enamel, feparated in the manner I have defcribed, 

 was warned in feveral waters before it was ufed, by which 

 means it was freed from the fulphate of lime, attached to 

 its furface } it was then dried. Examined then with a magni-. 

 fying glafs, it (bowed tranfparent parts, the fracture of which, 

 when broken, prefented very well-defined needle-rihaped cry-* 

 itals. This enamel was very hard, and perfectly refembled 

 the fragments which I had broken in fplinters, from the upper 

 part of a tooth, by ftriking it with a hammer. It only dif- 

 fered from it in having a whiter appearance fuperficially, 

 owing to the lime having been made more evident. Some 

 pieces of this enamel were laid on burning coals j they decree 

 pitated, and their particles were thrown to a great diftance. 



Other fragments, put into a red-hot crucible, having pro-, 

 duced the fame effect, I pulverized a certain quantity, and 

 heated it for fome minutes, in another crucible. This pow-, 

 der firft loll its very white colour, and became a little grey ; 

 but by continuing the fire, it regained its whitenefs : it then 

 crumbled eafily between the fingers ; its tafte was alcaline ; 

 when mixed with water, it was partly diffolved, and the fo-i 

 lution refembled lime-water. 



Another part of this powder triturated with muriate of 

 ammonia, foon produced the decompofition of this fait, and 

 difcovered the ammonia ; and laftly, the calcined enamel 

 was equally foluble in nitric, muriatic, and fulphuric acids, 

 without any apparent difference. The folutions, examined 

 by different re-agents, correfponded with folutions of lime. 

 Though it was evident, from thefe experiments, that lime 

 was thebafis of the enamel, yet it remained to be difcovered 

 what it was united to, before calcination. 



To obtain proofs on this head, I weighed four grammes of 

 enamel, prepared, as I have defcribed, with fulphuric acid ; 

 and, after having wafhed them well with a brufh, to remove 

 the fmall quantity of fulphate of lime, which was found dur- 

 ing the feparation of the ofleous part, and precipitated on iu 

 furface, I pulverized \hem, and proceeded to diftillafiqn in a 



cpale^ 



which was lime. 



Di filiation of 

 this enamel 

 drove off no 

 fluid. 



