8B French National Institute. 



there was always deposited a matter like yeast, which ap- 

 peared to him to be nothing else than an altered albumen 

 become almost insoluble, without losing, on that account, 

 its fermenting action; whence he concludes that albumen, 

 whether animal or vegetable, is the true ferment. 



M. Seguin has further ascertained that albumen is found 

 in three different degrees of insolubility and dispositions of 

 becoming fibrous ; that the more it is soluble the more ener- 

 getic is its action ; that the respccti^'e proportions of albu- 

 men and sugar in the different juices are whatdetermines the 

 vinous or acetic nature of the produce of the fermentation, 

 it being so much the more spirituous the more sugar it con- 

 tains; and lastlv, that the most of the fermentable juices 

 contain a bitter principle analogous to that of coffee, which 

 <roes for nolhino; in the fermentation, but which contributes 

 to the taste and the preservation of the fermented liquor. 



Tannin, that vegetable principle formerly discovered by 

 M. Ses;uin, and the character of which is to form with ge- 

 latine an insoluble compound, has been recently examined 

 by M. Bouillon Lagrange, professor in the Napoleon Ly- 

 ceum. 



He has found in it an affinity for the alkalis, for the 

 earths, and metallic oxides, and the faculty of converting 

 itself into gallic acid by absorbing oxygen. 



The tannins, as they are extracted from the various vege- 

 tables, vary a little in their composition ; and that which 

 Mr. Hatchett, tlie English chemist, has discovered in caout- 

 chouc is a little more oxygenated than the others. 



An Italian chemist, M. Morichini, having discovered the 

 fluoric acid in the enamel of the fossil grinders of the ele- 

 phant, analysed that of the human teeth, and thought he 

 discovered the same principle. M. Gay-Lussac has found 

 it also both in the fresh and fossil ivory, and in the tusks of 

 the boar. 



Messrs. Fourcroy and Vauquelin have repeated these ex- 

 periments, and have actually obtained this acid from tusks 

 and teeth altered by their remaining in the earth ; but not 

 from fresh tusks or teeth, nor even from those which, al- 

 though fossil, had not been altered. 



M. Vau- 



