g|^ OV THE PIRITE OF FRANCE. 



Analyfis of the Pirites of France compared with that of Saxony 



Pirke of Saxony 

 Firite of France, analyfed by Klaproth. 



Analyfii tabu- 

 lated. 



Silex - - - - 46,00 - - 

 Alumine - - - 42,00 - - 



■ - 29,50 

 . - 63,75 





Oiiide of iron - 2,50 - ■ 

 Lofs b) calcination 7,00 

 Lofs - - - - 2,50 



• , 6,75 



pirite of France 

 from that of 



Saxony. 



J 00,00 100.00 



ftpmarks on the M, Drappier thinks, on comparing his analyfis with that 

 difference of the made bv M. Klaprolh, that it may be concluded, fuppofing 

 there was no error in either analyfis, that either the pirite of 

 France is not the fame fubftance as that of Saxony, or that 

 minerals having the fame external charadiers, and efpecially 

 the fame form, may vary both in their chemical properties, 

 and in the proportions of their conflituent principles. M. 

 Klaproth fays that acids have no aft ion on the pirite of Sax- 

 ony, that, he found much difficulty in operating on it by pot- 

 afli, and that, in order to feparate its parts, he was obliged 

 to treat it twice with this alkali. The fame cheraift appears 

 rot to have found any water in this fubftance. This differ- 

 ence, it is true, may be explained, if it is confidered that the 

 pirite of Saxony contains more alumine, and that it adheres to 

 tlie tongue, while that of France has not this property, pro- 

 bably on account of the water which it contains. 



vir. 



Gay LuHac on 



fluoric acid in 

 inimal fub- 

 ftances. 



Experiments, Jheunng, contrary to the Ajfertions of Morichini, 

 that the Enamel of Teeth does not contain Fluoric Acid, In a 

 JLelter froinWyi. Br AH DE, Efq. 



To Mr. NICHOLSON. 



SIR, 



ITIaVING leen in one of the laft numbers of the Annales de 

 Chimie, an article entitled, " Lettre de Monfieur Gay-LufTac 

 a Monfieur Bertliollet, fur le prefence de Pacide fluorique dans 

 les fubftances animales," &c. I was furprifed to find that a 

 chemift at Rome, of the name of Morichini, had difcovered 



fluoric 



