J5§ ^*iw invtUAi, 



precipitate being then washed, and dried at a low red-heat^ 

 weighed grs. 50, (sp. gr. of it was 3.7826) . This experiment 

 must be considered as very satisfactory, from its near as];rec-» 

 meiiitwith M.Chcneoix's statement; from which it only dilibr* 

 in the proportion of 7.20 to 7.22, (vide Thompson, 2d edit, 

 vol. ii. p. 20.) 

 Analyses of dif- It remains to give an account of two or three anahscs of ciif- 

 o7the SineraT ^^^'^"^ portions of the mineral itself j in which, though the quan- 

 tity of silex is noticed, yet as its presence is merely accidental,, 

 it is excluded from the whole sum in calculating the proportions 

 of the other substances. 



I. grs. 



Quantity taken • • • • • • • • • ,.,...... ^30. 



Detached particles of minutely xtallized quartz, sepa- 

 rated during solution in nitric acid. 0.5. 



Sulphur separated during solution J. 6. 



Do. by calcuhition in sulph. of baryr, grs. 54 7.S. 



Precipitate by potash, dried at 300 Fahr. 20, 



Proportion of sulphur, about « 

 ————— of precipitate • • • 



29-9- 



ir. grs. 



Quantity taken • 13 -,\- 



Detached particles of quartz 0.4. 



Sulphur separated • 1.2. 



Do. in sulph. of baryt, grs. 20 2.9. 



Precipitate by potash 9. 



Proportion of sulphur about- 

 ■ of precipitate • • < 



13. 



III. grs. 



Quantity taken ♦ 22. 



Driven off by a strong red-heat 8. 



Precipitate by potash from nitric acid 13.5. 



Proportion of sulphur in the third analysis almost 

 Proportion of the precipitate by potash not quite 1% 



21.5. 



Too- 

 3 



