Analyses of Basalt and Lava from Etna. 23 



More recently, Berzelius, in his Memoir on Meteoric Stones, * 

 and C. M. Gmelin, in his Examination of Phonolites,-f- have 

 pointed out a method which may lead to the enlargement of our 

 chemical knowledge of compound minerals, and which consists 

 in first separating them into two portions by treatment with 

 acids, when the one is decomposed and gelatinized, while the 

 other remains undecomposed, and then subjecting each portion 

 separately to analysis. 



In this manner C. M. Gmelin analyzed different varieties of 

 basalt, I and found one portion to be decomposable in acids and 

 the other undecomposable ; and that the one was distinguishable 

 from the other by the circumstance of the former containing 

 potash, soda, and water, while the latter approached augite in 

 its composition. 



The following are the results of his analysis : — 



a. Basalt from Stettin, a basaltic conical hill in Hegau. 



Quantity of the gelatinized mass . 61.54 per cent. 

 ungelatinized mass 88.46 



b. Basalt from Hohenstoffeln in Hegau. 



Quantity of the gelatinized mass . 61.97 

 ungelatinized mass 68.03 



c. Basalt from Sternberg near Urach. 



Quantity of the gelatinized mass . 87.72 

 ungelatinized mass 12.28 



d. Basalt from the district of Wezlar. 



Quantity of the gelatinized mass in the un- 

 decomposed basalt . . 40.29 



weathered portion . 23.73 



ungelatinized mass in the 



undecomposed basalt . 59.71 



weathered portion . 76.27 



• Poggendorff"'s Annalen, vol. xxxiii. p. 10. 



t Transactions of the Wurtemberg Society, voLii. p. \i'3,z.n&.Poggendorff's 

 Annalen, vol. xiv. p. 357. 



+ Leonhard's Basalt Gebilde, part i. p. 266, &c. 



