NOTES. IXXXV 



C 28 ?) p. 255. Rose, Reise nach dem Ural, Bd. i. S. 364 and 367. 

 C 288 ) p. 255. Leop. von Buch, Briefe, S. 109129. Compare also Elie 

 de Beaumont on the contact of granite with the beds of the Jura (Mem. geol, 

 T. ii. p. 408). 



C 289 ) p. 255. Hoffmann, Reise, S. 30 and 37. 



(f 90 ) p. 255.. On the chemical process in the formation of specular iron, 

 see Gay-Lussac, in the Annales de Chemie, T. xxii. p. 415 ; and Mitseherlich, 

 in Poggend. Ann. Bd. xv. p. 630. Crystals of olivine have been formed 

 (probably from sublimation) in the cavities of the obsidian which I brought 

 from the Cerro del Jacal, in Mexico (Gustav. Rose, in Poggend. Ann. Bd. x. 

 S. 323). We thus find olivine in basalt, in lava, in obsidian, in artificial 

 scoriae, in meteoric stones, in the syenite of Elfdale, and (under the name of 

 hyalosiderite) in the wacke of the Kaiserstuhl. 



p 1 ) p. 256. Constantiu von Beust iiber die Porphyrgebilde, 1835, S. 89 

 96 ; his Beleuchtung der Werner'schen Gangtheorie, 1840, S. 6 ; C. von 

 Weissenbach, Abbildungen merkwiirdiger Gangverhaltnisse, 1836, fig. 12. 

 The structure in narrow bands is not however general, nor does the order of 

 succession of the different members of these masses necessarily indicate their 

 relative age; see Freiesleben, iiber die sachsischen Erzgange, 1843, S. 10 12. 

 (^ p. 256. Mitscherlich iiber die kunstliche Darstellung der Mineralien, 

 in the Abhandl. der Akad. der Wiss. zu Berlin, 182223, S. 2541. 



f 93 ) p. 257. Of minerals accidentally produced in the scoriae of artificial 

 works, crystals of feldspar have been discovered by Heine in a furnace for 

 fusing copper, and have been analysed by Kersteu (Poggend. Ann. Bd. xxxiii. 

 S. 337) ; crystals of augite in scorise at Sahl (Mitscherlich, in the Abhaudl. 

 der Akad. zu Berlin, 1822 23, S. 40) ; crystals of olivine under similar cir- 

 cumstances (Sefstrom. in Leonhard's " Basalt Gebilde," Bd. ii. S. 495) ; of 

 mica in old scoriae of Schloss Garpenberg (Mitscherlich, inLeonhard, S. 506) ; 

 crystals of magnetic oxide of iron in the scorise of Chatillon sur Seine (Leon- 

 hard, S. 441) ; specular iron produced in potters' clay (Mitscherlich, in 

 Leonhard, S. 234). 



(S 94 ) p. 257. Of minerals purposely produced, there have been idocrase 

 and garnet (Mitscherlich, in Poggendorffs Annalen der Physik, Bd. xxxiii, 

 S. 340) ; ruby (Gaudin, in the Comptes rendus de TAcadeuiie des Sciences, 

 T. iv. P. 1, p. 999) , olivine and augite (Mitscherlich and Berthier, in the 

 Annales de Chimie et de Physique, T. xxiv. p. 376). Although augite and 

 hornblende present, according to G. Rose, the greatest similarity in the form 

 of their crystals, and are almost identical in their chemical composition, yet 



