440 REACTION OF THE INTERIOR OF THE EARTH 



Tungurahua, and Antisana, by the side of augite and 

 oligoclase ; but on Chimborazo, up to a height of above 

 19,000 feet, I scarcely found any hornblende at all with 

 those two minerals. Of the many specimens brought 

 home from Chimborazo, hornblende has only been re- 

 cognised in two, and in those only in small quantity. 

 In the eruptions of Vesuvius in 1822 and 1850, augite 

 and hornblende crystals (the latter attaining a length of 

 between seven and eight tenths of an inch) were formed 

 contemporaneously by exhalations of vapours in fis- 

 sures. ( 619 ) On Etna, as Sartorius von Waltershausen 

 has remarked, hornblende belongs more particularly to 

 the older lavas. As the remarkable mineral which 

 Grustav Eose has called uralite, and which is widely 

 diffused in Western Asia and in several parts of Europe, 

 is nearly allied by structure and the form of its crystals 

 to hornblende and augite ( 62 ), I would here notice that 

 uralite crystals have been recognised for the first time 

 as belonging to the New Continent, by having been 

 discovered by Eose in a piece of trachyte which I 

 knocked off on the declivity of Tungurahua, 3200 feet 

 below the summit. 



Leudte. 



Leucites which in Europe belong exclusively to 

 Vesuvius, the Eocca Monfina, the Alban Hills near 

 Eome, the Kaiserstuhl in the Breisgau, and the Eifel 

 (on the western side of the Lacher See they are found 

 in blocks, not in the rock in situ, as on the Burgberg, 

 near Eieden) have never been found in the volcanic 

 mountains of the New Continent and the Asiatic portion 

 of the old. Leopold von Buch had discovered, so long 



