NOTES. k xxiii 



descent of the Col de la Seigne, between the Enclove de Montjovet and the 

 chalet of La Lanchette, and which he shewed to me at Bex, in the autumn of 

 1822. (Amiales de Chimie, T. xxiii. p. 262.) 



P) p. 250. Hoffman, in Poggend. Annalen, Bd. xvi. S. 552. Strata of 

 transition argillaceous schist in the Fichtelgebirge, which can be traced for a 

 distance of sixteen miles, are altered into gneiss only at the two extremities, 

 where they come into contact with granite. We are there able to trace the 

 gradual formation of the gneiss, and the development of the mica and of the 

 feldspathic amygdaloids, in the interior of the mass of schist, which, indeed, 

 contains in itself almost all the elements of those materials. 



(?**) p. 250. Among the works of art which have come down to us from 

 Greek and Roman antiquity, we remark the absence of columns or large 

 vases of jasper, and, at the present time, large blocks of jasper are obtained 

 only from the Ural mountains. The material worked under the name of 

 jasper in part of the Altai mountains (Revenuaia Sopka), is a superb ribboned 

 porphyry. The word jasper belongs to the Semitic languages, and, according 

 to the confused descriptions of Theophrastus (De Lap. 23 and 27) and of 

 Pliny (xxxvii. 8 and 9), who enumerate jasper among "opaque gems," the 

 name appears to have been given to fragments of Jaspachat, and to a sub- 

 stance which the ancients called jasponyx, and which we call opal-jasper. 

 Pliny considered a piece of jasper of the size of eleven inches so remarkable 

 as to deserve his mentioning that he had himself actually seen so great a 

 rarity: " Magnitudinem jaspidis undecim unciarum vidimus, formatamque 

 inde effigiem Neronis thoracatam." According to Theophrastus, the stone 

 which he calls smaragd, or emerald, and from which large obelisks were cut, 

 would be merely an imperfect jasper. 



P) p. 250. Humboldt, Lettre a M. Brochant de Villiers, in the Annafea 

 de Chimie et de Physique, T. xxiii. p. 261 ; Leop. von Buch, Geogn. Briefe 

 iiber das siidliche Tyrol, S. 101, 105, and 273. 



(S 76 ) p. 250. On the transformation of compact into granular limestone 

 by the action of granite in the Pyrennees, at the Montagues de Rancie, see 

 Dufrenoy, in the Memoires geologiques, T. ii. p. 440 ; in the Montagne de 

 1'Oisans, Elie de Beaumont, Mem. Geol. T. ii. p. 379 415 : on a similar 

 effect by the action of dioritic and pyroxenic porphyry (ophyte; Elie de 

 Beaumont, Geol. de la France, T. i. p. 72) between Tolosa and St. Sebastian, 

 Dufrenoy, in the Mem. geol. T. ii. p. 130 ; and by syenite in the Isle of 

 Skye, the fossils in the altered limestone being still distinguishable (Von 



