Hi NOTES. 



(Meeting of the Brit. Assoc. held at Oxford in 1847, p. 51.) Cordier's earliest 

 assumption had only been 56 geographical miles, without correction for the in- 

 creasing pressure of the strata with increasing depth, and for the hypsometric 

 form of the surface. The thickness of the solid portion of the Earth's crust is 

 probably very unequal. 



(2 s5 ) p. 170. Gay-Lussac, Reflexions sur les Volcans, in the Annales de 

 Chimie et de Physique, t. xxii. 1823, p. 418 and 426. Gay-Lussac, who, 

 together with Leopold von Buch and myself, had observed the great eruption of 

 Vesuvius in Sept. 1805, has the merit of having subjected the chemical hypo- 

 thesis to a strict critical examination. He sought the cause of volcanic pheno- 

 mena in an " affinite* tres-energique et non encore satisfaite entre les substances, 

 a laquelle un contact fortuit leur permettait d'obeir." His criticism was on the 

 whole favourable to the hypothesis of Davy and Ampere, " en supposant que les 

 radicaux de la silice, de 1'alumine, de la chaux, et du fer soient unis au chlore 

 dans 1'inte'rieur de la terre :" he also deemed it not improbable that, under certain 

 conditions, sea-water may penetrate (p. 419, 420, 423, and 426). On the diffi- 

 culties of a theory which rests on the penetration of water, compare Hopkins, in 

 the Meeting of the British Association, 1847, p. 38. 



( 238 ) p. 170. Hydrochloric acid is entirely wanting in the vapours emitted 

 by the South-American volcanoes (according to the fine analyses of Boussingault 

 at five craters, viz. those of Tolima, Purace, Pasto, Tuqueras, and Cumbal), but 

 not in the Italian ones. (Annales de Chimie, t. lii. 1833, p. 7 and 23.) 



(2 s7 ) p. 170. Kosmos, Bd. i. S. 247 (English edition, p. 226). Davy, 

 while most distinctly giving up the opinion that volcanic eruptions are a conse- 

 quence of the contact of the metallic bases with air and water, yet stated his 

 belief that the existence of oxydisable metalloids in the interior of the Earth 

 might act as a concurrent cause in volcanic processes which had already begun. 



C 238 ) p. 170. " Jattribue," said Boussingault, "la plupart des tremble- 

 ments de terre dans la Cordillere des Andes a des eTxmlements qui ont lieu dans 

 1'inte'rieur de ces montagnes par 1'entassement qui s'opere et qui est une conse- 

 quence de leur soulevement. Le massif qui constitue ces cimes gigantesques 

 n'a pas e'te souleve' a 1'dtat pateux; le soulevement n'a eu lieu qu'apres la solidi- 

 fication des roches. J'admets par consequent que le relief des Andes se compose 

 de fragments de toutes dimensions, entasse's les uns sur les autres. La consoli- 

 dation des fragments n'a pu etre tellement stable des le principe qu'il n'y ait des 

 tassements apres le soulevement, qu'il n'y ait des mouvements inte'rieurs dans ies 

 masses fragmentaires." (Boussingault, Sur les Tremblements de Terre des Andes, 

 In the Annales de Chimie et de Physique, t. Iviii. 1835, p. 8486.) In the 

 description of his memorable ascent of the Chimborazo (Ascension au Chimborazo/ 



