4-50 COSMOS. 



of chemical, crystal! o-mineralogical and geological knowledge, 

 have rendered him peculiarly well qualified to promulgate new 

 views on that set of minerals whose varied, but frequently 

 recurring association is the product of volcanic action. This 

 great geologist, partly at my instigation, has with the 

 greatest kindness, especially since the year 1834, repeatedly 

 examined the fragments which I brought from the slopes of 

 the volcanoes of New Granada, los Pastos, Quito, and the 

 high land of Mexico, and compared them with the spe- 

 cimens from other parts of the globe contained in the rich 

 mineral-collection of the Berlin Cabinet. Before my collec- 

 tions were separated from those of my companion Aime Bon- 

 pland, Leopold von Buch had examined them microscopically 

 with persevering diligence (in Paris, 1810 1811, between 

 his return from Norway and his voyage to Teneriffe). He 

 had also, at an earlier period, during my residence with Gay 

 Lussac at Rome (in the Summer of 1805) as well as after- 

 wards in France, made himself acquainted with what I had 

 noted down in my travelling journal on the spot, in the 

 month of July 1802, respecting certain volcanoes, and in 

 general on the affinity between volcanoes and certain porphy- 

 ries destitute of quartz 66 . I preserve as a memorial which I 



6(3 The unspecific and indefinite term "trachyte" (Rauhstein), which 

 is now so generally applied to the rock in which the volcanoes break 

 out, was first given to a rock of Auvergne, in the year 1822 by Hauy in 

 the second edition of his Traite de Mineralogie, vol. iv, p. 579, with a 

 mere notice of the derivation of the word and a short description in 

 which the older appellations of granite chauffe en place of Desmarets), 

 trap-porphyry and domite are not even mentioned. It was only by 

 oral communication, originating in Hauy's Lectures in the Jardin des 

 Plantes, that the term " trachyte " was propagated previous to 1822, for 

 example, in Leopold von Buch's treatise on basaltic islands and craters 

 of upheaval, published iu 1818, in Daubuisson's Traite de Mineralogie, 

 1819, and in Beudant's important work, Voyage en Hongrie. From 

 letters lately received by me from M. Elie de Beaumont, I find that 

 the recollections of M. Delafosse, formerly Aide-Naturaliste to Hauy, 

 and now Member of the Institute, fix the application of the term " tra- 

 chyte " between the years 1813 and 1816. The publication of the term 

 "domite" by Leop. v. Buch, seems according to Ewald, to have occurred 

 in the year 1809; it is first mentioned in the third letter to Karsten 

 (Geognost. Beolaclit. auf Reisen durch Deutschl. undItalien,~Bd.u, 1809, 

 s. 244). " The porphyry of the Puy de Dome," it -is there stated, "is 

 a peculiar, and hitherto nameless rock, consisting of crystals of fel- 

 spar with a glassy lustre, hornblende and small laminse of black mica. 

 In the clefts of this kind of rock, which I provisionally term domite, 



