TRUE VOLCANOES. 421 



invaluable, some sheets with remarks on the volcanic prod- 

 ucts of the elevated plateaux of Quito and Mexico, which 

 the great geologist communicated to me for my information 



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



llauv. and now Member of the Institute, fix the application of the 

 term "trachyte" between the years L813 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 let- 

 ter to Karsten (d'eor/nost. Beobacht. auf Ileisen durch Deuischland nnd 

 Ttalien, bd. ii., 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 feldspar with a glassy lustre, hornblende, and small lam- 

 ina? of black mica. In the clefts of this kind of rock, which I provi- 

 sionally term domite, I find beautiful drusic cavities, the walls of which 

 are covered with crystals of iron-glance. Through the whole length 

 of the Puy cones of domite alternate with cones of cinders." The 

 second volume of the Travels, containing the letters from Auvergne, 

 was printed in 180G, but not published till 1809, so that the publication 

 of the name of domite properly belongs to the latter year. It is singu- 

 lar that four years later, in Leopold von Buch's treatise on the trap 

 porphyry, domite is not even mentioned. In referring to a drawing 

 of the profile of the Cordilleras, contained in the journal of my travels 

 in the month of July, 1802, and included between the 4th degree north 

 and 4th degree south latitude, under the inscription "Affinite entre le 

 feu volcanique et les porphyres," my only object was to mention that 

 this profile, which represents the three breakings through of the vol- 

 canic groups of Popayan, Los Pastos, and Quito, as well as the erup- 

 tion of the trap porphyry in the granite and mica-slate of the Paramo 

 de Assuay (on the great road from Cadlud, at a height of 15,526 feet), 

 led Leopold von Buch, too kindly and too distinctly, to ascribe to me 

 the merit of having first noticed "that all the volcanoes of the chain 

 of the Andes have their foundation in a porphyry which is a peculiar 

 kind of rock, and belongs essentially to the volcanic formations" {Ab- 

 handlungen der Akademie da' Wissensch. zu Berlin, aus den Jahren 

 1812-1813, s. 131, 151, and 153). I may, indeed, have noticed the 

 phenomenon in a general way, but it had already, as early as 1789, 

 been remarked by Nose, whose merits have long been too little appreci- 

 ated, in his Orographical Letters, that the volcanic rock of the Siebenge- 

 birge is " a peculiarly Rhenish kind of porphyry, closely allied to ba- 

 salt and porphyritic schist." He says "that this formation is especial- 

 ly characterized by glassy feldspar," which he proposes should be called 

 sanidine, and that it belongs, judging from the age of its formation, to 

 the middle floetz rocks (Niederrkeinische Beise, th. i., s. 26, 28, and 47; 

 th. ii., s. 428). I do not find any grounds for Leopold von Buch's con- 

 jecture that Nose considered this porphyry formation, which he not 

 very happily terms granite porphyry, as well as the basalts, to be of 

 later date than the most recent floetz rocks. "The whole of this 

 rock," says the great geologist, so early removed from among us, 

 "should be named after the glassy feldspars (therefore sanidine por- 

 phyry), had it not already received the name of trap porphyry" (Abh. 

 der Berl. AJcad. aus den Jahren 1812-13, s. 134). The history of the 

 systematic nomenclature of a science is so far of importance as the 

 succession of prevalent opinions is found reflected in it. 



