234- Baron Humboldt on the Structure and Action of 



of the earth which always precede all the igneous eruptions in the 

 chain of the Andes, have violently shaken the whole mass of the 

 volcano, then the subterranean gulfs open, and there issue at the 

 same time water, fishes, and clay tufa. Such is the singular phe- 

 nomenon which brings to hght the Pimelodes cyclopum^ a fish to 

 which the inhabitants of the plain of Quito gave the name of 

 Prenadillay and which I described shortly after my return. 

 When to the north of Chimborazo, in the night of the 19th 

 June 1698, the summit of Carguaraizo, a mountain of the height 

 of 18,000 feet, broke down, the whole country round, to the ex- 

 tent of nearly two square leaguges, was covered with mud 

 and fishes. Seven years before, a pernicious fever, which de- 

 solated the city of Iburra, was attributed to a similar eruption 

 of fishes from the volcano of Imbaburu. 



I mention these facts, because they throw some light on the 

 difference which exists between the eruptions of dry ashes and 

 those of mud, wood, charcoal, or shells, serving to explain the 

 formation of tufa and trass. The quantity of ashes thrown 

 out by Vesuvius of late years, like all the circumstances con- 

 nected with volcanoes, and other great phenomena of nature 

 calculated to inspire terror, has been excessively exaggerated in 

 tlie public journals. Two chemists of Naples, Vicenzo Pepe 

 and Giuseppe di Nobili, have even aflirmed, notwithstanding 

 the contrary assertions of Monticelli and Covelli, that the ashes 

 contain gold and silver. According to my inquiries^ the bed of 

 ashes that fell during twelve days on the Bosch -Tre-Case side, 

 on the declivity of the cone, in the places where rapillo was 

 mingled with them, was only three feet deep, and in the plain, 

 did not rise higher than from fifteen to eighteen inches. Mea- 

 surements of this kind should not be taken in places where the 

 ashes are heaped up, like snow or sand, by the wind, or accu- 

 mulated by water in the form of mud. The times are gone 

 'when wonders only were looked for in volcanic phenomena, or 

 when the ashes of Etna were represented as being carried by 

 the winds as far as the peninsula of India. Some of the goid. 

 and silver veins of Mexico certainly occur in a trachy tic por- 

 phyry ; but the ashes of Vesuvius, which I carried along with 

 me, and which were analysed by an excellent chemist M. Henry 

 Rose, afford not the slightest traces of gold or silver. 



