Some Direct Experiments, Made With Acids, During My Abode At Caracas, Showed That The Pyrites Of Cuchivano Are Not Auriferous.

Our guides were amazed at my incredulity.

In vain I repeated that alum and sulphate of iron only could be obtained from this supposed gold mine; they continued picking up secretly every bit of pyrites they saw sparkling in the water. In countries possessing few mines, the inhabitants entertain exaggerated ideas respecting the facility with which riches are drawn from the bowels of the earth. How much time did we not lose during five years' travels, in visiting, on the pressing invitations of our hosts, ravines, of which the pyritous strata have borne for ages the imposing names of 'Minas de oro!' How often have we been grieved to see men of all classes, magistrates, pastors of villages, grave missionaries, grinding, with inexhaustible patience, amphibole, or yellow mica, in the hope of extracting gold from it by means of mercury! This rage for the search of mines strikes us the more in a climate where the ground needs only to be slightly raked to produce abundant harvests.

After visiting the pyritous marls of the Rio Juagua, we continued following the course of the crevice, which stretches along like a narrow canal overshadowed by very lofty trees. We observed strata on the left bank, opposite Cerro del Cuchivano, singularly crooked and twisted. This phenomenon I had often admired at the Ochsenberg, * in passing the lake of Lucerne. (* This mountain of Switzerland is composed of transition limestone. We find these same inflexions in the strata near Bonneville, at Nante d'Arpenas in Savoy, and in the valley of Estaubee in the Pyrenees. Another transition rock, the grauwakke of the Germans (very near the English killas), exhibits the same phenomenon in Scotland.) The calcareous beds of the Cuchivano and the neighbouring mountains keep pretty regularly the direction of north-north-east and south-south-west. Their inclination is sometimes north and sometimes south; most commonly they seem to take a direction towards the valley of Cumanacoa; and it cannot be doubted that the valley has an influence* on the inclination of the strata. (* The same observation may apply to the lake of Gemunden in Styria, which I visited with M. von Buch, and which is one of the most picturesque situations in Europe.)

We had suffered great fatigue, and were quite drenched by frequently crossing the torrent, when we reached the caverns of the Cuchivano. A wall of rock there rises perpendicularly to the height of eight hundred toises. It is seldom that in a zone where the force of vegetation everywhere conceals the soil and the rocks, we behold a great mountain presenting naked strata in a perpendicular section. In the middle of this section, and in a position unfortunately inaccessible to man, two caverns open in the form of crevices. We were assured that they are inhabited by nocturnal birds, the same as those we were soon to become acquainted with in the Cueva del Guacharo of Caripe. Near these caverns we saw strata of schistose marl, and found, with great astonishment, rock-crystals encased in beds of alpine limestone. They were hexahedral prisms, terminated with pyramids, fourteen lines long and eight thick. The crystals, perfectly transparent, were solitary, and often three or four toises distant from each other. They were enclosed in the calcareous mass, as the quartz crystals of Burgtonna,* (* In the duchy of Gotha.) and the boracite of Lunebourg, are contained in gypsum. There was no crevice near, or any vestige of calcareous spar.* (* This phenomenon reminds us of another equally rare, the quartz crystals found by M. Freiesleben in Saxony, near Burgorner, in the county of Mansfeld, in the middle of a rock of porous limestone (rauchwakke), lying immediately on the alpine limestone. The rock crystals, which are pretty common in the primitive limestone of Carrara, line the insides of cavities in the rocks, without being enveloped by the rock itself.)

We reposed at the foot of the cavern whence those flames were seen to issue, which of late years have become more frequent. Our guides and the farmer, an intelligent man, equally acquainted with the localities of the province, discussed, in the manner of the Creoles, the dangers to which the town of Cumanacoa would be exposed if the Cuchivano became an active volcano, or, as they expressed it, "se veniesse a reventar." It appeared to them evident, that since the great earthquakes of Quito and Cumana in 1797, New Andalusia was every day more and more undermined by subterranean fires. They cited the flames which had been seen to issue from the earth at Cumana; and the shocks felt in places where heretofore the ground had never been shaken. They recollected that at Macarapan, sulphurous emanations had been frequently perceived for some months past. We were struck with these facts, upon which were founded predictions that have since been almost all realized. Enormous convulsions of the earth took place at Caracas in 1812, and proved how tumultuously nature is agitated in the north-east part of Terra Firma.

But what is the cause of the luminous phenomena which are observed in the Cuchivano? The column of air which rises from the mouth of a burning volcano* is sometimes observed to shine with a splendid light. (* We must not confound this very rare phenomenon with the glimmering commonly observed a few toises above the brink of a crater, and which (as I remarked at Mount Vesuvius in 1805) is only the reflection of great masses of inflamed scoria, thrown up without sufficient force to pass the mouth of the volcano.) This light, which is believed to be owing to the hydrogen gas, was observed from Chillo, on the summit of the Cotopaxi, at a time when the mountain seemed in the greatest repose. According to the statements of the ancients, the Mons Albanus, near Rome, known at present under the name of Monte Cavo, appeared at times on fire during the night; but the Mons Albanus is a volcano recently extinguished, which, in the time of Cato, threw out rapilli;* (* "Albano monte biduum continenter lapidibus pluit." - Livy lib.

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