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Alexander von Humboldt: „Analysis of the Water of the Rio Vinagre, in the Andes of Popayan, by M. Mariano de Rivero; with geognostic and Physical Illustrations of some Phenomena which are exhibited by Sulphur, Sulphuretted Hydrogen, and Water, in Volcanoes“, in: ders., Sämtliche Schriften digital, herausgegeben von Oliver Lubrich und Thomas Nehrlich, Universität Bern 2021. URL: <https://humboldt.unibe.ch/text/1824-Analyse_de_l-2-neu> [abgerufen am 26.04.2024].
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| Titel | Analysis of the Water of the Rio Vinagre, in the Andes of Popayan, by M. Mariano de Rivero; with geognostic and Physical Illustrations of some Phenomena which are exhibited by Sulphur, Sulphuretted Hydrogen, and Water, in Volcanoes | ||||
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| Jahr | 1825 | ||||
| Ort | Boston, Massachusetts | ||||
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Nachweis in: The Boston Journal of Philosophy and the Arts 2:5 (1825), S. 460–466; 2:6 (1825), S. [513]–521.
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| Sprache | Englisch | ||||
| Typografischer Befund | Antiqua; Auszeichnung: Kursivierung; Fußnoten mit Asterisken und Kreuzen; Schmuck: Kapitälchen. | ||||
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|460|
“IN compliance with the desire of M. de Humboldt, I pro-cured some of the water of Rio Vinagre. It was sent to meby M. Torrés, who takes an interest in all that can contributeto scientific researches. This water has yielded per litre: sul-phuric acid, 1.080; muriatic acid, 0.184; alumine, 0.240;lime, 0.160; and some indications of iron.* The presenceof muriatic acid confirms the observations made on the va-pours and the stony productions of Vesuvius and of severalother volcanoes.”
I had made known, at the time of my return from America,the presence of the sulphuric and muriatic acids in the waterof the Rio Vinagre, which the aborigines call Pusambio. (SeeViews of the Cordilleras, and Monuments of the People ofAmerica, vol. ii. p. 166; Barometric Levelling of the Andes,No. 126; Caldas, Samanario del Nuevo Reyno de Granada,t. i. p. 265); but not being furnished with the salts of barytes.I had engaged MM. Rivero and Boussingault, when theydeparted from Bogota, to verify these facts. The analysis,which we owe to one of these expert chemists, is the firstwhich has been attempted on the water of the Rio Vinagre.I shall give some extracts from the journal of my travels, ingreat part still unpublished, explanatory of the local circum-stances. The town of Popayan is situated in the beautiful valley of theRio Cauca, on the Bogota road to Quito, at the foot of thetwo great volcanoes of Puracé and Sotarà.
* It cannot be doubted that the indications are by grammes and fractionsof grammes; a litre of the water of the Rio Vinagre includes 1.080 grammesof sulphuric acid, and 0.184 grammes of muriatic acid. This proportion ofsulphuric acid is nevertheless very sensible to the taste, and is manifest byan abundant precipitate with the salts of barytes.[The litre being 2.113 pints, the contents of the water in English grainswill be as follows: sulphuric acid 16.68; muriatic acid 2.84; alumine 3.7;lime 2.47. Edit.]|461| These volcanoes, almost extinct, and exhibiting only thephenomena of solfataras, form part of the central chain of theAndes of New Granada. At 1° 55′ and 2° 20′ of north lati-tude, the group of mountains which incloses the sources of theMagdalena is divided into three branches, of which the east-ern is continued towards Timana and the Nevados of Chitaand of Merida; the intermediate and central one towards theParamos of Guanacas and of Quimdiú; the western towardsthe platiniferous district of the Choco and the isthmus ofPanama. In ascending from the town of Popayan to the sum-mit of the volcano of Puracé, M. Bonpland and I found atthe height of 8672 feet a little plain (Llane del Corazon), in-habited by poor Indian husbandmen. This plain is separatedfrom the rest of the acclivity, with which it would otherwisebe continuous, by two ravines extremely deep: it is at theedge of these precipices that the village of Puracé is built.Springs rise every where from the trachytic rock; each gar-den is surrounded with a quickset hedge of narrow-leavedeuphorbium (lechero) of the most delicate green. Thisbeautiful verdure contrasts in a striking manner with the back-ground of black and arid mountains, which surround the vol-cano, and which are rent by the effects of the earthquakes. The site of the village is celebrated in the country on ac-count of three beautiful cascades [choreras] of the river ofPusambio, whose water is acid, and which the people, whoknow no other acid than vinegar, call Rio Vinagre, some-times Gran Vinagre. This river takes its rise at the heightof nearly 10,871 feet, in a very inaccessible spot. Althoughthe temperature of the water be little different in the lowercascades from that of the surrounding atmosphere, it is no lesscertain that the sources of the Pusambio or Venagre are veryhot. This fact was attested to me by the natives and by themissionary of the village of Puracé. In going to the summitof the volcano I saw a column of smoke rise at the place wherethe acid waters make their appearance. I have drawn thesecond of the falls of the Vinagre (plate xxx of the Views ofthe Cordilleras): the water which opens itself a passage acrossa cavern, is precipitated more than 383 feet in depth. Thefall has a very picturesque effect; but the inhabitants of Popa-yan would be better pleased if the river, instead of throwingitself into the Rio Cauca, became engulfed in some othercrevice; for such is the delicacy of constitution of animalswhich breath by gills, and which absorb the oxygen dissolved |462| in the water, that the Cauca, during a course of four leagues,is destitute of fish, on account of the mixture of its waters withthose of the Rio Vinagre,* which are charged both with oxideof iron and with sulphuric and muriatic acid. After staying aconsiderable time on the craggy wall of rock which bordersthe cascade, a pricking sensation is felt in the eyes from theminute spray in the atmosphere. Fish re-appear in the RioCauca at the point where it becomes enlarged by the influx ofthe Pindamon and of the Placé.† A little to the north of the sources of the Pusambio rise twoother rivulets charged in like manner with free sulphuric acid,which the people call the Little Vinegars (los dos Vinagreschicos): they throw themselves into the Rio de San Francis-co, which is itself but a tributary of the Gran Vinagre. Dur-ing my stay at Popayan it was an opinion generally receivedthat all these acid waters contained some iron dissolved by agreat quantity of carbonic acid. When it was merely remem-bered that the sources of the Vinagre are very hot, this opin-ion ought to have been abandoned. I boiled some water takenfrom the cascade; and I found, after the ebullition, the sameacid taste and the precipitates as in the unboiled water. Atthis period I had very few re-agents left. The nitrate of silver‡ gave a white and milky precipitate,indicating the presence of muriates. The presence of ironwas shown by the prussiate of lime, that of lime by the oxalateof potash. When the water was weighed with great care inthe office of the mint of Popayan, the weight of an equalquantity of the water of the Vinagre was found to be to that ofdistilled water as 2735½ gr. to 2731 gr.; that is to say thatthe specific gravity of the water of the cascade was 1.00 5. The waters which I describe, and of which M. Rivero hasgiven the first analysis, must not be confounded with those ofthe two subterraneous lakes which we have found near the sum-mit of the volcano; one is 14,356 feet high, the other, abovethe snows, 15.475 feet. This volcano of Puracé is a dome
* M. Caldas has even attributed to this mixture, doubtless with little rea-son, the absence of goitres in the valley of Rio Cauca.—Semanario, t. l. p.265. See my Memoir on the Goitres in the Cordilleras. (Magendie, Jour.de Physiol. t. iv, p. 109)† Journal de physique, t. lxii, p. 61.‡ The conjoint presence of the sulphuric and muriatic acids has also beenobserved by M. Vauquelin in the water which M. Leschenault had taken fromthe crater-lake of Mount Idienne in Java (Journal de Physique, t. lxv. p. 406.)See Phil. Mag. vol. xlii. pp. 126, 182.|463| of semivitreous trachyte of a bluish grey, and having a con-choidal fracture. It does not present a great crater at itssummit, but several little mouths. It differs very much fromthe neighbouring volcano, the Sotarà, which is of a conicalform, and which has thrown out an immense quantity of obsi-dians. These masses, covering the plains of Julumito, areballs or tears of obsidian, the surface of which is often tuber-cular. They present, what I have seen no where else in thetwo hemispheres, all the shades of colour, from deep black tothat of an artificial glass entirely colourless. It may appearsurprising to see that this deprivation of colour has not beenaccompanied by any inflation or porosity. The obsidians ofSotarà are mixed with fragments of enamel which resemblethe porcelain of Réaumur, and adhering to which I havefound masses of felspar which have resisted fusion. Here, as in the Andes of Quito, as at Mexico, and at theCanary Islands, the system of basaltic rocks lies far from thetrachytes which form the volcano of Puracé and of Sotarà.The basalts of the Tetilla of Julumito belong only to the leftbank of the Cauca. They rise from transition porphyries freefrom augite, containing some hornblende, a very little quartzin small crystals embedded in the mass, and a felspar whichpasses from the common to the vitreous variety. This por-phyry is covered, near to Los Serillos, with a blackish-greylimestone, traversed by veins of carbonate of lime, and somuch overcharged with carbon that in some parts it stains thefingers like an aluminous schist, or like the lydian* stone ofSteeben in the Fichtelgebirge. The trachytic dome of Puracé which gives birth to thelittle river of sulphuric acid, rises out of a porphyritic syenite(with common felspar), which in its turn is superimposed ontransition granite abounding in mica. This observation,† veryimportant for the position of volcanic rocks, may be made nearto Santa Barbara in ascending from Popayan to the village of
* M. Vauquelin has recently proved by a direct analysis the presence ofcarboa in the purest lydian stones. I had found, in a series of experimentsmade on the galvanic exciters in 1798, that the lydian stones of the transitionschists of Steeben produced jointly with zinc the same effect as graphite orcarburet of iron. I have since made some trials to prove chemically thepresence of carbon in several varieties of lydian stone. See my Experi-ments on the Nervous and Muscular Fibre (in German), t. ii. p. 163.† See an account of the whole of these phenomena of the volcanoes ofPopayan in my Essai sur le Gisement des Roches, 1823, pp. 129, 139, 340.|464| Puracé. The volcano, like the most part of the great volcanoesof the Andes, presents layers or mantles of melted stony matter,not real currents of lava. Some fragments of granular limestone,probably magnesian, which I found at more than 12,790 feethigh, seem to have been thrown up through crevices whichhave since become closed. They are like those of the FossoGrande of Vesuvius, which owe their granular texture to vol-canic fire. It is not possible to go on horse back further thanthe cascades of the Rio Vinagre. From thence we wereeight hours in mounting on foot to the summit of the volcanoand in descending from it. The weather was dreadful; snowand hail fell. I had a great deal of difficulty in lighting the tinderthe point of the conductor of Volta’s electrometer; the ballsof elder pith separated from 5 to 6 lines, and the electricitypassed often from positive to negative without there being anyother symptom of storm: for thunder and lightning are (ac-cording to my experience) generally very rare when we areabove 12,800 or 14,000 feet high. The hail was white;* thehailstones, from five to seven lines in diameter, composed oflayers varying in translucency. They were not only muchflattened towards the poles, but so much increased in theirequatorial diameter, that rings of ice separated themselves onthe least shock. I had already twice observed and describedthis phenomenon, in the mountains of Bareuth, and near Cra-cow, during a journey in Poland. Can it be admitted thatthe successive layers which are added to the central nucleusare in a state of fluidity so great that the rotary motion cancause the flattening of the spheroids? When the barometer indicated that we were come verynear the limit of perpetual snow, we found the masses of sul-phur disseminated in imperfectly columnar trachytic rocksaugmented. This phenomenon struck me the more, as Iknew how rare sulphur is on the sides of inflamed volcanoes:a column of yellowish smoke and a frightful noise informedus of the neighbourhood of one of the mouths (bocas) of thevolcano. We had some trouble to approach its edge; thedeclivity of the mountain being very steep, and the crevicesonly covered by a crust of sulphur, of whose thickness we
* I have already remarked elsewhere in the Ann. de Chimie, that at Paramode Guanacas, where the road from Bogota to Popayan passes to the heightof 14,700 feet, there has been seen fall, no snow, but red hail. Did it in-close those same germs of vegetable organization which have been discover-ed above the polar circle?|465| were ignorant. We believed we might rate the extent of thiscrust, which is often interrupted by rocks, at more than 12,000square feet. These little ridges of trachytic rocks act stronglyon the magnet. I tried to keep at as much distance fromthem as possible to determine the inclination of the needle.It was at the town of Popayan (height 5,825 English feet)23°.05, centesimal division; at the village of Puracé (height8671 feet) 21°.81; near the summit of the volcano of Puracé(height 14,542 feet) 20°.85. The intensity of the magneticforce varied very little at Popayan and at the village of Puracé;and the diminution of the inclination is certainly not the effectof the height, as is proved by so many other observations whichI have made on the summit of the Andes, but the effect oflocal attractions depending on certain centres of action in thetrachytes. The mouth of the volcano of Puracé is a perpen-dicular cleft, the visible opening of which is only 6 feet longand 3 broad. It is covered in form of a vault by a layer ofvery pure sulphur, which is 18 inches thick, and which theforce of the elastic vapours has split on the north side. Atthe distance of 12 feet from the mouth we felt an agreeableheat. The centigrade thermometer, which had kept till thenat 6°.2 (43° F.) (a cold not at all considerable in a time ofhail, and at a height of 14,356 feet), rose to 15° (61° F).Placed in such a manner as not to be incommoded by thevapours, we had the pleasure of drying our clothes. Thefrightful noise which is heard near this opening has almostalways the same intensity: it can only be compared to thatwhich would be caused by several steam-engines together,were the dense steam suffered to escape from all at the samemoment. We threw great stones into the crevice, and wediscovered on this occasion that the opening communicatedwith a basin full of boiling water. The vapours which escapewith so much violence are of the sulphurous acid, which isindicated by their suffocating smell. We shall soon see thatthe water of the subterraneous lake is charged with sulphu-retted hydrogen; but the odour of this gas is not smelt at thesummit of the volcano, because it is disguised by the muchstronger smell of the sulphurous acid vapours. I had not anymeans of determining the temperature of these vapours, whichseem to undergo a prodigiously strong pressure in the interiorof the volcano. The Indians pretend that the opening hasseveral compartments which are not all filled with water, andthat the noise which is heard at times in the interior of the |466| crevice is the forerunner of flames. I introduced by meansof a long pole, some papers coloured with the tincture of vio-lets, under the vault, where I could be sure of not touchingthe surface of the water. Drawing back the pole I found thepapers strongly reddened, but not at all inflamed, as was easyto be foreseen. We succeeded after several vain attempts in obtaining somewater from the crevice: this was by tying a tutuma (the fruitof the Cresentia Cujete) to a stick 8 feet long. The waterwas directly poured into a bottle and hermetically stopped.We examined it on our return to the village of Puracé; it ex-haled a strong smell of sulphuretted hydrogen; it had no acidtaste, but some weak precipitates caused by the nitrate of sil-ver showed the presence of muriatic acid. The crust of sul-phur which forms above the mouth arises without doubt fromthe contact of vapours of sulphurous acid with the sulphurettedhydrogen which the subterraneous lake disengages. Even thewater of this lake is covered with a coat of sulphur which dis-appeared in the places where we threw the stones. It re-sults from these observations, that only the presence of themuriatic acid, or of combinations of this acid with salifiablebases, indicates a feeble analogy between the waters of RioVinagre and those of the lakes. The first, which spring muchlower, at the declivity of the volcano of Puracé, are chargedwith free sulphuric acid; the others, which are found at thesummit of the volcano, contain sulphuretted hydrogen. As theupper mouths are found at very different heights above thelevel of the sea, it may be supposed that their subterraneouswaters are owing to the melting of the snows, and that they donot communicate. The Rio Vinagre receives its acid in theinterior of a volcano which abounds in sulphur, and the tem-perature of which appears extremely elevated, although forcenturies no luminous phenomenon has been perceived at itssummit. [To be continued.]
|513|
The good curate of the village of Puracé thought to rendera great service to his parishioners, as well as to the inhabi-tants of the town of Popayan, in causing, as he said, the chim-neys of the volcano to be cleaned now and then. He orderedthe Indians to take away the crust of sulphur which rises inform of a dome above the crevice. This crust has acquiredsometimes, as they affirm, a thickness of as much as four feetin less than two years. It lessens without doubt the openingby which the vapours of sulphurous acid escape; but it maybe conceived that the elastic force of these vapours is such,that, if the opening were entirely stopped up for some mo-ments, it would sooner break the new arch than producecommotions by acting against the rocky sides of the volcano.For several years the lakes, which represent in miniature the
crater-lakes of our extinguished volcanos, seem each to pre-serve the same level of their line of water; which proves thatthe evaporation is equal to the infiltration of the waters ofsnow and rain: but this equilibrium has not always beenequally steady. About the year 1790 the Boca grande caus-ed partial inundations. I dwell on this phenomenon, because
|514| it seems to throw some light on a problem of the geology ofvolcanos, which has not been sufficiently examined: I meanthe ejections of water and mud. At Vesuvius these ejectionsare only apparent, and come neither from the interior of thecrater, nor from the lateral crevices. An immense electrictension manifests itself in the atmosphere which surrounds thesummit of the volcano at the time of great eruptions.
Flashes of lightning cleave the air; the aqueous vapoursthrown out by the crater are cooled; thick clouds envelopthe summit during the continuance of this storm, confined toa little space; the water descends in torrents, and is mixedwith the tufaceous substances which it drags with it.* Theseeffects, purely meteorological, have given rise to the tradi-tions about boiling waters that issued from the crater of Ve-suvius in 1631; fabulous traditions, which are perpetuatedby an inscription at Portici.
In the volcanos of the Andes, which exceed the limit ofperpetual snow, the causes of inundations are very differentfrom those which we have just indicated. As the eruptionsof these colossal summits take place only after long intervals,(every thirty or forty years, or still more rarely) banks ofsnow of an enormous thickness accumulate on the sides ofthe mountains. The snows do not melt at the time of the ex-plosion only, but sometimes several days before. Thus inFebruary 1803, during my stay at Guayaquil, the inhabitantsof the province of Quito were frightened at the appearance ofthe cone of Cotopaxi, which lost a great part of its snows ina single night, and showed plainly the black colour of itsburnt rocks. Whatever idea may be formed of the power ofthe volcanic forces, and of the intensity of the subterraneousfires in the Andes, it cannot be admitted that the thick sidesof a cone could be uniformly warmed, and transmit the heatwith such rapidity (by the conductibility of their mass) to
* M. de la Condamine (Mémoires de l’Académie 1754, p. 18) had alreadyexpressed very precise ideas on the cause of these phenomena, which arefound equally well explained in the Storia dell’ incendio del 1737, publishedby the Academy of Naples. I saw in my last journey to Naples, (December1822) the ravages caused by the torrents of water from the side of Ottajano,at the foot of Vesuvius. They had transported into the plain, not only mud,but masses of lava 48 feet in circumference and 25 feet high. See the ex-cellent description of these phenomena by M M. Monticelli and Covelli.(Storia del Vesuvio degli anni 1821-23, p. 91-98) Phil. Mag. vol. lxiii. p. 46.By the mixture of the rain and the volcanic cinders, there is formed in theair (l. c. p. 94) a kind of pisolites with concentric layers, which I also foundon the plain of Hambato, among the ancient ejections of the Carguairazo.The inhabitants of the province of Quito call these pisolites earth hailstones. |515| the outside. The sudden melting of the snows, when, in theCordilleras, it precedes the eruptions, is probably owing onlyto an infinity of little fumaroles, which disengage hot vapoursthrough the fissured rock of the cone. These vapours, ac-cording to what I have had opportunity of observing in thecraters of Vesuvius, the Peak of Teneriffe, and the volcanoof Jorullo in Mexico, are more frequently pure water, whichdoes not act at all on the most sensible re-agents; at othertimes they contain muriatic acid. It is remarkable that thesame crevice gives at very near epochs, distilled (pure) wa-ter and very acid waters. The artificial spring which M.Gimbernat has had the ingenious idea of forming at the sum-mit of Vesuvius, by the condensation of the vapours in a glasstube, has sometimes shown these variations; they prove eitherthe change of chemical action in the interior of the volcano,or the accidental opening of some new communications. Inthe Andes of Quito, as in Iceland, and in the eruptions of Et-na of March 23, 1536, and March 6, 1755, the sudden melt-ing of the banks of snow produced great devastations.* At other times, by slow infiltrations, the snow waters areaccumulated in the lateral cavities of the volcano; shocks ofviolent earthquakes, which do not always coincide with theepoch of the fiery eruptions, open these cavities; and waterslong kept in, which support little fish of the genus Pimelodes, carry with them pulverized trachytes, pumice-stones, tufas,and other incoherent matters. These liquid ejections spreadsterility over the plains for centuries. Muddy clays (Coda-zales) covered a space of more than four square leagues, when,in the night of the 19th of June 1698, the Peak of Carguai-razo, the actual height of which exceeds 15,700 feet, sunkdown with a noise. The lakes of sulphureous water that wefound at the summit of Puracé, explain what the inhabitantsof Quito report of the fetid smell of the waters which descendsometimes from the sides of the volcanos during great erup-tions. Struck with the novelty of these phœnomena, whichwe only mention here, the Spanish Conquistadores have, sincethe sixteenth century, distinguished two sorts of volcanos,—the fire volcanos and the water volcanos (volcanes de fuego y deagua). This last denomination, which one might say was in-vented to bring near to each other the volcanists and the nep-tunists, and to put an end to the famous schism of dog-matical
* Ferrara, Campi Flegrei, 1810, p. 165.—Idem, Descriz. dell’ Etna, 1818,p. 89, 116—120.|516| geology, has been applied especially to the mountains of Gua-tin ala and of the Archipelago of the Philippines. The Vol-can de agua, placed between the volcano of Guatamala,* andthat of Pocaya, ruined, by torrents of water, and stones whichit sent forth the 11th of September 1541, the town of Almo-longa, which is the ancient capital of the country. Thismountain does not attain the limit of perpetual snow, but itremains covered with snow several months of the year.When we call to mind the confusion of the accounts that arefound in our own days in the public papers of Europe, everytime that Etna or Vesuvius are in action, we cannot complainof the uncertainty in which the chroniclers of Spanish Ameri-ca and the Conquistadores of the sixteenth century, leave usrespecting the phœnomena of volcanic inundations, so worthyof engaging the attention of natural philosophers. Duringthe eruption of Etna in 1792, there opened on the declivityof the volcano, three miles from the crater, a gulf.† from whichissued for several weeks water mixed with ashes, scoriæ, andclays. These liquid ejections, which must not be confound-ed with the phœnomenon of the Salses. ‡ or air volcanos, werevery thick. It is easily conceivable that in the equinoctialzone, even very low mountains may, by a particular disposi-tion of their subterraneous cavities, and by the excessiveabundance of the tropical rains, be subject to cause frightfulinundations each time that they undergo shocks of earth-quakes. Furthermore, the phœnomena which we have beendescribing are repeated from time to time far from the volca-nos, in secondary mountains, in the centre of Europe. Sadexamples have proved in our days that in the Alps of Swit-zerland, where no shocks of earthquakes are felt, a simplehydrostatic pressure lifts up and breaks with violence banksof rocks, throwing them to a great distance, as if they wereprojected by elastic forces. The trachytes of Puracé contain sulphur like those of Mont-
* Juarros, Compendio de la Historia de Gautemala, 1809, t. i. p. 72; t. ii.p. 351. Remesal. Hist. de la Provincia de San Vincente, lib. iv. cap. 6.—Also in the great eruption of the volcano of the province of Sinano in Japan(July 27, 1783, boiling waters were mixed with the rapilli. Mémoire sur laDynastie regnante des Djogouns, 1820, p 182.† Ferrara, Descr. dell’ Etna, p. 132. As this phenomenon seems to havesome relation to that of the Maya de Pelileo, which contains the carburets ofhydrogen, and which I made known at my return from America, I obtainedvery lately an explanatory manuscript note from the learned Sicilian geolo-gist, M. Ferrara, on the muddy eruption of Etna, observed March 25, 1792.‡ There is only the muddy torrent (fiume di fango) of Santa-Maria-Nasce-mi (March 18, 1790) in the Val di Noto, which seems to me to belong to theactions of the Salses.|517| Dore in Auvergne, of Budoshegy in Transylvania, of the Isleof Montserrat in the Little Antilles, and of the Antisana inthe Andes of Quito. It is still formed daily in the cleftsaround the gulfs of Puracé, either by a very slow sublima-tion, or by the contact of the sulphurous acid vapours withthe sulphuretted hydrogen of the lake. The volcano laboursin its interior like the solfataras; but it presents nothing in itsform that resembles the places which are designated by thatname, and which I have visited; for example, the solfataras ofPuzzuoli, the Peak of Teneriffe, and the volcano of Jo-rullo in Mexico. These last three are craters which havevomited lava; they show that their first state was verydifferent to that in which we see them at present. With veryelevated temperatures, the chemical products of a volcano arenot the same as with a very low temperature. If the appel-lation solfatara be given indefinitely to every place wheresulphur is formed or deposited, this denomination may alsobe applied to a district which I shall describe here, and whichcontrasts singularly with the trachytes of volcanos. In cross-ing the Cordilleras of the Andes of Quindiu, between the ba-sins of the Cauca and of the Magdalena (lat. 4° 50′—4° 45′)I saw an immense formation of gneiss and of micaceous schistresting immediately on an ancient granite. The layers ofmicaceous schist which alternate with strata of gneiss are freefrom garnets, whilst the gneiss contains many. But in thesesame primitive micaceous schists, a little to the west of thestation of the Moral, at the height of 6800 feet above the levelof the sea, in the Quebrada del Azufral, some decayed veins extremely full of crevices abound in sulphur,* and exhale asulphureous vapour, the temperature of which rose to 47° 8′centessimal (118° F.), when the surrounding air was at 20° 2′(63° F.) Here then is repeated on a small scale, in the cliftsof a primitive rock, the phœnomena of the trachytic solfatara of Budoshegy in Transylvania, which has been recently ex-amined by M. Bouè. The micaceous schist of Quindiu, whichsurrounds the open veins, is decomposed, and the sulphur isformed in masses considerable enough to become the objectof a sulphur-work which supports a family settled in the ra-vine of the Azufral. The rock contains some decomposedpyrites; but I much doubt whether these pyrites perform theimportant part in nature which has been so long ascribed tothem in geological treatises. In the midst of the graniticrocks of Quindiu rise the trachytes of the volcano of Tolima.
* See my Barometric and Geognstic Levelling of the Cordilleras, No. 102.|518| a truncated cone, which reminds us of the form of the Coto-paxi, and which, according to a geodesic measurement madeby me at the west of Ibagué, is the highest summit of the An-des in the northern hemisphere.* A rivulet which emits con-siderably the smell of sulphuretted hydrogen descends fromthe Peak of Tolima, and proves that the trachytes whichhave penetrated the granitic rocks also contain sulphur.Two learned travellers, M M. Rivero and Boussingault, haverecently visited this little solfatara in the micaceous schist ofQuindiu: they have sent some specimens to the cabinet ofthe Ecole des Mines at Paris, which contains the most com-plete and instructive series of geognostic specimens. Follow-ing the Cordillera of the Andes southwards, these same alter-nations of primitive formations, and of porphyritic and tra-chytic, are found:—but what was my surprise, when beyondthe equator I ascertained that the celebrated mountain of sul-phur of Ticsan (S. lat. 2° 10′), between Quito and Cuenca, isneither composed of trachyte, nor of chalk or of gypsum,but of micaceous schist. This mountain of sulphur, which the Indians call Quello, issituated, according to my barometric measurement, at theheight of 8000 feet above the level of the ocean. It is entire-ly composed of primitive micaceous schist (glimmerschiefer),which is not even anthracitic, as are the varieties of thisrock peculiar to transition countries. In some very deep ra-vines between Ticsan and Alausia, the micaceous schist is seenresting on gneiss. The sulphur is contained in a stratum ofquartz which is more than 12,00 feet thick: it lies in a toler-ably regular direction, N. 18° E., and inclined like the mica-ceous schist from 70° to 80° to the north-west. The bed ofquartz, which passes sometimes into the hornstone, is wroughtin an open working. The declivity of the Cerro Quello, onwhich the works were begun some centuries since, is oppo-site to the south-south-east; and the bed of quartz appearsto be prolonged towards the north-north-west, that is to say,towards the coast of the Pacific Ocean. It is however as-serted that the sulphur has not been found on the surface ofthe ground in this direction to the distance of 2000 toisesfrom Ticsan. All is covered there with a thick vegetation.Towards the end of the eighteenth century, masses of sulphurwere still worked, which were from 2 to 3 feet in diameter.At present they are working some quartzose strata much less
* Height 18,321 feet; N. lat. 14° 46′.|519| rich, in which the sulphur is only dispersed in nodules from3 to 4 inches thick. It is observed that the quantity of sul-phur increases with the depth; but the working has been sounskilfully directed that the lower strata are nearly inacces-sible. The quartz in which the sulphur is dispersed presentsneither great fissures nor cavities, or druses; nor have I beenable to find any specimen of crystallized sulphur. The mineral which is the object of the working of the CerroQuello does not form a mass of complication of veins, asmight be supposed: the sulphur is disseminated without anycontinuity by little masses in the quartz which traverses themicaceous schist in a direction parallel to its strata. Theclefts that have perhaps formerly united these masses are nolonger visible, but all the quartz seems to have undergone anextraordinary change. It is tarnished, often brittle, andbreaks in some parts on the least shock; which indicates animperceptible cleavage. The temperature of the rock didnot differ from that of the exterior air. The inhabitants liketo attribute the violent earthquakes to which their countryhas been sometimes exposed to concavities which they sup-pose to exist under the mountain of sulphur. If this hypothe-sis be well founded, it must be admitted that the cause whichit indicates acts but locally. In the great catastrophe of the4th of February 1797, which destroyed so many thousandIndians in the province of Quito—the three places wherethere is the most sulphur, the Cerro Quello, the Azufral ofCuesaca near to the villa of Ibarra, and the Machay of SaintSimon, near the volcano of Antisana, were but very feeblyagitated; but at a much earlier period there has been expe-rienced, even on the bed of quartz which includes the sulphurnear Ticsan, an explosion similar to that of a mine. The bed of quartz appears at the surface on the two sidesof the little river of Alausi; and facing the Cerro Quello isfound a little plain, where, in the seventeenth century, wassituated the village of Ticsan. The ruins of the church of Pueblo Viejo are still seen. An earthquake wholly local (forits effects were confined to a very small space of country)made the surrounding hills sink down: a part of the villagesunk: another part was thrown into the air, as happened atRiobamba, where I found the bones of the unfortunate in-habitants of the town thrown on the Cerro de la Culca, to aheight of several hundred feet. The Indians of Ticsan whosurvived this catastrophe constructed their habitations moreto the north, far from the mountain of sulphur whose neigh- |520| bourhood they dreaded. It may be that the coincidence ofthese phœnomena of explosion and of the position (gisement)of a substance easy to be converted into elastic vapours hasonly been accidental, but it may be also that ancient commu-nications with the interior of the globe, those upon which isformed by sublimation the immense deposit of sulphur, be-came re-established from time to time, and allow the volcanicforces to shake the surface of the soil. Near the ruins of Pueblo Viejo of Ticsan I found a hill of gypsum lying abovethe micaceous schist: as this hill is not covered by other for-mations, it is difficult to decide whether the gypsum, partlyfibrous and mixed with clay, is primitive, like that of Val Ca-naria, or transition, like the gypsum of the Tarentaise. The abundance of sulphur in primitive countries is a veryimportant geological fact, in relation to the study of volcanosand of rocks, through which the subterraneous fire has open-ed itself a passage. Before I had visited the Andes of Quitoand the mountain of Ticsan, sulphur was known only in thetransition limestone and gypsum; in the gypsums, marles andmuriatiferous clays of secondary countries, and in the rocksexclusively called volcanic. These different geological situa-tions, to which may be added the tertiary districts, very illexplained the frequency of the sulphureous vapours exhaledby the mouths of the volcanos, whose centre of action wasplaced (and doubtless with propriety) very much below thesecondary and intermediate rocks. In proportion as we be-come acquainted with a greater part of the globe, we not onlysee positive geognosy, that is to say, the view of the forma-tions and of the geological positions extended; but even geog-ony, or systematic geognosy, the conjectural science whichinvestigates the causes of phœnomena, begins to be founded onthe analogy of more certain facts. We may have beenstruck for some time past with the little masses of native sul-phur which are disseminated in some metalliferous veins, andwhich traverse granitic rocks; for example, in Schwarzwald,near Riepoldsau. The mountain of Ticsan which I havemade known leaves no further doubt respecting the existenceof sulphur in the primitive districts. It has also been latelyfound in Brazil, that the chloritic quartz formation whichcovers, in the Capitania de Minas Geraes, the primitive clay-slate contains both gold and sulphur. Laminæ of this rockstrongly heated burn with a blue flame. Near to Villarica,in the district called Antonio Pereira, a schist, of the sameage as that on which is superposed the intacolumite or chlo- |521| itic quartz, contains a calcareous bed traversed by veins ofquartz, which the Baron d’Eschwege (director of the goldand diamond mines of these countries) has found filled withlittle nodules of pulverulent sulphur. All these phenomenaincrease in interest, when we reflect that this learned geolo-gist, and also another German traveller (M. Pohl), incline tothe opinion that gold, micaceous iron, diamonds, euclases,platina, and palladium, which are peculiar to the alluvial dis-tricts of Brazil, have been derived either from the destructionof the great formation of chloritic quartz, or from that of aferruginous bed (itabarite), which is placed above this for-mation.
Analysis of the Water of the Rio Vinagre, inthe Andes of Popayan, by M. Mariano de Rivero; withgeognostic and Physical Illustrations of some Phenomenawhich are exhibited by Sulphur, Sulphuretted Hydrogen,and Water, in Volcanoes. By M. A. de Humboldt. [Phil. Mag.][Extract of a Letter, dated the 8th October 1823.]
I had made known, at the time of my return from America,the presence of the sulphuric and muriatic acids in the waterof the Rio Vinagre, which the aborigines call Pusambio. (SeeViews of the Cordilleras, and Monuments of the People ofAmerica, vol. ii. p. 166; Barometric Levelling of the Andes,No. 126; Caldas, Samanario del Nuevo Reyno de Granada,t. i. p. 265); but not being furnished with the salts of barytes.I had engaged MM. Rivero and Boussingault, when theydeparted from Bogota, to verify these facts. The analysis,which we owe to one of these expert chemists, is the firstwhich has been attempted on the water of the Rio Vinagre.I shall give some extracts from the journal of my travels, ingreat part still unpublished, explanatory of the local circum-stances. The town of Popayan is situated in the beautiful valley of theRio Cauca, on the Bogota road to Quito, at the foot of thetwo great volcanoes of Puracé and Sotarà.
* It cannot be doubted that the indications are by grammes and fractionsof grammes; a litre of the water of the Rio Vinagre includes 1.080 grammesof sulphuric acid, and 0.184 grammes of muriatic acid. This proportion ofsulphuric acid is nevertheless very sensible to the taste, and is manifest byan abundant precipitate with the salts of barytes.[The litre being 2.113 pints, the contents of the water in English grainswill be as follows: sulphuric acid 16.68; muriatic acid 2.84; alumine 3.7;lime 2.47. Edit.]|461| These volcanoes, almost extinct, and exhibiting only thephenomena of solfataras, form part of the central chain of theAndes of New Granada. At 1° 55′ and 2° 20′ of north lati-tude, the group of mountains which incloses the sources of theMagdalena is divided into three branches, of which the east-ern is continued towards Timana and the Nevados of Chitaand of Merida; the intermediate and central one towards theParamos of Guanacas and of Quimdiú; the western towardsthe platiniferous district of the Choco and the isthmus ofPanama. In ascending from the town of Popayan to the sum-mit of the volcano of Puracé, M. Bonpland and I found atthe height of 8672 feet a little plain (Llane del Corazon), in-habited by poor Indian husbandmen. This plain is separatedfrom the rest of the acclivity, with which it would otherwisebe continuous, by two ravines extremely deep: it is at theedge of these precipices that the village of Puracé is built.Springs rise every where from the trachytic rock; each gar-den is surrounded with a quickset hedge of narrow-leavedeuphorbium (lechero) of the most delicate green. Thisbeautiful verdure contrasts in a striking manner with the back-ground of black and arid mountains, which surround the vol-cano, and which are rent by the effects of the earthquakes. The site of the village is celebrated in the country on ac-count of three beautiful cascades [choreras] of the river ofPusambio, whose water is acid, and which the people, whoknow no other acid than vinegar, call Rio Vinagre, some-times Gran Vinagre. This river takes its rise at the heightof nearly 10,871 feet, in a very inaccessible spot. Althoughthe temperature of the water be little different in the lowercascades from that of the surrounding atmosphere, it is no lesscertain that the sources of the Pusambio or Venagre are veryhot. This fact was attested to me by the natives and by themissionary of the village of Puracé. In going to the summitof the volcano I saw a column of smoke rise at the place wherethe acid waters make their appearance. I have drawn thesecond of the falls of the Vinagre (plate xxx of the Views ofthe Cordilleras): the water which opens itself a passage acrossa cavern, is precipitated more than 383 feet in depth. Thefall has a very picturesque effect; but the inhabitants of Popa-yan would be better pleased if the river, instead of throwingitself into the Rio Cauca, became engulfed in some othercrevice; for such is the delicacy of constitution of animalswhich breath by gills, and which absorb the oxygen dissolved |462| in the water, that the Cauca, during a course of four leagues,is destitute of fish, on account of the mixture of its waters withthose of the Rio Vinagre,* which are charged both with oxideof iron and with sulphuric and muriatic acid. After staying aconsiderable time on the craggy wall of rock which bordersthe cascade, a pricking sensation is felt in the eyes from theminute spray in the atmosphere. Fish re-appear in the RioCauca at the point where it becomes enlarged by the influx ofthe Pindamon and of the Placé.† A little to the north of the sources of the Pusambio rise twoother rivulets charged in like manner with free sulphuric acid,which the people call the Little Vinegars (los dos Vinagreschicos): they throw themselves into the Rio de San Francis-co, which is itself but a tributary of the Gran Vinagre. Dur-ing my stay at Popayan it was an opinion generally receivedthat all these acid waters contained some iron dissolved by agreat quantity of carbonic acid. When it was merely remem-bered that the sources of the Vinagre are very hot, this opin-ion ought to have been abandoned. I boiled some water takenfrom the cascade; and I found, after the ebullition, the sameacid taste and the precipitates as in the unboiled water. Atthis period I had very few re-agents left. The nitrate of silver‡ gave a white and milky precipitate,indicating the presence of muriates. The presence of ironwas shown by the prussiate of lime, that of lime by the oxalateof potash. When the water was weighed with great care inthe office of the mint of Popayan, the weight of an equalquantity of the water of the Vinagre was found to be to that ofdistilled water as 2735½ gr. to 2731 gr.; that is to say thatthe specific gravity of the water of the cascade was 1.00 5. The waters which I describe, and of which M. Rivero hasgiven the first analysis, must not be confounded with those ofthe two subterraneous lakes which we have found near the sum-mit of the volcano; one is 14,356 feet high, the other, abovethe snows, 15.475 feet. This volcano of Puracé is a dome
* M. Caldas has even attributed to this mixture, doubtless with little rea-son, the absence of goitres in the valley of Rio Cauca.—Semanario, t. l. p.265. See my Memoir on the Goitres in the Cordilleras. (Magendie, Jour.de Physiol. t. iv, p. 109)† Journal de physique, t. lxii, p. 61.‡ The conjoint presence of the sulphuric and muriatic acids has also beenobserved by M. Vauquelin in the water which M. Leschenault had taken fromthe crater-lake of Mount Idienne in Java (Journal de Physique, t. lxv. p. 406.)See Phil. Mag. vol. xlii. pp. 126, 182.|463| of semivitreous trachyte of a bluish grey, and having a con-choidal fracture. It does not present a great crater at itssummit, but several little mouths. It differs very much fromthe neighbouring volcano, the Sotarà, which is of a conicalform, and which has thrown out an immense quantity of obsi-dians. These masses, covering the plains of Julumito, areballs or tears of obsidian, the surface of which is often tuber-cular. They present, what I have seen no where else in thetwo hemispheres, all the shades of colour, from deep black tothat of an artificial glass entirely colourless. It may appearsurprising to see that this deprivation of colour has not beenaccompanied by any inflation or porosity. The obsidians ofSotarà are mixed with fragments of enamel which resemblethe porcelain of Réaumur, and adhering to which I havefound masses of felspar which have resisted fusion. Here, as in the Andes of Quito, as at Mexico, and at theCanary Islands, the system of basaltic rocks lies far from thetrachytes which form the volcano of Puracé and of Sotarà.The basalts of the Tetilla of Julumito belong only to the leftbank of the Cauca. They rise from transition porphyries freefrom augite, containing some hornblende, a very little quartzin small crystals embedded in the mass, and a felspar whichpasses from the common to the vitreous variety. This por-phyry is covered, near to Los Serillos, with a blackish-greylimestone, traversed by veins of carbonate of lime, and somuch overcharged with carbon that in some parts it stains thefingers like an aluminous schist, or like the lydian* stone ofSteeben in the Fichtelgebirge. The trachytic dome of Puracé which gives birth to thelittle river of sulphuric acid, rises out of a porphyritic syenite(with common felspar), which in its turn is superimposed ontransition granite abounding in mica. This observation,† veryimportant for the position of volcanic rocks, may be made nearto Santa Barbara in ascending from Popayan to the village of
* M. Vauquelin has recently proved by a direct analysis the presence ofcarboa in the purest lydian stones. I had found, in a series of experimentsmade on the galvanic exciters in 1798, that the lydian stones of the transitionschists of Steeben produced jointly with zinc the same effect as graphite orcarburet of iron. I have since made some trials to prove chemically thepresence of carbon in several varieties of lydian stone. See my Experi-ments on the Nervous and Muscular Fibre (in German), t. ii. p. 163.† See an account of the whole of these phenomena of the volcanoes ofPopayan in my Essai sur le Gisement des Roches, 1823, pp. 129, 139, 340.|464| Puracé. The volcano, like the most part of the great volcanoesof the Andes, presents layers or mantles of melted stony matter,not real currents of lava. Some fragments of granular limestone,probably magnesian, which I found at more than 12,790 feethigh, seem to have been thrown up through crevices whichhave since become closed. They are like those of the FossoGrande of Vesuvius, which owe their granular texture to vol-canic fire. It is not possible to go on horse back further thanthe cascades of the Rio Vinagre. From thence we wereeight hours in mounting on foot to the summit of the volcanoand in descending from it. The weather was dreadful; snowand hail fell. I had a great deal of difficulty in lighting the tinderthe point of the conductor of Volta’s electrometer; the ballsof elder pith separated from 5 to 6 lines, and the electricitypassed often from positive to negative without there being anyother symptom of storm: for thunder and lightning are (ac-cording to my experience) generally very rare when we areabove 12,800 or 14,000 feet high. The hail was white;* thehailstones, from five to seven lines in diameter, composed oflayers varying in translucency. They were not only muchflattened towards the poles, but so much increased in theirequatorial diameter, that rings of ice separated themselves onthe least shock. I had already twice observed and describedthis phenomenon, in the mountains of Bareuth, and near Cra-cow, during a journey in Poland. Can it be admitted thatthe successive layers which are added to the central nucleusare in a state of fluidity so great that the rotary motion cancause the flattening of the spheroids? When the barometer indicated that we were come verynear the limit of perpetual snow, we found the masses of sul-phur disseminated in imperfectly columnar trachytic rocksaugmented. This phenomenon struck me the more, as Iknew how rare sulphur is on the sides of inflamed volcanoes:a column of yellowish smoke and a frightful noise informedus of the neighbourhood of one of the mouths (bocas) of thevolcano. We had some trouble to approach its edge; thedeclivity of the mountain being very steep, and the crevicesonly covered by a crust of sulphur, of whose thickness we
* I have already remarked elsewhere in the Ann. de Chimie, that at Paramode Guanacas, where the road from Bogota to Popayan passes to the heightof 14,700 feet, there has been seen fall, no snow, but red hail. Did it in-close those same germs of vegetable organization which have been discover-ed above the polar circle?|465| were ignorant. We believed we might rate the extent of thiscrust, which is often interrupted by rocks, at more than 12,000square feet. These little ridges of trachytic rocks act stronglyon the magnet. I tried to keep at as much distance fromthem as possible to determine the inclination of the needle.It was at the town of Popayan (height 5,825 English feet)23°.05, centesimal division; at the village of Puracé (height8671 feet) 21°.81; near the summit of the volcano of Puracé(height 14,542 feet) 20°.85. The intensity of the magneticforce varied very little at Popayan and at the village of Puracé;and the diminution of the inclination is certainly not the effectof the height, as is proved by so many other observations whichI have made on the summit of the Andes, but the effect oflocal attractions depending on certain centres of action in thetrachytes. The mouth of the volcano of Puracé is a perpen-dicular cleft, the visible opening of which is only 6 feet longand 3 broad. It is covered in form of a vault by a layer ofvery pure sulphur, which is 18 inches thick, and which theforce of the elastic vapours has split on the north side. Atthe distance of 12 feet from the mouth we felt an agreeableheat. The centigrade thermometer, which had kept till thenat 6°.2 (43° F.) (a cold not at all considerable in a time ofhail, and at a height of 14,356 feet), rose to 15° (61° F).Placed in such a manner as not to be incommoded by thevapours, we had the pleasure of drying our clothes. Thefrightful noise which is heard near this opening has almostalways the same intensity: it can only be compared to thatwhich would be caused by several steam-engines together,were the dense steam suffered to escape from all at the samemoment. We threw great stones into the crevice, and wediscovered on this occasion that the opening communicatedwith a basin full of boiling water. The vapours which escapewith so much violence are of the sulphurous acid, which isindicated by their suffocating smell. We shall soon see thatthe water of the subterraneous lake is charged with sulphu-retted hydrogen; but the odour of this gas is not smelt at thesummit of the volcano, because it is disguised by the muchstronger smell of the sulphurous acid vapours. I had not anymeans of determining the temperature of these vapours, whichseem to undergo a prodigiously strong pressure in the interiorof the volcano. The Indians pretend that the opening hasseveral compartments which are not all filled with water, andthat the noise which is heard at times in the interior of the |466| crevice is the forerunner of flames. I introduced by meansof a long pole, some papers coloured with the tincture of vio-lets, under the vault, where I could be sure of not touchingthe surface of the water. Drawing back the pole I found thepapers strongly reddened, but not at all inflamed, as was easyto be foreseen. We succeeded after several vain attempts in obtaining somewater from the crevice: this was by tying a tutuma (the fruitof the Cresentia Cujete) to a stick 8 feet long. The waterwas directly poured into a bottle and hermetically stopped.We examined it on our return to the village of Puracé; it ex-haled a strong smell of sulphuretted hydrogen; it had no acidtaste, but some weak precipitates caused by the nitrate of sil-ver showed the presence of muriatic acid. The crust of sul-phur which forms above the mouth arises without doubt fromthe contact of vapours of sulphurous acid with the sulphurettedhydrogen which the subterraneous lake disengages. Even thewater of this lake is covered with a coat of sulphur which dis-appeared in the places where we threw the stones. It re-sults from these observations, that only the presence of themuriatic acid, or of combinations of this acid with salifiablebases, indicates a feeble analogy between the waters of RioVinagre and those of the lakes. The first, which spring muchlower, at the declivity of the volcano of Puracé, are chargedwith free sulphuric acid; the others, which are found at thesummit of the volcano, contain sulphuretted hydrogen. As theupper mouths are found at very different heights above thelevel of the sea, it may be supposed that their subterraneouswaters are owing to the melting of the snows, and that they donot communicate. The Rio Vinagre receives its acid in theinterior of a volcano which abounds in sulphur, and the tem-perature of which appears extremely elevated, although forcenturies no luminous phenomenon has been perceived at itssummit. [To be continued.]
—Analysis of the Water of the Rio Vinagre, in theAndes of Popayan. By M. Mariano de Rivero. WithGeognostic and Physical Illustrations of some Phenomena whichare exhibited by Sulphur, Sulphuretted Hydrogen, in Water,in Volcanos. By M. A. de Humboldt. [Phil. Mag.](Concluded from p. 466.)
* M. de la Condamine (Mémoires de l’Académie 1754, p. 18) had alreadyexpressed very precise ideas on the cause of these phenomena, which arefound equally well explained in the Storia dell’ incendio del 1737, publishedby the Academy of Naples. I saw in my last journey to Naples, (December1822) the ravages caused by the torrents of water from the side of Ottajano,at the foot of Vesuvius. They had transported into the plain, not only mud,but masses of lava 48 feet in circumference and 25 feet high. See the ex-cellent description of these phenomena by M M. Monticelli and Covelli.(Storia del Vesuvio degli anni 1821-23, p. 91-98) Phil. Mag. vol. lxiii. p. 46.By the mixture of the rain and the volcanic cinders, there is formed in theair (l. c. p. 94) a kind of pisolites with concentric layers, which I also foundon the plain of Hambato, among the ancient ejections of the Carguairazo.The inhabitants of the province of Quito call these pisolites earth hailstones. |515| the outside. The sudden melting of the snows, when, in theCordilleras, it precedes the eruptions, is probably owing onlyto an infinity of little fumaroles, which disengage hot vapoursthrough the fissured rock of the cone. These vapours, ac-cording to what I have had opportunity of observing in thecraters of Vesuvius, the Peak of Teneriffe, and the volcanoof Jorullo in Mexico, are more frequently pure water, whichdoes not act at all on the most sensible re-agents; at othertimes they contain muriatic acid. It is remarkable that thesame crevice gives at very near epochs, distilled (pure) wa-ter and very acid waters. The artificial spring which M.Gimbernat has had the ingenious idea of forming at the sum-mit of Vesuvius, by the condensation of the vapours in a glasstube, has sometimes shown these variations; they prove eitherthe change of chemical action in the interior of the volcano,or the accidental opening of some new communications. Inthe Andes of Quito, as in Iceland, and in the eruptions of Et-na of March 23, 1536, and March 6, 1755, the sudden melt-ing of the banks of snow produced great devastations.* At other times, by slow infiltrations, the snow waters areaccumulated in the lateral cavities of the volcano; shocks ofviolent earthquakes, which do not always coincide with theepoch of the fiery eruptions, open these cavities; and waterslong kept in, which support little fish of the genus Pimelodes, carry with them pulverized trachytes, pumice-stones, tufas,and other incoherent matters. These liquid ejections spreadsterility over the plains for centuries. Muddy clays (Coda-zales) covered a space of more than four square leagues, when,in the night of the 19th of June 1698, the Peak of Carguai-razo, the actual height of which exceeds 15,700 feet, sunkdown with a noise. The lakes of sulphureous water that wefound at the summit of Puracé, explain what the inhabitantsof Quito report of the fetid smell of the waters which descendsometimes from the sides of the volcanos during great erup-tions. Struck with the novelty of these phœnomena, whichwe only mention here, the Spanish Conquistadores have, sincethe sixteenth century, distinguished two sorts of volcanos,—the fire volcanos and the water volcanos (volcanes de fuego y deagua). This last denomination, which one might say was in-vented to bring near to each other the volcanists and the nep-tunists, and to put an end to the famous schism of dog-matical
* Ferrara, Campi Flegrei, 1810, p. 165.—Idem, Descriz. dell’ Etna, 1818,p. 89, 116—120.|516| geology, has been applied especially to the mountains of Gua-tin ala and of the Archipelago of the Philippines. The Vol-can de agua, placed between the volcano of Guatamala,* andthat of Pocaya, ruined, by torrents of water, and stones whichit sent forth the 11th of September 1541, the town of Almo-longa, which is the ancient capital of the country. Thismountain does not attain the limit of perpetual snow, but itremains covered with snow several months of the year.When we call to mind the confusion of the accounts that arefound in our own days in the public papers of Europe, everytime that Etna or Vesuvius are in action, we cannot complainof the uncertainty in which the chroniclers of Spanish Ameri-ca and the Conquistadores of the sixteenth century, leave usrespecting the phœnomena of volcanic inundations, so worthyof engaging the attention of natural philosophers. Duringthe eruption of Etna in 1792, there opened on the declivityof the volcano, three miles from the crater, a gulf.† from whichissued for several weeks water mixed with ashes, scoriæ, andclays. These liquid ejections, which must not be confound-ed with the phœnomenon of the Salses. ‡ or air volcanos, werevery thick. It is easily conceivable that in the equinoctialzone, even very low mountains may, by a particular disposi-tion of their subterraneous cavities, and by the excessiveabundance of the tropical rains, be subject to cause frightfulinundations each time that they undergo shocks of earth-quakes. Furthermore, the phœnomena which we have beendescribing are repeated from time to time far from the volca-nos, in secondary mountains, in the centre of Europe. Sadexamples have proved in our days that in the Alps of Swit-zerland, where no shocks of earthquakes are felt, a simplehydrostatic pressure lifts up and breaks with violence banksof rocks, throwing them to a great distance, as if they wereprojected by elastic forces. The trachytes of Puracé contain sulphur like those of Mont-
* Juarros, Compendio de la Historia de Gautemala, 1809, t. i. p. 72; t. ii.p. 351. Remesal. Hist. de la Provincia de San Vincente, lib. iv. cap. 6.—Also in the great eruption of the volcano of the province of Sinano in Japan(July 27, 1783, boiling waters were mixed with the rapilli. Mémoire sur laDynastie regnante des Djogouns, 1820, p 182.† Ferrara, Descr. dell’ Etna, p. 132. As this phenomenon seems to havesome relation to that of the Maya de Pelileo, which contains the carburets ofhydrogen, and which I made known at my return from America, I obtainedvery lately an explanatory manuscript note from the learned Sicilian geolo-gist, M. Ferrara, on the muddy eruption of Etna, observed March 25, 1792.‡ There is only the muddy torrent (fiume di fango) of Santa-Maria-Nasce-mi (March 18, 1790) in the Val di Noto, which seems to me to belong to theactions of the Salses.|517| Dore in Auvergne, of Budoshegy in Transylvania, of the Isleof Montserrat in the Little Antilles, and of the Antisana inthe Andes of Quito. It is still formed daily in the cleftsaround the gulfs of Puracé, either by a very slow sublima-tion, or by the contact of the sulphurous acid vapours withthe sulphuretted hydrogen of the lake. The volcano laboursin its interior like the solfataras; but it presents nothing in itsform that resembles the places which are designated by thatname, and which I have visited; for example, the solfataras ofPuzzuoli, the Peak of Teneriffe, and the volcano of Jo-rullo in Mexico. These last three are craters which havevomited lava; they show that their first state was verydifferent to that in which we see them at present. With veryelevated temperatures, the chemical products of a volcano arenot the same as with a very low temperature. If the appel-lation solfatara be given indefinitely to every place wheresulphur is formed or deposited, this denomination may alsobe applied to a district which I shall describe here, and whichcontrasts singularly with the trachytes of volcanos. In cross-ing the Cordilleras of the Andes of Quindiu, between the ba-sins of the Cauca and of the Magdalena (lat. 4° 50′—4° 45′)I saw an immense formation of gneiss and of micaceous schistresting immediately on an ancient granite. The layers ofmicaceous schist which alternate with strata of gneiss are freefrom garnets, whilst the gneiss contains many. But in thesesame primitive micaceous schists, a little to the west of thestation of the Moral, at the height of 6800 feet above the levelof the sea, in the Quebrada del Azufral, some decayed veins extremely full of crevices abound in sulphur,* and exhale asulphureous vapour, the temperature of which rose to 47° 8′centessimal (118° F.), when the surrounding air was at 20° 2′(63° F.) Here then is repeated on a small scale, in the cliftsof a primitive rock, the phœnomena of the trachytic solfatara of Budoshegy in Transylvania, which has been recently ex-amined by M. Bouè. The micaceous schist of Quindiu, whichsurrounds the open veins, is decomposed, and the sulphur isformed in masses considerable enough to become the objectof a sulphur-work which supports a family settled in the ra-vine of the Azufral. The rock contains some decomposedpyrites; but I much doubt whether these pyrites perform theimportant part in nature which has been so long ascribed tothem in geological treatises. In the midst of the graniticrocks of Quindiu rise the trachytes of the volcano of Tolima.
* See my Barometric and Geognstic Levelling of the Cordilleras, No. 102.|518| a truncated cone, which reminds us of the form of the Coto-paxi, and which, according to a geodesic measurement madeby me at the west of Ibagué, is the highest summit of the An-des in the northern hemisphere.* A rivulet which emits con-siderably the smell of sulphuretted hydrogen descends fromthe Peak of Tolima, and proves that the trachytes whichhave penetrated the granitic rocks also contain sulphur.Two learned travellers, M M. Rivero and Boussingault, haverecently visited this little solfatara in the micaceous schist ofQuindiu: they have sent some specimens to the cabinet ofthe Ecole des Mines at Paris, which contains the most com-plete and instructive series of geognostic specimens. Follow-ing the Cordillera of the Andes southwards, these same alter-nations of primitive formations, and of porphyritic and tra-chytic, are found:—but what was my surprise, when beyondthe equator I ascertained that the celebrated mountain of sul-phur of Ticsan (S. lat. 2° 10′), between Quito and Cuenca, isneither composed of trachyte, nor of chalk or of gypsum,but of micaceous schist. This mountain of sulphur, which the Indians call Quello, issituated, according to my barometric measurement, at theheight of 8000 feet above the level of the ocean. It is entire-ly composed of primitive micaceous schist (glimmerschiefer),which is not even anthracitic, as are the varieties of thisrock peculiar to transition countries. In some very deep ra-vines between Ticsan and Alausia, the micaceous schist is seenresting on gneiss. The sulphur is contained in a stratum ofquartz which is more than 12,00 feet thick: it lies in a toler-ably regular direction, N. 18° E., and inclined like the mica-ceous schist from 70° to 80° to the north-west. The bed ofquartz, which passes sometimes into the hornstone, is wroughtin an open working. The declivity of the Cerro Quello, onwhich the works were begun some centuries since, is oppo-site to the south-south-east; and the bed of quartz appearsto be prolonged towards the north-north-west, that is to say,towards the coast of the Pacific Ocean. It is however as-serted that the sulphur has not been found on the surface ofthe ground in this direction to the distance of 2000 toisesfrom Ticsan. All is covered there with a thick vegetation.Towards the end of the eighteenth century, masses of sulphurwere still worked, which were from 2 to 3 feet in diameter.At present they are working some quartzose strata much less
* Height 18,321 feet; N. lat. 14° 46′.|519| rich, in which the sulphur is only dispersed in nodules from3 to 4 inches thick. It is observed that the quantity of sul-phur increases with the depth; but the working has been sounskilfully directed that the lower strata are nearly inacces-sible. The quartz in which the sulphur is dispersed presentsneither great fissures nor cavities, or druses; nor have I beenable to find any specimen of crystallized sulphur. The mineral which is the object of the working of the CerroQuello does not form a mass of complication of veins, asmight be supposed: the sulphur is disseminated without anycontinuity by little masses in the quartz which traverses themicaceous schist in a direction parallel to its strata. Theclefts that have perhaps formerly united these masses are nolonger visible, but all the quartz seems to have undergone anextraordinary change. It is tarnished, often brittle, andbreaks in some parts on the least shock; which indicates animperceptible cleavage. The temperature of the rock didnot differ from that of the exterior air. The inhabitants liketo attribute the violent earthquakes to which their countryhas been sometimes exposed to concavities which they sup-pose to exist under the mountain of sulphur. If this hypothe-sis be well founded, it must be admitted that the cause whichit indicates acts but locally. In the great catastrophe of the4th of February 1797, which destroyed so many thousandIndians in the province of Quito—the three places wherethere is the most sulphur, the Cerro Quello, the Azufral ofCuesaca near to the villa of Ibarra, and the Machay of SaintSimon, near the volcano of Antisana, were but very feeblyagitated; but at a much earlier period there has been expe-rienced, even on the bed of quartz which includes the sulphurnear Ticsan, an explosion similar to that of a mine. The bed of quartz appears at the surface on the two sidesof the little river of Alausi; and facing the Cerro Quello isfound a little plain, where, in the seventeenth century, wassituated the village of Ticsan. The ruins of the church of Pueblo Viejo are still seen. An earthquake wholly local (forits effects were confined to a very small space of country)made the surrounding hills sink down: a part of the villagesunk: another part was thrown into the air, as happened atRiobamba, where I found the bones of the unfortunate in-habitants of the town thrown on the Cerro de la Culca, to aheight of several hundred feet. The Indians of Ticsan whosurvived this catastrophe constructed their habitations moreto the north, far from the mountain of sulphur whose neigh- |520| bourhood they dreaded. It may be that the coincidence ofthese phœnomena of explosion and of the position (gisement)of a substance easy to be converted into elastic vapours hasonly been accidental, but it may be also that ancient commu-nications with the interior of the globe, those upon which isformed by sublimation the immense deposit of sulphur, be-came re-established from time to time, and allow the volcanicforces to shake the surface of the soil. Near the ruins of Pueblo Viejo of Ticsan I found a hill of gypsum lying abovethe micaceous schist: as this hill is not covered by other for-mations, it is difficult to decide whether the gypsum, partlyfibrous and mixed with clay, is primitive, like that of Val Ca-naria, or transition, like the gypsum of the Tarentaise. The abundance of sulphur in primitive countries is a veryimportant geological fact, in relation to the study of volcanosand of rocks, through which the subterraneous fire has open-ed itself a passage. Before I had visited the Andes of Quitoand the mountain of Ticsan, sulphur was known only in thetransition limestone and gypsum; in the gypsums, marles andmuriatiferous clays of secondary countries, and in the rocksexclusively called volcanic. These different geological situa-tions, to which may be added the tertiary districts, very illexplained the frequency of the sulphureous vapours exhaledby the mouths of the volcanos, whose centre of action wasplaced (and doubtless with propriety) very much below thesecondary and intermediate rocks. In proportion as we be-come acquainted with a greater part of the globe, we not onlysee positive geognosy, that is to say, the view of the forma-tions and of the geological positions extended; but even geog-ony, or systematic geognosy, the conjectural science whichinvestigates the causes of phœnomena, begins to be founded onthe analogy of more certain facts. We may have beenstruck for some time past with the little masses of native sul-phur which are disseminated in some metalliferous veins, andwhich traverse granitic rocks; for example, in Schwarzwald,near Riepoldsau. The mountain of Ticsan which I havemade known leaves no further doubt respecting the existenceof sulphur in the primitive districts. It has also been latelyfound in Brazil, that the chloritic quartz formation whichcovers, in the Capitania de Minas Geraes, the primitive clay-slate contains both gold and sulphur. Laminæ of this rockstrongly heated burn with a blue flame. Near to Villarica,in the district called Antonio Pereira, a schist, of the sameage as that on which is superposed the intacolumite or chlo- |521| itic quartz, contains a calcareous bed traversed by veins ofquartz, which the Baron d’Eschwege (director of the goldand diamond mines of these countries) has found filled withlittle nodules of pulverulent sulphur. All these phenomenaincrease in interest, when we reflect that this learned geolo-gist, and also another German traveller (M. Pohl), incline tothe opinion that gold, micaceous iron, diamonds, euclases,platina, and palladium, which are peculiar to the alluvial dis-tricts of Brazil, have been derived either from the destructionof the great formation of chloritic quartz, or from that of aferruginous bed (itabarite), which is placed above this for-mation.