Sulphur Mines of Sicily—Conflagration of a Sulphur Mine—The Solfataras of Krisuvick—Iwogasima in Japan—Solfatara of Puzzuoli—Crater of Teneriffe—Alaghez—BÜdÖshegy in Transylvania—Sulphur from the Throat of Popocatepetl—Sulphurous Springs—Pyrites—Mines of San Domingos in Portugal—The Baron of PommorÃo.

Though in every volcanic region of the globe sulphurous exhalations arise from a great number of craters or solfataras, yet sulphur is but rarely found in sufficient quantities to remunerate the miner’s toil. In this respect the island of Sicily is unrivalled, for no other country possesses such masses of this valuable, and in many cases indispensable, mineral.

The numerous sulphur pits of Sicily, which occur in crevices or hollows over a space of 150 geographical miles, are situated chiefly in the southern part of the island, in the districts between the sea-border of the province of Girgenti and the mountains of Etna, Mannaro, Castro Giovanni, and Catolica. They are no doubt the produce of a vast volcanic action which took place about the beginning of the tertiary period, when the sulphurous fumes, rising through countless clefts or fumaroles from the mysterious furnaces of the deep, condensed in the chalk and clay grounds of the superficial strata.

In former times, as long as the chief use of sulphur was confined to the fabrication of gunpowder, its production was comparatively insignificant; but since the manufacture of sulphuric acid has become a branch of industry of continually increasing importance, sulphur, the ingredient necessary to its formation, has considerably risen in value, and now constitutes the chief article of Sicilian exportation.

Girgenti, the most important town on the south coast of the island, though its dirty miserable streets and its 15,000 inhabitants form a melancholy contrast to the wealth and luxury of ancient Agrigentum, within whose lofty walls a population of 800,000 souls is said to have existed, owes to the increase of the sulphur trade the slight dawn of prosperity which has enlivened it during these latter years.

All the sulphur-pits in the south-west of the island send their produce to the port of Girgenti, and on every road one meets with long files of mules and asses loaded with sacks of sulphur.

The grape disease, against which this mineral is everywhere used in France and Italy as the only successful remedy, has given a new impulse to the sulphur trade by raising the price to about three times its former value. The merchants of Girgenti did not neglect this opportunity for making their fortunes, for as soon as the grape disease became a national calamity for the chief wine-producing countries, they bought up large tracts of sulphur-grounds, and thus acquired considerable wealth.

A visit paid by Dr. HÄckel^[67] in 1859 to the sulphur pits near Girgenti proves that mining operations in Sicily are still in the primitive condition described by all former travellers. Not even our commonest improvements are known; the pickaxe and the spade are almost the only implements employed, and with these the earth is excavated in the most slovenly manner, wherever a vein promises to be productive. The materials thus loosened from the rock are carried out of the mine in baskets and thrown into large heaps, from which the sulphur is extracted in the following wasteful manner. The conical mounds are covered with a mantle of moist clay, in which some openings are left for the emission of the smoke, and set fire to at the bottom. The melted sulphur collects in grooves or channels, and flows into square forms, where it congeals into a solid mass. This method, which is said to have been first introduced by the Saracens, causes, of course, a great loss of sulphur; but distilling ovens heated by coal have been found too expensive to answer. Dr. HÄckel traversed one of the longest excavations, which was sometimes so narrow that he could only with difficulty pass, and then expanded into high vaults whose roof was ornamented with beautiful crystals of celestine and gypsum. The workmen were completely naked, on account of the oppressive heat which reigns in these pits; and their dark brown skins, sprinkled with light yellow sulphur dust, gave them a very strange and savage appearance. Most of the inhabitants of Girgenti are at present employed in the sulphur mines, and comparatively few are engaged in cultivating the beautiful gardens and fields that extend from the foot of the town to the sea, and occupy the site where once the ancient city of Agrigentum rose from the shore to the terraced hills which are still crowned with the ruins of her colossal temples.

On an average, the sulphur-ores of Sicily yield about sixteen per cent. of brimstone, and the quantity annually produced has increased from 94,985 tons in 1851 to 184,173 tons in 1866. Besides Girgenti, the chief ports from which sulphur is exported are those of Licata, Terranova, SiculianaSiculiana, Palermo, Messina, and Catania.

One of the most remarkable events in the history of Sicilian sulphur mines occurred during the last century in the solfatara of Sommatino. This celebrated pit, which is situated on the precipitous right bank of the Salso Valley, took fire in 1787, through the negligence of the workmen, and as may easily be imagined from the inflammable nature of the materials, the conflagration caused the complete abandonment of the pit. After two years, however, during which the fire raged incessantly, the mountain suddenly burst asunder on its south-eastern flank, and a stream of melted sulphur, gushing forth from the cleft, precipitated itself into the neighbouring river. This phenomenon, which was evidently caused by Nature having performed on a vast scale an operation similar to that by which the sulphur is usually extracted from the ore, produced a mass of the purest brimstone, amounting to more than 40,000 tons, so that the owners of the pit, who had given up their property as totally lost, became enriched by the very circumstance which had seemed to menace them with utter ruin.

Next to the sulphur mines of Sicily, those of Teruel and Lorca, in Spain, which in 1862 furnished 12,639 tons, are the most considerable in Europe. The mines of Perticara di Talamella, in Italy, annually yield about 4,000 tons; and the Austrian sulphur pits of Swoszowice, near Cracovia, and of Radoboy, in Croatia, produced 1,867 tons in 1865.

In all these mines the sulphur has been deposited or condensed in times long past, undoubtedly in the same manner as it is formed in the solfataras of the present day, where the decomposition of the volanic gases on reaching the atmosphere causes the precipitation of sulphur.

Most of these still active solfataras are unproductive in a commercial sense, either from their inaccessible position in the crater basins of enormous volcanoes, or from their situation in remote deserts, or from the small quantities of the mineral forming on their surface.

The solfataras of Krisuvick in Iceland, for instance, are separated from the nearest ports by such rugged lava-fields as to render the cost of transport an almost insurmountable obstacle to their being worked with profit. But though undeserving of the mercantile speculator’s attention, these northern sulphur pits rank among the most striking natural wonders of Iceland.^[68]

The remote solfataras of Japan afford a more abundant supply. ‘The sulphur,’ says KÄmpfer, in his history of that singular country, ‘is the produce of a small island which, from the great quantity it affords of this substance, is called “Iwogasima,” or the Sulphur Island. It is not above a hundred years since the natives first ventured to explore that desert spot, which, from the smoke rising from its surface, was previously supposed to be the abode of demons. At length a bold adventurer obtained leave to visit the dreaded island. He chose fifty resolute men to accompany him on his hazardous expedition, and on landing found, instead of the fiends he expected to encounter, a volcanic soil, covered in many parts with thick deposits of sulphur, and emitting dense volumes of smoke from countless fumaroles. Ever since that time the island yields a considerable revenue to the Prince of Satzuma.’

One of the most celebrated solfataras is that of Puzzuoli, near Naples. It may be considered as a nearly extinguished crater, and appears, by the accounts of Strabo and others, to have been before the Christian era in very much its present state, giving vent continually to aqueous vapours, together with sulphureous and muriatic acid gases, like those evolved by Vesuvius. This remarkable spot has attracted the attention of naturalists and poets since the remotest antiquity, and Homer mentions it in his immortal narrative of the peregrinations of Ulysses. The process for the separation of the sulphur, which is condensed in considerable quantities amongst the gravel collected in the circle which forms the interior of the crater, is conducted in the following manner. The mixture of sulphur and gravel is dug up and submitted to distillation, to extract the sulphur; the gravel is then returned to its original place, and in the course of about thirty years is again so rich in sulphur as to serve for the same process once more.

‘The crater of the Peak of Teneriffe,’ says Leopold von Buch, ‘is now but an immense solfatara. The sulphureous vapours which escape from every part of the vast cauldron, decompose the rock, convert it into white clay, and cover it in many places with beautiful crystals of sulphur. By this constant chemical action, the soil towards the centre of the crater has been rendered so soft that in many places great caution is necessary to avoid sinking into the yielding mass, which has a temperature higher than that of boiling water.’

A remarkable sulphur formation occurs on the rocks surrounding the crater of the volcano Alaghez, situated in Northern Armenia. The sulphur is precipitated in thick crusts on their walls, and as the summit of the crater is inaccessible, the people of the neighbourhood, in order to collect the sulphur, fire at it with musket balls, and pick up the fragments thus detached.

Close beneath the summit of the Patuka, in Java, is a circular lake about fifteen hundred feet in diameter. The borders are covered with a rich vegetation; the water is clear and colourless, but appears yellowish from the reflection of the sulphur which covers the whole bottom of the lake. In 1818 Reinwardt found in this piece of water an islet completely composed of sulphur.

After the eruption of the Tashem Idjem, another Javanese volcano, in 1796, such quantities of sulphur were formed that several hundred shiploads could be gathered and exported as the produce of this single volcanic paroxysm.

The mountain BÜdÖshegy, in Transylvania, exhibits the remarkable phenomenon of sulphur caves. On entering one of these vast subterranean crevices, incrustations of sulphur are seen to cover the lower part of the walls; but respiration is still easy and free. On advancing a few steps the air acquires a sharp acidulous taste, and the feet begin to feel a warmth which gradually increases to an intolerable heat. On advancing still further the lights are extinguished. A speedy retreat is necessary, and imprudent visitors have been known to pay for their curiosity with their lives.

In the island of Milo there are likewise numerous caverns the walls of which are incrusted with sulphur and alum. A visit to these grottoes, which annually yield about five hundred tons of pure sulphur, is not without danger from the suffocating fumes that issue from their crevices.

Some of the Arabian volcanoes also produce considerable quantities of sulphur, such as the Dufan, which is called Djebel-el-Kebril, or ‘Sulphur Mountain’ by the Arabs, and is mentioned in the writings of Herodotus.

Though the craters of volcanoes are generally almost inaccessible, yet history mentions a curious instance where the most extraordinary exertions were made for collecting sulphur above the regions of perpetual snow. During the wondrous campaign which ended in the overthrow of the empire of Montezuma, Cortez, being in want of powder, sent a party under Francisco MontaÑo, a cavalier of determined resolution, to gather sulphur from the smoking throat of Popocatepetl, which rises, with its silvery sheet of everlasting snow, to the height of 17,852 feet above the level of the sea. After traversing the lower region, which was clothed with a dense forest, so thickly matted that in some places it was scarcely possible to penetrate it, the track of the Spaniards opened on a black surface of glazed volcanic sand and of lava, the broken fragments of which, arrested in its boiling process in a thousand fantastic forms, opposed continual impediments to their advance. They now came to the limits of perpetual snow, where new difficulties presented themselves, as the treacherous ice gave an imperfect footing, and a false step might precipitate them into the frozen chasms that yawned around. To increase their distress respiration in these aËrial regions became so difficult that every effort was attended with sharp pains in the head and limbs. At length they reached the edge of the crater, which presented an irregular ellipse at its mouth more than a league in circumference. A lurid flame burned gloomily at the bottom, sending up a sulphurous steam, which, cooling as it rose, was precipitated on the walls of the cavity. The party cast lots, and it fell on MontaÑo himself to descend in a basket into this hideous abyss, into which he was lowered by his companions to the depth of four hundred feet! This was repeated several times, till the adventurous cavalier had collected a sufficient quantity of sulphur for the wants of the army.

Many mineral springs owe their medicinal properties to the hydrosulphuric acid which they contain, and whose decomposition frequently gives rise to the formation of sulphur. When the large marble slab which covers the imperial source at Aix-la-Chapelle is removed at the end of every twenty years, about two hundred pounds of sulphur are collected from the walls above the spring.

Combinations of sulphur with metals, particularly with iron and copper (pyrites), occur in much more considerable masses and in a far greater number of localities than the pure uncombined mineral. Formerly the sulphides of iron (52½ per cent. sulphur, 47½ per cent. iron) and copper served only for the fabrication of vitriol and alum; but since the progress of chemical science has allowed them to be profitably used for the manufacture of sulphuric acid, they have acquired a far greater importance. Our own mines, which are situated chiefly in the county of Wicklow, produced in 1866 at least 135,000 tons of iron pyrites, besides which an additional quantity of about 100,000 tons was imported from other countries.

In Southern Spain the mines of cupriferous pyrites—particularly in the province of Huelva, and in the Sierra de Tharsis, which on account of the copper they contain were already worked in times anterior to the Roman occupation, and give proof of their ancient importance by the vast dimensions of their excavations—produced in 1863 no less than 246,137 tons. In Portugal the mines of San Domingos, in the province of Alentejo, likewise afford a remarkable example of the mining industry of the Romans, in the ancient adit which served for draining the works. They merely used the ores that were richest in copper, and rejected the poorer qualities, which form the immense mounds of scoriÆ round the mouth of the excavations. After having been abandoned for many centuries the mines of San Domingos are once more diligently worked. Their newly acquired importance is due chiefly to the enterprise of Mr. James Mason, now Baron of PommorÃo. A railroad nine miles long unites the mine with the left bank of the Guadiana, which has been rendered navigable for larger vessels for a length of ten miles. Moreover the port of PommorÃo has been excavated in the steep bank of the river for the convenient shipping of the pyrites. Before 1858 a solitary hermitage was the only dwelling at San Domingos, which is now a thriving village of five hundred houses, with a handsome church and a railroad station. The number of the workmen employed in 1866 amounted to two thousand, and large works were being erected for the separation of the copper. In 1859 the produce of these mines amounted to 7,887 tons, and in 1866 it had already risen to 167,028 tons, which formed the cargo of 544 ships. Such are the wonderful changes which can be brought about when the right man finds the right place for the employment of his energies. France produced in 1866 about 100,000 tons of pyrites, Prussia 38,248 tons, and Belgium 28,956 tons, so that the total production of Europe now probably amounts to more than a million tons. In Canada the ore of a vast deposit of pyrites is exported to the United States, where it serves for the fabrication of sulphuric acid. Thus a substance scarcely noticed twenty years ago has become an important article of commerce in both hemispheres.