SALT MINES.
Hence with diffusive salt old Ocean steeps,His emerald shallows, and his sapphire deeps.Oft in wide lakes, around their warmer brim,In hollow pyramids the crystals swim;Or, fused by earth-born fires, in cubic blocksShoot their wide forms, and harden into rocks.—Darwin.
Hence with diffusive salt old Ocean steeps,His emerald shallows, and his sapphire deeps.Oft in wide lakes, around their warmer brim,In hollow pyramids the crystals swim;Or, fused by earth-born fires, in cubic blocksShoot their wide forms, and harden into rocks.—Darwin.
Hence with diffusive salt old Ocean steeps,His emerald shallows, and his sapphire deeps.Oft in wide lakes, around their warmer brim,In hollow pyramids the crystals swim;Or, fused by earth-born fires, in cubic blocksShoot their wide forms, and harden into rocks.—Darwin.
Hence with diffusive salt old Ocean steeps,
His emerald shallows, and his sapphire deeps.
Oft in wide lakes, around their warmer brim,
In hollow pyramids the crystals swim;
Or, fused by earth-born fires, in cubic blocks
Shoot their wide forms, and harden into rocks.—Darwin.
Culinary salt, or, as it is termed in chemistry, muriate of soda, exists abundantly in a native state, both in a solid form, and dissolved in water. It occurs, in solution, not only throughout the wide range of the ocean, but in various springs, rivers and lakes; and is known, in its solid form, as a peculiar mineral, under the names ofrock-salt,fossil salt, andsalt-gem. Its beds are mostly beneath the surface of the ground, but sometimes rise into hills of considerable elevation. At Cordova, in Spain, a hill, between four and five hundred feet in hight, is nearly composed of this mineral. But the most celebrated salt mines are those of Wielicza, in Gallicia, commonly called the salt mines of Cracow, those of Tyrol, of Castile, (in Spain,) and of Cheshire, in England. In the province of Lahore, in Hindoostan, is a hill of rock-salt, of equal magnitude with that near Cordova. The mines of Iletski, in Russia, yield vast quantities of this substance. It is so plentiful in the desert of Caramania, and the air so dry, that it is there used as a material for building. It forms the surface of a large part of the northern desert of Lybia; and is found in great abundance in the mountains of Peru. It has a pure saline taste, without any mixture of bitterness; and crystallizes in cubes when obtained by slow evaporation from its solution. In Germany the mines of this kind are numerous: one of the largest is that of Hallein, near Saltzburg, in which the salt is hewn out from subterraneous caverns of a considerable range, and exhibits almost every diversity of color, as yellow, red, blue and white; in consequence of which it is dissolved in water, to be liberated from its impurities, and afterward recrystallized. The salt mines of Cracow, and those of Cheshire, merit a particular description.
Thus, cavern’d round, in Cracow’s mighty mines,With crystal walls a gorgeous city shines;Scoop’d in the briny rock long streets extendTheir hoary course, and glittering domes ascend:Down their bright steeps, emerging into day,Impetuous fountains burst their headlong way,O’er milk-white vales in ivory channels spread,And wondering seek their subterraneous bed.Form’d in pellucid salt, with chisel nice,The pale lamp glittering through the sculptur’d ice,With wild reverted eyes fair Lotta stands,And spreads to heaven, in vain, her glassy hands;Cold dews condense upon her pearly breast,And the big tear rolls lucid down her vest.Far gleaming o’er the town, transparent fanesRear their white towers, and wave their golden vanes:Long lines of lusters pour their trembling rays,And the bright vault resounds with mingled blaze.—Darwin.
Thus, cavern’d round, in Cracow’s mighty mines,With crystal walls a gorgeous city shines;Scoop’d in the briny rock long streets extendTheir hoary course, and glittering domes ascend:Down their bright steeps, emerging into day,Impetuous fountains burst their headlong way,O’er milk-white vales in ivory channels spread,And wondering seek their subterraneous bed.Form’d in pellucid salt, with chisel nice,The pale lamp glittering through the sculptur’d ice,With wild reverted eyes fair Lotta stands,And spreads to heaven, in vain, her glassy hands;Cold dews condense upon her pearly breast,And the big tear rolls lucid down her vest.Far gleaming o’er the town, transparent fanesRear their white towers, and wave their golden vanes:Long lines of lusters pour their trembling rays,And the bright vault resounds with mingled blaze.—Darwin.
Thus, cavern’d round, in Cracow’s mighty mines,With crystal walls a gorgeous city shines;Scoop’d in the briny rock long streets extendTheir hoary course, and glittering domes ascend:Down their bright steeps, emerging into day,Impetuous fountains burst their headlong way,O’er milk-white vales in ivory channels spread,And wondering seek their subterraneous bed.Form’d in pellucid salt, with chisel nice,The pale lamp glittering through the sculptur’d ice,With wild reverted eyes fair Lotta stands,And spreads to heaven, in vain, her glassy hands;Cold dews condense upon her pearly breast,And the big tear rolls lucid down her vest.Far gleaming o’er the town, transparent fanesRear their white towers, and wave their golden vanes:Long lines of lusters pour their trembling rays,And the bright vault resounds with mingled blaze.—Darwin.
Thus, cavern’d round, in Cracow’s mighty mines,
With crystal walls a gorgeous city shines;
Scoop’d in the briny rock long streets extend
Their hoary course, and glittering domes ascend:
Down their bright steeps, emerging into day,
Impetuous fountains burst their headlong way,
O’er milk-white vales in ivory channels spread,
And wondering seek their subterraneous bed.
Form’d in pellucid salt, with chisel nice,
The pale lamp glittering through the sculptur’d ice,
With wild reverted eyes fair Lotta stands,
And spreads to heaven, in vain, her glassy hands;
Cold dews condense upon her pearly breast,
And the big tear rolls lucid down her vest.
Far gleaming o’er the town, transparent fanes
Rear their white towers, and wave their golden vanes:
Long lines of lusters pour their trembling rays,
And the bright vault resounds with mingled blaze.—Darwin.
These celebrated excavations are about five miles distant from the city of Cracow, in a small town named Wielicza, which is entirely undermined, the cavities reaching to a considerable extent beyond its limits. The length of the great mine, a view of which is seen on the next page, from east to west, is six thousand feet; its breadth, from north to south, two thousand; and its greatest depth eight hundred; but the veins of salt are not limited to this extent, the depth and length of them, from east to west, being yet unknown, and their breadth only, hitherto determined. There are at present ten shafts; and not a single spring has been discovered throughout the extent of the mine.
In descending to the bottom, the visitor is surprised to find a kind of subterraneous commonwealth, consisting of many families, who have their peculiar laws and polity. Here are likewise public roads and carriages, horses being employed to draw the salt to the mouths of the mine, where it is taken up by engines. These horses, when once arrived at their destination, never more see the light of the sun; and many of the people seem buried alive in this strange abyss, having been born there, and never stirring out; while others are not denied frequent opportunities of breathing the fresh air in the fields, and enjoying the surrounding prospects. The subterraneous passages, or galleries, are very spacious, and in many of them chapels are hewn out of the rock-salt. In these passages crucifixes are set up, together with the images of saints, before which a light is kept constantly burning. The places where the salt is hewn out, and the empty cavities whence it has been removed, are called chambers, in several of which, where the water has stagnated, the bottoms and sides are covered with very thick incrustations of thousands of salt crystals, lying one on the other, and many of them weighing half a pound and upward. When candles are placed before them, the numerous rays of light reflected by these crystals emit a surprising luster.
GREAT SALT MINE OF CRACOW.
GREAT SALT MINE OF CRACOW.
GREAT SALT MINE OF CRACOW.
In several parts of the mine, huge columns of salt are left standing, to support the rock; and these are very fancifully ornamented. But the most curious object in the inhabited part, or subterraneous town, is a statue which is considered by the immured inhabitants as the actual transmutation of Lot’s wife into a pillar of salt; and in proportion as this statue appears either dry or moist, the state of the weather above ground is inferred. The windings in this mine are so numerous and intricate, that the workmen have frequently lost their way; and several, whose lights have been extinguished, have thus perished. The number of miners to whom it gives employment, is computed at between four and five hundred; but the whole amount of the men employed in it is about seven hundred.
The salt lies near the surface, in large, shapeless masses, from which blocks of sixty, eighty, or a hundred feet square, may be hewn; but at a considerable depth it is found in smaller lumps. About six hundred thousand quintals of salt are dug annually out of the mines of Cracow. The worst and cheapest is called green salt, from its greenish color, occasioned by a heterogenous mixture of a grayish mineral, or clay, and entirely consists of salt crystals of different dimensions. A finer sort is dug out in large blocks; and the third kind is thesal gemmæ, or crystal salt, which is found in small pieces interspersed in the rock, and, when detached from it, breaks into cubes of rectangular prisms. This is usually sold unprepared. The color of the salt stone is a dark gray mixed with yellow.
The Cheshire rock-salt, with very few exceptions, has hitherto been ascertained to exist only in the valleys bordering on the river Weaver and its tributary streams; in some places manifesting its presence by springs impregnated with salt, and in others being known by mines actually carried down into the substance of the salt strata. Between the source of the Weaver and Nantwich, many brine springs make their appearance; and occur again at several places, in proceeding down the stream. At Moulton, a mine has been sunk into the body of rock-salt, and a similar mine is wrought near Middlewich. At Northwich, brine springs are very abundant; and there also many mines have been sunk for the purpose of working out the fossil salt. In that vicinity a body of rock-salt has been met with in searching for coal.
The brines in this district are formed by the penetration of spring or rain waters to the upper surface of the rock-salt, in passing over which they acquire such a degree of strength, that one hundred parts have yielded twenty-seven of pure salt, thus nearly approaching to the perfect saturation of brine. Their strength is therefore much greater than that of the salt springs met with in Hungary, Germany and France. The brine having been pumped out of the pits, is first conveyed into large reservoirs, and afterward drawn off as it is needed, into pans made of wrought iron. Here heat is applied in a degree determined by the nature of the salt to be manufactured, and various additions are made to the brine, with a view either to assist the crystallization of the salt, or to promote the separation of the earthy particles, which exist in a very small proportion. The importance of the manufacture of Cheshire salt will be sufficiently obvious from the statement, that, besides the salt made for home consumption, the annual amount of which has exceeded sixteen thousand tuns, the average of the quantity sent yearly toLiverpool for exportation, has not been less than one hundred and forty thousand tuns.
The mine of rock-salt first worked was discovered by accident at Marbury, near Northwich about a century and a half ago; and this bed had been wrought for more than a century, when, in the same neighborhood, a second and inferior stratum was fallen in with, separated from the former by a bed of indurated clay. This lower stratum was ascertained to possess a very great degree of purity, and freedom from earthy admixture; on which account, and from the local advantages of Northwich for exportation, the fossil salt is worked in the vicinity of that place only. It occurs in two great strata or beds, lying nearly horizontally, and separated, the superincumbent from the subjacent stratum, by several layers of indurated clay, or argillaceous stone. These intervening beds possess, in conjunction, a very uniform thickness of from thirty to thirty-five feet, and are irregularly penetrated by veins of fossil salt. There is every reason to believe that the beds of rock-salt at Northwich, are perfectly distinct from any others in the salt district, and form what are termed by mineralogistsincumbent bodiesormasses of mineral.
These enormous masses stretch a mile and a half in a longitudinal direction from north-east to south-west; but their transverse extent, as measured by a line at right angles from the former, does not exceed forty-two hundred feet, somewhat more than three-quarters of a mile. Without this area, the brine which is met with, is of a very weak and inferior quality, and at a short distance disappears altogether. The thickness of the upper bed varies from sixty to ninety feet; and a general estimate made from its level, shows that its upper surface, which is ninety feet beneath that of the earth, is at least thirty-six feet beneath the low-water mark of the sea at Liverpool; a fact not unimportant in determining the nature of the formation of this mineral. The thickness of the lower bed has not hitherto been ascertained; but the workings are usually begun at the depth of from sixty to seventy-five feet, and are carried down for the space of fifteen or eighteen feet, through what forms the purest portion of the bed. In one of the mines a shaft has been sunk to a level of forty-two feet still lower, without passing through the body of rock-salt. There is thus an ascertained thickness of this bed of about a hundred and twenty feet, and without any direct evidence that it may not extend to a considerably greater depth.
Although two distinct beds, only, of fossil salt have been met with at Northwich, it has been ascertained that the same limitations do not exist throughout the whole of the salt district. At Lawton, near the source of the river Wheelock, three distinct beds have been found, separated by strata of indurated clay: one at the depth of one hundred and twenty-six feet, fourfeet in thickness; a second, thirty feet lower, twelve feet in thickness; and a third, forty-five feet further down, which was sunk into seventy-two feet, without passing through its substance. The intervening clay, the structure of which is very peculiar, is called the shaggy metal, and the fresh water which passes through its pores has the expressive appellation of Roaring Meg. This epithet will not appear too strong, when it is mentioned that in a mine in which the section of strata was taken, and where the “shaggy metal” was found at the depth of about eighty feet, the quantity of water ascertained to issue from its pores in one minute, was not less than three hundred and sixty gallons; a circumstance which greatly enhances the difficulty of passing a shaft down to the body of rock-salt.
In many of these beds of argillaceous stone, a portion of salt, sufficiently strong to affect the taste, is found to exist; and this saltness increases, as might be expected, in proportion as the body of rock-salt is approached. In the strata or layers immediately above the rock, which in all the mines are perfectly uniform in their appearance and structure, this is particularly remarkable, notwithstanding there are not, in these strata, any veins of rock-salt connected with the great mass below. On the contrary, the line between the clay and rock-salt is drawn with great distinctness in every instance, without presenting any of those inequalities which would arise from a mutual penetration of the strata. Not any marine exuviæ, or organic remains, are found in the strata above the rock-salt; and the almost universal occurrence of gypsum, in connection with beds of fossil salt, is a fact still more deserving of observation, because it appears, not only in these mines, but also in the salt mines of Hungary, Poland and Transylvania; on which account Werner, in his geognostic system, assigns to the rock-salt and fletz gypsum a conjunct situation.
The fossil salt extracted from the Northwich mines is of different degrees of purity, and more or less blended with earthy and metallic substances. The purer portion of the lower bed yields a rock-salt, which, being principally exported to the Baltic, obtains the name of Prussian rock. The extent of the cavity formed by the workings, varies in different mines, the average depth being about sixteen feet. In some of the pits, where pillars from eighteen to twenty-four feet square form the supports of the mine, the appearance of the cavity is singularly striking, and the brilliancy of the effect is greatly increased when the mine is illuminated by candles fixed to the sides of the rock. The scene thus formed almost appears to realize the magic palaces of eastern poets. Some of the pits are worked in aisles or streets, but the choice here is wholly arbitrary. Among the methods employed in working out the rock-salt, the operation of blasting is applied to the separation of largemasses from the body of the rock, and these are afterward broken down by the mechanical implements in common use. The present number of mines is eleven or twelve, from which there are raised, on an annual average, fifty or sixty thousand tuns of rock-salt. The greater part of this quantity is exported to Ireland and the Baltic, the remainder being employed in the Cheshire district, in the manufacture of white salt, by solution and subsequent evaporation.
The general situation occupied by the rock-salt in Cheshire is very similar to that of the Transylvanian and Polish mines, the beds of this mineral being disposed in small plains, bounded by hills of inconsiderable hight, forming a kind of basin or hollow, from which there is usually only a narrow egress for the waters. The situation of the Austrian salt mines near Saltzburg is, however, very different. The mineral there appears to be disposed in beds of great thickness, which occur near the summits of limestone hills, at a great elevation above the adjoining country. This is a singular fact; and if the hypothesis be allowed that rock-salt is formed from the waters of the sea, it is necessary to suppose the occurrence on this spot of the most vast and surprising changes!
Though there are no saltminesin the United States, there are saltspringsin several places. By far the most important and valuable of these, are in the neighborhood of Syracuse, in the state of New York. The land containing these springs, is owned by the state, and is leased free of rent, to be used only for the manufacture of salt. The wells are dug, and the water pumped up at the expense of the state, and the manufacturer pays a duty of one cent on each bushel he makes. Some of the wells are sunk to the depth of four hundred feet. Fine salt is prepared by boiling; and coarse by solar evaporation. In 1850, the number of salt manufactories in this vicinity was one hundred and ninety-two; and the quantity of salt produced in 1853, amounted to more than five million bushels. The salt of this region has been thoroughly tested, and found to be fully equal to any of foreign manufacture.