The History of Salt

In some countries there are vast quantities of rock or fossil salt. Salt has been divided into three kinds: native or rock salt; common or sea salt, also called white-salt; and bay-salt. Under the title of bay-salt are ranked all kinds of common salt, extracted from the water, wherever it is dissolved by means of the sun’s heat and the operation of the air. If sea-water is evaporated by means of a gentle heat we also obtain what is known as bay-salt. Common salt, or sea-salt, or white-salt, which is extracted from the sea, is composed of hydrochloric acid, saturated with soda, and is found in salt water and salt-springs, also in coal and gypsum-beds. “The sea itself, if desiccated, would afford a bed of salt five hundred feet thick, one hundred for every mile.”

In England, and especially in Cheshire, there are large salt-mines, at Nantwich and Middlewich, which have existed ever since the Roman occupation of Britain; and in the year 1670 the Staffordshire salt-mines were discovered, and accordingly excavated. Those in Cheshire have been renowned for centuries; their great extent is such that the surface has subsided on account of its being undermined for so many miles.

“In England, the Trias is the chief repository of salt, or chloride of sodium; and brine-springs, which are subterranean streams of water impregnated with salt from percolating through saliferous strata, are abundant in the great plain of the red marls and sandstones of Cheshire. The salt, however, is not uniform in extent, but occupies limited areas.” The saliferous strata of Northwich present the following series:

Droitwich, in Worcestershire, which is situated nearly in the centre of the county, has been celebrated for the production of salt from its brine-springs from the time of the Romans, who imposed a tax on the Britons, who, it appears, worked the mines; and also made salt a part of the pay of their soldiers’ salarium, or salary.[32 - Hence arose the custom of asking for salt at the Eton Montem.] Ever since, this inexhaustible fountain of saline water has continued flowing up, and yielding salt in undiminished quantities. It is very likely that the manufacture is coëval with the town itself; but it was not till the year 1725 that the strong brine for which it is now celebrated was discovered. From one spring, even, the enormous amount of one thousand tons of salt are obtained every week. At the depth of thirty or forty feet is a bed of hard gypsum, about one hundred and fifty feet in thickness; through this a small hole is bored to the stream of brine, which is about twenty-two inches in depth, and beneath this is the rock-salt. The brine rising quickly through the aperture is pumped into a capacious reservoir, whence it is conveyed into iron boilers for evaporation. It is supposed to be much stronger than any other in the kingdom, containing above one-fourth part its weight of salt. “One of the shafts is sunk to a depth of nearly five hundred feet, and passes through four layers of salt, eighty-five feet in aggregate thickness. Some of the beds of salt in Cheshire are from seventy to one hundred and twenty feet in thickness;” and it is sometimes so hard that it requires to be blasted with gunpowder.

In those districts where the marls of the Trias are covered by other beds, and the salt-springs force their way through the superincumbent deposits to the surface, these solutions of the chloride of sodium undergo a chemical change, acquiring other properties, and are then called mineral waters. The Cheltenham waters originate thus.[33 - Sir R. S. Murchison, “The Mineral Springs of Gloucestershire and Worcestershire.”] Beneath the town of Cheltenham lie the Triassic deposits, the reservoir of the rock-salt and brine-springs, which generate the mineral waters, and from which they derive their saline ingredients. In their passage to the surface they go through various modifications, by reason of the superincumbent beds of Lias, which are impregnated with iron pyrites and the sulphate of lime. From the analyses of these waters, it appears that their principal constituents are the chloride of sodium (muriate of soda), or sea-salt, and the sulphates of soda and magnesia. Sulphate of lime, oxide of iron, and the chloride of magnesium are present in some wells only, and in much smaller quantities. Besides these ingredients, iodine and bromine have been detected by Dr. Daubeny, who instituted experiments to ascertain whether these two active principles, which the French chemists had recently discovered in modern marine productions, did not exist in mineral waters issuing from strata formed in the ancient seas. As the saline springs of the red marls rise up through the Lias they undergo certain chemical changes. From the decomposition of the sulphate of iron which takes place, a vast quantity of sulphuric acid must be generated, which, reacting on the different bases of magnesia, lime, etc., contained in the strata, forms those sulphates so prevalent in the higher or pyritous beds of the Lias; the oxide of iron being at the same time more or less completely separated. By this means the mineral waters, which are probably mere brine-springs at the greatest depths, acquire additional medicinal qualities as they ascend to the places whence they flow. At the same time, it must be borne in mind that fresh water is continually falling from the atmosphere upon the surface of the Lias clays, and percolating through the uppermost strata.[34 - Dr. Mantell’s “Wonders of Geology.”]

The medicinal properties which are peculiar to these mineral waters will be considered further on, when we come to discuss the action of salt on the system, in health and disease, and the restorative results which are due solely to its instrumentality.

The salt district is in the line which joins the Severn, the Dee, and the Mersey, and doubtless once consisted of lakes flooded at every tide, which, drying at certain seasons and at low tides, deposited beds of salt, from Droitwich in Worcestershire, through Nantwich, to the Mersey; brine-springs flowing over beds of salt, or rock-salt, being found at different places on the entire line.

In the year 1863 a bed of rock-salt was discovered near the mouth of the Tees, at Middlesborough, and also on the Durham side of the river. The boring at Middlesborough showed that it was about 100 feet in thickness. Of late, borings have been made near Port Clarence, on the Durham side, but with what result I am not informed.

Scotland, as well as Ireland, is deficient in the more recent formation; for salt, as well as chalk, does not occur. Both are entirely absent; but geologists inform us that at one time chalk did exist, judging from the presence of flints in considerable quantities in Aberdeenshire, which they say affords unequivocal evidence of the former presence of cretaceous strata now integrated; and they account for it thus: the soft chalk being exposed to the action of the rain and storms, has been gradually washed away, while the flints which were embedded in it still remain. If this hypothesis is correct, that at one time chalk existed and is now absent, we may by inference, though we possess no evidence, presume that salt likewise, at some period or other, was present in this part of the United Kingdom. Chalk being entirely composed of the accumulation of marine shells ground to impalpable powder, which has been gradually consolidated, and being very rich in organic remains of shells, star-fish, sponges, fishes, and lizards, must have been deposited by sea-water, as its various ingredients indicate; therefore, during its deposition, salt, if originating from sea-water, must of necessity have left some marks characteristic of itself, in conjunction with the chalk; both being, more or less, intimately connected with sea-water, though the formation of one may not have been simultaneous with the formation of the other.[35 - There are the noted salt-works near Portobello, Edinburgh, which have been so truthfully presented to us on canvas by Mr. Edward Duncan.]

In our lately acquired “gem of the sea,” Cyprus, there have been found extensive lakes of salt near Larnaca, the capital, so that this liberally-abused island possesses at least something which may prove of pecuniary value to its present owners. Being for several centuries under the benighted rule of the Turk, this staple of commerce has been entirely neglected, so as not to have been of the slightest use to the inhabitants or to the greedy pachas.

In the south of Western Australia there are vast salt marshes which only require to be worked so as to become the means of enriching the colonists, and indirectly attracting emigrants to this hitherto unprofitable portion of a dependency of England. The principal, which is called Lake Austen, is 1400 feet above the level of the sea.

Salt is also to be found in our Indian Empire, in Rajpootana and elsewhere, and is of considerable value to that country, especially while it remains in the hands of the enterprising European; according to Mr. Wynne, there is a salt range which extends from Kalabagh to a point north of Tank. After acquainting us with its geographical position, he says: “The coincidence between the physical features and the geological structure of the ground is intimate, the axial lines of the mountains carrying on the Salt Range feature being also axes of anticlinals lying for the most part along the scarped acclivities presented towards the Indus plains. These plains are part of the great quasi-desert flat over which the Indus has in past times capriciously wandered towards the Arabian Sea. Whether they are due in any degree to marine explosion is uncertain, though the sea may very possibly once have covered the low ground in question. The ridges of the Salt Range, as they exist at present, doubtless mark the same great later, or post-tertiary, period of mountain-forming activity, in which originated not only the remainder of the Salt Range, but also the Western Himalaya and the Suliman and Afghan mountains.” When we come to consider the geological bearings of salt, and its presumed origin, and other points in connection with it, I shall again revert to this highly interesting paper of Mr. Wynne’s.

In the Deccan, half-way between Bombay and Nagpur, there is a very remarkable salt lake. It is a circular hollow, about one mile across, and from 300 to 400 feet deep, having at the bottom a shallow lake of salt water without any outlet. This hollow, I must tell my reader, is ascribed by scientific men to a volcanic explosion.

There are so many lakes of salt, which are completely isolated and so many miles from the sea, that it is next to impossible to account for their existence if we do not ascribe them to volcanic action. If they are situated in low-lying districts, we may justly presume that at one time the sea must have been present, or that the deposition must have resulted from occasional, or tidal, overflow of salt water; but when they are many miles from the coast, and many feet above or below the sea-level, then they may be due to volcanic agency; and we shall find further on several other salt lakes of variable depths or altitudes which would seem to corroborate this hypothesis. The sea is undoubtedly a most formidable agent in the disintegration of land, and often destroys whole tracts, forcing its resistless waves into the interior of continents, and then, owing to some unexplained cause, retiring to its original boundary. This may take centuries to complete, for revolutions effected by nature are not accomplished speedily, unless there is some sudden spasmodic upheaving, arising from earthquakes or storms. In 1282, the isthmus uniting Friesland with the north of Holland was totally destroyed by violent storms. In our own country a similar phenomenon occurred in the year 1475, when a large tongue of land at the mouth of the Humber was entirely broken up and carried away by the sea. In 1510 an irruption of the Baltic formed the Frische-Haff, an opening 6000 feet broad, and from twelve to fifteen fathoms in depth. The eastern coast of England is continually receding, owing to the encroachment of the sea. The rate of encroachment of the sea at Owthorne, in Yorkshire, is reckoned at four yards in every year, and several villages have been swallowed up by the ocean; and in like manner the cliffs of Norfolk and Suffolk are suffering a continual decay.

Though the sea is so destructive an element, it is also an agent in the reproduction of land. The rocks and sand washed away from one place are conveyed by tides and currents far into the sea, and are deposited in strata, and then, in course of time, form shoals and banks, which subsequently become promontories and islands. Alluvial land has thus been formed, and in a similar way have many of the stratified rocks been deposited; and as animals and plants have been carried away and imbedded in the deposits of rivers, or floods, so at some future period, though countless ages may elapse during the process, will such animals and plants be discovered deposited in these newer strata, just as we find organic remains in the older rocks. The gradual deposition of strata has been the work of an incalculable period of time, but the process may be traced every day in the sections of marine estuaries and lakes. Owing to this continual receding of the land in one part, and elevation of land in another, there is an incessant change, from which, though occupying many ages, and proceeding so slowly that it would be unobservable were it not for accurate investigation, we may easily conjecture that what is now land may at one time have been the bed of the ocean, and where the sea now sweeps with overpowering fury, there may once have been meadows and forests. The salt lakes, if not originating from volcanic force, no doubt are the remains of the great ocean, which, when it receded, left here and there, in what once were luxuriant valleys, large reservoirs, indicating that in bygone ages it had covered the land.

In Germany, Spain, Italy, Hungary, and Poland, there are extensive mines of rock-salt, and also in various other parts of Europe.[36 - In Prussia salt is obtained from the brine-springs of that part of Saxony which is subject to her jurisdiction. It also exists in abundance in Bavaria and Würtemberg; and it is the chief mineral production of the Grand Duchy of Baden.] There are also large mountains wholly composed of this fossil salt, two of which are in those provinces of Russia known as Astrakhan and Orenburg; and in the Crimea salt is said to be daily accumulating in the inland lakes. In Asiatic Russia there are extensive beds of salt, near Lake Indur, in lat. 48° 30´, long. 69°. The Caspian Sea, called by the Turks “Cozgoun Denghizi,” “the sea of crows and cormorants,” is “a great salt-water lake,” according to Dr. William Smith, though Dr. Lemprière says that “its waters are sweet.”

The most interesting salt-mine is that of Wieliczka, near Cracow, in Galicia; it has been celebrated for centuries, and has been worked for the last six hundred years. This wonderful mine is excavated in a ridge of hills at the northern extremity of the chain which joins the Carpathian mountains. When the stranger reaches the mine there bursts upon his view a little world, the beauty of which is scarcely to be imagined. He beholds a spacious plain containing a kind of subterranean city, with houses, carriages, and roads, all scooped out of one vast rock of salt, as bright and glittering as crystal, while the blaze of the lights continually burning for the general use is reflected from the dazzling columns which support the lofty arched vaults of the mine, which are beautifully tinged with all the colours of the rainbow, and sparkle with the lustre of precious stones, affording a more splendid and fairy-like aspect than anything above ground can possibly exhibit. In various parts of this spacious plain stand the huts of the miners and their families, some single, and others in clusters, like villages. They have very little communication with the world above them, and many hundreds of persons are born and pass the whole of their lives here.

Through the midst of this plain lies a road which is always filled with carriages laden with masses of salt from the furthest part of the mine. The drivers are generally singing, and the salt looks like a load of gems. A great number of horses are kept in the mine, and, when once let down, never see daylight again.

Such is the marvellous salt-mine of Wieliczka, which is more renowned on account of its magnitude, its age, and the weird and almost supernatural aspect it presents to the visitor, than any other. Those subterranean palaces, with their magnificent appurtenances, their fantastic occupants, and other dreams of the imaginative, are not more strange or astonishing to the fascinated reader of romance than this extraordinary, glistening, cavernous, mineral city, with its numerous lamps, its crystallised walls, its roads, and the plaintive songs of the drivers as they drive their horses through its sunless thoroughfares, presents to the eyes of the surprised traveller.

There are valuable mines of salt in France, and in Greece, near Missolonghi, but these have no special points of interest connected with them.

In Abyssinia there are extensive and inexhaustible beds of salt, which is used in quite a different way from what it is in other countries, for little bars of it are circulated in place of small coin; but it is only when it reaches the Amhara and Galla districts that it becomes valuable.[37 - “In one village they only found one earthen pot containing food, which Bruce took possession of, leaving in its place a wedge of salt, which, strange to say, is still used as small money in Gondar and all over Abyssinia.” – Bruce’s “Travels in Abyssinia.”]

In other parts of the African continent there are large mountains of rock-salt, and those of Tunis and Algiers are especially notable.

Salt is also to be found in Asia, in large mountains, in marshes, and in lakes, to some of which I have already alluded. In the north of Persia there is a large salt desert, and near Ispahan there are quantities of rock-salt. The island of Ormuz, in the Persian Gulf, almost consists of fossil salt; it is indeed so very plentiful that the atmosphere is completely charged with it, so that the dwellings of the inhabitants are encrusted with a tolerable thick layer, giving them a peculiar glistening appearance; this phenomenon is owing to the small particles of salt continually floating in the air and rising from the ground, much in the same way as we see dew deposited on the top of a garden wall or on a lawn after a hot summer’s day.

We learn from Herodotus that there was a salt lake in Phrygia, in Asia Minor. “Having so said, and fulfilled his promise, Xerxes continued his route onwards. After passing by a city of Phrygia, called Anaua, and a lake out of which salt is produced, he came to Colossæ, a large city of Phrygia.”[38 - Polymnia, book vii. chap. xxx.] I have previously alluded to the Dead Sea and the interesting phenomena which it presents; due south of it is the Valley of Salt.

There are salt springs and springs from inflammable gas in China, in long. 101° 29´, lat. 29°, near Thibet; and there is a large salt lake possessing the strange name of Tsomoriri, many feet above the level of the sea, in Western Thibet.[39 - The geographical features of this almost unknown country are peculiarly interesting, and are unique when compared with others; the great height of its mountains, its remarkable elevation, the large rivers which take their rise here, and the numerous salt lakes, the altitude of some being from 13,800 to 15,400 feet above the level of the sea, all combine to excite our curiosity, which is increased by the fact that we know next to nothing of the interior or of the habits of the people.] “The Chinese bore well through the rocks, and prepare the salt by firing the gas of others, so that one heats 300 kettles by gas-fire.” The celestials, with their habitual aptitude and industry, have obtained this salt for many centuries, and simply by this ingenious method.

As a fact illustrating the value of salt in Siberia, I may as well mention that in our own country a ton of salt is sold for fifteen shillings, whilst on the Yenesei river as much as fifteen pounds is given for the same quantity. The Muscovite we thus see is as acutely alive to the beneficent results of a free use of salt as a dietetic, as we English, and it would seem as if he were more so.

In some countries remote from the sea, which are devoid of salt-mines, and where the water is not impregnated with it, the inhabitants, aware of its usefulness, have a method of extracting it from the ashes of vegetables. This fact would certainly seem to indicate that salt has been used by various nations, as if mankind had an intuitive knowledge of the benefits arising from the use of salt, and that consequently, if there were no lakes containing it, or mountains from which they could procure it, they were determined to obtain it if even by artificial means.

As an illustration of the presence of salt in places distant from the sea, I need only refer to the Great Salt Lake of Utah, on the shores of which stand the Mormon city. Long before the founder of the Latter Day Saints thought of establishing a quasi-religious community, travellers who had the temerity to wander over the wild prairies of the Oregon, the home of the bison and the hunting-ground of the Indian, and who explored the secrets of the then unknown land of the “Far West,” were struck with amazement at the glistening aspect of the surface; for in many places it was covered over with an impure kind of salt, apparently a combination of muriate and sulphate of soda,[40 - “Many springs in Sicily contain muriate of soda; and the ‘fuime salso’ in particular is impregnated with so large a quantity that cattle refuse to drink it. There is a hot spring at St. Nectaire, in Auvergne, which may be mentioned as one of many, containing a large proportion of muriate of soda, together with magnesia and other ingredients.” – Sir Charles Lyell’s “Principles of Geology.”] or more probably an impure form of the chloride of sodium. On tasting the water which had collected in numerous little pools of no more than a few inches in depth, they found it so bitter and pungent that it acted on the mucous membrane almost as powerfully as a corrosive poison. This large tract of country was at that time teeming with life, for they daily saw vast herds of bisons, and frequently came upon the hidden towns of the prairie-dog; in fact, wherever they went, they either crossed the path of these wild denizens of the plain, or else the sky was darkened by innumerable flocks of birds. The district was wonderfully healthy, and totally free from malaria or other causes generative of disease; the Indians, too, were splendid specimens of humanity; they had not as yet been tainted by too close a proximity with the so-called superior civilisation of the white man, neither had they been so unfortunate as to have fallen a prey to the vices and diseases which generally accompany the humanising European.

On the pampas of La Plata, which is the treeless abode of the wild horses of South America, there are several salt lakes, not many miles distant from the river Quinto, and over these boundless wastes thousands of wild cattle and horses gallop at pleasure, and afford an inexhaustible stock of game for the lasso of the fearless and expert Gaucho. Now it is a well-authenticated fact that those diseases which are so destructive to the horses and cattle of Europe are almost unknown in these regions. I do not mean to assert that these salt lakes of La Plata account for the exemption which this district enjoys from equine diseases; but there is no doubt that the exhalations from them purify the atmosphere, and that their influence extends for many miles because of the open nature of the country. As a natural result, the whole region is constantly kept in a healthy state; for air, charged with the chloride of sodium, must of necessity act as a preventive to everything inimical to health, and pure air we know (though how few really know what that blessing is) is of a paramount importance in the rearing of cattle. The foot-and-mouth disease, comparatively, has never played such havoc as it does in Europe, and pneumonia, which is almost intractable to treatment in this part of the world, and which is frequently fatal when it is complicated with inflammation of the pleura, hardly ever appears in these parts, where stables and farms are not far off from being rudimentary in construction, and would appear to an English farmer, accustomed to the cosy-looking farmsteads of his own country, very ill-calculated for successful farming, and not at all adapted for bringing his cattle and horses to perfection; yet it is just the reverse, for there is no other part of South America so well fitted for the breeding of cattle, and there is no other locality, whether in the Old or New Worlds, so completely free from disease as the open pampas of La Plata.

CHAPTER V

GEOLOGICAL FORMATION OF SALT

Sir Isaac Newton, in his incomparable work upon Optics, likens a particle of salt to a chaos, because of its “being dense, hard, dry, earthy in the centre; and rare, soft and moist in the circumference.” This ingenious definition is what one would expect from such an observant and profound investigator; and I do not think that we shall be able to find a better description of a salt-crystal than that which this great philosopher has bequeathed us.

Regarding the original formation of rock-salt, there are many opinions, theories and conjectures, and to the present day it is an undecided question. We are, as I have previously stated, in complete ignorance of the origin of the chloride of sodium; we must consider it as one of those geological secrets upon which we shall never be able to enlighten ourselves, if we cannot obtain stronger evidence than that which we have at present. Science is at fault in this, as she is in many other subjects which have perplexed and interested from time to time those who study and seek to unravel the various obscure and complicated phenomena of nature.

No satisfactory or elucidatory theory has, as yet, been advanced to account for the occurrence of the formation of salt. Some geologists have maintained that it was deposited from the ocean, but in what way they do not explain; indeed, it is difficult to suppose how it could have been so, for salt, or rather sea water, holds in solution many ingredients which are not present in this rock. Besides, the several strata above it contain organic remains, as do also those below, though altogether of an entirely different kind; rock-salt itself contains none whatever; from this fact some have inferred that the formation took place during the epoch which elapsed between the destruction of one creation and the calling of another into existence. Others suppose that it is simply the result of volcanic action: this hypothesis is correct to a certain extent, as far as isolated salt lakes like that of Tsomoriri in Western Thibet, and that lake midway between Bombay and Nagpur, are concerned; or those huge mountains consisting entirely of fossil salt, like the one near Cardona, fifty miles from Barcelona, in Spain, or those in Lahore, or in Peru; but it altogether fails as regards non-isolated salt lakes and salt marshes, or such a large inland sea as the Caspian. Some light may be thrown upon it by the recent explorations in the North-Western Provinces of India, for Mr. Wynne tells us that “the geological structure” (of the Indian Salt Range) “of the trans-Indus extension of the Salt Range repeats in a great measure that of the western portion of the Salt Range proper, but with some considerable differences. The Palœozoic rocks, so far as presented by the red-marl, rock-salt, and gypsum, are quite the same, and so are the Carboniferous and Triassic groups, but others of the sub-Carboniferous beds present themselves with a different association from those of cis-Indus.” Mr. Wynne also informs us that the mineral productions of the range are valuable, and consist of the salt of Kalabagh and the Lun Nullah, the alum of Kalabagh and the Chichali Pass, the coal or lignite from the Jurassic[41 - The Jurassic formation presents a remarkable contrast with that of the Triassic, in the profusion of organic remains; for while the latter contains next to none, the former teems with marine fossils, a proof that the strata were unfavourable for the preservation of organic structures. – Dr. Mantell’s “Wonders of Geology.”] beds of the Kalabagh Hills: we also learn that gypsum is present with the salt, as it is in Poland, Transylvania, and Hungary; for in these three countries there is a layer of gypsum between the stratum of stone and the bed of salt. This gypsiferous layer is of various colours; it is crystallised, striated, and mixed with sea-shells: this admixture would decidedly lead us to conclude that the salt was originally deposited in bygone ages from the sea. On the contrary, the salt in Cheshire is not accompanied by a bed of gypsum, there are no vestiges of marine exuviæ, nor indeed any organic remains to be detected in any of the strata.

If the formation of salt (I am referring to mountains of rock-salt such as we see near Cordova, in Spain,[42 - There is a mountain composed entirely of rock-salt not far from this old Moorish city; it is 500 feet in height and three miles in circumference; it is completely isolated, and gypsum is also present. In other countries there are similar enormous masses, which require to be dug out and pulverised by machinery on account of their hardness.] and salt-mines as we see in Galicia, and Cheshire, and also isolated salt lakes, like that which exists in Western Thibet) is solely due to volcanic action, or marine explosion, we may easily account for its irregular and unequal distribution; also for its elevation into mountains, and as beds beneath the surface of the earth, by reason of the greater or less force which was employed for its upheaval; and also the thickness or solidity of those strata of rocks through which it was propelled in its upward course. If this were so, it is strange that it should be entirely free from organic remains, whose absence therefore is a formidable objection to this theory. Being accompanied by gypsum in some districts and not in others, would decidedly point to the presumed fact that salt has been the result of some volcanic agency; for were it not so we should find, on the contrary, owing to gradual formation, that gypsum would invariably be present with it, in the same way as we find one stratum of rock either above or below the stratum of another rock.

From the fact that deposits of salt are not confined to any particular group of strata – for while the salt-mines of Galicia belong to the tertiary formations, those in the State of New York are found in the middle of the Silurian system – we may say that salt is not subject to geological laws by reason of its somewhat erratic appearances in different strata. As the chlorides of sodium and gypsum are frequently sublimed from volcanic vents, an igneous origin has been ascribed to many of the beds of salt and gypsum; and Mr. Bakewell threw out the suggestion that the consolidation of both salt and gypsum must have been effected by heat, because the great deposit of gypsum that occurs with rock-salt at Bex, in Switzerland, was found by M. Carpentier to be anhydrous when exposed to the atmosphere. If this hypothesis is correct, and if salt and gypsum[43 - Gypsum, or sulphate of lime, consists of sulphuric acid 46·31, lime 32·90, and water 20·79. The massive gypsum is called Alabaster; the transparent gypsum Selenite; powdered calcined gypsum forms Plaster of Paris. The fibrous gypsum has a silken lustre, and is used for ear-rings, brooches, and other ornaments. Fibrous gypsum of great beauty occurs in Derbyshire; veins and masses of this substance abound in the red marls bordering the valley of the Trent.] were at some period in a state of fusion, it is difficult to believe that when consolidated they are so perfectly distinct and in two different strata, so that one contains organic remains, whilst the other is altogether free from the slightest vestige. It may have been possible that one was in a state of fusion when the other was consolidated, and different degrees of heat might have been necessary for the purpose.

We also may account for the absence of organic remains in rock-salt to the following cause: the chloride of sodium, when in a state of fusion, might have possessed the property of disintegrating, dissolving, and absorbing within itself, however minute they might be, all particles of organic matter with which it came into contact. Dr. Mantell writes: “It cannot, however, be with certainty determined whether the absence or paucity of fossils in a deposit is owing to the actual reduction of the amount of life in the seas of a given area, or to the mineral character of the strata not having been favourable to the preservation of organic remains.”

A very serious difficulty presents itself in the great thickness of many strata of salt; which, if regarded as the solid residuum of sea-water, must have necessarily required a proportionate volume of water, unless the seas of those distant periods contained a larger amount of saline ingredients than they do at the present time: an inference for which there are no reasonable grounds.

Wherever there are deposits of the chloride of sodium, they are almost always accompanied with layers and intercalations of gypsum; and the peculiar circumstance of two powerful acids, the sulphuric (in the gypsum, or sulphate of lime), and the muriatic or hydrochloric (in the chloride of sodium), being so abundantly and uniformly present, seems to point to a common origin; both are productions of volcanic agency, though of the two I think salt frequently owes its origin more to the subterranean activity than the gypsum, because we find there are beds of salt where there is no gypsum, and isolated salt lakes which might have been elevated into mountains had the process, during their production, been of the same force as that used in the formation of rock-salt, owing to an unexplainable interruption and premature desinence.

The relation between the formation of gypsum and volcanic action seems to be borne out by the fact that in North America, where the coal measures are not associated with rocks resulting from volcanic agency, there are no gypsum-beds; while on the contrary, there are large deposits of gypsum, where igneous rocks are interpolated beneath the stratum of coal, in Nova Scotia.[44 - Geological Journal, vol. iii. p. 257.]

Sir Charles Lyell, after a careful inquiry into the phenomena exhibited by these strata of gypsum, gives his opinion that the production of these gypsiferous beds in the carboniferous sea was closely connected with volcanic agency, whether in the form of heated vapours or stufas, or of hot mineral springs, or some other effects resulting from submarine igneous irruptions.

Salt or brine springs occur in various parts of the United States in the old transition slate rocks. Sir Charles Lyell tells us that, “in the middle of the horizontal Silurian rocks, in the State of New York, there is a formation of red, green, and blueish-grey marls, with beds of gypsum, and occasional salt-springs, the whole being from 800 to 1000 feet, and indistinguishable in mineral character from parts of the Trias of Europe.” Salt-springs also occur in England in the coal measures. The rock-salt of Cheshire and the brine-springs of Worcestershire occur in what is called the old red sandstone group. The salt of Ischl, in the Austrian Alps, belongs to the oolitic, as does also that found in the Lias of Switzerland. The immense mass or bed of salt near Cordova occurs in the cretaceous group; while the salt deposit of Wieliczka belongs to the supracretaceous group.[45 - Pereira’s “Materia Medica,” vol. i. p. 581.]

The reader doubtless remembers, as I stated in the first chapter, that the origin of salt is one of those enigmas of nature which, as yet, has completely frustrated the most accomplished and scientific geologists, and no suggestion has yet been made which will satisfactorily and conclusively account for its formation; for whatever hypothesis has been stated, there is sure to be an objection so difficult to overcome, that the author has been fain to admit that it is thoroughly impracticable, and therefore inadmissible. That it is decidedly not amenable to the received laws of geology, is apparent, which all must admit; therefore one cannot possibly apply them so as to determine the place it occupies in relation to other strata, or practically fix that period of time in which it was deposited; for it is erratic, and its position is anomalous – erratic in the variety of appearances it assumes in creation, and anomalous because it belongs to no particular strata, and therefore no exact period of time can be assigned to it as to other formations.

That salt is either due to volcanic agency, marine explosion, or to overflow of sea-water and subsequent evaporation, or resilience, and ultimate deposition, are the only three hypotheses which can with any credibility be advanced to account for its formation.

That we have it presented to us in six different conformations are facts which when considered separately seem to point to one common origin, but when taken as a whole indicate a separate inception.

Is it due to volcanic agency? In some respects it undoubtedly is, otherwise how can we reasonably account for those gigantic mountains of fossil or rock salt, which rise up isolated in the midst of a country perfectly free for miles round of saline deposits, which present not even the slightest trace of it? How can we account for it by any other means when we find it in intimate relation with gypsum, which we know is solely the production of subterranean activity? What reason can we possibly assign for those salt lakes which are above or below the sea-level and are perfectly solitary, and which have no communication with the sea or with rivers, if they are not phenomena resulting from volcanic agency? And how can we account for those masses of salt below the earth’s surface which in some countries is of such adamantine hardness that it requires to be blasted with gunpowder, if it is not the production of volcanic force? If so, why is it that no remains of organic matter are found imbedded in it? How comes it, if it is the result of subterranean agency, that organic remains are found in the gypsum and none in the salt, when both are caused by volcanic explosion? Thus we see the theory of volcanic explosion is met with a most formidable objection.

If marine explosion is the sole cause of the formation of salt, and if the sea has through rents and crevices of the earth forced up its superabundant saline constituents wherever there has been a vent for their egress, and which has in the course of time become condensed owing to the evaporation of the water or through its percolating into the lower strata, another difficulty crops up quite as unanswerable seemingly as that which stands in the way of the volcanic hypothesis: there are no remains of marine organisms to be found, nor are there any traces of vegetable matter.

The overflow and evaporation of sea-water and the subsequent deposition of salt holds good in certain respects as regards salt lakes and salt marshes when they are in close proximity or in the same locality; but then those other inorganic constituents which are found as a general rule in sea-water are not present in those open reservoirs, which is a difficulty as formidable as the others, and admits of no evasion.

These are the three hypotheses with their obstacles; the hypotheses feasible, the obstacles apparently unanswerable.

We have salt, or the chloride of sodium, presented to us in six different conditions, viz.: sea or salt water, salt or brine springs, salt lakes, salt mines, mountain or fossil or rock salt, and salt marshes. The characteristics of salt are just the same fundamentally, whether we extract it by evaporation from sea-water or salt lakes; whether we obtain it from salt-springs; whether we dig it out of the earth or by the excavation of salt mountains; or whether we acquire it from salt marshes: there is no alteration in its ingredients, though it may be impure from the admixture of arsenic or the sulphates of soda and magnesia, or other impurities, or it may be discoloured red by the oxide of iron derived from decomposed trap-rocks; still, for all that, the chloride of sodium remains intact. The properties of salt are not subject to the slightest change or modification: the acid is the hydrochloric or muriatic, the base sodium, and the combination, the chloride of sodium.