The History of Salt
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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 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 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 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 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 Jurassic41 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 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 gypsum43 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
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
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.
We find salt, or the chloride of sodium, in sea-water, the amount averaging from 4 to 5·7 per cent., so that we see it is present in no inconsiderable quantity; it is more or less impure from other salts being held in solution in conjunction: where it comes from no suggestion has yet been broached. We know that it is present, and we also know that it can be obtained by adopting certain measures for extracting it; and we are aware, from recent investigations, that the colour and density of the sea is dependent on the quantity held in solution. This is all we really know regarding the presence of the chloride of sodium in the ocean.
The salt which we obtain from brine-springs contains the same constituents as that which we extract from the sea, though in their course upwards they collect on their way soluble salts, and therefore the water goes through certain modifications, which the reader doubtless recollects. For instance, the brine-springs of Lancashire and Worcestershire rise up through strata of sandstone and red marl, which contain large beds of rock-salt. The origin of the brine, therefore, may be derived from beds of fossil-salt; but as the muriate of soda is one of the products in volcanic regions, the original source of salt may be as deep as that of lava.46
We have also seen that the base of all mineral waters is the chloride of sodium, and that their ingredients are collected and dissolved as they ascend to the surface; therefore they may probably both have the same origin as the sea, as regards the chloride of sodium, which they both hold in solution. We can account for their other characteristics by the wide expansiveness of the sea, which is perpetually absorbing and emitting vapours, and by the several strata through which the mineral waters pass. There may be, though there is nothing that we can advance as corroborative, a subterranean communication existing between them, which would imply a common origin, the differences arising from the physical surroundings, atmospheric influences, and the absorption of soluble salts from the several strata.