Salt, being existent in all animal and vegetable life, is coeval with life itself; it was present in the first herbage which gave nourishment to the first beast that, in its turn, became food for the first omnivorous man. In the beginning, man consumed the saline essences that were required to preserve his body in health, in the form of sodium chloride, which he absorbed in the uncooked flesh of animals, birds, and fishes, and in raw green-foods. The herbivorous animals were equally dependent upon salt, and, finding it in only infinitesimal quantities in the grasses upon which they fed, instinct directed them to the sea swamp pasturage and to the outcropping salt deposits. So long as man’s diet consisted of uncooked foods, his fresh meat provided him with a sufficiency of salt, but directly he employed a cook-pot in the preparation of his food, the boiling processes denuded it of 70 per cent. of its natural salt, and it became necessary for him to make up the deficiency. It must have been at this period that his herds directed his attention to the “salt licks” from which they satisfied their own saline wants, and enabled him to secure salt as a distinct and separate condiment.

It is probable that, from the Palaeolithic Age down to the time of the early Roman writers, man was content to season his victuals by the simple process of licking a piece of rock-salt, and we have no record to indicate the period when salt was first employed in the cooking of food. From varieties of grain and fragments of pottery that have been discovered in the dwellings of the cave-men of Belgium, it is supposed that salt was employed in the cooking of wheat and barley some five thousand years ago. Thirteen centuries before Christ, fish preserved in salt was eaten in Ancient Troy, and, according to Herodotus, the Egyptians not only salted ducks, quails, and a species of sardine which inhabited the Nile, but also employed salt or brine as an antiseptic in preparing the bodies of the illustrious dead for the process of embalming.

We cannot determine the period in which salt came to be regarded as a symbol of sanctity or entered into the religious ceremonials of the ancients. We know that in the Levitical Law, promulgated in 1500 B.C., every meat-offering was seasoned with salt, and salt is referred to in the “Verbal Instructions” which were enunciated by the founder of Buddhism, five centuries later. By the time of Pythagoras, about 600 B.C., salt was regarded as the emblem of justice, but who shall say when the Arabs first employed it as a token of friendship, or the Chinese offered their first oblation to Phelo, the salt deity of Celestial worship? We read in Herodotus that caravans brought salt from North Africa, and Schleiden tells us that the priests of Egypt preferred the salt of Hammomen to that evaporated from sea-water; but these references do not help us to fix the date when salt became an article of commerce, or tell us when or where or by whom it was first produced in a manufactured form. It was rock-salt which the Egyptians procured from the salt basin of the Sahara, and rock-salt from the margin of the Red Sea was the variety that is referred to by the compilers of Biblical history. But, although the natural crude product was probably the sole form in which it was known in the Western world by the Ancients, and through the vaunted golden epochs of Babylon, Byzantium, and Greece, the Chinese—who had invented explosives before the Romans had perfected the catapult, and had learnt to navigate by the compass while yet the mariners of the Mediterranean were dependent upon the stars and their wits—had probably been familiar for ages with a salt manufactured by a process, the origin of which they had forgotten, but the practice of which was to remain in operation, almost without revision, for further thousands of years.

The first mention of salt in the Chinese language is found in the annals of the Emperor Yu (2205–2197 B.C.), who ordered the province of Shantung to supply the Court with that commodity. During the Chow dynasty (1122–249 B.C.) the administration of the salt industry was conducted by Court officials, but the Crown monopoly of salt was not instituted until the days of Kuan Chung, who died 645 B.C. Between A.D. 561 and A.D. 583, references to various taxes on salt lead us to the conclusion that salt was produced at that period from sea-water, salt marshes, and salt springs, and at the present day salt is produced in China in three varieties—sea-salt, lake-salt, and well-salt. As the success of the boiling operation (which antedated by unnumbered centuries the comparatively modern industry of extracting salt from sea-water by evaporation in the sun) depends mainly on the condition of the brine and the time allowed in each stage of the process, the details were the subject of many series of experiments in the pursuit of the perfect system, but since about the twelfth century the following method has been consistently followed by the Chinese salt-makers. The whole of the sea-shore in the neighbourhood of the salt works is measured out and divided into a number of small, regular squares; the surface layer in each is dug out; the bottom of each pit thus formed is then strewn with straw, and the earth that has been removed is thrown back upon it. When these brine ovens, as they were called—which are shaped like chests, 9 ft. long, 2 ft. broad, and 3 ft. deep—are prepared, they are soaked with sea-water. The sea-water in the interior of the ovens forms brine, and flows through little ditches into wells which have been dug for its reception. From these wells, which are about 8 ft. deep, the brine is drawn out and carried to the boiling ovens. These brine ovens are furnished with large evaporating pans, three to five of which are attached to each oven. The boiling takes place at once and is continued without interruption, from 11 p.m. until 10.30 on the following morning, and during this period the salt is taken out six times. As soon as the salt begins to harden, pods of the tsao-chio tree are thrown into the pans, in order that the particles of salt may combine more quickly, and as soon as it is precipitated, it is removed and the pans are refilled with fresh brine. On an average, 600 cathés of the best brine yield 140 cathés of pure salt, which is produced in three qualities and colours—white, dark, and yellow. The white is the best, the dark is less esteemed, and the yellow, which is much inferior, has a bitter taste.

Since the fifteenth century, the Chinese have produced salt by solar evaporation of salt water, according to a simple but satisfactory process. Pits are dug on the sea-shore and bamboos are laid crosswise over them. The whole is covered with double mats, and sand is strewn over the top. Every morning and evening the covering of sand is soaked with sea-water by the tide, and the salt liquor finds its way into the pits. As soon as the water has receded, the salt workers appear with flaming bundles of straw, to test the saline character of the moisture, which is not regarded as fully impregnated unless the salt vapour arising from the pits extinguishes the fire. The brine thus produced is drawn off and run into secondary or crystallizing ponds, the level of which is set a foot or so below the first series of pits. The secondary ponds, which are smaller and of less depth, are provided with carefully-rolled, hard clay bottoms. When a sufficiently thick crystalline deposit has been formed at the bottom of the secondary ponds, workmen, starting at the centre, scrape the bottoms, working outward spirally and finishing at the corner of the pond, where the coarse crystalline product is collected and allowed to drain. When drained and dried, the salt is ready for transfer to the market.

In Japan, where the manufacture of sea-salt by boiling or by spontaneous evaporation was introduced more than two thousand years ago, the process is similar to that employed in China, but in some parts of the kingdom the evaporation basin generally employed in solar evaporation is dispensed with. In the latter method, a level field is formed close to the sea and sprinkled over with fine sand. Sea-water is then poured into the field, and, after evaporation of the water, the salt crystallizes and adheres to the sand. The mixture of salt and sand is next thrown into a kind of extracting apparatus and sea-water is poured upon it, whereupon the salt is dissolved and filtered in the form of a thick salt liquid. In other Japanese salt fields the concentrated liquor is poured into a crystallization basin prepared for the purpose, and, upon evaporation of the water by the sun’s heat, the salt crystallizes.

In Italy most of the salt is made by solar evaporation. The salt grounds, which occupy extensive areas, are furnished with reservoirs for the preparation of the sea-water by saturation and for the deposit of salt. The former are known as condensers and the latter as crystallizing beds, and in both the work is carried on by solar evaporation only. Every salt-ground, or salt-garden, as it is called, has a feeding channel for the inflow of sea-water, a drainage channel, and a network of internal channels at low and high levels, as are required for immission or drainage purposes. In Portugal and Spain, salt is made by solar evaporation from sea-water, and although there are differences between the several methods, they apply only to details regarding the areas of the salt-grounds or the sizes of the reservoirs.

Let it be clearly understood that all commercial salt is produced either from the sea or from rock-salt. Sea-water is evaporated to precipitate its salt either by the heat of the sun or by artificial heat. Rock-salt is mined and refined for market purposes, and it is resolved into brine from which the salt is extracted by solar heat or the process of boiling, but whether the salines are obtained from salt lakes or from natural brine springs, or are prepared by flooding salt deposits with water and pumping it out in the form of fully saturated brine, rock-salt is the foundation for them all. And in all the processes of manufacture the basic principle is the same, and consists of applying heat to drive off the liquid which contains the salt and collecting the crystalline deposit which remains.

The principle of what is described as the boiling process is fundamental and unalterable, and for thousands of years the plant and utensils employed in the process underwent no material change. Since the sixteenth century in England, variations in the shape, size, and capacity of the pans have been introduced, and experiments have been made in the re-arrangement of the receptacles and redistribution of the furnaces, while coal fuel has been substituted for straw and wood, but it is only in the past twenty-five years that any material success has been achieved in the matter of economizing and accelerating the process of production, controlling the heat in order to regulate the grain of the salt, producing more than one grade of salt in one operation, or of automatically and continuously collecting the salt as it is precipitated from the brine.

The earliest exact and detailed description that we have of salt-making appears in De Re Metallica, a famous work by Georgius Agricola, of Saxony, which was published in 1556, and which for the following 180 years, remained the standard text-book on mining and metallurgy. In Chapter XII of this work, the preparation of which occupied Agricola for a quarter of a century, he gives the exhaustive particulars relating to the boiling process from which the ensuing account is compiled.

After explaining the method by which sea-water is received into the first series of prepared trenches, in which the first stage of evaporation takes place and is thereafter carried into the second basins, where it is thickened by further evaporation to the constituency in which it is ready to be converted into salt, Agricola tells us that the liquor is then boiled in pans placed in sheds arranged for the purpose. Each shed is divided into three parts. In the first part is stored the firewood or straw, and in the second is the fireplace on which is placed the caldron. To the right of the caldron is a tub for the brine that is to be converted into salt, and on the left is a bench upon which the salt is placed before being removed to the third compartment, where it is moulded into cones or tablets and left to dry in the warm air.

The fireplaces are made 8½ ft. long and 7¾ ft. wide; if wood is burned in them they are nearly 4 ft. high, but if straw fuel is used, they are 6 ft. in height. The caldrons are rectangular, 8 ft. long and 7 ft. wide, and 6 in. deep. They are made of sheets of iron or lead, “not very thick so that the water is heated more quickly by the fire and is boiled away rapidly.” To prevent the brine from leaking out at the points where the metal plates are fastened with rivets, the caldrons are smeared over with a cement of ox-liver, or ox-blood, mixed with ashes. As soon as the first dipperful of brine is poured from the brine tub into the caldron, the wood or straw is ignited in the fireplace. If the firewood consists of faggots or brushwood, the salt will be white, but if straw is burned the salt is not infrequently blackish from the sparks which rise with the smoke and settle upon the water.

In order to accelerate the condensation of the brine, the salt-maker adds and mixes into it bullock’s blood, or calf’s blood, or buck’s blood, which dissolves and is distributed into all the corners of the caldron. When the boiling water seems to be mixed with scum, it is skimmed with a ladle, and from the firing of the furnace to the skimming of the boiling scum is the work of half an hour. After this it boils down for another quarter of an hour, and thereafter it begins to condense into salt. When the brine commences to thicken with the heat, it is stirred assiduously with a wooden spatula, and then allowed to boil for an hour. At this stage beer is added to the contents of the caldron, which is protected from the wind by boards, and the salt is then withdrawn with a shovel and thrown into baskets. The remaining brine is allowed to boil for another three-quarters of an hour, when the salt is again removed and placed in the drying compartment. In this manner the salters alternately boil the brine and collect the salt, “day and night, with the exception only of the annual feast days.” No caldron is able to stand the fire for more than half a year. New caldrons are washed out three times in the first two weeks, and afterwards once a week. In this manner the incrustations fall from the bottom of the caldron, and if this is not done the salt would have to be made more slowly over a fiercer fire, which not only requires more brine but burns the plates of the caldron. If any cracks make their appearance in the caldron, they are filled up with cement. The salt made during the first two weeks in a new caldron is usually inferior in quality, being stained by the rust at the bottom where incrustations have not yet adhered.

Agricola’s description is full of technical exactness in regard to those parts of the apparatus and the process which are of comparatively insignificant interest, but it is, unfortunately, silent about details on which fuller information would be useful. He tells us the capacity of the tubs in which the brine is conserved, but not of the caldrons in which it is boiled, and we cannot calculate the quantity by the dimensions of the receptacles, since he omits to mention the depth to which they are filled. He explains that it takes half an hour to fill the baskets with the salt that is drawn from the caldron, but as he does not give us the dimensions of the baskets employed, or the amount of wood or straw consumed, we cannot determine the length of time required to make a certain quantity of salt, or the cost in fuel. But, condensed and simplified by the elimination of extraneous particulars and complex technicalities, the foregoing enables us to obtain a fair idea of the methods employed by the salter of Halle, in Saxony, assisted by his wife as helper and a youthful stoker—working naked, on account of the great heat, save for a straw cap and a breech cloth—in the first half of the sixteenth century.

The subject of the formation of rock-salt deposits will be treated in a later chapter, in which a description will be given of rock-salt mining in Cheshire. The primitive methods that characterized the brine industry have been adhered to with equal tenacity in the winning of rock-salt. It is extraordinary that, in the manufacture and in the mining of salt, each successive generation of salt-men, in inheriting their methods from their forefathers, or adapting them from the miners of another country, have always preserved the intense conservatism that appears to be inseparable from the industry, and have resisted all innovations that have promised to simplify or expedite their labours.

It would be an interminable and unprofitable undertaking to conduct the reader upon a tour of the salt mines of the world, and explain the different methods that are adopted to conform with the local and geological conditions which obtain in the various salt regions. The systems followed in most countries are governed by traditions that have their origin in immemorial times, and the disposition to perpetuate the operations without change through succeeding ages is, perhaps, traceable to the races that work the mines rather than to the deposits in which they work. The process of solar evaporation which is employed to-day on the shores of the Mediterranean and the Adriatic is practically the same as it was when the civilization of China was in its infancy; the implements and methods in present use in the salt mines of Austria, Russia, and Rumania were introduced by the discoverers of the lodes in the darkest ages. We cannot even fix the comparatively recent period in which it was decreed that the Rumanian mines of Tirgu-Ocna and Ocnele-Mari should be exploited by convict labour, while the Slavic mine was to find employment for free workers only. Every country, every salt district, and almost every mine has its peculiar and distinguishing rules, customs, and methods of work, which are interesting in themselves but of insufficient importance to warrant detailed consideration in a treatise of this scope. There are, however, certain salt regions and mines which, by reason of their magnitude and the possession of unprecedented features, have obtained rank among the lesser wonders of the world, and for this reason we must devote a little space to “the Great Salt” of Wieliezka, in Hungary, and to the great Rumanian salt deposits.

The famous mines of Wieliezka, in the lower Carpathians, about eight miles from the city of Cracow—with their underground roads, houses, and monuments; their churches, ball-rooms, and restaurants; their lakes, bridges, and railway stations—constitute a city commemorative of the art and industry of bygone periods, and present a spectacle, weird and splendid, that reminds one of the marvels of the Thousand-and-One Nights. The Wieliezka system, which has been in operation since the thirteenth century, extends over an area of about twelve square miles, and reaches a maximum depth of some 12,000 ft. The various galleries at present accessible have an aggregate length of 65 miles, and the total length of mining railways is about thirty miles. Each mine consists of five storeys. The first storey is about 200 ft. below the surface, and between the different storeys a body of earth or salt from 80 ft. to 100 ft. thick is left. As in Northwich, many of the old workings in Wieliezka have fallen in, and whole chambers and streets have been engulfed in the holes. Broad staircases connect the various storeys, each of which boasts its distinctive chambers and thoroughfares. The air in the upper levels is much more moist than in the lower excavations, with the result that the salt statues in these apartments are gradually losing their shape. The head of one is nearly gone, the arms of another are wasted; while the deeper furrows, which are observable upon the sculptured bodies, give them a grotesque appearance. The smoke of lamps and wicks adds to the moisture of the air and darkens the surface of the statues, which might be carved in black marble. Onward and downward one proceeds, the stairways appear to be innumerable; the visitor loses all sense of depth, distance, and direction; chambers and passages lead to further chambers and passages, until the tour of the workings leaves one with a dominating impression of limitless repetition. Everything is of solid salt, except where some insecure roof is supported by huge timbers or a wooden bridge is thrown over some vast chasm. As depth is attained the air grows drier and purer, and the points and faces of the rock become more crystalline and beautiful. Onward and downward still, through labyrinths of shafts, galleries, and chambers, up crooked passages, and under vaulted archways, that lead into innumerable, unnamed smaller apartments.

Groups and gangs of miners, naked to the hips, are everywhere busy with pick, mallet, and wedge, with which they block out and separate the salt slabs from the solid mass. The process has the simplicity of the age in which it was first employed. The blocks are marked out on the surface of the rock by grooves. One side is then deepened to the required thickness, and the face is split off by wedges inserted under the block. It is then divided into pieces of 100 lb. each and removed to the shafts, where it is hoisted, stage after stage, to the surface. The number of labourers continually engaged is from one to two thousand. The miners, who are muscular, healthy-looking men, are divided into gangs. The work is carried on in shifts of six hours each, and in each shift a gang will quarry out about 1,000 lb. weight of salt.

The Letow ball-room, which lies at a depth of 216 ft. below the surface, dates from 1750, and has been the scene of many Royal visits and splendid entertainments. One end of the spacious chamber is adorned with a colossal Austrian eagle, and in an alcove at the opposite end is set up a crystal throne. The giant chamber which bears the name of Michalowice, a fearsome and stupendous excavation, was completed in 1701, as the result of forty years of continuous labour. It is 59 ft. long by 92 ft. broad, and the roof, supported by a wooden framework, has a height of 118 ft. The chamber is lit by a salt chandelier furnished with 300 electric bulbs. The Francis Joseph ball-room is another of the wonders of this subterranean city. It is an immensely large and immensely lofty apartment, lit by six large chandeliers fashioned of crystalline rock-salt. Salt statues of Vulcan and Neptune, which adorn the hall, reflect the electric light from myriad brilliant points and angles, and contribute to the general impression of flashing splendour which the scene conveys. Beneath these great reception rooms, are smaller halls, each beautiful in itself, bearing the names of royal or princely personages. Massive pyramids of salt and sculptured monuments, with carved inscriptions, perpetuate the memories of Emperors and Empresses of Austria, or commemorate their visits to the mines. Near to the Letow ball-room is the celebrated St. Anthony’s Chapel, which was hewn in 1698, and for upwards of two centuries has been the resort of thousands of the devout. The vestibule in the chapel consists of a symmetrical archway with figures at the sides. The interior is beautified by an altar bearing a sculptured representation of the Crucifixion, and flanked by salt effigies of kneeling monks. Hard by St. Anthony’s Chapel a magnificent shrine is hewn in one of the passages, peopled with figured saints, which leads to the Queen’s Chapel, with the superbly-chiselled altar and its view of Bethlehem carved in the solid salt.

The central railway station in the third storey, and the great restaurant, with its ponderous pillars and its long vista of latticed galleries, are among the many marvels of the mines, but nothing it contains is so wonderful as the subterranean lake, lying 700 ft. below the surface of the earth. The waters of the lake are dark, thick, and heavy, and as the boat glides over its surface the slumberous wavelets roll up against the sides of the grotto with a ghost-like swish. A ponderous solitude over weighs all. The Styx alone of all the legendary rivers of death could rival this in stillness. The boat is guided through the Stephanie and Rudolf grottoes by ropes running on pulleys along the sides of the curious craft, and the boatman, with his hands resting on the stern, pushes it with his feet braced against the rope. Of the sixteen lakes in different parts of the mine, this is the only one upon which visitors are allowed to go. The report of a gun fired in the centre of the lake fills the vault with long and lingering echoes, and the voice of the boatman sounds like a giant’s voice uprising from the depths of chaos.

The illumination of the mine is arranged according to a regular tariff based on the number of visitors sharing the expense. For any number of persons up to twenty, the illumination, which comprehends the employment of over a thousand candles and electric lamps, costs about ninety shillings, but for an additional sovereign, which is charged when a party numbers over thirty persons, the whole mine becomes a blaze of light.

Serious calamities at Wieliczka are now practically unknown, owing to the care exercised by the officials, but minor accidents are unavoidable. Some few years ago a huge mass of rock-salt, weighing some 200 tons, fell from the roof of one of the chambers; in 1868 the mines were flooded by the bursting of a subterranean salt lake; and a fire in 1815 resulted in the loss of several hundred lives. The early history of the mines contains the record of several terrible disasters, including an incendiary fire in 1510, which caused a great number of deaths, and another fire in 1644, which raged for over a year, and consumed all the people, horses, and mules who were in the mine when the fire occurred.

The working of the three great Rumanian salt deposits present other examples of the persistent survival of ancient methods, but it must be admitted that an attempt was made at one time to introduce modern machinery. It was demonstrated that the machine produced more salt in a given time, and that the waste of about 25 per cent. of the salt attendant upon manual labour and the use of picks was saved, but as the supply of salt is practically inexhaustible, and there is no limit set upon the time of winning it, and as man-power, especially convict man-power, is cheaper than machinery, the authorities soon reverted to the old system. In the Slanic mine, in which the salt is crystalline, white, and almost absolutely pure, the free labourers, of whom about 500 are employed, are divided into gangs of six men. Each man takes an oblong piece of the floor of the mine, about as big as an ordinary tombstone, and, using his pick, scoops round it a narrow groove about 5 in. deep. This done, he summons the rest of his gang, and, standing beside him on the slab, they raise and bring down their picks simultaneously at the word of command. Force is necessary, but rhythmical accuracy in the planting of the blow is more essential, and by long practice the men have become so extraordinarily expert that they scarcely ever diverge a hair’s breadth from the point at which they aim. In a few minutes the persistent blows detach the slab, which the six men raise with the aid of a lever. The gang proceed from slab to slab until all six have been detached and lifted, after which each man breaks his own slab into chunks and loads it into a truck for removal to the shaft, through which it is hauled to the surface. An expert miner’s earnings at this work range from half a crown to three shillings a day.

The convicts employed in the Tirgu-Ocna and Ocnele-Mari mines are paid from sixpence to eightpence a day for their work, and, save that liberty and the hospitality of the local taverns are denied them, their condition is little worse than that of the free labourers. As capital punishment does not obtain in Rumania, the convict miners include murderers, brigands, and the worst class of criminals, and armed soldiers escort them to and fro between the prison and the mine, and remain on guard while they are at work. Dashes for liberty used to be common, and organized attempts to escape have also been attempted, but now, on the first sign of suspicious behaviour on the part of the convicts, the order is given for the whole gang to throw themselves flat upon the ground. As those who disobey the order are immediately shot, instantaneous compliance with the command is usually observed. On one occasion a body of disaffected convicts had recourse to a form of passive resistance, and when the day’s work was over they refused to leave the mine. The guards and overseers thereupon withdrew and left the mutineers to reflect in an intolerably salt atmosphere upon the virtues of fresh water, of which they had no supply. After two days of torture, the men capitulated. But the work of superintending the convicts in the mines is a delicate and dangerous task. The overseers are compelled to mix with the men, and it is but the work of a few silent minutes for a gang to overpower an unpopular official and squeeze the breath out of his body. As the murder is a communal affair, and the practice of making an example of one man pour l’encourager les autres is not adopted in Rumania, the extent of punishment inflicted upon the whole gang is less than would be meted out to individual offenders. As the salt reserves in the three principal mines of Rumania are estimated at 8,774,000,000 tons, and the annual extraction has never exceeded 150,000 tons, it follows that, at the present rate of progress, the deposits cannot be exhausted for several millenniums.

Where the salt deposits are composed of a mineral that is white, odourless, and practically pure, as in the Wieliezka system and the mines of Rumania, and particularly if labour is abundant and cheap, and the industry is a monopoly of the State, rock-salt mining will always hold its own.

Even in this country, when the old open-pan system of evaporating salt from brine produced only two tons of salt for the consumption of a ton of fuel, rock-salt could be raised, purified, and marketed in competition with white salt, but the modern boiling processes have effected such substantial improvements and consequent economical advantages, that the rock-salt industry appears to be doomed to decay. Rock-salt, as quarried from its native bed, is found in many variations of colour, from grey and yellow to green and brick red, according to the nature of the impurities of the locality in which the deposit lies, and such salt must be cleansed from all traces of iron, clay, gypsum, or bitumen before it is fit for domestic use. Many processes have been experimented with for the removal of impurities. One of the most plausible methods was based on the fact that salt fuses at a temperature of about 1,750 degrees, and the theory was to remove all impurities from the fluid mass by the agency of compressed air. The principle was unsuccessfully experimented with in Würtemberg nearly half a century ago, but a modern adaptation of the process claimed to be more successful. The molten material, in this case, ran into rotating pans and gradually overflowed; and it was then shovelled into another receptacle and, while subjected to the action of compressed air, raised by small buckets to a certain height and emptied into inclined screens, through which it was automatically graded. It was claimed that from the time of casting the crude material into the furnace, until the perfect white salt appeared, the process occupied only fifteen minutes, and that rock-salt could be broken in the mine, transported, fused, and packed ready for table use in less than two hours.

At the time when the master-patent for this process was taken out, the latest brine-evaporating systems were unperfected, and there was some possibility that the invention might be capable of taking the rock-salt direct from the mine, eliminating at one stroke all its impurities, and in the course of an hour or two delivering into the warehouse an anhydrous salt “at a fraction of the cost of the ordinary process” of evaporating salt from brine. But by the time that this bold claim was put forward on behalf of the process, the admitted total cost of production had been advanced from 4s. to 5s. 8d. per ton, while the latest patent brine-evaporating system was producing the manufactured article at a total inclusive cost of 3s. 6d. per ton. Since then, this rock process was installed in Mexico, persevered with for a while, and finally discarded because, in the words of Mr. W. L. Bonney, the United States Consul, “the experiment proved a failure.” Even if the latest brine process has not “relegated rock-salt mining into the limbo of extinct enterprises,” it appears certain that it will never be able to be worked in competition with the process by which salt is manufactured direct from brine where brine is available.