SALT AND SALT TRADE. The chemical nature of common salt, as a chloride of sodium, is treated under SODIUM. The vast Mores of rock-salt and salt-brine in Cheshire and Worcestershire, whence England obtains her supply, are described in the GEOG. DIV., under such headings as CHESHIRE, DROITIVICII, NANTWICH, NORTIDVICH, &C. A few additional detsila in this place are all that will be needed.
A rocky bed is the source of nearly all our inland salt; but as sub terranean streams flow over this bed and become saturated with salt, the original form is changed. It is simply a question of manufactur ing convenience, whether to raise the solid salt and purify it by dis solving, boiling, evaporating, &c.; or to raise the liquid brine and operate upon that. The salt-works adopt the latter course in most parts of England ; but at Northwich they also operate upon a rocky kind of salt, which is transparent and colourless, and is loosened by blasting. There are other kinds of rock salt, much rougher and darker. On many parts of the coast salt is obtained from sea-water, at places called salters.; but as the salt would be too costly if evapo rated by heat, the makers mostly rely on the aloes process of evapora tion by exposure to the open air. At Lymington both methods are combined.
In Cheshire the brine springs have been known and worked from very early times, but the bed of salt whence the brine is obtained was not known until about two hundred years ago. In the pita, the rock salt is loosened much in the same way as coal, by blasting and by the pick, and is brought to the surface to be dissolved in water. The brine aprings in the valley of the Weaver mostly spring from a depth varying from 10 to 60 yards. The brine is pumped by steam power into large cisterns, where it is more completely saturated by an addi tion of rock salt. The brine then passes through wooden troughs to the evaporating pans, large flat open vessels with flues underneath. The evaporation, and the conversion into grains or crystals of salt vary according as common salt, stared salt, jlakey salt, fishery salt, dm.; are to be produced ; but in all, the crystals are allowed to form, and are then removed to the drying house. The blocks of common salt familiar in the shops are produced by transferring the crystals from the pan to wooden moulds, whence they are removed to be dried.
Nearly the whole of the salt exported is made in Cheshire, and is sent down the river Weaver, which communicates with the Mersey, to Liverpool. The sources of supply are said to be inexhaustible; and latterly the salt-manufacturers have so far extended their works, that the opening of new markets would be of the greatest advantage to them. The Staffordshire rock-salt is chiefly exported from Hull, and
that of Worcestershire from the port of Gloucester.
A duty of 10s. per bushel was laid on salt in 1798, which in 1S05 was increased to 15s. In 1823 this duty was reduced to 2s.; and on the 5th January, 1825, was wholly repealed. Salt, used in the fisheries was always duty-free, and in 1321 the quantity so used was 2,406,602 bushels ; and about 150,000 bushels, required by bleachers, was also exempt from the duty. A duty of only 5.., which was afterwards reduced to 2.. Gd., was charged on pelt used for agricultural purposes. During the existence of the duty, the retail price was 4id. per 1h.; it is now about id. Salt is now used more largely than hitherto by the poor, and is employed in manufactures and in agriculture to an extent which is only compatible with cheapness.
In 1852 an estimate was made that 300,000 tons of salt were used in the United Kingdom annually for domestic purposes, 200,000 tons for manure and manufactures, and 500,000 tons exported. In that year the prices varied from 2s. 6d. to 12s. per ton. The aggregate value of the whole was set down at 350,0001. In Cheshire only, in that year, there were 20 salt mines and 97 salt works belonging to 47 proprietors, employing 8000 persons, and an invested capital of 1,000,000/. lu 1658 the total produce was believed to have risen from 1,000,000 tons to 1,400,000 tons annually, of which about one half is exported. If the above figures are correct, the domestic consumption must be far more than 16 lbs, per head, which was an estimate made several years ago. In 1858, the salt-manufacturers of Cheshire and Worcestershire memorialised the government, praying that means might be adopted fur facilitating the consumption of British salt in India and China. A relaxation had been made in 1846, by which British pelt was admitted under certain conditions into India; and the memorialists asked for still more favourable conditions. As for China, they suggested that, in any treaty between the two countries, a demand should be made for the admission of British salt, either free or under a small duty. The Cheshire manufacturers have, in fact, more salt than they know what to do with ; and they are looking out for an extended market. At present, the two best customers are Calcutta and New Orleans, each of which takes about 80,000 tons a-year.