Page:Cyclopaedia, Chambers - Supplement, Volume 2.djvu/404

 SAL

SAL

to the fmallncfs of the grain, and fometimes to a mixture of- a calcarious, or alkaline fait with it. And 5. fome kinds have an agreeable imcll in large heaps ; fuch are the Portu- gal, and the Hampfhire bay falls ; and this feems owing to the fea water, they were made from, having a bituminous matter, in it. 6. It differs greatly in tafte, according to the various foreign mixtures it contains ; and it will often alter in tafte, and other qualities, by long keeping. Thus the Jalt of Peccais is fo bitter, when new made, as not to be eat- able, but after keeping a while, it becomes very pleafant. This is owing to its containing at firft a large portion of the bittern fait, or Epfom fait-, which liquifies in keeping, and running oft' in form of a fluid, leaves the reft of a good tafte. In general, bay fait is much fitter for Life, after it has been kept fome time in a dry place, than when it is firft made.

From the accounts already given of the bay fait of other countries, and the manner of preparing it, it feems evident, that our being obliged to purchafe it of other nations is the effect of our want of application to the making it ourfelves ; fince it is evident that it may be very well made, both in England, and in many of our American colonies. Brozvnr of Salt, p. 202.

In England, a very advantageous fort of works might be fet on foot in the following manner. A number of fait pits mould be made in a row in the marih, and their bottoms lined with plaifter, or fome ftrong cement that will not ea- fily bregk up ; and by this caution, the fait may be drawn white and pure like the Portugal kind, not grey like the French. Over each pit covers fhould be made of thin boards. or rather of canvas painted white, and ftretched on frame; of wood, and thefe fhould be fixed to ftrong polls, erected on the north fide of the pits, and contrived to be eafily drawn back to them, in the manner of draw-bridges. Thefe covers, thus fixed, may be let down over the pits, in man ner of a fhed or penthoufe, in rainy weather, to keep the brine from being diluted with frefh water ; and in dry wea- ther they may be railed almoft to a perpendicular, but in- clining a little toward the fouth, fo as to form a wall with a fouth afpedt ; and thus they would ferve for a double ufe, being a covering to the pits in rainy weather, and reflect- ors of the fun's heat in fair. The reflexion of fo large a body of the fun's rays, in the. courfe of a bright day, would greatly promote the evaporation of the brine ; and the hinges, on which the reflectors turn, being placed at ten inches from the ground, when the reflectors ftand upright, there will be a fpace under them, through which the air will continually flow in a brifk current, and this will greatly promote the evaporation of the water.

The paflages of communication between the pits muft be narrow and winding, and muft be wholly flopped up in wet weather, that no frefh water run into the brine. This channel fhould be covered alfo with boards, and at the en- trance of the pits there muft not be a pond, as is the cuftom in France, but only a narrow covered trench, running pa- rallel with the lide of the pits which is oppofite to the re- flectors ; and the pond, which forms the entrance of the pits m the French fait marines, muft in thefe be detached from them, and initead of it, there muft be formed a fourth . brine pond, communicating with the third by a long and narrow channel.

If thefe contrivances fhould be reduced to practice in Eni^ land, the fait will probably cryftallize much fafler there than in the French marines, and the brine may be kept as deep, and even deeper than in the French pits ; and a mower of rain will only retard the work for the fmall time in which it is falling: whereas, in the French works, it throws them back three or four days, as no fait can be farmed till all the water it brought be evaporated.

Four ciftems may be dug adjoining to the brine pits, to admit the brine in the fait ponds, when the weather is very rainy; and as to the fait water in the refervoir, if it fhould be found neceflary to preferve it from rain in cifterns, when fo much rain falls, as to make it frefher than fea water, it may be let out, and fea water admitted in its place. And in order to promote the evaporation, and to make the fait water in the refervoir fitter to fupply the firft brine pond with brine of a due ftrength, it may be proper, by means of a fmall fire engine, continually to force up the fait water in the refervoir, as often as occafion requires, and by means of a diverger, fitted to the engine, to make it defcend again into the refervoir like a fhower of rain ; by which means, the evaporation of the watery vapours will be greatly promoted, after much the fame manner as is praclifed at fe- veral of the fait works in Germany, where the brine is very weak. Broxvnrig of Salt, p. 209.

Thus by augmenting the force of the fun's heat, and of the air, by promoting the evaporation of the watery vapours, and preventing the brine from being diluted with rain, it is very probable that, during the rummer feafon, double the quantity of fait might be prepared at an Englifh work with thefe contrivances, that is now ufually prepared at a French [alt marfh of equal magnitude. Befide thefe methods of managing fea water, it is certain

that very large quantities of bay fait might be prepared in Eng- land with great eafe, from the natural brine of falf fpria^ and from the common foffile, or rock fait of. Chefhire, dif- folved in weak brine, or in fea water. Upon the whole bay fdt might thus be made here at a moderate pri*:e, -jr.,] j n fufBcient quantities to fupply both the nation itfeli, and i-\\ our colonies. Brim Salt, a name given to that fort of common fait which is not made from fca water, but from the water of fait wel!s and fprings. Great quantities of this fait are made in moll of the inland countries, as in Germany, Switzerland, Hun- gary, and in fome parts of France and England. In Somerfetftiire, Cumberland, Weftmoreland, Durham, and Yorkfhire, there are many fait fprings, but they are either too weakly impregnated, or fituated where fuel is fcarce, and for thofe, and other reafons, are not worked ; but in other parts of England there are many rich and valu- able fait fprings, which are worked to great advantage : of thefe fome are fituated in Staffordfhire, a great many in Lancafhire, but the chief are thofe at Droitwich in Wor- ceilerfhire, and Nortwich in Chefhire ; about which laft place there are many rich mines of foffile 'fait, above and beneath the beds of which the fait fprings are ufually found. At Nantwich, in the laft county, there are alfo fome fait wells, which have been of very long Handing, being fup- pofed by many to have been worked in the time of the Ro- mans. The brine of th^fe fprings is found to differ very greatly in its ftrength and qualities ; fome yielding greatly more fait than others, and the fait extracted from fome of them being found improper for many ufes, for which that of others ferves very well.

The brine of Barton and Nortwich is almoft fully faturated with falt^ a pound of it yielding fix ounces of fait ; that of 'Droitwich, Upwich, and Middlewich, contains about one fourth fait; fome of the fprings at Nantwich yield a fixth part_/«/f, and thofe of Weftoi{ in Staftbrdihire, afford only one ninth part. In England, we feldom boil weakcrbrine than rhe laft; but in Germany, and fome other places, where fait is fcarce, they work fprings, whofe water is not higher impregnated than the common "fea water, containing about fo fait. Brownrig on Salt, p. 98. Befide common fait, the brine of molt fprings is impreg- nated with feveral other ingredients, the nature and proper- ties of which ought to be known to every perfon who works the fprings, in order to his managing his affairs with judge- ment. The brine of almoft allyo/r wells has fomewhat of a fulphureous principle mixed in it, as may be obferved from its fetid fmell, but this foon goes off in the boiling. E)r. Lifter obferves, that the brine of the pits at Droitwich ftinks like rotten eggs, and will make any thing ftink in twelve hours that is falted with it, whether it be flefh of young, or of grown animals ; and yet the jalt, prepared from this brine, is accounted the beft of any inland fait m England, and feems indeed as good as any in the world. Nay, this very brine, after it has been boiled a little and clarified^ proves an excellent pickle for beef, or any other meat, and for other domeftic ufes. Philof. Tranf. Abr. Vol. 2. p. 362.

In the fait mines at Bevieux, in the Pais deVaux, there are always found large veins of virgin fulphur, and the people who dig in them are often killed with damps and explofions. Scbeucb'zer of the Salt Works at Bevieux. The brine of many of the Englifh fprings turns black as ink on being mixed with galls, and has in it a ferrugineous ochre, which fubfides from it when it is expofed to the air in an open veffel, and falls to the bottom of the fait pan, as foon as the liquor begins to boil.

Brine of our fait fprings has alfo ufually mixed with it a very large proportion of what is called fcratcb. This is a fparry fubftance, analogous to that which forms the crufts in our teakettles, and the incruflations of mofs, bV. in our petrifying fprings. The Droitwich brine is very free from this, but the other brines of England, as well as thofe of Germany, and other places, all abound with it. At the bottom of fome of our fait wells there is alfo found a black mud, which, when ftirred up, blackens and infects the whole fpring, like ink ; and befide thefe ingredients, the brine of moft fprings is impregnated with feveral other falts, as well as the marine one. In all the German fait fprings the liquor leaves a bitter ponderous fluid, refembling our bittern, pro- duced in the working of fea fait, but fecming to partake more of the muriatic, or calcarious^//, than the bitter purg- ing one of fea water, as may be concluded from the nume- rous experiments made on it by Hoffman. This is alfo ob- ferved by Leigh, in his Natural Hiftory of Lancafhire and Chefhire, who obferves, that befide the marine fait, the wa- ters of the fait wells in thofe counties always contain a quan- tity of a calcarious nitre ; and both the obfervations of Hoff- man on the German brine pits, and the experiments made on the waters of feveral of our own fprings, feem to con- firm, that the waters of this kind in general contain among them other falts, or mineral alkalies. Hoffman, Obf. Med. Chym. Lib. 2. Obf. 18. Leigh's Nat. Hift. Lancafhire, p. 44.

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