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Sal

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,-It has alfo been prepared in India (probably inthe fame manner as in Egypt ) from time im-memorial. liefore treating of the properties ofthis fait we fhall give an account of its manu-facture, firft in Egypt , and then in the variouscountries of Europe .

a On account of the great want of wood inEgypt the principal fuel of the country is com-poied of the dung of camels, cows, and otherdomeflic graminivorous quadrupeds, mixed upwith chopped ftraw and dried in the fun. Thefoot produced by the combuftion of this fuel isthe material from which fal ammoniac is pre-pared, by fublirnation. The veffels made ufeof on this occafion, are very thin globular glafsballoons, with a fliort neck terminating in amouth about if inch in diameter. The largeflballoons are about 36 inches acrofs, but theyare of very various fizes, being capable of con-taining when three-quarters full, from 12 to50 lbs. of foot. In order to fecure them asmuch as poffible from breaking during the pro-cefs, they are coated with a mixture of muddepofited by the Nile , and chopped ftraw.

It has been affirmed by the Jefuit le PereSicard and fome others, that the foot is mixedwith a certain proportion of common fait andcamels’ urine, but this appears to be a miftake;being abfolutely contradidfed by the moft accu-rate enquirers. From thefe it appears that noother ingredient is made ufe of but foot, withwhich, moderately preffed down, the balloonsare filled to within about four finger’s breadthof the neck. The veffels thus charged are ar-ranged, to the number of 60 or 70, in an ob-long furnace of brick, and fecured with clay fothat their necks alone are in contact with theexternal air. The furnace is now very gra-dually heated by means of ftraw for the firftthree or four hours, and afterwards with a mix-ture of ftraw and the common fuel of thecountry, viz. dried dung. In the courfe of fixor feven hours a thick fomewhat acid empyreu-matic fmoke begins to rife out of the balloons,and continues for about fifteen hours. Thefublirnation of the fal ammoniac commencesthree or four hours before the fmoke ceafes, andcontinues from fifteen to forty hours, accordingto the fize of the balloon, without any furthercare being required than to regulate the fireproperly, and to pafs an iron rod occafionallydown the necks of the balloons to prevent themfrom being clogged up by the fait as it rifes,

and thus producing an explofion. When thefublirnation ceafes, the fire is allowed to go out,and the veffels as foon as they are fufficientlycool are removed from the furnace and broken}the cake of fal ammoniac, which occupies theirupper part, is in the form of a very {hallowbalon, and weighs on an average fomewhatmore than 4 of the foot employed} it has ge-nerally a yellowilh white tinge and is apt to befouled with a little charcoal, efpecially if theheat has been too great.

The proportion of fait from a given quantityof foot is liable however to confiderable varia-tion: it is found that the dung of the fameanimal affords a foot much richer in fait whenit is fed on frefti vegetables than on hay andother dry food. There is befides a great dif-ference in the foot from the dung of differentanimals fimilarly circumftanced as to food.According to Mr. Granger, the Egyptian falammoniac makers efteem the foot of cow-dungwhen the animal is fed on grafs, to be by farthe beft, 26 lbs. of this affording no lefs than6 lbs. of fait. According to Haftelquift, how-ever, the foot from the dung of goats and fheepis in the higheft eftimation.

In this very fimple manufacture, the fal am-moniac appears to exift ready formed in thefoot, and the aCtion of the heat is confined tothe mere feparation of the faline from the otheringredients. The foot itfelf is of a deep blackcolour, has very fenfibly the tafte of fal ammo-niac, and when ftrongly heated gives out afulphureous odour.

In Europe , where dung is employed to betterpurpofe than for fuel, the manufacture of falammoniac is a much more complicated procefs,efpecially when carried on in the beft and mofteconomical manner. A kind of intermediatemethod however is praCtifed with fuccefs infome eftabliflnnents in the Netherlands , ofwhich the following are the principal details. 0

-A kind of fuel capable of furnilhing fal am-moniac by its combuftion, is firft prepared, theingredients of which are25 parts by meafure of pulverized pit coal

5 do.-- of common chimney foot

2 do.-of clay

To thefe is added a faturated folution ofcommon fait in fufficient quantity to bring thewhole to a confidence for being moulded intoballs. The balls are of an oval form, andafter being dried in the air are ready for ufe.

b Lcmere in Mem. de l'Acad. des Sciences, 1730, p ipi. Grander in ditto, l 73 Jt p* HaiTelouift in Phil. Tranf.Vol. Ll . p 5O4.

* Journ. des Mines,'No 10, p. 3.