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S U L

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.commercial demands for this fubftance are fup-plied from the former fource. Of mineral ful-phur there are two great families, firft, nativefulphur, or uncombined with any confiderableproportion of other ingrediehts. Secondly,fulphur in union with metallic bafes, formingthe various pyrites and fulphurated ores. Ofthefe, the latter are defcribed under the variousmetals from which they derive their fpecificcharacters; the former we fhall now proceed to.give an account of.*

The colour of native fulphur is a pale{lightly greenilh yellow, palling on one handinto grey, and on the other into lemon yellow.It occurs in rnafs, difleminated, in roundedfragments, cellular, ftalaftitic, fuperficial, and.cryflallized. Its primitive form is a very acuteoftohedron compofed of two tetrahedral pyra-mids with fcalene triangular [faces joined bafeto bafe; the common bale of the two pyramids,is a rhomb, the two diagonals of which are toeach other in the proportion of five to four.The other varieties of cryllallization that itprefents, are the following.

1. The primitive figure with the fummits.truncated.

2. The fame as the preceeding with a lowtetrahedral pyramid fet upon the terminal trun-catures.

3. The primitive figure with two oppolitefolid angles of the common bafe truncated.

4. The primitive figure with a tetrahedralprifm interpofed between the pyramids.

5. A cuneiform oCtohedron.

6. A cuneiform hexahedron.

The cryftals are generally fmali .and ill de-fined, but thofe from Sicily are for the mollpart perfeCl, and are fometimes full five inchesin length. They are generally grouped toge-ther. The cryftals externally are very brilliant,with a luftre between refinous and adamantine;the other varieties are more or lefs gliftening.-Its fracture is fine-grained uneven, palling onthe one hand to conchoidal, and on the otherto fplintery. The cryftals are often femi-tranf-parent, the other varieties are more or lefstranllucent. It is foft, brittle, and eafily fran-gible. Sp. gr. 1.99-—2.03. _ ’

Sulphur by friction acquires the refinouseleCtricity; the tranfparent cryftals are in a highdegree double-refraCtive.

Sulphur is found fometimes, though rarely., inveins in primitive mountains, its common repo-fitory is in beds of fecondary gypfum, where it■pccprs principally in nodules; it is fometimes

* Hauy, BrO'

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alfo met with in beds of indurated marl anstcompact limeftone. Volcanoes alfo abound infulphur, which fublimes in the rifts and cavitiesof the lava.

.Stratified fulphur is met with in Sicily , atConilla near Cadiz in Spain, near Bex in Swit-zerland , in Lorraine, Hanover, Gallitzia, andPoland: volcanic fulphur is obtained from Etna in Sicily , the Solfatara near Vefuvius, Heclain Iceland , the Peak of TenerifFe, the Souffrierein Guadalupe, &c.

The proper native fulphur feldom containsany foreign matter except a fmali proportion ofearth; the whole preparation therefore whichit requires for the purpofes of commerce is tobe freed from its earth by diftillation, and thenmelted and call into moulds.

The fulphur at the Solfatara is in nodules con<fiderably mixed with a white earth; thefe beingdug up and .broken to fmali pieces, are put intoearthen pots arranged in a double row along avery fimple furnace; the hole in the upper partof each pot by which it is charged is clofedwith an earthen pipe, and a little lute: and onthe .application of a gentle heat the fulphur isvolatilized, and pafles through the pipe into anearthen receiver where it concretes; the con-tents of the receivers are then melted in a caul-dron, the impurities either rife to the top wherethey are fcummed off, or fubfide to the bottom;and the fulphur thus purified is run intomoulds.

in England a large quantity of fulphur is■Obtained at a fin all expence from the pyriticalcopper ore during the reading which this un-dergoes previous to the procefs of fmelting.At the celebrated Parys mine in Anglefey,works for this purpofe are conftrudted on alarge fcale. At the foot of a low but fteepridge of rock, are conftrufted mafles of ma-fonry not unlike high blaft furnaces, exceptthat the top is capped with a dome of brick-work, from which proceeds a horizontal flue,about the fize of a common chimney, whichterminates in a fquare or oblong brick chamber,built at the top of the rock. Some lighted fuelis introduced by means of a door in the domeof this roafting furnace, and a few baflcetfuls ofore, broken into moderately fmali pieces, are.thrown on it, frefh parcels of ore being addedfrom time to time as the preceding parcels getlighted; a fufficiency of air for the flow com-buftion required in this procefs, is let in bymeans of a door at the bottom of the kiln,which alfo ferves to take out the ore by whei^

bat, Jamefon.