B

Book III.

Of MINERALS.

from old Stones, whence it has its Name,from Earth, from Afhes, and alfo from Pi-geons Dung. I fhall not defcribe here themany different Ways of making Saltpetre,feeing they are largely defcrib'd in the Tran-fa&ions of the Royal Society at London;and alfo becaufe 'tis eafie to fee it made invery many Places in France, and efpeciallyat the Royal Arfenal at Paris, where 'tismade in great Quantities, and where theydivide it into a Matter of half a Dozen Sorts,according as 'tis, more or lefs purified ; butthe fineft and beft is what will hardlydiifolve in Water, which they fend inCasks to the Frontiers ; and this Saltpetremay be kept almoft in any Place withoutLots or Decay, but is not at all expos'd toSale.

Befides the Saltpetre of feveral Sorts madein Europe, we have it brought in large Piecesfrom the Eaft-lndies, fometimes rough andunpolifh'd, and at other Times as well purifiedand refin'd as any whatever : There aremoreover other Sorts of Natural Saltpetre,fuch as is found flicking to Rocks and oldWalls, in fmall white Cryftals, and is whatthe Ancients call'd Aphronitrum. Saltpetre ismade alfo in Egypt, with Nile Water, afterthe fame Manner as common Salt is madewith us at Broiiage or Rochelle ; and this fameSaltpetre, made of the Water of the RiverNile, is that which was fo common in France,about twenty Years ago, and which ufed tobe fold at a cheap Rate to the Whitfters, toblanch or whiten Linnen, under the Nameof White Pot-afhes, Alkali, Natrum, or Ana-trum.

There is nothing almoft has more perplex'dthe Ancients, as well as Moderns, than theNatrum of Egypt, even whilft it was thecommoneft Thing in the World ; for atParis, alone, was confum'd of it more thanloooooo Pounds yearly, without reckoningwhat the Butchers and Tanners made ufe ofto fait their Skins and Hides, which was theReafon it was prohibited afterwards ; andfince it is become fo fcarce, that at prefent 'tisat its Weight in Silver, and is alfo prohibitedto be fold by Merchants under large Penal-ties. Some will have this Natrum of Egyptto have been a natural Borax, or a Saltdrawn naturally out of the Earth in greyhard Pieces; fome that 'twas the volatile Salt

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and Froth of GJafs Metal taken from thePots and Furnaces of Glafs Founders, andthat it is either grey, white, brown, orbluifh, altogether unfit for Vitrification, andfit for nothing but to throw to Sheep or Pi-geons ; but nothing can be more wide ofTruth than this, fince the true Salt of Glafsis ftill fo common among us, that it's foldnot above a Groat or five Pence a Pound,and never given to any Sorts of Cattle orBeaft, but us'd chiefly by Potters, and DutchWare-makers to prepare the Sand wherewiththey whiten and varnifh their Things ; andagain Light and Darknefs are not more con-trary than thofe two; for the Salt of Glafs isin Cakes or Stones, extreamly heavy likeMarble, contracting no Moifture by theAir ; whereas the Egyptian Natrum is a whiteSalt in great Cryftal weighty Maffes, faitand naufeous to the Tafte ; and befides cafi-ly diffolving into Liquor, when expos'd tothe Air, and is of fome Ufe too in Medicine,being an Ingredient of the Lap. Crul'tii. Asfor Natural Saltpetre we have but very littleof it, and confequently make ufe of the Ar-tificial or Factitious, which ought to be madechoice of, good and well work'd, accordingto what Degree cr Quality it is of; bunhowever, let it be always dry, and as voidas poffible of Salt. The common Sort, whengood, muft be as white, dry, and free fromSalt as may be; the Refin'd aiio, the whiter,dryer and more beautiful, long and largeCryftals 'tis in, the better, and more valua-ble.

The Ufe of Saltpetre is very confiderable,as well upon Account of the great Quantitiesemploy'd in making Gun-Powder, as thatAbundance of Artificers make ufe of it, andthat diverfe chymical Preparations are madethereof. This great Confumption is the Rea-fon why the Sale of it is forbidden to Gro-cers and others ; and that thofe in and aboutParis that employ any of ir, are fore'd (un-der Pain of Confifcation, and a Fine) to buyit at the Arfenal ; and even then are not toufe it to the Purpcfes of feafoning Meat, orthe like, though it be proper enough for thatEnd, as Mr. Lemeiy affures us.

Nitrum, Sal Nitrum, Sal Petr.e,Saltpetre or Nitre is a Mineral Salt, Lemery,partly volatile, and partly fix'd,which they make from Stones and Earth

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