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Of METALS.

Book II.

their Ware of a reddifh Colour ; and thereare feveral other Tradefmen that have Oc-cafiion for it.

Of White Lead.

White Lead is Pig Lead reduc'd to Leaves,arid afterward roul'd as you would do a Sheetof Paper, but fo that this roul'd Lead doesnot touch one upon the other. This Lead foroul'd is put upon fmall Sticks, which arelaid in Pots, the Bottom of which is cover'dwith Vinegar. Thefe Pots being fill'd rnuftbeftop'd, fo as that no Air may get in, andafterwards left in a Dunghil for thirty Daystogether, after which they open the Veffels,and find therein the Lead, become whiteand brittle; taking then thele Leaves outthey break them in Pieces, and afterwardsexpofe them to the Air to dry them.

Choice is to be made of fuch White Leadas is brittle, white without and within,in handfome Scales, and with as few blackilhFlakes, Dull, and other Impurities as canbe.

The White Lead has no other Ufe, that Iknow of, but for the Painters, being groundwith Oil or Water, it being then the moftbeautiful White that we have, and of the longeftDuration, but then it is a very dangerousDrugg, both to grind or to beat to Powder.

Of Cerufe.

The true Cerufe, or Chalk of Lead,Pomet. is White Lead in Powder and groundwith Water, and afterwards put in-to Moulds, and fo made up into little Cakes,which they dry, and afterwards put intoblue Paper, as we find them. This Cerufe,fo prepar'd, is that which one may call theChalk of Lead, and not that which we fellat prefenc, that comes from Ho/land or Eng-land, it being almoft all common Chalk, as Iam going to relate.

The true Cerufe is that which we call theVenetian, becaufe the Venetians were the firftthat made it, but as it is extreamiy dear,we have little but the other Sort whichcomes from Holland, becaufe the Paintersefteem it as much as the Venetian, but theyare very much in the wrong ; for the DutchCerufe ground with Oil or Water, is a White

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of no long Duration becaufe of the Chalkthat is in it, which does not happen to thetrue Venetian Cerufe, which is only the WhiteLead ground; fo that if one had the trueVenetian Cerufe there would be no Need ofgrinding White Lead, and confequently theDanger would be avoided that Perlbns meetwith by grinding it, which often occafionsfeveral Difeafes, and fometimes Death it-felf.

If they who have Occafion for Cerufe toufe in Medicine, or to make Salt of Saturn,would ufe the true Venetian Cerufe, theywould find their Operations more perfect:And inftead of taking the Cerufe in Cake,they might take the White Lead ground andmake it ferve all their Purpofes ; but then itmuft be bought of honeft Perfons, for nonebut they who ground it can anfwer for it:However the true White Lead ground is ex-treamiy white, foft, and friable.

It is remark'd, that the Hollanders tomake their Cerufe, ufe only the Duft thatcomes in Bruifing their White Lead ; and asthis Duft could not fupply fo great a Quan-tity of Cerufe as is us'd in France, and otheECountries, and they could not otherwife affordit fo cheap, they mix a Sort of Marie orwhite Chalk with it. As for that whichcomes from England, it is ftill worfe thanthat from Holland, becaufe they mix more ofthat Stuff with it, and it is not of fo gooda Colour. They who grind the White Leadto make Cerufe of it, have Water-Mills,and afterwards they caft it in little Moulds toform it into Cakes, which to have its properQualities fhould be extreamiy white, fofr,friable and dry, and the leaft broke or mix'dwith little Duft that can be, efpecially if itbe for Sale ; you ftould rejecl: that which hasnot a good Body, but cracks in handling it,which proceeds from its being made up be-fore it was well dried, or by having beendamag'd by fome Wet coming to ir.

Cerufa, or Cerufe, is a Lead thatis penetrated, rarified, and half Lemery.diffolv'd by the Vapour of Vine-gar, and reduc'd into a very white Sub-ftance that is heavy and friable. When youwou'd make this Cerufe, the Lead is to bebeat into fine thin Plates, which are fufpend-ed or hung over Earthen Pots, in which theyhave put Vinegar; and when the Pots areVol. II. S full

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