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throughout their whole fubdance with red orblue veins. This foap is harder than the whitefoap of the fame materials becaui'e it requiresto be dried to a greater degree to take the mar-bling. This is performed by adding to thefoap, as foon as it is compleatly made and fe-parated from the fpent ley, a frefh quantity ofley and immediately after a folution of fulphatof iron. A decompofition between the twotakes place, and a black oxyd of iron is fepa-rated which is entangled within the liquidfoap. The boiler is then cooled, and the leywhich fettles is drawn off, after which the foapis again melted. A workman then {binds overthe boiler and ftirs the foap with a wooden in-ftrument whilft another throws in at intervals aquantity of colocothar or brown red oxyd ofiron, ground up with water into an uniformliquid. This difufes both the oxyds throughthe foap, which is then cooled and framed.There appears to be fome manual dexterityrequired in dirring tliefe ingredients together,fo as to diffufe the marbling diffidently throughthe mafs without mixing it compleatly.

All the foaps which we have hitherto men-tioned are made with foda in one form orother, which alkali appears too to have been ofthe molt antient ufe in foap-making; but thereis another fpecies in which the foie alkali is thevegetable in the form of pearl-adi, pot-alhes,vvood-afhes, and the like, and in which nocommon fait is employed. Thefe potafh foapsdiffer eflentially from the others in remainingalways foft and pafty however long they arekept. On this account they are not employedin common domedic ufes, but are chiefly ufedin fcouring wool and other purpofes of manu-facture. However as they are perfect foaps,and entirely foluble in water, they may be par-tially employed in rendering water foapy for,-any purpofe of cleanfing.

Soft .foap is always coloured, generally of abrown or deep green, which however only de-pends on the nature of the oil ufed, for with■olive oil it is white. It is much ftronger and*oore acrid than the hard foaps, but in otherrefpeCts it has the fame chemical properties.Tile confidence fliould be that of a tenaciouspajte or glue even in the hotted dimmer, andit lould melt readily in water forming a whitean. lg it doth. I he mode of manufacture ofthis ioap differs in this effential particular fromthe other txiat no reparation takes place be-tween the foap and the fpent ley as in the foda

foaps, but the whole contents of the boiler afterfudicient boiling and evaporation are convertedinto foap ; neither is there any of the procefsof framing and drying. A good deal of prac-tical skill alfo (more than can be learnt fromhooks.) feems to he required in producing theproper union between the oil and alkali, andthe procefs appears liable to Hidden and oftenunaccountable failures, from the refufal of thematerials to unite with fudicient intimacy, orfrom their difutiion after having already com-bined.

The manufacture of the bed foft foap inFlanders and Picardy is thus deferibed. 5 Theoils ufed in thefe works are linfeed, hemp,poppy, colefeed, and rape. Of thefe the twolad are the cheaped and lead edeemed. Fifhoil alfo anfwers perfectly well, but the ofFenfivefrnell of the foap made from it is fo permanentthat its ufe is forbidden. The alkali is gene-rally Dantzic, or Ruffian pearl-adi which ismixed with lime and lixiviated, till a ley drongenough to bear an egg is obtained, and onlyone degree of drength is ufed except refervinga weaker ley for occafional dilution of the in-gredients. The boilers are the fame as forhard foap, and fliould not he filled more thanhalf-full, on account of the great rifing of thecontents whild they are incorporating. Theproportions of the materials are on an averageabout 30 parts of oil to 40 of drong ley, whichyield about 65 parts of foap. The manage-ment of the boiling and gradual addition of theley to the oil require confiderable attention,and if it has fucceeded properly, the oil andalkali unite into an uniform gluey faponaceousmafs, after which the boiling is continued tillenough of the watery part has evaporated toleave the remainder of the proper confidencewhen cold, which is known to be the cafewhen a fample taken out and cooled does notdick to the fingers and draw out in threads, butremains brown, fomewhat did’, and granulated.The boiler is then entirely emptied, and thefoap is barrelled for fale.

When the boiling has not been continuedlong enough, the foap is apt to ferment, andfpoil by keeping.

Soap is manufactured in this country princi-pally from tallow or any other fat; and the al-kali employed is either barilla or pearl-afh, or amixture of the two, according to the price andpractice of the manufacturer. But as potadialone will not make a ftifF foap, recourfe is

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