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had to the aCtion of common fait, which,when added after the potalh and oil are united,produces a reparation of the compound fromthe water incorporated with it, hardens it, andrenders it equal to the foda foaps.

The following is the ufual method of mak-ing the common white and yellow foap ufcdin domeftic purpofes. f

White hard foap is generally made withthree feparate charges of ley. The potafh(fuppofing this to be the alkali) is previouflydiffolved with water in a fmall boiler with alittle fire, and the folution is poured over a vatcontaining common wood-afhes mixed withlime, which makes the firft and ftrongeft ley.

As foon as this has run off the aflres areturned, more lime is added, and water ispumped on, which forms the fecond or weakley. The large boiler is then charged with thetallow, and about two-thirds of the ftrong leybeing added, a moderate fire is kept up to in-corporate the materials, which is known bytheir running into a IhifF glue. If this doesnot take place in about 7 hours (with 29 cwt.of tallow in the boiler) more alkali mull beadded. The tallow is then kilted or faturated,and the fire is drawn and the materials allowedto remain at reft for a Ihort time. Commonfait is then thrown in, and ftirred up with longpoles till it is thoroughly incorporated, and tillthe matter changes from a dark coloured glueto a thin foapy fubftance. A brisk fire is thenmade, and the materials boiled for a few mi-nutes, when the fire is again drawn, and thematerials in the boiler allowed to fettle for anhour and a half, during which the fpent leesfink to the bottom of the boiler, and arepumped off. The fecond operation, beginswith raifing the fire and adding to the foapymafs the weak ley, which is to be managed thefame as at firft and again brings it to the ft ateof a glue, which a very little fait will reftoreto the faponaccous ftate, and after boiling andcooling the fecond lees are pumped off. In thethird operation the third part of the. ftrong leywhich was .refer ved is added, which as before,changes the mafs to a thick glue, that muft begrained with fait as before.

The contents are then boiled ftrongly forthree hours, more or lefs, till by taking.dim-ples occafionaily with a trowel, the foap feelsfufliciently hard and dry to the. touch, andthe ley will be feen to run quite clear from thefoap on the. trowel, leaving.this latter in roundlumps. The bcii of foap is then finilhed by

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pumping off the fpent ley, and feraping off aquantity of light froth from the top of thefoap. The foap is then fit for framing, whichis a perfectly Ample procefs, and has alreadybeen deferibed.

With regard to the proportion of ingredi-ents, it is reckoned that 16 bufliels of goodwood-allies are equal in alkali to 1 cwt. of thebelt pearl-afh, and that this latter quantity willfatuvate 2 cwt. of tallow, and produce 3 cwt.

1 qr. of foap, fo that 12 parts of tallow willmake 20 of foap. Alfo, 12 bufliels of wood-afhes are reckoned equal to 1 cwt. of barilla,and the latter quantity will faturate if cwt. oftallow. A boil of 29 cwt. of tallow with10 cwt. of barilla, and 5 cwt. of pearlalh (asthefe alkalies are often mixed) requires about8 cwt. of common fait.

Common fait appears to have two diftinCtufes in foap-making; one is, that of promotingthe graining or reparation of the foap from the -fpent ley, which it does probably Amply by ab-ftraCting the watery part. • In this way it is ofas much ufe in the foda as the potafh foaps,.and in each it confiderably haftens the procefs;but it is by no means effential, and on accountof its high price appears to be feldom ufed,where barilla or foda is the foie alkali. Butwhere a large portion of the alkali is potafh,the foap would remain in the ftate of a foft'pally mafs (as we have already feen) and actu-ally does fo, till the addition of common fait,.which then brings the foap to the fame ftate asthe foda foaps.

It is therefore probable, as fuggefted byPelletier, that in thefe cafes a double decom-pofition takes place between the oil and potafhon the one hand, and the muriatic acid andfoda on the other, and that the products ofthis change of principles are a foap with oiland foda, and muriat of- potafh in the motherliquor.

To iliuftrate this, the fame ingenious che- -mi.ft made the following experiments: 3 lbs.of olive oil were boiled with a potafh ley 10J-lawing the fame precife procefs as that alreadydeferibed for the l'oda foap with this oil, and therefult was a foft foap of the confidence of but-ter weighing 8 lbs. On the other hand 6 lbs.of. common fait were diffolved in fufficientwater, and this folution was added by degreesto the foft foap again made fluid by boiling.After keeping up the fire for two hours, thewhole was cooled, and a very l'olid foap col-lected at the lurface which was again melted .usuavuiication,