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battening trie feparation of the foap from theremaining ley, but much remains to be done bythe fcientific chemiit in illuftrating this veryimportant manufacture.

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The- chemical • properties of every alkalinefoap are the following: when wetted, it fwells,foftens, and abforbs a large quantity of water,and if more is added it diflolves therein, makinga foiution which at firft is fomewhat opalefcentor grey but by repofe becomes clear. Soap-water when agitated forms a large quantity ofwhite frothy bubbles which remain for a con-fiderable time before they burft, and may beinflated to a vaft bulk, as is feen in the commonarnufement of blowing foap-bubbles. Hotwater diflolves foap more rapidly and in largerproportion than cold. Soap will keep in a dryplace for a great length of time unaltered, butwhen damp, a part of the alkali graduallyfeparates and appears on the furface as a falineefflorefcence of carbonat of foda. Diftilledper Ji, it yields molt of its oil tolerably pure*after which the refidue blackens, exhales a fetidfmell and black fmoke, and finally the alkalialone is left in a carbonated Hate .

Soap is alfo foluble in alcohol.

The foiution of foap is decompofed by all the ■acids, which curdle it, or feparate the oil in theform of white lumps. An excefsof acid re-diflblves the curd, and the oil is transferred to the'acid, but on boiling this foiution, the oil fepa-rates entirely, and rifes to the furface. Thefoiution. is alfo curdled by lime, barvtic orItrontian water, and in this cafe the curdconfifts of the oil . united with the earth andconcreted by this union. All the foluble faltsof thefe and the other earthy bafes equallydecompofe loap-water, and form a curdy preci-pitate, which is the reafon why hard water, thatalways contains fulphat of lime, and often otherearthy falts, immediately curdles foap- inftead offorming an. uniform foiution. The metallicfalts alfo produce the fame effeft, and a com-bination of the oil and metallic oxyd is produced.

Thefe feveral deconapofitions have been exa-mined by Berthollet . h The oleo-calcareouscurdy precipitate formed by adding a iolution offoap to lime-water, is not altered by cauftic al-kali, which proves that oil has a ftronger affinitywith lime than with alkali, but if a carbonatedalkali is ufed, the oleo-calcareous compound isdecompofed, the lime becomes carbonated, andfeparates, and the alkali goes to the oil. Thisalfo affords another preemptive argument a-

gainft the exiftence of carbonic acid in commonfoap. Ammonia has no more effedi on the oleo-calcareous compound than the fixed alkalies have,but if carbonated ammonia is digelted with it,carbonated lime is produced, and the ammoniaand oil unite compleatly. If this latter foiutionis evaporated, a foap remains, which is morepungent than common foap, is largely folublein alcohol, but imperfectly fo in water. A.fimilar ammoniacal foap is formed, and fepa-rates immediately in white curds by adding afoiution of common foap to muriated ammonia.

It has been mentioned that all the earthyfalts decompofe foap. With Epfom fait anoleo-maguefian precipitate is formed which isundtuous, dries with difficulty, is infoluble inboiling water, but eafily diflolves in alcohol orexpreffed oil. In a moderate heat it melts intoa yellowiffi tranfparent mafs.

An oleo-aluminous compound is formed byadding alum to a foiution of common foap.This forms a foft flexible mafs, which prefervesits fupplenefs in drying,, and is fcarcely folublein water, alcohol, or oil.

The fame excellent chemift examined feveralof the oleo-nretallic compounds formed by add-ing a foiution of foap to the metallic folutions.With' corrofive Tublimate a quantity of finallcoagula were produced, and more readily withnitrat of mercury. This combination is vifeid,dries with difficulty, diflolves in oil and alcohol.It becomes of a deep Hate colour by expofure tothe air, and readily foftens by heat.

Sulphat of zinc, decompofed by foap gave ayellowifli white compound;, the nitro-muriat:one of a dull leaden colour.

Nitro-muriat of tin gave a white compound,.which differed from all the others in not beingfufible by heat, owing to. the quantity of me- ■tallic oxyd which it .contained.

The falts of iron give a reddifh-brown oilycompound, very tenacious and eafily fufible.It is readily foluble in oil and oil of turpentine.

Sulphat of copper gives a. copious greenmafs refittous in appearance, which becomesbrittle on drying. Digetted in alcohol its colourdeepens, hut it does not diflolvs except withheat. Ether much improves the colour anddiflolves a portion. This compound is readilyand largely foluble in oils to which it gives agreen colour.

Acetite of lead gives a white tenacious mafs,very adhefive when heated, and refemblingdiachylon, which is a diredt combination ofoil and litharge.

b Mem. ue I'Acad. ler 17 So.