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with fulpTiuric acid; and a third, which indeedfomewhat refembles the laft, and was employedhy De Segner, previous to Crell’s experiments,is to laturate the diddled acid liquor with potalh,and then to decompofe it by diftillation withhalf as much fulphuric acid as there was carbo-liat of potafli-employed.

The fame acid may alfo be prepared accordingto Guyton, in the following way : mix anykind of animal fat with fome powdered quick-lime, melt the mixture in an iron pot for a time,and when cold, lixiviate the refidue with warm■Water, which diSolves out the febat of lime.Evaporate this liquor to drynefs, by which abrown fait is left, which calcine iii a crucible,then lixiviate and filter the folution, and evapo-rate to drynefs. Laftly, decompofe this calca-reous fait by fulphuric acid, and the limpidpungent acid of fat will rife.

Before we proceed to defcribe the Selats , wefhall mention that peculiar acid difcovered byThenard, which alone he confiders as purefebacic acid. His procefs was the following:A large quantity of pork lard was diftilled perfe ; the produ£t was waflied with much warmwater and all the watery liquids were united.Acetited lead was then poured in, and a floc-culent precipitate fell down, which was collectedand dried, and confifted of febat of lead. Thiswas then put into a retort with fulphuric acidand diftilled. The liquor in the recipient hadno acid property but on the furface of the liquorremaining in the retort there floated a meltedmafs refembling fat in appearance, which wascarefully collected, and after walhing was boiledwith water. At this heat it difiolved, and oncooling if depofited tender needled cryftals,which were decidedly acid, and which theauthor confiders as the pure febacic acid . Toafeertain whether they were or were not producedby the fulphuric acid, fome of the limply diftilledliquor of lard was treated with water, filteredand evaporated, and fome of the fame cryftalswere feparated on cooling, Ihewing therefore thatthis fuliftance either exifted in that ftate in thefrefh lard, or was produced by the mere acSlionof fire, and not by the fulphuric acid.

This febacic acid is without fmell, has aflight ly acid tafte, reddens litmus, melts in heatike greaie, and is much more foluble in hotwater than in cold, fo that a hot folution at allconcentrated, readily concretes by cooling. Itis alfo foluble largely in alcohol, and cryfttlliz.esin fmall needles, but by careful management

lt may be obtamed m the form of broad brilliantplates.

VOJL. II.

Thenard alfo afferts that along with the fe-bacic acid much acetous acid is contained in thediftilled liquor of lard, and that it is this, andnot the true febacic acid which is given out,when according to Segnev’s method the liquoris faturated with potalh, evaporated to drynefs,and decompofed by fulphuric acid. In proofof which he afferts that in performing the ex-periment, he obtained under thefe circum(lances,an acid, which, like the acetous, produces adeliquefeent foliated fait with potalh that hasa very pungent tafte, that forms with nitrat ofmercury a precipitate which crvftalfizes inplates, and that gives much acetous acid whentreated with fulphuric acid. With regard tothe acid obtained by Crell’s fecond proccfs, thatis, by treating the fat with alkali and alum, anddecompofing by fulphuric acid, Thenard affertsthat on repeating this procefs he obtained noacetous acid, but only muriatic , fince it pre-cipitates nitrat of filver, and forms a cubic Hitwith foda, which fait, decompofed feparatelyby fulphuric acid, gives a penetrating acidvapour, which united with the nitric acid iscapable of diflolving gold. This acid he at-tributes to employing the common potalh ofcommerce, which always contains fome muriat,for in repeating the experiment with purepotafli, he obtained no acid except a minutequantity of vinegar.

Such are the experiments of this chemift,who is certainly worthy of the higheft confi-dence, and they eftablilh the fait of thereexifting an inodorous, not eafily volatile, andcryftallizable acid fubftance in the products ofdiftilled fat, to which the term Sebacic acid oughtprobably to be applied.

This acid precipitates the acetite and nitratof lead, nitrat of filver, and acetite and nitratof mercury; it faturates the alkaline bafes, andforms with them foluble falts; with potafli itforms a fait which does not abforb moiiturcfrom the air, and is decompofed by the mineralacids ; it does not trouble barytic, lime, orftrontian water.

We cannot however admit the explanationgiven by this ingenious chemift of the natureof Crell’s volatile acid, to the full extent, with-out further experiments, though it is fufficientlyprobable that it is a very compound liquor,containing a large quantity of acetous acid,perhaps with fome fulphureous, and intimatelycombined with a portion of animal oil.

Every acid procured in any manner fromanimal fat is probably formed hj the diftillation orby the aftion of the fulphuric acid, and not20