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■when protected from the free accefs of atmos-pherical air.

Chemiftry is indebted principally to the in-dustry and talents of M. Fourcroy, for what isknown concerning this Angular fubltance, fothat its chemical hiftory is of recent date, andit makes fuch an important addition to ourknowledge in what has hitherto been the moltdefective part of chemiftry, that of animal mat-ter, that we Shall examine it with fome minute-nefs.

The hiftory of the difcovery of this fubftancelies within a fmall compafs.—A very largeburying-ground, belonging to the church desInnocens, at Paris, had for many centuries beentlte receptacle of a confiderable part of the po-pulation of that metropolis.* The method ofdepositing the bodies had long been to dig largepits from twenty-five to thirty feet deep, capableof containing from twelve to fifteen hundredbodies, which, when filled, were covered witha few feet of earth, and fuffered to remain un-difturbed for a longer or Shorter time, that isfrom fifteen to thirty years, according as roomwas wanted. The average number of burialshad been for many years about three thoufandannually, fo that the foil for many feet beneathan area of feven thoufand Square yards, wasalmoft an entire mafs of animal matter, whichhad gradually rifen feveral feet above the naturallevel of the neighbouring ground. For nearlytwo centuries complaints had been made of theinfalubrity of fuch an immenfe mafs of putre-faftion, within the heart of a large clofely-builtpopulous city, and at laft, in the year 1782, thegovernment undertook the formidable operationof removing the greater part of the foil, withall its contents. This bufinefs neceffarily ex-po fed to view the Situation of thefe commonburying-pits, in every different period of Spon-taneous change, and the obfervations of feveralable Scientific men, affifted by the experiencelong acquired by the grave-diggers, enabledthem to collect the following very intereftingparticulars.

In the firft of thefe pits which was examined,and which had been filled up about fifteen years,the bodies were found Sunken to the bottom ofthe coffins, as if they had been prefled downwith a weight; on removing what remained ofthe linen fhroud, the body beneath it was foundconverted into irregular maffes of a foft unc-tuous cheefe-like fubftance, grey brown inco our, breaking down under the fingers like

pernvaceti. The frnell of the bodies thusThouret. J, Phyf. tom. 38. *• Fourcroy An,

changed was not very offenfive, fo-that theycould be handled without much repugnance.On further examination, it was found that everypart of the body, except the bones, nails, andhair, was converted, Sooner or later, into thisfpermaceti-iike fubftance; and by the evidenceof the grave-diggers it appeared that this changewas completed in thefe large receptacles in aboutthree years, and that it was more periedt in thecenter of the pits than in the upper extremities,where the bodies were nearer the Surface, andtherefore more expofed to the action of the funand air. b Several varieties of texture and appear-ance of this fubftance were noted,Sometimes quitedry and brittle, with a polifhed Surface and a me-tallic luftre, at other times waxy, or foft as curd.

We Shall not dwell further on the contents ofthis very interesting memoir, in which everyparticular that could be collected on fo novel aSubject, is detailed with great accuracy andapparent fidelity; we Shall proceed to the che-mical analyfis of this fubftance. c

Expofed to a heat not greater than boilingwater, it melted, and by very flow distillationcontinued for many days, and regulated fo asto produce as little decompofition as poffible bythe mere heat, it gave about one-fixteenth ofits weight of a very fetid water, holding a quan-tity of ammonia in Solution. The remainingmafs was rendered fomewhat more brittle bythis procefs.

A long expofure to the air produced a Similareffect in diSfipating much of the alkali, andbringing the refidue to a nearer refemblance towax.

Its habitude with water Shewed its Sapo-naceous nature in a very Striking manner. Whenrubbed in a mortar with a little cold diftilledwater, it readily and uniformly mixed with it,into a whitifh emulfion, which, on adding moreliquid, refembled exactly a Solution of foap inwater, frothed in the fame manner by agitation,and was, like foap, curdled and decompofed byhard well water, by acids, by lime water, andby metallic falts. On filtering the folution,which tock place very Slowly, the clear liquorremained exceffively fetid, and on long Standing,left by evaporation ammoniacal pholphate.

Mixed with lime and a little water, a Strongodour of ammonia was given out, together witha very fetid gas, and after heating and lixivia-ting, the refidue was a mixture of the lime withthe oily bafe of the fubje£t of experiment, fromwhich the lime was afterwards Separable bymuriatic acid, leaving a dry, combuftible, unc-

Chid, tom. 5. * Fourcroy An. Chid* tom. 8.