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degree of heat putrefaction is much promoted.For the fame reafon alfo fubftances putrefymuch more flowly when expofed to a dryingwind, than in a fheltered place.

The obvious phenomena of putrefaction arethe following, in any animal matter kept at apretty uniform temperature, in a place notmuch expofed to currents of air, the fubftancefirft becomes foft and flabby, or if it is alreadyfoft, as in the cafe of the coagulum of blood,it refolves itfelf into a dark fluid, the colourthen changes to green or brown, and an un-pleafant fmell begins to iffue from it. As theprocefs advances the foft parts then melt downinto a putrid pulpy mafs, and the fluids becometurbid, and the effluvia become exceffivelyloathfome and fickening, and after a time, theparts fwell and become puffy, and difengagethe putrid gas in a flow but fenfible efferve-fcence. A foul and brown ferum then fweatsout from the pulpy mafs, and about this timethe effluvium is very fenfibly ammoniacal as isapparent from its effeCts on the eyes and throat,and by forming a white vapour with muriaticacid gas. Things continue nearly in this ftatefor a confiderable time, during which a largepart of the putrid fubftance is evaporated, andcarried off in the putrid gas and dilperfed inthe atmofphere, after which the extreme fcetorfubfides, and finally the procefs of putrefactionceafes, and leaves a kind of fat foetid earthymatter.

Such is the regular procefs of putrefaction,as far as relates to the external circumflances,and obvious phenomena, but it may be ob-ferved, that fome parts putrefy much more rea-dily than others, and fome fcarcely at all.Perhaps the moft putrefcent fubftance that weknow is the blood, which property it owespartly to its fluidity and partly to the largequantity of fibrin and uncondenfed albumen,which it contains, and efpecially to the former.Animal parts alfo feem to be (ceteris paribus)more putrefcent in proportion to the numberof conflituent parts which they contain Thefubftances abfolutely or nearly imputrefcible,are bone and condenfed albumen, the latter fuch

it exifts in cuticle, nail, hair, &c. whichlong remain unaltered in the midft of putrefy-ing fubftances. Animals// alfo putrefies withgreat difficulty, and hence the people that livein the moft northern parts of America , the Ef-kimaux and others, preferve fifh and meat to apertain degree from putrefaction by immerfionin nin oil. J

The gaffes certainly known to be produced

by putrefaCtion are carbonic acid, carburettedhydrogen, fulphuretted and phoiparetted hy-drogen, and ammonia, but either thefe or fomeof thefe muft be confiderably changed by thefolution of the animal matter, or fome com-pound not yet examined muft be produced inthat ftate of putrefaCtion where the gas evolvedoccafions fuch dreadful effeCts upon thofe thatunfortunately fall in the way of it, even whendiluted confiderably with common air. Thisis faid to be the cafe when the abdomen of alarge animal is firft burft after fome days, orperhaps weeks of putrefaction ; the gas fromwhich caufes inftant fainting, and iometimesdeath, and even when the perfon expofed to itrecovers the firft fhock, it leaves exceflive debi-lity and other alarming fymptoms for a confi-derable time. The moft deleterious gas thatwe know is, perhaps, carburetted hydrogen,but the effeCts of this as obtained by chemicalmeans, are far fhort of thofe above mentioned,when equally diluted.

The generation of ammonia has been fatis-faCtorily accounted for fince the difcovery qfthe conflituent parts of the volatile alkali, bythe new combination formed between the azotof the animal matter, and the hydrogen, ofwhich latter there are many fources, and parti-cularly that of the decompofition of water. Asammonia is always produced during putrefac-tion, it feems rational to fuppofe that one im-portant purpofe of the moifture neceffary to theprocefs is to afford, by its decompofition, thehydrogen of the volatile alkali.

The circumflances which tend to the gene-ration of the nitrous acid, (which is an un-doubted produCt of putrefaCtion) have beenmentioned under the article Nitrat of Potojh ,but many more experiments muft be made, andfads obferved, before we can explain, why incertain cafes the azot tends to unite with oxy-gen to form this acid, and in others with hy-drogen to form ammonia.

That peculiar change which takes place inanimal flefh, whereby it is converted into a-'fpermaceti-like fubftance inftead of undergoingthe ufual mode of putrid decompofition, hasbeen mentioned under the article Adipocre .PUTTY.

True putty is made by calcining an alloy ofequal parts of tin and lead : a white powder isthus produced that is the bafe of moft of theopake enamels, and is alfo uied in the polifhingof metals, ftones, and glafs.

The glaziers’ putty, ufed by them for fallen--ing panes of glafs into fafhes, was perhaps ori-