PUTREFACTION is the term applied to the spontaneous decomposition of organic sub 'stances, when such decomposition is accompanied by an offensive odor. In other respects it may be regarded as identical with fermentation (q.v.). In the process of putrefaction, organic compounds of a higher order are resolved into lower organic compounds, into in organic compoundi (such as water, ammonia, sulphureted hydrogen, etc.), or into simple -chemical elements) such as hydrogen or nitrogen). The substances which most readily putrefy are the protein bodies (albumen, fibrine, caseine, etc.), and gelatigenous tissues, glue, etc.;. the only necessary conditions being the presence of moisture and the access of air at the commencement of.the process. Since animals are mainly composed of the pro tein bodies, they are especially liable to under& this change; but many vegetable products, which :are rich in these bodies (e.g., seeds), are also prone to this form of decomposition.
The peculiar smell is readily accounted for when the nature of the resulting compounds is considered.
The putrefaction of organic matters is prevented by a variety of conditions, amongst . which may he mentioned (1) exclosion of air, (2) perfect dryness, (3) a freezing tempera ture (as, e.g., in the case of the mammoths preserved in the Siberian ice), (4) a high tem perature (about 2501, and (5) antiputrescent or antiseptic substances of various kinds. It is worthy of notice that all bodies susceptible of putrefactive decomposition may act as ferments, and may thus induce specialehanges in sugar, urea, etc., which would not have occurred except in the presence of the putrefying matter.