PUTREFACTION. The spontaneous decom position of animal and vegetable substances, attended by the evolution of fetid gases. The putrefactive fermentation of animal substances s usually attended by more fetid and noxious leichalations than those arising from vegetable products. This appears principally referable to the more abundant presence of nitrogen in the former; and hence, those vegetables which abound in nitrous principles, such as most (if not all) of the cruciform plants, exhale peculiarly nauseous effluvia; hence, also, such animal pro ducts as are destitute of nitrogen, are either unsusceptible of what is commonly called putre faction, or suffer it slowly and imperfectly. The formation of ammonia or of ammoniacal com pounds is a characteristic of most cases of ani mal putrefaction; while other combinations of hydrogen are also formed, especially carburetted hydrogen, and sulphuretted hydrogen, together with complicated and often highly infectious vapors or gases, in which sulphur and phos phorus are frequently discerned. These putre factive effluvia are, for the most part, easily decomposed, and resolved into new and com paratively innocuous compounds by the agency of chlorine; hence the importance of that body as a powerful and rapidly acting disinfectant. The rapidity of putrefaction and the nature of its products are, to a great extent, influenced by temperature, moisture, and access of air; they do not ensue below the freezing point, nor in dry substances, nor under the entire exclusion of oxygen; and hence, various means suggest themselves of retarding or preventing putrefac tion, as well as of modifying its results. A tem
perature between 60° and 80°, a due degree of humidity, and free access of air, are the circum stances under which it proceeds most rapidly. The most effective antiputrefactives, or antisep tics, are substances which either absoru or re move a portion of the water or moisture, and enter into new combinations with the organic matter. The astringent or tannic principle of vegetables is also a powerful preserver of most organic tissues; it enters into chemical combina tion with the albuminous and gelatinous mem branes and fibers; and the resulting compound, of which leather furnishes a characteristic exam ple, is comparatively little prone to change, although the tanning material itself, as well as the animal principles with which it unites, are sepa rately liable to decay. Among saline substances, the antiputrefactive powers of salt are commonly known: when a piece of flesh 13 salted, brine runs from it, in consequence of the energy with which the salt abstracts the component water of the muscular fiber: the flesh becomes indurated, and its susceptibility to putrefactive changes is greatly diminished; but it becomes at the same time less easy of digestion as an article of food.