ANTISEPTICS (anti [Gk.], against, and septos [Gk.], putrid, from (_____, to make rotten), substances which have the property of preventing or arresting putrefaction in dead animal or vegetable matter. The access of air, together with a moderate amount of warmth and of moisture, are necessary to the occurrence of the putrefactive changes, which consist essentially in the breaking up of the complex organic material, and the formation of new and simpler combinations among its constituent elements. During the process various gases and vapours are evolved, and the lower forms of animal and vegetable life are observed to grow and multiply in the putrefying substance. The exciting causes of putrefaction have long formed a subject of scientific discussion, two widely-different theories being maintained respecting them. By the one, the changes which occur during the process are held to be from the first the result of chemical decomposition in the organic substance, whose atoms are in a state of motion or activity, which is capable of being communicated by catalytic action to other organic material in contact with it (Liebig); while, further, it is asserted that minute living organisms maybe evolved from, the dead material as the result of these chemical transformations. By the other theory, which is founded mainly upon the researches of Pasteur, the putre-factive changes are ascribed to the agency of organised germs ever present in the atmosphere, which, finding a suitable nidus in the putrescible material, grow and multiply, producing the chemical decompositions as the result of their action. Putrefaction, it is further maintained, may be entirely prevented by means which exclude the access of germs. The subject derives much interest and importance from its relation to the doctrines of the origin of life, as well as to questions concerning the sources of contagion and epidemic disease, and continues to the pre-sent time a matter of keen inquiry and experiment among physiologists. (See BIOLOGY.)
Putrefaction may be prevented by removing one or more of the conditions essential to its occurrence. Thus, by exclusion of the atmosphere, dead matter, which would speedily undergo decomposition, may be kept intact for an indefinite length of time, as shown in the method of pre-serving meat by hermetically sealing the jars after the expulsion of the air by heat. Again, the preservative influence of a low temperature is well known; and ex-treme cold is a powerful antiseptic, as proved in the case of the frozen mammoths of northern Asia. Furthermore, the abstraction of moisture will prevent corruption in dead matter. In warm and dry climates animal food may be preserved by exposure to the sun. In the ancient practice of embalming the dead, which is the earliest illustration of the systematic use of antiseptics, the moister portions of the body were removed before the preservative agents were added. (See EMBALMING.) Numerous chemical substances have the power of counteracting the putrefactive process. Many of these have been long known and used for this purpose. In embalming, besides the application of various aromatics and resins, the body was washed with cedar oil and natron (soda), and pitch or tar were used as anti septics. Pitch was used by the Bomans in wine-making to control the fermentive process. The fumes of sulphur were largely employed by the ancients for purposes of purification, while common salt has been known and used for ages as one of the best preservatives from decay. The mineral acids possess antiseptic properties, as do also many of the metallic saltsthe chloride of zinc, in the form of Sir W. Burnet's disinfecting fluid, being one of the most potent of them. Alcohol is well known for its power of preserving animal substances from decay. Quinine has been found to possess strong antiseptic properties. The tar products, notably carbolic acid, are among the most approved and extensively used of all antiseptic agents. The various substances named possess the power of pre-venting putrefaction in dead animal or vegetable matter, and to a greater or less degree of arresting it where already begun. They likewise exert a similar action on the ana-logous process of fermentation. They differ from mere disinfectants, which destroy the emanations from putre-scent material, but do not necessarily arrest the progress of decay. (See DISINFECTANTS.) Some antiseptics, how-ever, such as sulphurous acid, are powerful disinfectants also, while others, such as quinine, have no disinfectant properties at all. Various opinions are entertained regard-ing the modus operandi of antiseptics. By those who hold the purely chemical theory of putrefaction they are believed to operate in different ways according to their chemical properties; thus, sulphurous acid is said to act by deoxidising the putrescible matter; the mineral acids and metallic salts by combining with the substance, and forming a permanent compound; and the tar acids in a similar manner. On the other hand, the supporters of the germ theory maintain that carbolic acid, and indeed all true antiseptics, produce their effect by acting as poisons to the infusorial organisms which are held to be essential to the occurrence of the putrefactive pro-cess.
One of the most important applications of antiseptics has been their introduction into medical and surgical practice. Although their internal administration, with the view of counteracting diseases believed to be due to morbid poisons, has not hitherto yielded any marked practical result, their employment in the treatment of wounds has, in the hands of Professor Lister of Edinburgh, attracted much interest, and has exercised an important influence on surgical practice during the past ten years. Professor Lister, adopting the germ theory of putrefaction, and regarding many of the evils arising in connection with open wounds as the result of putrid discharges, produced by the agency of atmospheric germs, seeks to exclude the access of these to wounded surfaces by the employment of antiseptics, particularly carbolic acid, the power of which in destroying living organisms is undoubted. Dressings of gauze, made antiseptic by previous treatment with strong carbolic acid, are applied to wounds. The acid well diluted with water is likewise employed as a lotion, and, during the dressing of wounds and the performance of operations, is also ap- plied in the form of spray to the surrounding atmosphere, with the object of preventing all access of germs. Boracic acid is also employed by Mr Lister as an antiseptic. The chief benefits claimed for this method of treatment are, that wounds, however extensive, may heal without the occur- rence of putrefaction in the discharges, and that thereby the risks of blood poisoning (pyaemia, &c.) are reduced to a minimum. Although the antiseptic system in surgery is but on its trial, and its practical advantages over the methods of treatment in general use are still questioned by many high authorities, it has already obtained wide repute, and is extensively employed by surgeons both in this and other countries. (j. o. A.)