Vickipedia

ANTISEPTICS (anti, against, septikos, causing putrefaction) are substances which prevent or arrest putrefaction and analogous fermentive changes. It has been proved that Putrefaction (q. v.), fermentation of grape-juice (vinous fermentation), of milk, (lactic fermentation), and many, though probably not all other fermentations, depend upon the presence of microscopic vegetable organisms (see GERM THEORY). To prevent these processes, then, it is necessary either (1) to exclude these organisms altogether ; (2) to interfere with conditions which permit of their development; or (3) to destroy their vitality.

(1) These organisms, or their germs, are present in ordinary air; but it has been shown by Pasteur, Tyndall, Lister, Roberts, and others, that if air be filtered through cotton wool, or (if moving slowly) through a fine bent tube, it may be allowed to come in contact with putrescible substances, if these themselves contain no living organisms or germs, without causing putrefaction. This method, however, has had no important practical applications.

(2) Their growth may be arrested (a) by a low temperature. Thus large quantities of fresh meat are imported from America, and even Australia and New Zealand, in chambers cooled to near the freezing-point. Carcases of the long extinct mammoth, with the flesh still present, have been found in the ice-cliffs of Siberia. The longer time that meat, milk, &c., keep in cold than in hot weather is familiar. (b) By absence of moisture. Thus, if the contents of an egg be thrown out on a plate, and thoroughly dried in an oven, the whole becomes of a hard, horny consistence, and may be kept in this state for years. If soaked in water, it will soon begin to putrefy. In the same way meat may be kept fresh by thoroughly drying it. The preservation of fruits, &c., in strong syrup is an example of a similar action.

(3) The vitality of these organisms may be destroyed (a) by heat; e.g., meat and other eatables can be preserved for an indefinite time if they are boiled and hermetically sealed while still hot in tin vessels (see PRESERVES); (&) by various chemical substances. Some of the most important are common salt and saltpeter, used in curing fish, pickling meat, &c.; alcohol, in preserving zoological specimens, vegetable essences, fruits, &c.; sulphurous acid, boracic acid, and arsenious acid; many salts, as chloride of zinc (Burnett’s solution, q. v.), permanganate of potash (Condy’s fluid, see under MANGANESE), sulphate of copper (blue vitriol) corrosive sublimate, nitrate of silver; chlorine (given off by chloride of lime), iodine, iodoform (CHI₃), glycerine, boroglyceride (C₃H₅Bo₃), eucalyptus oil, thymol, creasote, carbolic acid, salicylic acid, tannic acid, quinine, the patent preparation ’sanitas,’ charcoal (both vegetable and animal), dry mould, used in the earth-closet system (see SEWAGE EARTH-CLOSET). All these substances act directly or indirectly as poisons to the organism-which produce putrefaction, &c.; most of them are either poisonous or very unpalatable to man, and cannot therefore be used in preserving food. Many of them are, however, used in the arts to arrest the decomposition of putrescible substances; e. g., in the manufacture of size for writing-paper from scraps of hides, sulphite of soda or antichlore, containing sulphurous acid, is added; hides are preserved by salt, or, when tanned, by tannin, a compound of tannic acid; timber is found less liable to decay if charged with an antiseptic, such as sulphate of copper, chloride of zinc, corrosive sublimate, or creasote. It is placed in a steam-box, so that the air contained in its pores is replaced by steam; the whole casing is then closed tight, and allowed to cool; the steam condenses and leaves a vacuum in and around the wood. If one of these substances is then introduced, it finds its way into the innermost pores of the timber (see also WOOD-PRESERVING). ,

But next to the preservation of food, the most important purposes for which antiseptic methods and substances are used, are the prevention of infectious diseases, and the treatment of wounds.

The properties of the infectious matter of infectious disease are closely analogous to those of the organisms that lead to putrefaction, &c.; and even in cases where its organic nature has not been proved (see GERM THEORY), can be rendered inert by a proper use of A., or by exposure to a high temperature. Thus anything that has come near the patient suffering from an Infections disease, and discharges from his person, can be made harmless by carbolic acid, chloride of zinc, or some other antiseptic; his bedding is roasted in an oven at a temperature of 212° P. or more; the room where he has been treated is fumigated with chlorine or sulphurous acid; and so the disease is prevented from spreading. This is, in fact, one of the chief aims of medical practice at the present day (see disinfectants).

Many of the evil effects which follow wounds and surgical operations are due to the presence of organisms (see PYAEMIA); and the effects of their antiseptic treatment, introduced by Mr. Lister, have been marvelous (see CARBOLIC ACID.).