DISINFECTANTS, agents used for de stroying or rendering inert the germs of in fectious diseases. It has been amply proved that a large number of diseases are of microbic origin, and when these low forms of micro organisms are introduced into the bodies of sus ceptible individuals they multiply and thereby become capable of producing certain diseases which are called infectious. Any agent capable of destroying these organisms is a disinfectant or germicide, and through disinfection we have a powerful and effective means of controlling these diseases and checking the spread of them.
In order to disinfect thoroughly we must first identify the source of infection. In the eruptive fevers, such as measles, scarlet fever, smallpox, etc., the infectious germ comes di rectly from the body of the patient suffering with the disease, attaching itself to clothing, bedclothes, etc., and to objects handled by the infected person. The same is true of infectious skin-diseases, such as barbers' itch, ringworm, etc. In pneumonia, tuberculosis, diphtheria and whooping-cough the sputum and the breath carry the germ of infection; in cholera the alvine discharges and possibly the vomits; in typhoid fever infection is generally due to the specific germ found in the discharges from the bowels; in malaria, anthrax and elephantiasis the germ is found in the blood and is trans ferred by biting insects; in hydrophobia it occurs in the saliva, spinal cord and brain ; in gonorrhoea in the urethral discharges, etc. Some of the infecting agents do not multiply outside of the body, while others under favorable condi tions are highly procreative. While, therefore, the object of disinfection would be accomplished by destroying all infected material, where this is not admissible it is necessary to subject it to a process of disinfection inimical to the life of the infecting germ. This must be complete and thorough. The selection of an appropriate dis infectant for each disease is the result of labora tory research. A culture of a germ is made in a medium best adapted to its propagation and by experimenting with various germicides one is found which proves most destructive to the germ in the shortest possible time. The best and cheapest disinfectant is heat, particularly moist heat. There is no infectious germ known that can survive boiling water continued for a time — longer or shorter, depending on the germ.
In the use of heat various kinds of mechani cal apparatus for both dry and moist (super heated steam) heating are used. Boiling in fected clothes with or without the addition of a chemical disinfectant is a popular means of dis infection. Where it is impossible to use either of these agents resort is had to fumigation with gaseous vapors of the disinfectant. Cold (freezing) is a natural disinfectant, but fails in the case of typhoid germs, which have been known to survive freezing for 103 days; and the same is true of the tuberculosis germ. Cam
pfior, medicated papers or the burning of in cense may clear an odorous atmosphere impreg nated with sewer-gas or fumes of decomposing animals or vegetable matter; but these are not true disinfectants.
Of late the utility of steam disinfection has been forcibly demonstrated, and most cities and quarantine stations have established plants for this process. Clothing, bedding, etc., known or believed to be infected are placed in chambers or cylinders and subjected to superheated steam (220° to 230° F.) for 20 or 30 minutes. This thoroughly disinfects all infected material. Dry heat is not so effective. A practical disin fectant for many domestic purposes, both inex pensive and easy of application, is chlorinated lime in the proportion of six ounces to a gallon of water. All typhoid or cholera stools, like wise the sputum of pneumonia or tuberculosis patients, are rendered innocuous by it in less than 30 minutes, if used in equal quantity with the material to be disinfected. It may also be used as a spray, particularly for cellars, and the dry chlorinated lime is useful in the case of pnvies and garbage cans. Carbolic acid in a 3-per cent solution—that is, in the proportion of four ounces to a gallon of water —is one of the best. It does not stain or burn and is suffi ciently powerful to disinfect floors and wood work, although for this purpose a 5-per cent solution is generally used. For clothing the 3 per cent bath is used and the immersion should be not less than one hour. The cresols are cheaper and still more effective, a 2-per cent solution being equal to a 5-per cent solution of carbolic acid. Borax is a good disinfectant for open sores, but should be used only under the direction of a physician, as it frequently devel ops poisonous effects through absorption into the blood. Potassium permanganate is an ef fective disinfectant for water tanks and pipes. It is non-poisonous, comparatively cheap and possesses the power of destroying the noisome odors of putrescence. It depends for its action upon its generation of nascent oxygen. Another bactericide of great oxidizing power is hydrogen peroxide. Corrosive sublimate in proportion of one part to 1,000 parts water is not only an efficient disinfectant, but a powerful insecticide as well. It can be applied to woodwork, walls, floors, etc., but its corrosive action on metal renders its uses limited on sewers, drains and the like. Milk of lime or common whitewash, so highly recommended by the German govern ment in the cholera epidemic of 1892, is a ready and efficient means of disinfection. This may be prepared by sprinkling with water a quart of quicklime in a suitable vessel and, when the lime is reduced to a powder, adding three or more quarts of water, allowing the mixture to stand. It may then be applied with a brush to walls, floors, etc. Drains are flushed and all excreta from infected cases treated with equal parts of lime solution.