Nature’s means of disinfecting are by dilution, sunlight, desiccation, time and antibiosis. The direct rays of the sun are Nature’s greatest germicide. Few of the microörganisms will live in the direct rays, but there are none that will withstand them for more than a few hours. Germs can not withstand the effect of dryness. Thus we see there is in Nature that which works as a most efficient germicide. The combination of sunlight and dryness forms a most desirable means of disinfection. When germs become attenuated through the effects of these natural processes they do little harm when introduced into the body.
One of the most important adjuncts to the work of disinfection is personal cleanliness and sanitation of the environment.
Other Agents
Fire is not a practical disinfectant. It can be used only with those articles that are of little or no value since the article that is being disinfected is destroyed. The burning of all refuse and garbage is by all means the best method. Burning is the most satisfactory and cheapest method in disinfecting sputum and other excreta from the body, and in disposing of articles of little value saturated or contaminated with such.
The dry heat method of disinfecting requires specially built apparatus such as dry air sterilizers. This form is not practicable for use in disinfecting fabrics and other materials that are destroyed or injured by extremely high temperature required to destroy the germ life. Metals are easily injured by this method as they are likely to be scorched. All forms of life are destroyed in an hour’s time when exposed to a temperature of 150° C. Such articles as glassware will withstand this heat or even higher and may be thoroughly sterilized in from one to two hours. This insures proper penetration and sufficient heat to completely destroy all life.
Boiling is one of the most satisfactory and easiest methods of disinfecting. Continuous boiling for an hour in water at 100° C. will result in the destruction of most germs of the so-called infectious dis-eases. There are some of the spores, such as those of anthrax and tetanus, that will survive the most strenuous processes of boiling. However, most of the germs will be destroyed before the boiling point is reached.
Boiling is the best method to be used in disinfecting bedding, body linen, towels and other fabrics which will not be harmed by this process. There is a great variety of articles that may be disinfected in this way, such as utensils and bed pans. The surfaces of the floors, walls, beds, and other objects may be cleansed with boiling water. In this use it is advisable to add some disinfectant to the water.
Steam is not only a disinfectant but it is also a sterilizing agent. All forms of germ life, including spores, are completely destroyed. It is therefore our best known disinfectant. There are many objects that are injured and some ruined by steam, such as silk, wool, furs, oilcloth and rubber goods, and articles containing varnish or glue. There is danger from staining and running of colors. Disinfection may be either with streaming steam or with steam under pressure. For the use of streaming steam no particular device is necessary. Some means of providing the steam and some place to hang or place the objects and articles to be disinfected are the two essentials for this method. It is not necessary to have an air-tight place. To use steam under pressure there must be a specially constructed apparatus. There are many such devices on the market and they are used in institutions where it is found necessary to disinfect with steam.
Sterilization may be accomplished in twenty minutes with steam at about one atmosphere of pressure which will give a temperature of about 120° C. A temperature of about 125° C. is obtained with the pressure at about twenty pounds to the square inch. This reduces the time for sterilization to about fifteen minutes.