Rural Hygiene

by Henry N. Ogden

Disinfecting by heat.

Better than any chemical agent known to be a destroyer of bacteria is heat in one form or another. This may be steam or hot water or dry heat. If a high enough temperature is maintained for a sufficient length of time, the action is absolutely destructive to all germs. Fire does, of course, destroy bacteria along with whatever material the bacteria are concealed in, but such a disinfectant is of little value for ordinary purposes, since the object of disinfection is to destroy bacteria without destroying the surface on which they are lodged. In some old buildings, where consumption or smallpox, for example, has become permanent, it may be that the surest way of killing all the bacteria is to burn up the house.

Dry heat.

Unfortunately, even a moderate heat cannot always be applied. One's hands, for example, can neither be heated in an oven to the necessary temperature for destroying bacteria in their pores, nor can they be immersed in boiling water or steam for a sufficient time to secure thorough disinfection. Therefore, with the body, chemical means for disinfection must be employed. Also when it is desired to disinfect a liquid, such as beef broth, in which the experimenter desires to grow some particular species to the exclusion of all others, dry heat is inapplicable because it would evaporate the liquid, nor is chemical disinfection possible because of its antiseptic effect on the bacteria to be cultivated. Moist heat, therefore, must be used. When dry heat is used, it is usually for the disinfection of glassware or earthenware or metallic objects, the quality of which will not be affected by the necessary temperature, namely, 150 degrees Centigrade, or about 300 degrees Fahrenheit. This temperature must be maintained for at least an hour, and it is not certain even then to penetrate in full power to the middle of blankets or comfortables. Except for glassware to be used in a laboratory, dry heat, such as would be obtained by a kitchen oven, is not to be recommended.

Boiling water.

Boiling water, on the other hand, is the most effective and penetrating disinfecting agent available. One has only to expose an object to boiling water for five minutes to absolutely kill all disease-bearing bacteria contained, and since bed linen, clothes, blankets, and such articles as are naturally used in a sick room have to be washed after a patient's recovery, it requires but very little additional trouble to subject the soiled articles to that temperature of the water which will secure disinfection at the same time. But the water must be boiling. The mere fact that it was once boiling water gives it, half an hour later, no disinfecting properties, and complete disinfection can be secured only by actually boiling the garments or articles for at least five minutes. The apparatus necessary therefore—and no better piece of disinfecting apparatus can be secured anywhere—is a good old-fashioned wash boiler. The action is more certain, that is, more penetrating, if a little washing soda is added to the water at the rate of a tablespoonful of soda to a gallon of water. This solution is admirable for washing dishes, spoons, knives, forks, and other eating utensils used by sick persons. It is always a mistake to wash dishes from the sick room in the same vessel with other dishes. They should not only be washed separately, but they should be washed in boiling water, and preferably in a soap solution as just described.

Steam.

For some purposes, steam is better even than hot water; its effect on cotton and woolen garments is not so disastrous. A comfortable or blanket, for instance, may be subjected to steam without losing its elastic quality, and for small garments, an ordinary steamer, such as is used for puddings, answers admirably. Cities use steam sterilizers because of the greater convenience in furnishing steam to a large tank as compared with filling and emptying a tank with water and then providing sufficient heat to boil that water. The exposure to steam should last from half an hour to an hour, depending on whether the objects to be disinfected are small, open, and loose, or large, compact, and dense. Some articles, like bales of rugs, rolls of wool, and large bundles of cloth, cannot be sterilized at the center by ordinary steam, and while it is not likely that infection at the centers of such tightly rolled bundles has occurred if exposure took place while rolled up, yet it is certain that the disinfection does not reach these centers. In the case of such bundles as rugs from infected countries, where any single rug may become the medium of infection, it is requisite to thoroughly sterilize all parts of the bundle. For this purpose, it is necessary not merely to expose the articles to live steam, but to have the live steam under pressure so that it is forced into the inside of the packages by an excess of external pressure. This is probably not available in an ordinary house, where boiling must continue to be the method of disinfection.

Drying, light, and soil.

Before leaving this chapter, three agencies for disinfection may be pointed out, not perhaps to be depended on, but in order that the kindly provisions of nature may be appreciated. All germs removed from the body, which is their natural home, and exposed to the air are subject to drying and thus are killed. Unfortunately, this does not become true except after long periods of time, nor is it equally true with all germs, but it is certainly one of the methods by which the evil effects of disease germs may be lessened. The germ of consumption lasts as long as any germ, and yet this, when dried in the street, loses its vitality after about a week. Similarly, the typhoid fever germs, unless kept in a moist condition, dry up and die in a few days. With the drying, however, comes the danger that in the process they may be lifted by the wind and carried in the air to the mouths or nostrils of well persons, so that it is not wise to depend solely on this method of disinfection.