598 Introduction to the Study of Science 



usually directed by public health officials after a case of in- 

 fectious disease. But it is now generally recognized that the 

 usual practice is not thorough and is worse than no disinfection 

 because it does not destroy the disease germs, but merely quiets 

 the suspicion and consequently lessens the precautions of 

 those who occupy the room or use articles exposed to infection. 

 Concurrent disinfection or that done throughout the course of 

 the disease is the most efficient sort. When this is thoroughly 

 done, it may render disinfection after the recovery of the patient 

 unnecessary. 



For some kinds of disease, as, for example, tuberculosis and 

 anthrax, subsequent disinfection is indispensable, because the 

 germs adhere to walls, furniture, and clothing, and remain alive 

 and virulent for months. Disinfection by fumigation may 

 be made fairly effective. But it should not prevent thorough 

 cleaning of ceiling, walls, and floor of the room, the removal of 

 the old wall paper, if such is used, and fresh decoration of walls 

 and woodwork. Hot water and soap may, when vigorously 

 used, be germicidal as well as cleansing. 



Several kinds of disinfectants have come into common use. 

 Sulfur is often burned in a closed room ; it destroys bacteria and 

 insects imprisoned there, but it also destroys the colors of tex- 

 tiles by bleaching them. Formalin is preferable, though it 

 fails often to kill certain kinds of pestiferous insects that may 

 inhabit a room. There are many methods of using formalin. 

 It may be evaporated on hot radiators, or in other ways. Some- 

 times formalin lamps are burned, though these can hardly be 

 considered satisfactory. 



A convenient method of fumigation is as follows : The 

 quantities of materials necessary for a room 10' by 10' by 10' 

 are given ; these may serve as a unit in computing for larger 

 rooms. All windows and doorways, except one, should be 

 tightly sealed with strips of paper. Articles in the room should 

 be opened so that the disinfectant may have ready access to 

 all parts. A large galvanized metal pail or tub of about six- 



