58 DESTRUCTION OF BACTERIA BY CHEMICALS 



disinfected should be allowed in the room with a case of the 

 more serious infections. Books in large numbers are disin- 

 fected by exposing them in a chamber to which formaldehyde 

 vapor can be admitted. In small numbers they may be ren- 

 dered harmless by sprinkling pure formalin solution on every 

 second page and laying them in a tightly closed drawer. 



Instruments. Instruments, including syringes, may be 

 boiled for five minutes in a 1 per cent, solution of washing 

 soda. Knives, however, should be kept in alcohol. Gauze 

 should be sterilized at 120 C. or 248 F. and 15 pounds' 

 pressure. 



Many hospitals use gauze over and over again. The prin- 

 ciple in such reclamation is that the gauze must be sterilized 

 after such cleaning that no spore formers or other highly 

 resistant viruses remain hidden in clots or masses of pus. 

 Gauze dressings should be received in plain soapy water in 

 which they are washed with gloved hands; they are then 

 rinsed in several changes of clean water, sorted and sterilized 

 in an autoclave. If preferred they can be received in weak 

 cresol solution but not in bichloride. Dressings from such 

 diseases as anthrax, actinomycosis, tetanus, gas bacillus 

 infection, and symptomatic anthrax would better not be 

 re-used. 



Pasteurization. This consists in the heating of a substance, 

 milk usually, to a temperature below the boiling-point, usually 

 140 F. or 56 C., which kills the non-spore-bearing bacilli, 

 and holding there for a few minutes. It is then cooled as 

 rapidly as possible to a point at which bacteria do not usually 

 multiply, that of the ice-chest. This does not sterilize the 

 substance, but in the case of milk may render it more likely 

 to spoil afterward if not properly taken care of. 



Sunlight. A most admirable disinfectant is sunlight. 

 Direct sunlight will eventually kill all bacteria, and it is wise 

 to expose materials from the sick-room, whether from an 

 infectious case or not, to as much sunlight as possible. 



