CHEMICAL STERILIZATION AND DISINFECTION 99 



carbolic acid in solution. A 3 or 4 per cent, solution of 

 commercial carbolic acid in water requires longer for disin- 

 fection; but it is, at the same time, open to fewer objections 

 than are solutions of the inorganic salts; though here, too, 

 we find a somewhat analogous reaction between the car- 

 bolic acid and proteid matters. Under ordinary circum- 

 stances its action is complete in from twenty minutes to 

 a half-hour. It is not reliable for the disinfection of 

 resistant spores; such, for instance, as those of bacillvs 

 anthracis. 



All tissues containing infectious organisms should be 

 burned, and all cloths, test-tubes, flasks, and dishes should 

 be bolied in 2 per cent, soda (ordinary washing-soda) solu- 

 tion for fifteen to twenty minutes, or placed in the steam 

 sterilizer for half an hour. 



Intestinal evacuations may best be disinfected with 

 boiling water or with milk of lime, a mixture composed of 

 lime in solution and in suspension — ordinary fluid "white 

 wash." This should be thoroughly mixed with the evacua- 

 tions until the mass contains a considerable excess of the 

 lime, and should remain in contact with them for one or 

 two hours. Excreta may also be easily disinfected by 

 thoroughly mixing them with two or three times their 

 volume of boiling water, after which they are kept covered 

 until cool. 



Sputum in which tubercle bacilli are present, as well as 

 the vessel containing it, must be boiled in 2 per cent, soda 

 for fifteen minutes, or steamed in the sterilizer for at least 

 a half-hour. 



On the whole, in the laboratory we should rely more upon 

 the destructive properties of heat than upon those of chemical 

 agents. 



