CHEMICAL STERILIZA TION AND DISINFECTION. 6 9 



the evacuations until the mass reacts distinctly alkaline, 

 and should remain in contact with the infective sub- 

 stance for one or two hours. If boiling water be used 

 the amount should be about double the volume of the 

 mass to be disinfected. They should be thoroughly 

 mixed and allowed to stand, covered, until cold. 



Sputum in which tubercle bacilli are present, as well 

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

 soda solution for fifteen minutes, or steamed in the 

 sterilizer for at least half an hour. 



On the whole, in the laboratory we should as yet 

 rely more upon the destructive properties of heat than 

 upon those of chemical agents. 



From what has been said, the absurdity of sprinkling 

 about, here and there, a little carbolic acid or in placing 

 about apartments in which infectious diseases are in 

 progress little vessels of carbolic acid, must be plain. 

 The disinfection of water-closets and cesspools by allow- 

 ing now and then a few cubic centimetres of some so- 

 called disinfectant to trickle through the pipes is ridic- 

 ulous. A disinfectant must be applied to the bacteria, 

 and must be in contact with them for a long enough time 

 to insure the destruction of their life. 



In the light of the latest experiments upon disinfec- 

 tants, the place formerly occupied by many agents in the 

 list of substances employed for the purpose, will most 

 likely be changed as they are studied more closely. 



The agents, then, which will prove of most value in 

 the laboratory for the purpose of rendering infectious 

 materials harmless are : Heat, either by burning, by 

 steaming for from half an hour to an hour, or by boil- 

 ing in a 2 per cent, sodium carbonate solution for fifteen 

 minutes ; 3 to 4 per cent, solution of commercial car- 



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