CHEMICAL STERILIZATION AND DISINFECTION 103 



From what has been said, the absurdity of sprinkling 

 here and there a little carbolic acid, or of placing vessels 

 of carbolic acid about apartments in which infectious 

 diseases are in progress, must be plain. Treatment of water- 

 closets and cesspools by allowing now and then a few cubic 

 centimeters of some so-called disinfectant to trickle through 

 the pipes is ridiculous. 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 disinfectants, 

 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 greatest 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 boiling in a 2 per cent, sodium car- 

 bonate solution for fifteen minutes; 3 to 4 per cent, solution 

 of commercial carbolic acid; milk of lime, and a solution of 

 chlorinated lime ("chloride of lime") containing not less 

 than 0.25 per cent, of free chlorine. The chloride of lime 

 from which such a solution is to be made should be fresh 

 and of good quality. Good chlorinated lime, as purchased 

 in the shops, should contain not less than 25 to 30 per cent, 

 of available chlorine. The materials to be disinfected in 

 either of the lime solutions should remain in them for about 

 two hours. The solutions should be freshly prepared when 

 needed, as they rapidly decompose upon standing. 



