70 BACTERIOLOGY. 



boiling water or with milk of lime, a mixture composed 

 of lime in solution and in suspension ordinary fluid 

 " white- wash/ 7 This should be thoroughly mixed 

 with the evacuations until the mass reacts distinctly 

 alkaline, and should remain in contact with the infective 

 substance 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 ster- 

 ilizer 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 sprink- 

 ling 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 allowing now and then a few cubic centimetres of 

 some so-called disinfectant to trickle through the pipes 

 is ridiculous. A disinfectant must be applied to the bac- 

 teria, 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 disin- 

 fectants, 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 



