186 BACTERIOLOGY. 



work of others, the conclusions reached by us may be 

 summarized as follows : 



1. Disinfection of Infected Dwellings. 



Exposed surfaces of walls, * carpets, hangings, etc., 

 in rooms may be superficially disinfected by means 

 of formaldehyde gas. All apertures in the rooms should 

 be tightly closed and from 6 to 12 ounces of formalin 

 or its equivalent used to generate the gas for each 1000 

 cubic feet. The time of exposure should be not less 

 than four hours, and a suitable apparatus should be 

 employed. The temperature of the apartment should 

 be as high as possible, and certainly not below 52 F. 

 When generated very rapidly the formaldehyde gives 

 much better results than when giveu off slowly. 



Under these conditions spore-free bacteria and the 

 contagion of the exanthemata are surely destroyed when 

 freely exposed to the action of the gas. Spore-bearing 

 bacteria are not thus generally destroyed; but these 

 latter are of such rare occurrence in disease, that in 

 house disinfection they may usually be disregarded, 

 and, if present, special measures can be taken. 



The penetrative power of formaldehyde gas in the 

 ordinary room, at the usual temperature, even when 

 used in double the strength necessary for surface disin- 

 fection, is extremely limited, not passing, as a rule, 

 through more than one layer of cloth of medium thick- 

 ness. Articles, therefore, such as bedding, carpets, 

 upholstery, clothing, and the like, should, when pos- 

 sible, be subjected to steam, hot air, or formaldehyde 

 disinfection in special chambers constructed for the 

 purpose. If not, they must be thoroughly exposed on 

 all sides. 



