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 given 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, 
