312 THE HOUSE FLY—DISEASE CARRIER 
Inasmuch as chemical disinfection can be relied upon 
to destroy pathogenic bacteria, and inasmuch as burial 
greatly reduces the danger from animal parasites, a 
suitable combination of the two methods (chemical dis¬ 
infection and burial) can be used with reasonable safety. 
(5) Sewers: In partly sewered towns, the effluent 
from these privies may be emptied into the sewers. If 
conditions are such that the addition of this material 
to the sewage is dangerous, then the entire sewerage 
system needs correction. 
Paper .—Only toilet paper so far has been used, and 
the septic action seems to digest it. Other experiments 
indicate that newspaper would be disposed of by septic 
action in the tank, but perhaps some increase in the 
size of the tank would be required. 
Cleaning .—Although no water has been added since 
the model was put into operation, the contents of the 
liquefying tank have remained fluid, and it is prob¬ 
able that in a tank having the capacity of an oil bar¬ 
rel, the amount of sludge from the dejecta of a family 
of five people would not be sufficient to require the 
cleaning of the liquefying tank oftener than once in 
six months to a year. 
