41 
PURIFICATION AND DISPOSAL OF SE^yAGE. 
1. Dilution. 
This method is allowable for cities situated on the sea or on rivers whose flow is very 
large as compared with the sewage (100 ; 1) and the unfiltered water of which is not used 
as a water supply. 
2. Sewage farming. 
3. Chemical precipitation. 
4. Intermittent filtration. 
Needs sandy soil. 
5. Septic tank. 
6. Contact bed treatment. 
7. Continuous filtration : 
a. Scott-Moncrieflf system. , 
b. The Ducat. 
c. Whitaker & Bryant. 
d. F. Stoddart. 
e. G. Salford. 
