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was greater than the number in the 4-foot coke-bed effluent, and, indeed, showed no difference from
the raw sewage in this respect.
The ratio of the number of B. coli to the total number of bacteria in the crude sewage and in
the effluents is approximately as follows—
Crude sewage (26 samples)—Ratio of B. coli to total number of bacteria = 1:12
4-foot coke-bed effluent (15 samples)—Ratio of B. coli to total number
of bacteria = 1 : 12
6-foot primary coke-bed effluent (8 samples)—Ratio of B. coli to total
number of bacteria = 1 : 11
6-foot secondary coke-bed effluent (3 samples)—Ratio of B. coli to total
number of bacteria = 1 :43
These results would seem to indicate that the result of the bacterial treatment of the raw
sewage in the coke-beds was to effect no material alteration in the number of B. coli relative to the
total number of bacteria in the case of the 4-foot and 6-foot primary coke-beds and to bring about
a decrease in the case of the 6-foot secondary coke-bed. In the latter case, however, only 3
samples were examined.

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