202 Messrs Purvis and Rayner, The chemical, ete. 
The chemical and bacterial condition of the Cam above and 
below the sewage effluent outfall. By J. E. Purvis, M.A., and | 
A. E. Rayner, M.A. 
[Read 24 February 1913.] 
THE river was investigated at various poimts extending from 
100 feet above the outfall and at 8 feet from the outfall: and at 
+ of a mile, 4 a mile, ? of a mile, 14 miles, 2 miles, 24 miles, 
3 miles and 4 miles below the outfall. 
Chemically, the river purifies itself moderately well from the 
contaminating effluent ; for at about 2 of a mile below the effluent, 
the albuminoid ammonia and the oxygen absorbed figures were 
lower than at 100 feet above the effluent outfall. 
Bacterially, the dangerous pollution, as indicated by B. coh, 
is well-marked at between 3 and 4 miles below the outfall. The 
potential danger of such contamination is in the direction of cattle 
quenching their thirst, of bathers, and of watercress. 
