22 
TABLE III 
Effect of Fluorescein on Coliform Organisms 
in the Presence of Direct Sunlight1 
MPN/m1 MPN/m1 
Time with dye without dye Time with dye without dye 
O hour 24,000 24,000 4 hours 2,300 23 
72,000 72,000 : 620 6.2 
2 hours 2,300 2,300 6 hours 230 0.6 
25300 230 230 nil 
1, A mixture of 5% unchlorinated primary effluent in sea water 
with and without 0.01% sodium fluorscein was used. A 500 ml 
mixture in an open beaker was exposed to sunlight for the time 
indicated. MPN*s were determined by Standard Methods. 
