In spite of the fact that these experiments demonstrated in a most convincing way the practicability of purifying water reservoirs in this manner, no great practical use has been made of the process. This has been due, doubtless, to the fact that many experimenters were not satisfied respecting the desirability of purifying a water supply by the addition of a substance known to be of such a poisonous character as sulphate of copper. The present high cost of the reagent and the danger of injury to fish have also had a limiting influence.

1 American Journal of Public Health, September, 1915, page 918.