424 Elimination of Algce in Lochs and Ponds, [Sess. 



for information in regard to the deleterious effects pro- 

 duced by plants other than bacteria in water-supplies with 

 which they were familiar. The replies were sufficiently 

 startling, and called for immediate remedy. A few examples 

 may be given, the State only being named and not the city 

 or town. Indiana reported, " The taste of the water was 

 said by the people to be woody or fishy, like rotten wood or 

 decayed fish. At one time the report got out that the body 

 of a missing man had been found in the reservoir." The 

 following is from Massachusetts : " The odour was so bad last 

 year that it was almost impossible to take it as far as the 

 mouth to taste. Horses refused it at the street watering- 

 troughs, and dogs fled from it." The situation in l^ew Jersey 

 was thus described : " Have seen Uroglena so abundant that 

 an odour could be plainly detected one-third of a mile away." 

 N"ot to multiply examples, here, finally, is the reply from 

 Texas : " At this time of the year " — i.e., in the height of 

 summer — "Algae are fierce. Some days we are on top, and 

 some days the Algae are on top. It costs us an average 

 of 25 dollars a -month for cleaning out Algse from two 

 reservoirs." 



Following upon such alarming reports, experiments were 

 instituted in the State Laboratory of Plant Physiology at 

 Washington. In order to cope successfully with this con- 

 tamination of water by Algse, it was felt to be necessary that 

 the remedy should fulfil these three conditions : first, that 

 it should be readily available ; second, that it should be cheap 

 enough for practical use in the largest reservoirs, and by the 

 poorest communities ; and third, that it should be absolutely 

 harmless to man. Many substances were experimented with, 

 as free chlorine, sulphur dioxide, and sodium, potassium, and 

 ammonium salts. However, these and others were all re- 

 jected, and sulphate of copper was at length fixed upon, as 

 fulfilling all the necessary conditions. The earliest trials with 

 this form of native copper were carried out on the water- cress 

 beds of Virginia, where the plant is largely grown for market 

 purposes. The offending Alga in this case was Spirogyra, 

 which with us is frequently very troublesome in fresh-water 

 aquaria and other places. Spraying the plants with a strong 

 solution of sulphate of copper was at first tried, but this did 



