The Plankton Algae of tJie Palisades Interstate Park 131 



when caramel solution or a leaf extract was added the reaction was 

 much slower. 



The Method of Applying Copper Sulphate. After determining 

 the amount of copper sulphate needed and making the proper adjust- 

 ments for temperature, chemical nature of the water, and the other 

 factors mentioned above, the problem of the method of placing the 

 copper sulphate in the water arises. The best method is that first 

 devised by Moore and Kellerman (see figure 19) whose instructions 

 follow : 



" The method of introducing the copper sulphate into a water 

 supply is extremely simple. Place the required number of pounds 

 of copper sulphate in a coarse bag — ■ gunny sack or some equally 

 loose mesh — and, attaching this to the stern of a rowboat near the 

 surface of the water, row slowly back and forth over the reservoir, 

 on each trip keeping the boat within 10 to 20 feet of the previous 

 path. In this manner about 100 pounds of copper sulphate can be 

 distributed in one hour. By increasing the number of boats, and, in 

 the case of very deep reservoirs, hanging two or three bags to each 

 boat, the treatment of even a large reservoir may be accomplished in 

 from four to six hours. It is necessary, of course, to reduce as much 

 as possible the time required for applying the copper, so that for 

 immense supplies with a capacity of several billion gallons it would 

 probably be desirable to use a launch, carrying long projecting spars 

 to which could be attached bags each containing several hundred 

 pounds of copper sulphate." 



The application should be made, if possible, at a time when the 

 wind is blowing and the water in circulation, in order to secure an 

 even distribution of the copper sulphate. ' There are usually shallow 

 places in a lake where it is impossible to row a boat or where, if a 

 boat can be pushed through, the disturbance of the muddy bottom may 

 cause a too rapid precipitation of the copper. Huff ('16) has found 

 a small hand pump, the type used for spraying trees, very useful in 

 distributing a strong copper sulphate solution in these inaccesible 

 places which frequently form breeding centers for the algae. This 

 gives a much more uniform distribution in these inaccessible places 

 than sowing broadcast finely powered copper sulphate. 



The number of applications necessary for eradication of algae 

 depends upon varying conditions. If the algae in a body of water 

 have been killed off the inference might be drawn that the trouble 

 has been eliminated for all time, but experience has shown that the 

 same algae or other algae sometimes reappear in large numbers in 

 the same season. The explanation for this rests upon the rapid 

 multiplication of these organisms, the increase in the number of indi- 

 viduals being a geometric and not an arithmetic progression. From 

 the theoretical standpoint a single cell left in a lake could produce a 

 bloom within 30 to 40 days if conditions for its reproduction were 

 not limited by certain factors. In practice it has been found that 

 after the eradication of the algae it is generally a month before they 

 again become troublesome and that three treatments during a season 

 are sufficient to hold the algae in check. The fear expressed by some 



