l'J07.] 



PUBLIC DOCUMENT— No. 33. 



173 



of water, while the other jar was left untreated. The jars 

 were j^laced side by side in the laboratory, and exposed to 

 the organisms of the air. The water was taken from the 

 pond jirevious to its being treated. The results of the experi- 

 ments are shown in the f ollowino* table : — 



Table showing the Results of treating Pond Water with Copper Sulfate 

 at the Bate of 1 Part of Copper Sulfate to 4,000,000 of Water. 

 (^Experiment made in Laboratory , in Glass AquarHa Jars.) 



[Number of bactoria per c. c. of water.] 



June 14, 

 15, 

 16, 

 17. 



18, 

 19, 

 20, 

 21, 

 •2-2, 

 23, 

 24, 

 2"), 

 20, 



28, 



29, 



30, 



July 1, 



3, 



4, 

 5, 

 7, 

 9. 

 11, 

 13, 

 15, 



1", 

 19, 



Date. 



Pond Water 

 untreated. 



7,158 

 5,T'23 

 4,849 

 4,849 

 4,444 

 6,188 

 7,9-27 

 G,112 

 4,772 

 6,302 



5,.313 

 6,273 

 7,004 

 6,927 

 8,282 

 8,926 

 6,419 

 7,004 

 7,409 

 8,107 

 6,792 

 7,972 



10,168 

 6,412 

 6,989 

 7,399 

 6,034 

 8,632 



10,656 



Pond Water 

 treated. 



301 



15 



* 38 



32 



24 



31 



43 



59 



101 



120 



54 



134 



126 



98 



170 



242 



310 



270 



298 



340 



930 



872 



800 



1,060 



1,000 



940 



946 



1,390 



1,240 



1 One hour after treatment. 



