UKMk] public DOCUMENT — No. 33. 145 



pur})()se of studying the effects of copper sulfate on bacteria ; 

 but as the bacteria showed no appreciable increase at this 

 time, we thought it not worth while to inaugurate another 

 experiment. Sami)les of water taken one hour and twenty- 

 four hours after treatment Avere tested for copper by the foods 

 and feeding department of the station ; and, while possible 

 traces of the copper were found, they were so small and un- 

 certain that no copper could be reported. In these tests the 

 ferrocyanide method was employed, which in numerous other 

 cases has failed to give relial)le results where such small quan- 

 tities of copper are present. 



At the time these chemical tests were being made for cop- 

 per there came to our notice a test described and recommended 

 by Dr. Ewerts,i which claimed to detect one part of copper 

 in 30,000,000 parts of water. This test is based on the in- 

 hibiting action of copper to diastatic action. This method 

 was given a trial in the foods and feeding chemical laboratory, 

 and found to be unsatisfactory. Quite likely, however, a 

 detailed study of this latter method, together with some 

 practice, will prove it to be of some value. 



The result of this single experiment with copper sulfate 

 in treating; the college reservoir is not sufficient in itself to 

 allow deductions of great value. They corroborate, however, 

 the experiments made by Messrs. Moore and Kellerman on 

 the Belchcrtown reservoir, and those made elsewhere, in 

 showing that Anahmna is extremely susceptible to copper, 

 and can readily be killed hy this method of treatment. 

 Moreover, the general clearing up and rapid disappearance 

 of odor from the water two or three days after treatmcmt, 

 together with the falling off" of bacteria, was quite noticeable. 

 It should be stated, however, that there was a fall of about 

 20° in the temperature on the third day after treatment, 

 which would have a tendency to aff'ect Anabcena ; and about 

 one and one-half inches of rain fell between the 19th and 

 24th of June. 



» Ztschr. Pflanzeukrank, Bd. XIV., 3 Heft., p. 133. 



