UlOi;.] PUBLK; IKX^UMENT— No. 83. 145 



purpose of studying the ellects of copper sulfate on bacteria; 

 but as the bacteria .showed no a)»j)rcciable increase at this 

 time, we thonijfht it not worth while to inauirurate another 

 experiment. Samples of water taken one hour and twenty- 

 four liours after treatment were tested for cop})er by the foods 

 and feeding de[)artment of the station ; and, while ptjssiblc 

 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 emph)3'ed, which in numerous other 

 cases has failed to give relialih? results where such small (quan- 

 tities of copper are i)resent. 



At the time these chemical tests were l)eing made for coj)- 

 per there came to our notice a test described and reconmuMided 

 by Dr. Ewerts,^ which claimed to detect one part of copi)cr 

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

 hil)iling action of copper to diastatic action. This method 

 was^iv^en a trial in the foods and feeding chemical laboratory, 

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

 detailed study of this latter method, together with some 

 practice, will prove it to l^e of some value. 



The result of this single experiment with copj^er sulfate 

 in treatino; 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 Belchertown reservoir, and those made elsewhere, in 

 showing that Anahmna is extremely suscei)tiblc to copi)er, 

 and can readil}^ be killed by this method of treatment. 

 Moreover, the general clearing up and rapid disappearance 

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

 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 Avould have a tendency to affect xinahoina ; and about 

 one and one-half inches of rain fell between the lUth and 

 24th of June. 



» Ztsclir. Priauzeukraiik, Bd. XIV., 3 Heft., p. 133. 



