38 METHOD OF DESTROYING ALG^ JN WATER SUPPLIES. 



Effect vpon Bacillus coll of erpomre 1o colloklal .solution of copper at room temperature.^ 



[Determination made in tubes of bouillon. + indicates growth after -48 hours' inoculation: - indicates 



no growth.] 



Duration of exposure to action of copper. 



10 hours. 

 16 hours. 

 '20 hours. 

 50 hours. 



Check. 



15 sq. mm- 



copper foil 



iu 10 ce. of 



water. 



+ 

 + 

 + 



+ 

 + 



+ 

 + 



100 sq.mm. 



copper foil 



in 10 cc.of 



water. 



+ 

 + 



+ 

 + 



2'25 sq. mm. 



copper foil 



in 10 cc.of 



water. 



+ 



a Experiment conducted in test tubes containing 10 cc. each of sterilized water. The copper foil was 

 erilized and added immediately before inoculating the tubes with the usual :! mm. looji of a 'Jl-hour 



sten 



culture of H. ro/l 



Effect upon Bacillus coli of exposure to colloidal snliilion of copjyerat room temperature.^ 



[Determination made iu Petri dLshes.] 



i hour . . . 



1 hour ... 

 li hours . 



2 hours . . 

 21 hours . 



3 hours . 

 3 J, hours . 



4 hours . 

 8 hours . 

 12 hours 



Duration of exi)osure to action of copper. 



a Experiment conducted in test tubes, each containing 5 cc. of sterilized water. The copper foil 

 was sterilized and added immediately before inoculating the tubes with the usual 3-mm. loop of a 

 24-hour ctllture of B. coli. 



Effect upon par<tcolon of e.rjiosu re to collodial .solution of copper at room temperature. « 



[Determination- made in tubes of bouillon. + indicates growth after 48 hours' inoculation; - indi- 

 cates no growth.] 



Duration of exposure to action of copper 



Check. 



j 15 sq. mm. 

 copper foil 

 in 10 cc.of 

 water. 



100 sq. mm. 

 copper foil 

 in 10 cc. of 

 water. 



5 hours 

 10 hours 

 16 hours 

 20 hours 

 50 hours 



225 sq.mm. 

 copper foil 

 in 10 cc. of 

 water. 



« Experiment conducted in test tubes containing 10 cc. each of sterilized water. The copper foil was 

 sterilized and added immediatelv before inoculating the tubes with the usual 3 mm. loop of a 24-hour 

 culture of paracolon. This experiment was duplicated upon another form of paracolon with exactly 

 the same results. 



