EFFECT OF COPPER UPON WATER BACTERIA. 



59 



RESISTANCE OF VARIOUS BACTERIA. 



Several species of bacteria occurring commonl}^ in Potomac River 

 water have been isolated, and comparative tests have been carried on 

 with these bacteria and with the colon bacillus. An examination of 

 the tables showing- the exact results of these tests indicates clearly 

 that no danger to most of the common saprophytic bacteria can be 

 expected from using concentrations of copper sufficiently strong to 

 destroy Bacillus coli. To allow as little variation as possible in the 

 different tests all experiments were carried out in triple-distilled water. 

 This will probabh^ explain the sensitiveness of most of the bacteria to 

 copper solutions, for, as Gildersleeve ^' has stated, "The resistance of 

 bacteria washed in distilled water is lessened, due in all probabilit}^ to 

 the fact that some of the slimy substance w^hich surrounds the bac- 

 terial cell and protects it to some extent from the action of detrimental 

 agencies is removed.'' For purposes of comparison the table showing 

 the action of copper sulfate on various bacteria in tap water, pub- 

 lished by Gildersleeve/' is reproduced below. 





Dilution. 



Average 

 number 

 tothe cu- 

 bic cen- 

 timeter 



in 

 control. 



Percentage destroyed in hours specified. 



Organi.sm. 



1. 



'■ 



3. 



4. 



5. 



6. 



7. 



8. 



9. 



10. 



11. 



12. 



24. 





f 1: 250,000 

 1: 500,000 

 1:1,000,000 

 1:1,500,000 

 1:2,000,000 

 1: 2-50, COO 

 1- 500 000 



110, 000 

 100, 000 

 140, 000 

 120, 000 

 130, 000 

 105, 000 

 190 non 



100 





























99 



inn 























B. typhosus 



78 ion 























50 



4 



100 



99 



80 



87 



8 



95 



40 



31 



20 



20 



90 



68 



33 



5 



3 



93 



65 



28 



10 







95 



15 



9 



4 







99 



50 



15 



8 



1 



85 



7 



99 

 55 



100 

 80 





















82 



87 



87 



93 98 



100 



















100 

 99 

 95 

 10 



100 

 95 

 50 

 30 

 20 

 99 

 90 

 85 

 10 

 10 



100 

 92 

 51 

 18 

 12 

 99 

 26 

 11 

 12 

 1 



100 

 70 

 30 

 22 

 8 























B coli communis 



1:1,000,000 1 99,000 

 1:1,500,000 -• 150,000 

 1:2,000,000 ! 110,000 

 ■ 1: 250,000 11,500 

 1: 500,000 vy(\ nno 



100 

 99 

 14 























100 

 27 





















50 



85 



90 



92 1 93 



93 



95 



98 



100 



1 



97 [100 

 62 85 















B. dysenterife ... 



1:1,000,000 

 1:1,500,000 

 1:2,000,000 

 1: 250,000 

 1: 500,000 

 1:1,000,000 

 1:1,500,000 

 1:2,000,000 

 1: 250,000 

 1: 500,000 

 1:1,000,000 

 1:1,500,000 

 1:2,000,000 

 1: 250, 000 

 1: 500,000 

 1:1,000,000 

 1:1,500.000 

 1:2,000,000 

 1: 2-50, 000 

 1: 500,000 

 1:1,000,000 

 1:1,500,000 

 ,1:2,000,000 



72, 000 



12, 400 



13, 600 



92, 000 



86, 000 



101.000 



89, 000 



94, .500 



115,000 



106, 000 



111,000 



99, 000 



118, 000 



102, 000 



109, 900 



110,000 



107, 000 



98, 000 



92, 000 



88, 000 



86, 000 



100, 000 



95, 000 



99 

 60 

 30 



99+ 



70 



45 



ioo 



75 

 60 











40 

 25 

 100 

 99 

 89 

 80 

 31 



42 

 30 



si 



62 



85 

 62 



87 

 68 



90 

 71 



91 

 75 



100 

 98 





100 

 96 

 40 

 40 























96 

 70 

 80 



99 



85 

 83 



100 

 95 



85 

















98 

 88 



98 

 91 



99 

 91 



100 

 93 









97 



100 





98 

 82 

 27 

 22 

 99 

 80 

 16 

 17 

 8 



100 

 90 

 42 

 36 

 99 + 

 95 

 33 

 30 

 8 





















B. proteus A^ul- I 



95 

 69 

 51 

 100 

 97 

 33 

 38 

 10 



98 

 90 

 65 



100 

 93 

 78 















gans 



98 

 80 



99+ 



85 



100 



88 



! 







92 95 



100 



j 



99 

 45 

 46 

 11 



99+ 

 47 

 46 

 15 



100 

 61 

 48 

 30 







1 





B. prodigiosus ... 



63 



51 

 38 



69 

 52 

 41 







93 



60 

 43 



61 

 50 



92 



88 





90 

 30 

 28 

 10 



100 

 70 

 96 

 30 





' 















pyogenes au- 

 reus 



78 

 58 

 50 



85 

 69 

 64 



97 

 85 

 79 



99 

 93 



82 



99 

 95 



85 



100 

 99 

 98 









100 

 99 











99+ 



100 



« studies on the Bactericidal Action of Copper on Organisms in Water. 

 Journal of Medical Science, vol. 129, 1905, p. 754. 

 &0p. cit., p. 759. 

 100— vn 



American 



