EFFECT OF COPPER UPON WATER BACTERIA. 65 



T.\BLE XXI. — Effect of carbon diorid upon toxicity of copper stdfate to Bacillus coli.^ 



1 Experiment conducted in Weber resistance glass test tubes, each containing 10 c. c. of water triple 

 distilled from glas.s, portions of which had been treated previously with the desired amount of copper 

 .sulfate. All tubes inoculated with a 2 mm. loop of culture of Bacillus coli received from Prof. Theo- 

 bald Smith. The temperature during this experiment varied from 18° to 22° C. 



Table XXII. — Effect of water containing calcium monocarbonate and various quantities 



of copper sulfate upon Bacillus coli.''- 



1 Various dilutions of copper sulfate were tubed in Weber resistance glas.s, thoroughly boiled, a small 

 measured quantity of calcium carbonate added to each tube, and these solutions cooled and kept in 

 a Novy jar in an atmosphere free of carbon dioxid. All tubes inoculated with a 2 mm. loop of cul- 

 ture of Bacillus coli received from the Bureau of Animal Industry and isolated from hog. The tem- 

 perature during this experiment varied from 18° to 22° C. 



Table XXIII.— jE^ed of carbon dioxid content of water containing calcium carbonate 

 and various quantities of copper sulfate upon Bacillus coli. ' 



'Various dilutions of copper sulfate were- tubed in Weber re.sistance glass, thoroughly boiled, a 

 small measured quantity of calcium carbonate added to each tube, and these solutions cooled and 

 kept in a Novy jar in an atmosphere compo.sed largely of carbon dioxid. All tubes inoculated with 

 a 2 mm. loop of culture of Bacillus coli received from the Bureau of Animal Industry and isolated 

 from hog. The temperature during this experiment varied from 18° to 22° C. 



Table XXIV. — Toxicity of copper sulfate to Bacillus coliin tap water free of carbon dioxid. ^ 



1 Experiment conducted in Weber resistance glass test tubes, each containing 10 c. c. of Potomac tap 

 water, portions of which had been treated previously with the desired amount of copper sulfate. 

 All tubes inoculated with a 2 mm. loop of culture of Bacillus coli received from the Bureau of Animal 

 Industry, isolated from hog. The temperature during this experiment varied from 18° to 22° C. 



18270— No. 100—07 5 



