66 



MISCELLANEOUS PAPERS. 



Table XXV. — Toxicity of copper sulfate to Bacillus coli in tap water free of carbon dioxid.^ 





Check. 



1 part copper sulfate to— 



Duration of exposure to action of copper 

 sulfate. 



10,000 

 parts of 

 water. 



50,000 

 parts of 

 water. 



100,000 

 parts of 

 water. 



500,000 

 parts of 

 water. 



1.000,000 

 parts of 

 water. 





Colonies. 



4, 600 



1,450 



1,500 



250 



Colonies. 



1,800 















Colonies. 



4,800 















Colonies. 



3,700 



20 











Colonies. 



4,500 



80 



5 







Colonies. 

 4,000 



2 hours ... 



100 



6 hours 



2 



24 hours 











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 Prof. Theobald Smith. 

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



Table XXVI. — Effect of carbon dioxid upon toxicity of copper sulfate to Bacillus coli.''- 





Check. 



1 part copper sulfate to— 



Duration of exposure to action of copper 

 sulfate. 



10,000 

 parts of 

 water. 



50,000 

 parts of 

 water. 



100,000 

 parts of 

 water. 



500,000 

 parts of 

 water. 



1,000,000 

 parts of 

 water. 





Colonies. 

 4,200 

 2,800 

 1,460 

 1,540 



Colonies. 



4,000 



10 



15 







Colonies. 



9,800 







15 

 



Colonies. 



1,270 







20 







Colonies. 



5,100 



110 



10 







Colonies. 

 1,100 



2 hours 



260 



6 hours 



35 













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

 water, portions of which had been treated previouslj^ with the desired amo\uit 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. 



Table XXVII. — Effect of carbon dioxid upon toxicity of copper sulfate to Bacillus coli.^ 





Check. 



1 part copper sulfate to— 



Duration of exposure to action of copper 

 sulfate. 



10,000 

 parts of 

 water. 



50,000 

 parts of 

 water. 



100,000 

 parts of 

 water. 



500,000 

 parts of 

 water. 



1.000,000 

 parts of 

 water. 





Colonies. 

 3,800 

 2,300 

 1, 600 

 3,500 



Colonies. 



3,000 







10 







Colonies. 



8,500 



5 



12 

 



Colonies. 



5,200 



15 



10 



10 



Colonies. 



4,400 



2,150 



120 



35 



Colonies. 

 5,500 



2 hours . 



1,500 





100 



24 hours . t 











1 Experiment conducted in Weber resistance glass test tiibes, 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 Prof. Theobald Smith. 

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



An examination of the foregoing tables shows that with the three 

 types of water the presence of carbon dioxid increases the resistance of 

 the bacilli in question. In the solution containing monocarbonate of 

 lime and copper sulfate the bacteria are extremely sensitive, even the 

 bacteria in the check solutions dying rapidly, while in the solutions 

 charged with carbon dioxid the bacteria were able to persist in con- 

 siderable numbers in the dilute copper solutions in spite of the fact 

 that most of the copper must have remained in solution. This point 

 is interesting in connection with the work of Engels,^* who reports a 



« Weitere Studien liber die Sterilization von Trinkwasser auf chemischen Wege. 

 Centralbl. f. Bakt., Parasit., u. Infekt., vol. 32 Orig., 1902, pp. 495-521. 



100— vn 



