64 



MISCELLANEOUS PAPERS. 



Table XVIII.— -E^'^d of copper sulfate upon Bacillus caudatus. 



EFFECT OF CARBON DIOXID ON VIABIIilTY OF BACILLUS COLI 



AND BACILLUS TYPHI. 



A careful study of the ga.s content of both tap and triple di.stilled 

 water has shown that for the typhoid ana colon bacilli the presence of 

 carbon dioxid in the water is as.sociated with heightened resistance to 

 toxic agents, such as solutions of copper salts, precipitated copper 

 salts, and copper metal. This is the more strange when one considers 

 that the presence of carbon dioxid in water causes the copper to 

 remain in solution, and in case of insoluble copper, either precipitated 

 or metallic, the carbon dioxid .serves to bring a considerable amount 

 of copper into solution. It should be noted, however, that water 

 heavily saturated with carbon dioxid is toxic to Bacillus coll and 

 Bacillus typlu. 



A series of experiments designed to test the effect of carbon dioxid 

 on Bacillus coli, the various conditions of triple distilled water with 

 and without copper, triple-distilled water plus calcium carbonate with 

 and without copper, and tap water with and without copper are tabu- 

 lated below. 

 Table XX.— Toxicity of copper sulfate to Bacillus coli in the absence of carbon dioxid.^ 



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

 distilled from gla.ss. portions of which had been treated jireviously with the desired amount ot 

 copper sulfate. All tubes inoculated with a 2 mm. loop of culture of Bacillus coil received from 

 Prof. Theobald Smith. The temperature during this experiment varied from 18° to 22 «.. 



100— VII 



