EFFECT OF COPPER UPON WATER BACTERIA. 67 



rather high toxicity for calcium chlorid, and of Pfuhl,'' who suggests 

 a calcium salt — milk of lime — for water sterilization. The use of lime 

 or a similar agent ma}^ be highly desirable in connection with treathig 

 a contaminated reservoir with copper, though the inferior germicidal 

 power of lime makes it improbable that the latter alone could be used 

 safely. 



In regard to chemical water analysis, it seems probable that the 

 determination of carbon dioxid or the determination of monocarbon- 

 ate and bicarbonate alkalinity may have importance hitherto unrecog- 

 nized, and the variations in the longevity determinations of Bacillus coli 

 and Bacillus typhi may be due in part to the mineral constituents of a 

 water, in part to methods of experimentation, and in part to the car- 

 bon dioxid content. Extended field tests must be made before gen- 

 eralizations on the possible effect of the gas content of a water supply 

 can be determined. 



The carbon dioxid content of a water may possibly explain the 

 peculiar results obtained by Clark and Gage.^ They have reported 

 practically no toxic action from metallic copper, or at least ver}" little 

 difference in the action of metallic copper, iron, tin, zinc, and lead^ 

 Their figures are rather misleading because of the great number of 

 da^'S the experiments were carried on, and, as Phelps^ has shown, 

 metallic copper is coated with some insoluble substance after a few da3\s' 

 exposure to Boston tap water and no longer has great toxic action. 

 The lack of toxicity of metallic copper and the similarity of its action 

 to the action of other metals, as reported b}' Clark and Gage, is 

 entirely at variance with the work of Kraemer, ^^ Pennington,^ Gil- 

 dersleeve,-^' Stewart, s' and Moore and Kellerman.^^ Investigators 

 generally have agreed that it would be possible to practical!}' sterilize 



« Uber die Disinfection der Typhus and Cholera-ausleerungen mit Kalk. Zeitschr. 

 f. Hyg. n. Infekt., vol. 6-s, 1889, pp. 97-104. 



?'The Use of Copper Sulphate in Water Fihration. Journal of Infectious Diseases. 

 Supplement Xo. 2, February, 1906, pp. 172-174. 



(^Experiments on the Storage of Typhoid Infected Water in Copper Canteens. 

 Public Health Papers and Eeports, American Public Health Association, vol. 31, part 

 1, 1905, pp. 75-90. 



'^Copper Treatment of Water. American Journal of Pharmacy, vol. 76, December, 

 1904, pp. 574-579. 



The Use of Copper in Destroying Typhoid Organisms and the Effects of Copper on 

 Man. American Journal of Pharmacy, vol. 77, June, 1905, pp. 265-281. 



^ The Action of Electrically Charged Copper Upon Certain Organisms in Water. 

 American Journal of Medical Science, vol. 129, 1905, pp. 751-754. 



/'Studies on the Bactericidal Action of Copper on Organisms in Water. American 

 Journal of Medical Science, vol. 129, 1905, pp. 754-760. 



Q X. Study of the Action of Colloidal Solutions of Copper upon Bacillus Typhosus, 

 American Journal of Medical Science, vol. 129, 1905, pp. 760-769. 



-^Buls. 64 and 76, Bureau of Plant Industry, U. S. Dept. of Agriculture. 



100— VII 



