COLLOIDAL SOLUTIONS. 



37 



electricjil method may be perfected for rapidly obtaining a strong" 

 colloidal solution, which will furnish a more convenient means of 

 application than that of the crude salt. 



In regard to the bacteria causing cholera and typhoid, the impor- 

 tance of the specitic toxic efi'ect of colloidal copper is probably much 

 greater than with alga>. The following tables show the proportions 

 of the area of copptM- to the quantity of water and to the time and the 

 tempoi'ature necessary to jjiodui-e the complete sterilization of water 

 containing these pathogenic germs: 



Efect upon BuciUuxtmilii of I'.rpoanri' to collnlddl mlution of copper (d room temperalure.C' 



[Determination made in tnhi's of lionilloii. + indicates srowlli after is honrs' inocnliition: indi- 

 cates no growth.] 



"Experiment condncted in test tubes containing 10 cc. each of sterilized water. The copper foil 



was sterilized ;m<l added iiinnediatcly hcl'orc inuculatintr the tubes with tlie usual 3 mm. loop of a 

 21-h(nu- culture of Ji. ti/ii/ii. This experiment was duplicated with three separate strains of tyi)h()id 

 with idi'Utical results. 



Efccl upon Biirll/nn ti/j)lii of expoiture to colloidal solution of copper at room temperalure.O' 



[Determination made in Petri dishes.] 



"Kxperinient conducted in test tubes, each containing 5 cc. of sterilized water. The copper foil 

 was sterilized, and added innnediately before inoculating the tubes with the usual 3 mm. loop of a 

 21 hour culture of 7i. /(/p/(/. 



