56 KRAEMER— ACTION OF COPPER FOIL [April 13, 



of copper in 1,000,000,000 parts of water is sufficient to kill these 

 plants. . . . Locke found that the traces of copper contained in 

 water distilled in copper vessels were sufficient to destroy tubifex 

 (one of the annelid worms) and tadpoles, while Bucholtz states 

 that the development of bacteria is stopped by a solution of copper 

 sulphate under 1 per cent, in strength. Copper thus seems to have 

 a very powerful poisonous action on certain living forms and to be 

 harmless to others, and the subject deserves further investigation. 

 It is possible that it may prove to act prejudicially to some human 

 parasites, and it is certainly less dangerous to man than many other 

 remedies used as parasiticides and disinfectants." 



It was not, however, until the publication of the bulletin on "A 

 Method of Destroying or Preventing the Growth of Algae and Cer- 

 tain Pathogenic Bacteria in Water Supplies" by Moore and Keller- 

 man, 6 nearly a year ago, that the very great practical significance 

 of work along these lines became apparent and general interest was 

 aroused in the subject. 



Since last fall we have been carrying on a series of experiments 

 in the Microscopical Laboratory of the Philadelphia College of 

 Pharmacy ' with the view of testing the efficiency of metallic copper 

 for destroying typhoid and colon bacilli in water. Some of the 

 results obtained have already been published. 7 



In presenting the results of our experiments sufficient of the 

 details will be given to show the manner in which the work was 

 conducted. 



In the first series of experiments here recorded water under three 

 different conditions was employed : ' («) Distilled water which was 

 prepared from tap water by first treating it with potassium perman- 

 ganate and then distilling it two or three times by means of 

 apparatus constructed entirely of glass ; (b) filtered tap water, 

 prepared by means of a Berkefeld filter attached to a copper spigot ; 

 (V) tap water, collected after being allowed to run for five minutes, 

 the spigot being the usual copper one. All of these were sterilized 

 in an autoclave at 1 io° for 30 minutes. 2 



The cultures of typhoid and colon which were used were pure 

 cultures developed in bouillon for 18 to 24 hours. 



1 1 acknowledge my indebtedness to Mr. John R. Rippetoe for valuable assis- 

 tance in carrying on the experiments recorded in this paper. 



2 In all of our work we found in the blank experiments that water which had 

 been sterilized in an autoclave remained sterile. 



