64 KRAKMER— ACTION OF COPPER FOIL [April 13, 



At the beginning of our investigation a number of experiments 

 were made with a view of testing the comparative efficiency of both 

 copper foil and copper sulphate in destroying the organisms in 

 tap water, and it is thought that the results obtained are of suffi- 

 cient interest to present at this time. 



It is observed that in the case of the Berkefeld filtered water, 99 

 per cent, of the original number of organisms were removed by 

 the process of filtration. When copper foil was introduced into 

 the water about 75 per cent, of the organisms were destroyed in 

 8 hours, although in other experiments where larger quantities of 

 water were used from 85 to 97 per cent, of the organisms were 

 destroyed. When copper sulphate was added to the tap water, so 

 that there was 1 part to 100,000 of water, 97 per cent, of the 

 organisms was destroyed in 8 hours. When the strength was reduced 

 so that there was 1 part of copper sulphate to 1,000,000 parts of 

 water, there was a reduction of 86 per cent. 



Owing to the sensitiveness of typhoid and colon bacilli to the 

 influence of copper, as previously shown, it may be inferred that 

 they would have been included in the 75 to 97 per cent, of the 

 organisms destroyed. 



CONCLUSIONS. 



From the experiments thus far conducted as well as the results 

 obtained by other writers, the following conclusions may be drawn : 



1. Certain intestinal bacteria like colon and typhoid are com- 

 pletely destroyed by placing clean copper foil in water containing 

 them, or by adding the organisms to water previously in contact 

 with copper foil. 



2. The toxicity of water in which either copper coins or copper 

 foil has been added is probably due to a solution of some salt of 

 copper, as first suggested by Nageli. 



3. The copper is probably in the form of a crystalloid rather 

 than that of a colloid, as it has the property of permeating the cell 

 walls and organized cell contents of both animals and plants, 

 thereby producing the toxic effects. 



4. While the effects produced by the oligodynamic action of 

 copper are apparently different from those of true chemical poisons, 

 the difference is probably in degree only and not in kind. 



5. Certain lower organisms including both plants and animals 

 possess a specific sensitiveness to minute quantities of copper, and 



