62 



KRAE.MER— ACTION OF COPPER FOIL 



[April 13, 



In the case of stone filtered water (Table V) a longer time was 

 required to affect the organisms. This is probably accounted for 

 by the fact that the water contained other substances which modi- 

 fied the action of the copper either precipitating it, absorbing it, 

 or even adsorbing it, and thus weakening the solution. 1 



As showing the influence of a material which would be in the 

 nature of a food to the organisms and which at the same time 

 would have a tendency to inhibit the oligodynamic action of the 

 copper solution, the following experiments were conducted using 

 filtered water : (a) Berkefeld filtered water ; (&) stone filtered water. 

 In both series of experiments 1 cc. of nutrient bouillon was added 

 to 200 cc. of water, which was then sterilized in the autoclave, 

 and the typhoid organisms added after cooling. 



Table VI. — Experiments with Bacillus typhi in Filtered Water Con- 

 taining Bouillon. 



In the case of the Berkefeld-filtered water it is seen that there 

 was no growth in the flasks to which bouillon had not been added, 

 after four hours ; and while there was a diminution of the number 



'Nageli found (p. 13 of his paper) that the oligodynamic action of a copper so- 

 lution could be lessened by the introduction of the following substances : Sulphur 

 (either roll or flowers), carbon (either graphite or soot), coke, coal, peat, black 

 oxide of manganese, starch, cellulose (either as Swedish filter paper, or cotton, 

 linen or wood fiber), silk, wool, stearic acid, paraffin, gum, dextrin, egg albumin 

 and glue. 



True and Oglevee s have studied the influence of insoluble substances on the 

 toxic action of poisons and have confirmed several of Nageli's observations. 



Moore and Kellerman have shown in their recent bulletin the relative decrease 

 of toxicity of copper sulphate solutions depending on the amount of organic 

 matter present, the amount of carbon dioxide in solution or the temporary hard- 

 ness of the water. 



