52 KRAEMER— ACTION OF COPPER FOIL 



[April 13, 



In these experiments Nageli used 2 -pfennig pieces, consisting of 

 95 parts of copper, 4 of tin and 1 of zinc. These were cleaned 

 with sand, and twelve of them were placed in 12 liters of distilled 

 water and allowed to remain for several days. The solution was 

 evaporated, the residue dissolved in hydrochloric acid, and the 

 copper precipitated as sulphide. This precipitate was dissolved in 

 nitric acid and an excess of ammonia added, producing a blue solu- 

 tion. On comparing the intensity of color of this solution with 

 that of other solutions containing known quantities of copper sul- 

 phate, Nageli estimated that it contained 1.3 parts of copper to 100 

 million parts of water. He found that this solution was toxic to 

 various species of Spirogyra, and a further experiment showed that 

 if the solution were diluted ten times, that is, so that it contained 

 1.3 part of copper to 1,000 million parts of water, it would still kill 

 Spirogyra. 



Inasmuch as solutions containing such extremely minute quanti- 

 ties of copper were toxic to Spirogyra, Nageli was inclined to believe 

 that the toxic action was different from ordinary chemical poison- 

 ing. This view appeared to him to be strengthened by the fact 

 that the effects produced in the cells were different from those pro- 

 duced by ordinary poisons or those resulting from the natural death 

 of the organism. 



It has been supposed by some later investigators 1 that Nageli did 

 not regard the copper as being in a state of solution, yet the 

 experiments just described clearly show what his information was 

 on this point, and in another part of his paper he distinctly states 

 that he so regards it. The marvellous thing to him, as to us, was 

 that such minute quantities of copper exerted toxic action, and at 

 first he was inclined to believe that the effect produced was due to 

 a new force " Isagitat," and in his original manuscript he used the 

 word " isagische " in describing it. But this term was later replaced 



1 On page 23 of his paper Nageli says, " Die oligodynamischen Eigenschaften 

 des Wassers lassen sich also in alien Fallen auf Stoffe, die ini demselben gelost 

 sind, zuruckfiihren. Nun weicht aber das durch Metalle oligodynamische 

 gewordene Wasser in seinem Verhalten wesentlich ab von anderen Losungen. 

 Eine Salz or Zuckerlosung verliert ihre eigenschaften nicht, wenn unloslicbe 

 Korper in dieselbe gelegt werden und sie erteilt den Wandungen des Gefasses 

 nicht die Fahigkeit, reines Wasser wieder salsig or siiss zu machen, wahrende 

 analoge Erscheinungen bei den Kupferlosungen eintreten." 



