84 EXPERIMENTAL RESEARCHES 



regarded as something entirely different, namely, 

 that the amido group is quite free and that the 

 arsenic acid radical is attached to the benzol 

 ring in the para position. Atoxyl must, there- 

 fore, be regarded as the sodium salt of paramido- 

 phenyl-arsinic acid. 



We have obtained a great number of sub- 

 stances derived from it, and have tested them 

 therapeutically. Thus we found that, e.g., by 

 the introduction of the acetyl radical into the 

 amido group the acetyl-amido-phenyl-arsinic 

 acid is produced, which is far less toxic for mice 

 than atoxyl. By means of this substance it is 

 even possible to solve one of the most difficult 

 therapeutic problems imaginable. For mice 

 that have been infected with our most virulent 

 strains, and which, without treatment, would 

 die within three days, can in two-thirds of the 

 cases be saved by this substance if it is given 

 twelve to fourteen hours before death. Such 

 curative results have never yet been published ; 

 for in previous communications there were men- 

 tioned almost exclusively experiments carried 

 out at earlier periods of infection. In our cases 

 acetyl-atoxyl cures mice in nearly 100 per 

 cent. Unfortunately, acetyl-atoxyl is decom- 

 posed in other animals, especially in the horse, 



