Refractometric Studies. 



151 



of arsphenamine is 100 milligrams. Considering the arsenic 

 contents of these two substances, 50 milligrams of arsenic in 

 the form of neoarsphenamine is tolerated as compared to 30 

 milligrams in the form of arsphenamine. Here it is evident that a 

 change in the amino group resulted in the reduction of the toxicity 

 amounting to about 40 per cent. The minimum therapeutic dose, 

 however, was increased from 23 milligrams to 40 milligrams or in 

 terms of arsenic from 6.9 milligrams to 8.0 milligram, i.e., the 

 curative power decreased 16 per cent. In the 3, 5:3', 5' — tet- 

 raamino 4, 4' — dihydroxyarsenobenzene 1 we have a derivative 

 which contains two more amino groups than arsphenamine. 

 The maximum tolerated dose established by us is equal to seventy 

 milligrams per kilo or in terms of arsenic 18.2 milligrams, an increase 

 in toxicity of 39 per cent. The therapeutic effect remains as with 

 arsphenamine. We also prepared 4, 4' — dihydroxyarsenobenzene 

 — 3, 3' — diaminoacetic acid, 4, 4' — dihydroxyarsenobenzene — 

 3, 3' — alpha diaminopropionic acid, 4, 4' — dihydroxyarsenoben- 

 zene — 3, 3' alpha diaminobutyric acid, 4, 4' — dihydroxyarsenoben- 

 zene — 3, 3' alpha diaminovaleric acid. All of the above com- 

 pounds are derivatives of arsphenamine in which both amino 

 groups contain fatty acid substituents. In each case we observed 

 a considerable reduction in the toxicity as well as therapeutic 

 effect. We may conclude, therefore, that the toxicity as well as 

 the curative power of organic arseno compounds is dependent to a 

 considerable extent upon the fact as to whether the amino groups 

 are free or substituted. 



73 (1655) 



Refractometric studies with the sera of syphilitic patients under 

 arsphenamin and neo-arsphenamin treatment. 



By KEIICHI TOKUDA. 



[From the Dermatological Research Laboratories and the Wistar 

 Institute of Anatomy and Biology, Philadelphia, Pa.] 



Refractometric studies were made by the writer upon thirty- 

 two cases of untreated syphilis and the following observations 

 were made: 



1 Raiziss, G. W., and Gavron, J. L., Jour. Am. Chem. Soc. 



