4 8 



Scientific Proceedings (51). 



35 (73i) 



The diffusion of iodo-eosin from ether through rubber 

 membrane into ether. 



By Jacob Rosewbloom. 



[From the Laboratory of Biological Chemistry of the University of 



Rosenbloom and Gies 1 have shown that many ether soluble 

 substances diffuse from ether through rubber membrane into ether, 

 but oddly various phospholipins do not possess this property. 



Together with Boas, 2 I was able to show that various choles- 

 terolesters diffuse from ether through rubber membrane into ether. 

 This is very interesting on account of the high molecular weight 

 of these esters. Cholesterol-stearate with a molecular weight of 

 652.51 diffuses very readily. 



For some time I have been trying to find an ether soluble 

 substance of higher molecular weight than cholesterol-stearate 

 and which could be easily detected in the diffusate. The free 

 dye-acid of iodoeosin fulfilled these requirements. This free dye- 

 acid has been employed by Professor Ehrlich as a very delicate 

 reagent for free alkali in the erythrocytes of man. 3 



Iodo-eosin is the potassium salt of tetraiodo-fluoresce'fn with 

 the following formula, 



As a salt it dissolves in dilute alkalies with red color, but is insoluble 

 in ether or any other organic solvent. The free dye-acid, however, 

 is obtained as a yellow precipitate from the alkaline solution of 

 iodo-eosin by adding hydrochloric acid in excess, and it dissolves 

 readily in ether, or in any other organic solvent, but is insoluble in 



1 Proc. Amer. Soc. Biol. Chem., 1910, 2, p. 8; Jr. Biol. Chem., 191 1, IX, p. xiv. 

 Biochemical Bulletin, 1912, II, p. 64; George Crocker Special Research Fund, Vol. 3; 

 (In press.) 



1 Proc. Soc. Exp. Biol, and Med., 1911, VIII, p. 132. 

 • Ehrlich-Lazarus, "Die Anemia," Vienna, 1898. 



Pittsburgh, Pittsburgh, Pa.] 



