1912] 



William H. Welker 



71 



the diffusibility of lipins and other substances throtigh rubber mem- 

 branes. The solubility of the above mentioned product in alcohol- 

 ether Solution led Dr. Gies to propose a study of the comparative 

 diffusibility of the protein through membranes of rubber, parchment 

 and collodion. Such an investigation was accordingly conducted 

 by the diffusion process described on page 55. The data in the 

 accompanying tables indicate the conditions and the results of the 

 tests in this connection.^ 



IL COMPARATIVE DIFFUSION EXPERIMENTS 



Experiments with rubber membranes. The results of the 

 tests in the first four series show collectively [Table i (1-15)] that 

 biuret-reacting matter appeared in the diffusates; that the rubber 

 itself did not yield such substance; and that the occurrence of biuret- 



TABLE I 



Results of experiments with rubber membranes 



A. Data showing the dißusibility of biuret-reacting material 

 First Series. With Rubber Condoms. 



Second Series. With Rubber Condoms. 



* In the tables, " ether-alc. sol." indicates the protein Solution as it was made 

 available by the above mentioned process before final precipitation with five 

 volumes of ether. Such precipitation was efifected only when the solid was 

 desired for special reasons. See the data pertaining to the eighth series of tests, 

 Table i. 



