108 L. C. CRAIG, W. KÖNIGSBERG, A. STRACHER, T. P. KING 

 the Moore-Stein ninhydrin procedure.' The figures at each point on the 

 weight curve give the ninhydrin values per mg. and definitely indicate a 

 range of sizes. 



The first 35% of the solute to pass was recovered and put in a second 

 cell. Now weight analysis gave Curve 3 and ninhydrin gave Curve 4. Here 

 a mixture of sizes is definitely being fractionated. 



A rough survey of the solvent question and other variables intimately 

 involved with it such as pH, salt content, temperature, etc., seemed to show 

 that with the polypeptides and smaller proteins 0-01n acetic acid at 25° 

 seemed to offer an environment most favorable to ideality. A survey was 

 then made of a number of solutes of increasing molecular weight in a cell 

 with Visking 20/32 cellophane. These data^ are given in Table 1, where the 

 escape rate is expressed as a 50% escape time. For comparison a few data 

 are given in 0-1n acetic acid and in 0-01n acetic acid in 18/32 Visking, a less 

 porous casing. The molecular weights listed are those from the literature. 



Table 1 does not list all the solutes studied. A number were not included 

 because they showed too great a deviation from ideality. There is not time 



Table 1 

 50% ESCAPE TIMES OF VARIOUS POLYPEPTIDES AND PROTEINS 



* A protamine from the rainbow trout obtained through the courtesy of the Nordisk 

 Insulinlaboratorium, Denmark. 



