igii] Ernest D. Clark 199 



Pension was then filtered through a hardened filter and the clear 

 filtrate subjected in each case to the tests previously applied to the 

 dialysates. The results were the same. In every case, all the tests 

 were made, in blank, on distilled water in which we had previously 

 immersed the collodion bags or the filter papers employed in the 

 various treatments. In this way we guarded against erroneous 

 conclusions due to accidental contamination of our Solutions with 

 substances from the paper or collodion. Blank Fehling tests were 

 made in every case in which that reagent was used. 



The foregoing experiments were repeated in every detail two 

 months later and the following results obtained : 



Polysaccharid. Reducing substance. 



lodine Solution Fehling Solution 



Diffusate from Preparation i Bright red Reduction 



Diffusate from Preparation 2 Bright red Reduction 



Diffusate from Preparation 3 Bright red Reduction 



Diffusate from Preparation 4 Bright red Reduction 



Experiments with Solutions in hot water. All the results 

 just described were obtained by the use of suspensions of soluble 

 starch in cold water. In the Lintner diastatic method the soluble 

 starch is always dissolved, with the aid of heat, in water rendered 

 neutral to rosolic acid. Therefore, we repeated the dialysis experi- 

 ments with soluble starch under the conditions that prevail in the 

 Lintner diastatic determinations. First, we titrated 100 c.c. portions 

 of our distilled water with n/ioo sodium hydroxide Solution, using 

 rosolic acid as the indicator. The larger volumes of the same 

 supply of distilled water were treated with sufficient n/ioo sodium 

 hydroxide Solution to exactly neutralize the water. Two gram 

 portions of each preparation of soluble starch were suspended in 25 

 c.c. of cold neutral water and poured into 75 c.c. of neutral water 

 at 95° C. The resultant mixture was kept at 95° for 30 minutes, 

 and then was made up to exactly 100 c.c. These Solutions were 

 somewhat opalescent but clear. One-half of each of these volumes 

 of soluble starch Solution was dialyzed as before, with 50 c.c. of 

 neutral water on the outside of the membrane in each case. The 

 usual blank tests were also made, with negative results, for all the 

 filter paper and collodion used. Dialysis was continued for twelve 



