200 Lintncr Soliihle Starch [Dec. 



hoiirs in each experiment. Tests applied to the water surround- 

 ing the bags then gave the following resnlts : 



Polysaccharid. Reducing suhstance. 



lodine Solution ^ehling Solution 



Diffusate from Preparation i Purple, changing to blue Reduction 



with excess of iodine 

 Diffusate from Preparation 2 Purple, changing to blue No reduction 



with excess of iodine 

 Diffusate from Preparation 3 Purple, changing to blue No reduction 



with excess of iodine 

 Diffusate from Preparation 4 Purple, changing to blue No reduction 



with excess of iodine 



4. Fractional precipitations with magnesium sulfate. The 



results described above, as well as those which were obtained on 

 the dialysates and which are outlined below, made it evident that 

 our Solutions of Lintner soluble starch contained several carbohy- 

 drates. We concluded to attempt fractional Separation of these 

 substances and successfully employed magnesium sulfate for that 

 purpose. 



DiFFUSATES. The dialysates from Lintner soluble starch Solu- 

 tions which had been obtained in cold water in the manner described 

 above did not yield precipitates when the diffusates were saturated 

 with magnesium sulfate, although the diffusates gave red colorations 

 when treated with iodine Solution. Similar results were obtained 

 with diffusates from such starch Solutions in dialysis experiments 

 of longer duration (24 hours) with 10 c.c. of external water instead 

 of 50 c.c. as in the previous experiments. 



We then tried the effect of magnesium sulfate on the more con- 

 centrated diffusates obtained in the dialysis of aqueous Solutions of 

 Lintner soluble starch prepared with the aid of heat. A series of 

 dialysis experiments was made in the manner already indicated upon 

 starch Solutions prepared at temperatures of 95° (as before) and 

 75°. The latter temperature was found to be just sufificient to 

 effect Solution of the soluble starch and also to produce a water- 

 clear fluid. 



After a dialysis period of twenty hours, each of the diffusates 

 from the soluble starch Solutions made at both 75° and 95° showed 

 the following properties : deep blue color with iodine Solution, pre- 

 cipitate upon the addition of an excess of alcohol, and reducing 

 action upon Fehling-Benedict Solution. 



