A STUDY OF LINTNER SOLUBLE STARCHi 



ERNEST D. CLARK 



(Laborafory of Biological Chemistry, of Columbia University, at the College of 

 Physicians and Surgeons, New York.) 



Contents 



Page 



I. Introduction i94 



IL Experimental i95 



1. Origin of the potato starch employed in these experiments 195 



2. Preparation of Lintner soluble starch 196 



Preparation i. From commercial starch (A) 196 



Preparation 2. From commercial starch (B) 196 



Preparation 3. From our own starch (A) 197 



Preparation 4. From our own starch (B) 197 



3. Dialysis experiments with soluble starch Solutions i97 



Experiments with Solutions in cold water i97 



Experiments with Solutions in hot water 199 



4. Fractional precipitation of soluble starch Solutions with mag- 



nesium Sulfate 200 



Diffusates 200 



Diffusion residues 201 



5. Fractional precipitation of soluble starch Solutions with alcohol . . 201 



Alcoholic precipitates from diffusion residues 201 



Alcoholic filtrates from diffusion residues 202 



6. Comparative properties of Lintner soluble starch and soluble 



starch prepared with the aid of saliva 204 



III. Summary of general conclusions 205 



I. INTRODUCTION 

 About three years ago Meyer^ used Lintner soluble starch as 

 the Substrate in some experiments on the quantitative determination 

 of diastatic activity. The degree of hydrolysis in Meyer's earlier 

 estimations was ascertained from the extent to which Fehling Solu- 

 tion was reduced under certain uniform analytic conditions. Sub- 



*A preliminary report of this investigation was published in the Journal of 

 Biological Chemistry, 1909-10, vii, Proceedings of the American Society of Bio- 

 logical Chemists, p. Iv. 



" Meyer : Determination of diastatic power, etc. Dissertation, Columbia Uni- 

 versity, 1908. 



194 



