ioo6 
Journal of Agricultural Research vol xxra, no. i* 
they yield reducing sugars, thereby increasing the aooarent starch 
content. 
Several methods of analysis were formulated and tried, with varying 
degrees of success. The method finally adopted is based on: (a) Ex¬ 
traction of the material with ether, alcohol of from 25 to 35 per cent 
strength, depending on the material, alcohol of full strength, and finally 
again with ether to eliminate interfering soluble substances; (b) gelatini- 
zation and conversion of the starch by digestion with an infusion of barley 
malt; (c) elimination of interfering polysaccharids by precipitating these 
substances in 60 per cent alcohol; (d) evaporation of the filtrate to drive 
off the alcohol, and subsequent acid hydrolysis of the starch conversion 
products; (e) defecation of the resulting dextrose solution with phospho- 
tungstic acid; and (f) determination of the dextrose by copper reduction. 
A sample of starch for use as a standard was prepared, and definite 
quantities were added to charges of linseed meal of known purity. These 
charges were analyzed by the proposed method. From 97.2 to 99.9 per 
cent of the starch known to be present was accounted for by the determi¬ 
nations. 
The possibility of adsorption of the starch conversion products by col¬ 
loids coagulated by the 60 per cent alcohol was investigated, by precipi¬ 
tating twice with 60 per cent alcohol and analyzing both filtrates. If 
there is any adsorption, for practical purposes the amount is negligible. 
LITERATURE CITED 
(1) Association or Official Agricultural Chemist's. 
1920. official and tentative methods of analysis. As compiled by the 
committee on revision of methods. Revised to November 1, 1919. 
417 p., 18 fig. Washington, D. C. Bibliographies at ends of chapters. 
(2) Cassal, N. C. 
1911. NOTE on the colorimetric ESTIMATION OF starch. In Chem. Engin. 
and Works Chemist, v. 1, p. 68-70. 
(3) Davis, William A., and Daish, Arthur John. 
1914. METHODS OF ESTIMATING CARBOHYDRATES. H. THE ESTIMATION OF 
STARCH IN PLANT MATERIAL. In JoUT. AgT. Sci., V. 6, p. 152-168, I fig. 
(4) Horton, Edward. 
1921. ON THE USE OF TAKA-DIASTASE IN ESTIMATING STARCH. In JotlT. Agr. 
Sci., v. 11, p. 240-257. 
(5) Neville, Allen. 
1913. linseed mucilage. In Jour. Agr. Sci., v. 5, p. 113-128. 
(6) Schneider, Edward C. 
1912. A NUTRITION INVESTIGATION ON THE INSOLUBLE CARBOHYDRATES OR 
marc OF THE apple. In Amer. Jour. Physiol., v. 30, p. 258-270. Bib¬ 
liographical footnotes. 
(7) Van Kampen, G. B. 
1914. DER GEHALT DES LEINSAMENS AN WASSERLdSLICHEN KOHLENHYDRATEN. 
In Landw. Vers. Stat., Bd. 83, p. 471-476. Bibliographical footnotes. 
(8) Walton, G. P. 
1918. REPORT OF CHAIRMAN, LINSEED PRODUCTS COMMITTEE, ASSOC. FEED CON¬ 
TROL officials, u. s. In Flour and Feed, v. 18, no. 9, p. 38-39. 
