42 BULLETIN 11*7, r. s. DEPARTMENT of AOMCtTLTtTRE. 
According to Bailey/ 4 the nitrogen extracted by boiling 50 per 
cent ethyl alcohol from wheat flour is approximately 93 per cent 
gliadin nitrogen. 
DETERMINATION OF PROTEINS SOLUBLE IN DILUTE SALT SOLUTIONS (NX 5.7= SALT- 
SOLUBLE PROTEINS).' 
Weigh 6 grams of the flour into a 200 cubic centimeter flask and 
introduce exactly 100 cubic centimeters of 5 per cent postassium 
sulphate solution. Shake at 30 minute intervals for three hours or, 
better, agitate at moderate speed in a shaker for one hour, let settle 
30 minutes, filter and determine the nitrogen in 50 cubic centimeters 
of the filtrate as directed under " Protein in wheat and flour," page 36. 
COLD WATER SOLUBLE EXTRACT IN FLOUR. 1 6 
Weigh 20 grams of the flour into a 500 cubic centimeter Erlen- 
meyer flask and add gradually 200 cubic centimeters of water at a 
temperature not higher than 10° C, shake vigorously when about 50 
cubic centimeters of water have been added and continue shaking 
during the addition of the remainder. Allow to stand at 10° C. for 
40 minutes, shaking occasionally. Filter through a large, dry, 
coarse filter paper, returning the first runnings to the filter until a 
clear filtrate is obtained. Pipette 20 cubic centimeters of the clear 
filtrate into a tared dish, evaporate to dryness on a steam bath and 
dry in an oven at 100° C. for periods of 30 minutes to constant weight. 
TOTAL WATER SOLUBLE NITROGEN AND WATER SOLUBLE NON-PROTEIN NITROGEN.? 
Place 20 grams of flour into a 500 cubic centimeter Erlenmeyer 
flask. Add 400 cubic centimeters of distilled water and shake at 
intervals for 2 hours. At the end of this period clarify by filtration 
through paper. Determine total nitrogen in 50 cubic centimeters of 
the filtrate, the equivalent to 2\ grams of material, using the method 
described above for protein in wheat and flour. This is the total 
water soluble portion. Pipette 100 cubic centimeters of the flour 
extract into a 200 cubic centimeter volumetric flask, add 25 cubic 
centimeters of freshly prepared 0.1 normal sodium hydroxid solution 
followed by 27 cubic centimeters of 0.1 normal copper sulphate solu- 
tion. Shake vigorously several tunes until a water-clear supernatant 
liquid remains after the precipitate settles. Make to mark, filter, 
and determine total nitrogen by the Kjeldahl method on 100 cubic 
centimeters, the equal of 2\ grams of the original sample. 
GLUTENIN (DETERMINATION BY DIFFERENCE). 
Deduct the sum of the potassium sulphate soluble nitrogen and the 
alcohol-soluble nitrogen from the total nitrogen and multiply the 
difference by 5.7, taking into consideration the values cited by 
Bailey and Blish. 
14 Journal of Biological Chemistry, vol. 22, No. 1, p. 345; Concerning the Identity of the Proteins 
Extracted from Wheat Flour by the Usual Solvents, by C. H. Bailey and M. J . Blish, 1915. 
15 Official and Tentative Methods of Analysis of the Association of Official Agricultural Chemists. Re- 
vised to November 1, 1919. P. 168, par. 11. 
16 Official and Tentative Methods of Analysis of the Association of Official Agricultural Chemists. 
Revised to November 1, 1919. P . 168, par. 14. 
" Journal of Biological Chemistry, vol. 33, No. 3, p. 551; A Study of the Nonprotein Nitrogen of 
Wheat Flour, by M. J. Blish. 1918. 
