COMPARISON OF AMERICAN WHEATS. 
23 
This shows a general increase in strength with an increase in pro- 
tein content, the only exception being with hard spring wheat having 
a crude protein content of over 15 per cent. Between the lower per- 
centages of protein wider variation in volume is noticeable with all 
classes than between the higher percentages. In fact, many samples 
having a very high protein content are lower in strength than those 
having a medium content. 
This exception is an illustration of the fact that total crude pro- 
tein is not always an indication of strength due apparently to differ- 
a/=?UOE rffOTE/N Or WHE/VT /=5£-/P CENT 
3 /O // /S /3 
Fig. 19.- — Diagram showing the relation between the protein content and 
the loaf volume of soft and hard red winter and hard red spring wheat. 
Samples from the crops of 1909 to 1913, inclusive. 
ences in the composition or properties of the gluten protein or, as 
has been shown by the number of investigators, to the presence or 
absence of associated inorganic substances. 1 In this connection men- 
1 Guthrie, F. B. The absorption of water by the gluten of different wheats. In Agr. 
Gaz. N. S. Wales, v. 7, pt. 9, p. 583-589. 1896. 
Fleurent, E. Sur une methode chimique d'appreciation de la valeur boulangere des 
farines de ble. In Compt. Rend. Acad. Sci. [Paris], t. 123, no. 19, p. 75-758. 1896. 
Snyder, Harry. The proteids of wheat flour. In Minn. Agr. Exp. Sta. Bui. 63, p. 519- 
533. 1899. 
Shutt, F. T. The relationship of composition to bread-making value. In Canada Cent. 
Exp. Farms Bui. 57, pt. 2, p. 37-51. 1907. 
Wood, T. B. The Chemistry of strength of wheat flour. In Jour. Agr. Sci., v. 2, pt. 2, 
p. 139-159, 2 fig. ; pt. 3, p. 267-277, pi. 5-6. 1907. 
Baker, J. L., and Hulton, II. F. E. Considerations affecting the " strength " of wheat 
flours. In Jour. Soc. Chem. Indus., v. 27, no. 8, p. 368-376. 1908. 
Willard, J. T., and Swanson, C. O. The baking qualities of flour as influenced by 
certain chemical substances, milling by-products and germination of the wheat, Kans. 
Agr. Exp. Sta. Bui. 190, p. 237-285, illus, 1913, 
