=Wheat Products.=--The principal product of wheat is flour. The milling process for wheat is highly interesting both from a chemical and technical point of view, but cannot be described in full in this manual. The old-fashioned milling of wheat, namely, pressing between stones and separation of the flour by bolting has been almost entirely superseded by the modern milling with metal rollers. [Illustration: FIG. 32.--WHEAT STARCH. × 200.--(_Courtesy of Bureau of Chemistry._)] Altogether nearly a hundred different products are made incident or final to the milling of wheat. Only those products, however, which are used for human food interest us at the present time. =Chief Varieties of Flour.=--The highest grade of wheat flour is known usually by the term “patent”; a lower grade is known as “bakers’ flour” and a third as low grade flour. A barrel of flour weighs 196 pounds and requires about 258 pounds of wheat for its manufacture. The whole product from the 258.35 pounds of wheat is shown in the appended table. In general it may be said that about 75 percent of the weight of the wheat is obtained as merchantable flour of some kind, about 60 to 70 percent being good grade or straight flour. About 24 percent of the weight of the wheat is obtained as cattle food and about 1 percent is lost during the process of manufacture. PRODUCT. POUNDS. PERCENTAGE. Patent flour, 149.37 57.82 Bakers’ flour, 29.13 11.28 Low grade flour, 17.50 6.77 ------ ------ Total flour, 196.00 75.87 Bran, 45.56 17.64 Shorts, 9.80 3.79 Screenings, 4.99 1.93 Waste, 2.00 0.77 ------ ------ Total weight, 258.35 100.00 [Illustration: FIG. 33.--WHEAT STARCH UNDER POLARIZED LIGHT. × 200.--(_Courtesy of Bureau of Chemistry_).] =Special Names of Flour.=--In addition to the classification above mentioned other names are used in many commercial senses for flour. These additional names are “family,” “red dog,” “blended,” gluten, etc. Many flours are also named after the name of the mill or locality or bear simply fanciful names. _Graham Flour._--This term was originally applied to the coarse, unbolted flour which was made by grinding the whole wheat. The name, therefore, should be applied to all flour made from well grained wheat, ground, and unbolted. Most of the flours however, which are sold nowadays as graham flours are produced by a more or less perfect bolting process. From the above it is seen that true graham flour will contain practically the same constituents as the wheat kernel itself and in the same proportion and have the same composition as wheat.