=Adulterations of Flour.=--The adulteration of wheat flour is not practiced to any extent in this country. The most common adulteration arises from grinding with wheat foreign seeds and other foreign matter, rust, smut, etc., which may be present in the grain. Other adulterations are the mixture with wheat flour of the starch or flour of maize and other cereals. The adulteration with any form of terra alba or white powdered earthy substance is exceedingly rare. Although some attempts have been made to introduce such adulterations in this country they have not reached any commercial success. The adulterations, with the exception of those with white earthy powders, are most readily ascertained by microscopic examination for foreign matters and other varieties of starch than grow naturally in the wheat. =Standard.=--The United States standard for flour is as follows: =Flour= is the fine, sound product made by bolting wheat meal and contains not more than thirteen and one-half (13.5) percent of moisture, not less than one and twenty-five hundredths (1.25) percent of nitrogen, not more than one (1.0) percent of ash, and not more than fifty hundredths (0.50) percent of fiber. =Graham flour= is unbolted wheat meal. =Whole wheat flour=, entire =wheat= flour, improperly so called, is fine wheat meal from which a part of the bran has been removed. =Gluten flour= is the product made from flour by the removal of starch, and contains not less than five and six-tenths (5.6) percent of nitrogen and not more than ten (10) percent of moisture. =Age of Flour.=--The freshly ground flour is most highly esteemed by many consumers on account of palatability and freedom from all danger of mold and ferments. Older flours are likely to lose flavor, become moldy and infested with weavil and other insect pests. The last-named evils are avoided by the use of wheat containing no fungus, none of the eggs of the weavil, nor of other insects, and enclosing the freshly ground flour in packages not accessible to infection. Even then it is advisable to consume the flour as soon as convenient after the milling process. Many manufacturers and experts contend that flour is improved by keeping for a certain length of time, and this contention is based on the assumption that the flour assumes a lighter color and improves in flavor on keeping. There is of course a certain limit to improvements of this kind.