=Adulterations.=--There is probably no bread or cake making material which is subjected to more extensive adulteration than buckwheat flour. Much of what is sold as buckwheat flour may be regarded as imitations of that substance. Mixtures of rye flour, Indian corn flour, wheat flour, and other ground cereals are used as a substitute for buckwheat. There can be no objection from the hygienic point of view to such substitutes but the use of these mixtures under the name of buckwheat can be regarded in no other light than as an unpardonable fraud. =Detection of Adulterations.=--There is rarely any mineral adulteration practiced with buckwheat flour and if so it is easily detected by incineration. Any content of ash, unless baking powder has been used, above 2 percent may be regarded with suspicion as indicating an admixture of some mineral substance. The cereal flours used for adulteration are readily detected by the microscope in the hands of an experienced observer. The field of the microscope has only to be compared with the microscopic appearance of genuine buckwheat starch in order to detect the added substance. =Buckwheat Starch.=--The microscopic appearance of buckwheat starch is shown in the accompanying figure. The granules of buckwheat starch are very characteristic. They consist of chains or groups of more or less angular granules with a well defined nucleus, and without rings or with very faint rings. The contour of buckwheat starch is more angular than that of any other common cereal with exception of maize and rice, and it is this and the relative size which enable the observer to distinguish it from other starches. The size of the granules is quite uniform, varying usually only from 10 to 15 microns[23] in diameter. In so far as the angular appearance is concerned the granules of buckwheat starch have a general resemblance to that of maize and rice and oats, but a comparison under the microscope of the three starches reveals lines of distinction which with a little practice would prevent the observer from drawing a false conclusion. [23] A micron is one thousandth of a millimeter. [Illustration: FIG. 23.--BUCKWHEAT STARCH. × 200.--(_Courtesy of Bureau of Chemistry._)] INDIAN CORN (_Zea mays_). Next to wheat the most important cereal used as a human food in the United States is Indian corn. According to the magnitude of the crop, Indian corn is the leading cereal of the country. Statistical data on the production of Indian corn in the United States during 1906 are given in the following table: Acreage, 96,737,581 Yield per acre, 30.3 bushels Production, 2,927,416,091 „ Value per bushel, 39.9 cents Total value, 1,166,626,479 dollars