Water is contained in stale bread in the same quantity as in fresh bread; but exists in a modified molecular condition: upon heating stale bread, it acquires the properties of fresh bread. The following substances are used in the adulteration of wheaten flour:[P] Potato-starch. Meals of various grains (rice, barley, corn, oats and rye). Vegetable meals, (beans, horse-beans, kidney-beans, peas, vetch, lentils, etc.). Darnel meal. Buckwheat flour. Linseed-meal. Mineral substances (plaster, chalk, lime, alum, and sulphate of copper). [P] Most of the substances here enumerated are rarely, if ever, used for the adulteration of flour in this country. The analyst should, however, give attention to the examination for such salts as alum, sulphate of copper, plaster, kaolin, etc.--_Trans._ In order to detect these substances, the gluten, the starch, and the ash are separately examined. _a._ EXAMINATION OF THE GLUTEN. In order to separate the gluten, two parts of the flour to be examined and one part of water are mixed into a paste, and this is placed in a fine linen sack, in which it is kneaded under a stream of water so long as the washings have a turbid appearance: these are preserved. The gluten obtained from good wheaten flour possesses a light-yellow color; emits a stale odor; and spreads out, when placed in a saucer. In case the flour has been too strongly heated in the grinding, or otherwise badly prepared, the gluten is granulous, difficult to collect in the hand, and somewhat resembles flint-stone in appearance. Gluten prepared from a mixture of equal parts of wheat and _rye_ is adhesive, blackish, without homogeneousness, spreads out more readily than pure wheaten gluten, separates easily and adheres somewhat to the fingers. Gluten obtained from a mixture of wheat and _barley_ is non-adhesive, of a dirty reddish-brown color, and appears to be formed of intertwined vermicular filaments. Gluten formed from a mixture of equal parts of wheat and _oats_ has a blackish-yellow color and exhibits, at the surface, numerous small white specks. The gluten from a mixture of wheat and _corn_ has a yellowish color, is non-adhesive, but firm, and does not readily spread. Gluten prepared from a mixture of wheat and _leguminous flour_ is neither cohesive nor elastic, and, if the proportion of the latter present be considerable, can be separated and passed through a sieve, like starch. The gluten obtained from a mixture of equal parts of wheat and _buckwheat_ flour is very homogeneous, and is as easily prepared as the gluten from pure wheaten flour. It possesses when moist a dark-grey color; which changes to a deep black upon drying. The proportion of gluten in flour is exceedingly variable: good flour contains from 10 to 11 per cent. of dry gluten; poor flour from 8 to 9 per cent. of moist gluten, equal to about one-third of its weight of the dry compound. _b._ EXAMINATION OF THE STARCH.