The only substances for making _loaf bread_, by which term is meant, bread which is light, white, and porous, is the flour of wheat; and it is to the larger quantity of gluten, that wheat flour owes the property of being converted into loaf-bread. The average quantity of gluten contained in wheat flour, amounts to about one-fifth of the whole weight of the meal; but it varies in quantity in different kinds of wheat, according to the soil and season in which the corn has been reared, culture, and various other circumstances. Wheat kept in damp storehouses affords scarcely any gluten, and hence, in proportion as the flour of wheat is altered and deteriorated, which happens, as it is known, when it is kept too much compressed, without being occasionally stirred up and aired in hot and close granaries; in a word, as it undergoes a chemical change, its property of making good bread is diminished; and chemical analysis shows the quantity of gluten has become lessened under such circumstances; and when it is greatly diminished the meal forms no longer a tenaceous ductile dough. The spoiled flour produces a kind of bread which is heavy, harsh, and difficult of digestion. The greater the proportion of gluten, the easier the panification of bread-flour is effected, and the better is the bread. The wheat of the South of Europe generally contains a larger quantity of gluten, and is therefore more excellent for the manufacture of Maccaroni, Vermicelli, and other alimentary substances, requiring a glutenous paste. Sir H. Davy found the flour of the wheat of this country to consist of from twenty to twenty-four per cent. of gluten. Barley contains six, and rye five per cent. of gluten. We may now understand why potatoes, rice, beans, pease, buckwheat, millet, oats, and other nutritive cereal grains, abounding in starch, cannot be made into light and porous bread, although they are well calculated for being made into wholesome puddings, and why they only form crude, heavy, insipid cakes, when made into dough and baked, and not light porous loaf-bread. In further confirmation of this statement it may be remarked, that if gluten of wheat, or only a portion of wheaten flour be incorporated by kneading with the before-named kinds of flour, a fermentable cohesive paste is produced, from which perfect bread may be made. THEORY OF THE PANIFICATION OF BREAD FLOUR. Bread, when chemically examined, is very different from flour; it no longer forms with water a tenaceous ductile mass, nor can starch, gluten, and saccharine mucilage be separated from it.