The _Journal of Trade_ gives the following simple mode of testing for this adulterant: "Persons can test the bread they buy for themselves, by taking a piece of it and soaking it in water. Take this water and mix it with an equal part of fresh milk, and if the bread contains alum, the mixture will coagulate. If a better test is required, boil the mixture, and it will form perfect clot." Whiting can be detected by dipping the ends of the thumb and forefinger in sweet oil and rubbing the flour between them. If whiting is present, the flour will become sticky like putty, and remain white; whereas pure flour, when so rubbed, becomes darker in color, but not sticky. Plaster of Paris, chalk, and other alkaline adulterants may be detected by a few drops of lemon juice: if either be present, effervescence will take place. CHEMISTRY OF BREAD-MAKING.--Good flour alone will not insure good bread. As much depends upon its preparation as upon the selection of material; for the very best of flour may be transformed into the poorest of bread through improper or careless preparation. Good bread cannot be produced at random. It is not the fruit of any luck or chance, but the practical result of certain fixed laws and principles to which all may conform. The first step in the conversion of flour into bread is to incorporate with it a given amount of fluid, by which each atom of flour is surrounded with a thin film of moisture, in order to hydrate the starch, to dissolve the sugar and albumen, and to develop the adhesiveness of the gluten, thus binding the whole into one coherent mass termed _dough_, a word from a verb meaning to wet or moisten. If nothing more be done, and this simple form of dough be baked, the starch granules will be ruptured by the heat and thus properly prepared for food; but the moistening will have developed the glue-like property of the gluten to the extent of firmly cementing the particles of flour together, so that the mass will be hard and tough, and almost incapable of mastication. If, however, the dough be thoroughly kneaded, rolled very thin, made into small cakes, and then quickly baked with sufficient heat, the result will be a brittle kind of bread termed unleavened bread, which, although it requires a lengthy process of mastication, is more wholesome and digestible than soft bread, which is likely to be swallowed insufficiently insalivated. The gluten of wheat flour, beside being adhesive, is likewise remarkably elastic. This is the reason why wheat flour is much more easily made into light bread than the product of other cereals which contain less or a different quality of gluten. Now if while the atoms of flour are supplied with moisture, they are likewise supplied with some form of gaseous substance, the elastic walls of the gluten cells will become distended, causing the dough to "rise," or grow in bulk, and at the same time become light, or porous, in texture.