BAKING POWDER

2 compound used in place of yeast, in which an acid acting upon an alkali generates carbon dioxide (‘‘car bonie acid gas’’) and thus causes the dough or batter to ‘‘rise.’’ As this action takes place as soon as the powder is moistened, the dough is made ready for baking more promptly than with yeast. The alkali emploved is nearly always bicarbonate of sodium (‘‘haking-soda’’), and cornstarch is generally used as the filler. There is, however, a wide variation in the acid constituent, and baking powders may therefore be conveniently cla ed according to its nature. They may be recognized as follows: (1) Tartrate powders, in which the acid constituent is cream of tartar or tartaric acid. (2) Alum powders, in which the acid constituent is generally aluminum sulphate. (3) Phosphate powders, in which the acid constituent is some form of phosphorie acid. The ‘‘filler’’? is commercially nece ary in order to absorb atmospheric moisture and thus to prevent the premature activity of the acid and alkali. Without this protection, only baking powder just freshly made could be relied upon except in very dry climates or very dry weather. In the proce of baking, the chemical constituents undergo certain changes, so that the residue in the finished bread is of different character from the original ingredients. That left in food, when tartrate powders are used, is rochelle salts; powders founded on phosphates deposit calcium and sodium phosphates; and alum powders leave glauber’s salt and a salt of aluminum. The quantity is, however, in each case very small. The use of a leavening agent (whether baking powder or yeast) not only enhances the appearance and flavor of food but also aids its digestion by rendermg it more easily acted upon by the stomach secretions. This merit is, however, lost—or is at least counterbalanced—when exce ive quantities of leavening are employed. The date when baking powder was first manufactured 1s involved in some doubt; but it is known that it was made by a Boston firm prior to 1855, the common name then being ‘‘yeast powder.’’ Phosphate powders first appeared in 1857, cream of tartar powders in 1867, and alum powders about the year 1875. Care should he taken to keep baking powder in a dry place as undue dampne breaks down the protection of the starch filler and causes the powder to lose its strength.