Twenty lessons in domestic science

With a properly compounded baking powder, the chemical reaction will always be the same, and any influence which it may exert upon the flavors of the finished food will always be the same. Baking powder has these two advantages over yeast: (1) The gas is given off at once upon the addition of water or in the oven during the heating; (2) and the presence of butter, lard or eggs does not hinder the chemical action. The leavening, from whichever source, is always the result of the same gas, carbon dioxid, and in the study of baking powder we are interested in learning how this gas is produced by chemical action. Sources of Carbon Dioxide Carbon dioxid is found in nature combined chemically with many metals, and these combinations are known as salts of carbonic acid, or more commonly as carbonates. Those with which one is most familiar are chalk, marble and limestone, all of which are different forms of calcium carbonate. If any of these are heated to a very high temperature, carbon dioxid gas is set free and lime remains ; but this very high temperature is never reached in baking. Baking soda is another carbonate with which all are familiar. The Ingredients of Baking Powder Soda Soda is the carbonate which is used at home for cooking purposes ; it is also commonly known as saleratus, or baking soda. This is the carbonate used almost exclusively in the manufacture of baking powder and always named on the label as soda. It is sometimes referred to as the alkali of the baking powder. It is a white crystalline substance of very high purity, being as free from impurities as granulated sugar. It is manufactured from common salt through the action of acid ammonium carbonate. The reaction is represented by the following equation : NaCl pluB NH« HCO, equals NaH COa plus NH CI v Salt Acid Ammonium Soda Ammonium Carbonate Chloride Soda; when heated, readily gives off carbon dioxid gas, and hence may be, and often is, used in cooking without the addition of any other substance for the purpose of leavening. The heat, however, does not drive off all of the gas. The reaction which takes place is represented by the following formula: SNaHCO, equals NaaC08 plus H20 plus C02 Soda Normal sodium Water Carbon Carbonate Dioxid The residue of normal sodium carbonate thus left in the bread gives it a disagreeable, alkaline taste, and also colors the bread an objectionable yellow; hence, soda by itself is unsatisfactory for use as 'a leavening agent. Domestic Science LESSON No. 2 Ammonium Carbonate Ammonium carbonate has been sometimes used as a leavening agent. This, upon being heated, breaks up into two different gases, ammonia gas and carbon dioxid gas. Some of the ammonia gas remains in the bread when cooked ; therefore, its use in baking powder has been almost entirely discontinued. Magnesium Carbonate