SODA AND CREAM OF TARTAR.--Some housewives are inclined to use soda and cream of tartar for leavening purposes; but there is really no advantage in doing this when baking powder can be obtained, for some baking powders are a combination of these two ingredients and produce the same result. In fact, the housewife cannot measure soda and cream of tartar so accurately as the chemist can combine them in the manufacture of baking powder. Nevertheless, if their use is preferred, they should be measured in the proportion of twice as much cream of tartar as soda. As in the case of soda alone, these leavening agents should be sifted with the dry ingredients. A small quantity of cream of tartar is used without soda in such mixtures as angel-food cake, in which egg white alone is used to make the mixture light. The addition of the cream of tartar has the effect of so solidifying the egg white that it holds up until the heat of the oven hardens it permanently.

BAKING POWDER.--Without doubt, baking powder is the most satisfactory of the chemical leavening agents. It comes in three varieties, but they are all similar in composition, for each contains an alkali in the form of soda and an acid of some kind, as well as a filler of starch, which serves to prevent the acid and the alkali from acting upon each other. When moisture is added to baking powder, chemical action sets in, but it is not very rapid, as is apparent when a cake or a muffin mixture is allowed to stand before baking. The bubbles of gas that form in such a mixture can easily be observed if the mixture is stirred after it has stood for a short time. When both moisture and heat are applied to baking powder, however, the chemical action that takes place is more rapid, and this accounts for its usefulness in baking hot breads and cake.

The price of the different kinds of baking powder, which usually varies from 10 cents to 50 cents a pound, is generally an indication of the ingredients that they contain. Powders that sell for 40 to 50 cents a pound usually contain cream of tartar for the acid, the high price of this substance accounting for the price of the powder. Powders that may be purchased for 30 to 40 cents a pound generally contain acid phosphate of lime, and as this substance is cheaper than cream of tartar, a baking-powder mixture containing it may well be sold for less. The cheapest grade of powders, or those which sell for 10 to 25 cents a pound, have for their acid a salt of aluminum called alum. Still other powders that are sometimes made up to sell for 20 to 30 cents a pound contain a mixture of phosphate and alum.

As baking powders vary in price, so do they vary in their keeping qualities, their effectiveness, and their tendency toward being injurious. Most phosphate and alum powders do not keep so well as the cream-of-tartar powders, and the longer they are kept, the less effective do they become. The powders that contain phosphate yield more gas for each teaspoonful used than do the other varieties. Much controversy has taken place with regard to the different kinds of baking powder and their effects on the digestive tract, but authorities have not yet agreed on this matter. However, if foods made with the aid of baking powders are not used excessively, no concern need be felt as to their injurious effect. The housewife in her choice of baking powder should be guided by the price she can afford to pay and the results she is able to get after she has become well informed as to the effect of the different varieties. She may easily become familiar with the composition of baking powder, for a statement of what substances each kind contains is generally found on the label of every variety. This information is invaluable to the housewife, as it will assist her considerably in making a selection.

The proportion of baking powder to be used in a batter or a dough is regulated by the quantity of flour employed and not, as is the case with soda and molasses or sour milk, by the quantity of liquid, the usual proportion being 2 level teaspoonfuls to 1 cupful of flour. Sometimes this proportion is decreased, 6 or 7 teaspoonfuls being used instead of 8 to each quart of flour in the making of large quantities of some kinds of baked foods. In adding baking powder to a mixture, as in adding other dry leavening agents, it should be sifted with flour and the other dry ingredients.

Although baking powder may be purchased at various prices, a good grade can be made in the home without much effort and usually for less than that which can be bought ready made. For these reasons, many housewives prefer to make their own. The following recipe tells how to make a cream-of-tartar powder that is very satisfactory: