A. Class Experiments. Soda as a Leavening Agent.

1. To find out why soda makes cakes light.

Add a teaspoon of vinegar to a pinch of soda in a test tube. Tip the tube and hold the mouth of this test tube just above another containing a teaspoon of lime water. After a moment, cover the mouth of the lime-water tube and shake it. What is present? What caused the bubbles in the first tube?

2. What kind of substances must be put with soda to produce this gas?

a. Dip a piece of blue litmus paper into vinegar and note the effect on the paper. Hold it in the fumes of ammonia, an alkaline sub-stance, and see the result.

b. Now test the following and determine whether they are acid, alkaline, or neutral (neither acid nor alkaline):

1 - water.

2 - sour milk.

3 - sweet milk.

4 - molasses and water.

5 - cream of tartar dissolved in hot water.

6 - thin starch paste.

7 - soda and water.

c. Pour a few drops of soda and water into each of the tubes. Which cause effervescence ?

3. Will bubbles of gas go on forming indefinitely? To a little soda and water add, successively, small amounts of vinegar. Do bubbles continue to form? Has all the gas in the soda been set free? Has soda an agreeable taste? What would be the difficulty, if there were more soda in bread or cake than the acid present could act on?

4. How much soda can be used with a given amount of acid?

Dissolve a teaspoon of soda in quarter of a cup of water in a measuring cup. Then dilute half a cup of thick sour milk with about half a cup of water. Add, slowly, the soda solution to the sour milk until it is neutral to both red and blue litmus paper.

Calculate the amount of soda to use with one cup of sour milk.

B. Prepare Sour Milk Griddlecakes Use one-fourth of the following proportions:

Liquid (Thick, sour milk)



Fat (Melted butter)



1 C.

1 to 11/4 c.


1 tbsp.

1 tsp.


How will you combine the ingredients? Cook by dropping spoonfuls of the batter on a griddle or frying pan, using enough fat to keep the cakes from sticking. A soapstone griddle should not be greased. When the cake is full of bubbles and the under side is brown, turn the cakes over, using a spatula or a cake turner, and brown the other side also.


Soda has two chemical names : bicarbonate of soda, and acid sodium carbonate. In spite of the latter name, soda is alkaline to litmus and not acid in any of its properties. It is manufactured from common salt by a number of different processes.

Our grandmothers used saleratus in place of soda. This is bicarbonate of potash and, like soda, gives off carbon dioxide when it is combined with an acid. As this was originally manufactured it was not finely powdered, but in a more or less scaly mass which could by no means have been easily sifted with the flour in making use of it. In order, then, to get it properly mixed, it was necessary to dissolve it in the liquid used. This probably accounts for the many cooks who still dissolve the soda in the sour milk used with it, instead of sifting it with the flour. This is, obviously, a waste of soda, because all the gas which bubbles off is lost as leavening, since there is no gluten present to retain the gas.

Since definite amounts of acid act on definite amounts of soda, a question naturally arises in regard to the acidity of sour milk. Is it always uniformly acid? This must be answered in the negative for milk that has not clabbered. But after that stage has been reached, the acidity remains fairly constant, until changes take place in the milk which render it unfit for food. Therefore, the proportion of soda that can wisely be used with a cup of clabbered milk is a definite one. Many recipes, especially when enough other flavoring, such as chocolate or spice, is used to disguise the taste of an excess, call for a larger proportion of soda. The result is greatly improved if the soda is reduced to the correct amount, and if more leavening is needed the added amount is supplied by the addition of baking powder.

Great caution must be taken when molasses is used to act as the acid with soda. Modern molasses is entirely different in respect to its acidity, being always much less acid than of old. It is safer to allow not more than a quarter of a teaspoon of soda to a cup of molasses, if the molasses is bought in bulk. Use baking powder for the rest of the leavening. If the molasses is canned, it may have practically no acidity whatever, and baking powder should be used instead of any soda.


1. How does baking soda differ from washing soda?

2. What finally becomes of the carbon dioxide gas from the soda used in griddle-cakes?

3. Is carbon dioxide harmful?

4. What is soda water? How is it made?

5. Wherein lies the chief danger of drinking soda water at a public store if it is managed carelessly? Are there any laws in your town or city governing this?

6. Why is soda soothing to a burn? When should it not be used for this purpose?