Methods Of Making Mixtures Light

1. Incorporation of Air. Physical change. - Air expands when heated. Methods: (a) By beating mixture.

(b) By adding beaten eggs.

2. Steam.

Physical Change

Steam occupies 1600 times more space than the water which produced it. Methods: (a) Moisture, as in pop-overs. (6) Snow pancakes.

3. Fermentation.

Chemical Change

C02 liberated. Methods: (a) Yeast.

(6) Salt-rising bread.

4. Acid and Alkali.

Chemical Change

C02 liberated. Methods: (a) Baking powder.

(6) Soda and an acid, as cream of tartar, sour milk, molasses.

Experiment 57

Make a solution of 1/2 ts. soda and 1/4 c. water. Taste. Test with litmus paper.

Name some of the properties of an alkali. Test various washing powders with litmus paper. Are they alkalies?

Experiment 58

Make a solution of 1 slightly rounding ts. of cream of tartar and 1/4 c. water. Taste. Test with litmus paper. Name some of the properties of an acid. Test lemon, vinegar, molasses, etc., with litmus paper. Are they acids or alkalies?

Experiment 59

Put solutions of experiments 57 and 58 together. What causes the effervescence? Taste. Test with litmus paper. What effect have the acid and alkali had on each other? Is the result acid or alkaline? What causes the salty taste? What is formed by the union of an acid and alkali?

Experiment 60

Make a solution of alum and water. Taste. Test with litmus paper. Has the alum an acid or alkaline reaction? Is it substituted for the cream of tartar or for the soda in baking powder? Add soda to the alum solution; what is the result? What effect did it have upon the tongue? Is alum a healthful ingredient in baking powder?

Experiment 61

Test sour milk with litmus paper. Is it acid or alkaline? Add a little soda; what is the result? Repeat with molasses, brown sugar, chocolate.

Experiment 62

Mix baking powder with water; what is the result? Warm gently. Is the chemical action increased by heat? Test with litmus paper. Is the reaction either acid or alkaline? Taste. What has been formed by the union of soda and the acid?

Experiment 63

Pass the gas given off when soda and cream of tartar solutions are put together through limewater; what gas is formed? Test the gas given off when baking powder is moistened with water. What gas is generated when an acid is added to bicarbonate of soda?