1. Dissolve half a teaspoonful of baking powder in two table-spoonfuls of water and heat in a test tube, or saucepan, over a flame; notice the effervescence when the bubbling is at its height, and hold a lighted match in the mouth of the tube. This is a simple test for carbon dioxide.
2. Dissolve 2 teaspoonfuls of cream of tartar in 1/2 cup water in a glass.
Dissolve 1 teaspoonful of bicarbonate of soda in \ cup water in a glass.
Taste both of these.
Test both with litmus paper, noting the change of color. There are several vegetable coloring matters that change color in this way, in the presence of an acid or an alkaline substance.
Turn the two solutions together, and test with both blue and pink litmus paper, after the solution has stood for several minutes. What results?
Taste this mixed solution to see if you can detect any difference.
To prove that there is a substance still left, evaporate the water.
3. A pretty form of this experiment is to use, instead of litmus the water in which red cabbage has previously been boiled and which therefore contains some of the coloring matter of the cabbage. The changes in color are very striking, and prove conclusively that neither the cream of tartar nor the soda remains such.