In this chemistry activity, learners fill two test tubes with a solution of "artificial stomach fluid," consisting of hydrochloric acid in the same concentration as in human stomachs, some soap to create bubbles, and an acid base indicator. To one tube they add an antacid powder; in the other tube, they add an anti-gas powder. By observing the resulting reactions, learners observe how antacids and antigas medicines work on their stomach fluids. Cost estimates are per 100 learners. For safety reasons, this activity works best as a demonstration for younger audiences.