This is called the _litmus test_. All ordinary acids, if not too strong, will turn litmus pink. All bases or alkalies will turn it blue. If it is already pink when you put it into an acid, it will stay pink, of course; if it is already blue when you put it into a base, it will stay blue. But if you put a piece of litmus paper into something that is neither an acid nor a base, like sugar or salt, it will still stay the same color. So, to test for a base, use a piece of litmus paper that is pink and see if it turns blue, or if you want to test for an acid, use blue litmus paper. Do this experiment: EXPERIMENT 110. With pink and blue litmus paper, test the different substances named below to see which are acids and which are bases. Make a list of all the acids and another list for all the bases. Do not put down anything that is neither acid or base. You cannot be sure a thing is an acid unless it turns _blue_ litmus _pink_. A piece of pink litmus would stay pink in an acid, but it would also stay pink in things that were neither acid nor base, like salt or water. In the same way you cannot be sure a thing is a base unless it turns _pink_ litmus _blue_. Here is a list of things to try: 1, sugar; 2, orange; 3, dilute sulfuric acid; 4, baking soda in water; 5, alum in water; 6, washing soda in water; 7, ammonia; 8, dilute lye; 9, lemon juice; 10, vinegar; 11, washing powder in water; 12, sour milk; 13, cornstarch in water; 14, wet kitchen soap; 15, oil; 16, salt in water. You may have to make the orange and sour milk test at home. You may take two pieces of litmus paper home with you and test anything else that you may care to. If you have a garden, try the soil in it. If it is acid it needs lime. _APPLICATION 81._ A boy spilled some greasy soup on his best dark blue coat. Which of the following methods would have served to clean the coat? to sponge it (a) with cold water; (b) with water (hot) and ammonia; (c) with hot water and vinegar; (d) with concentrated nitric acid; to sprinkle lye on the spot and pour boiling water over it. _APPLICATION 82._ A woman scorched the oatmeal she was cooking for breakfast. When she wanted to wash the pan, she found that the blackened cereal stuck fast to the bottom. Which of the following things would have served best to loosen the burned oatmeal from the pan: lye and hot water, ammonia, vinegar, salt water, lemon juice? INFERENCE EXERCISE Explain the following: 521. After clothes have been washed with washing soda or strong soap, they should be thoroughly rinsed. Otherwise they will be badly eaten as they dry. 522. Carbon will burn; oxygen will support combustion; yet carbon dioxid (CO_2), which is made of both these elements, will neither burn nor support combustion. 523. You can clean silver by putting it in hot soda solution in contact with aluminum.