Whether a substance is an acid or a base is dependent on its pH level. If a substance has a pH of more than 7, then it is a basic. If the pH level is lower than 7, then that substance is acidic. In chemistry, salt is a substance that results from a reaction of an acid (typically weak) and a base (typically strong). Acetic acid is used in vinegar. Citric acid naturally occurs in citrus fruits. Much of your stomach liquid is acidic and is used to break down foods. Bases have the ability to accept free nitrogen and can neutralize acids. Examples of household bases include soaps, lye, and Tums. Salt has many beneficial qualities. In modern salt therapy, a halo generator emits sodium chloride in small particles that attach to your airways to kill bacteria and act as an anti-inflammatory agent.