Related Clues:

• Kind of rock or rain
• HCl and others
• Tart-tasting
• Aspirin, e.g.
• Citric ___
• Test subject
• Word with indigestion or test
• Sour-tasting
• Battery fill
• They have pH's of less than 7
• Caustic liquids
• Boric and citric
• Hydrochloric, for one
• Litmus-reddening substance
• Sharp-tongued