Related Clues:

• Etcher's supply
• Caustic stuff
• Caustic chemical
• Battery component
• Kind of rock or rain
• Tart-tasting
• Aspirin, e.g.
• Citric ___
• Test subject
• Word with indigestion or test
• Sour-tasting
• Battery fill
• Hydrochloric, for one
• Litmus-reddening substance
• Sharp-tongued