Related Clues:

• Litmus reddener
• Lysergic, for one
• Alkali counterpart
• Users drop it
• The 'A' in DNA
• Heartburn cause
• Base antagonist?
• Like vinegar or grapefruit juice
• Beyond sarcastic
• See 43 Across
• Part of RNA
• Sulphuric or nitric
• Boric, e.g.
• Low-pH substance
• Sour-tasting substance