Historical clue formulations

• Acidic — 2026-09-12
• Nonbasic characteristic — 2023-02-16
• Figure that denotes acidity — 2019-10-13
• Marked acidity — 2013-06-28
• Vinegar quality — 2011-09-23
• Boast of some shampoos — 2010-04-05
• Acid test finding — 1999-06-30
• Like some shampoos — 1994-11-26