Historical clue formulations

• ___ acid (aqua fortis) — 2020-09-08
• Kind of acid — 2011-07-19
• Kind of acid — 2006-11-05
• Kind of acid — 2005-11-28
• ___ acid — 2004-02-27
• Kind of acid — 2003-06-23
• Kind of acid — 2001-04-26