Historical clue formulations

• Kind of acid used to make Silly Putty — 2024-09-03
• ___ acid — 2016-08-14
• Kind of acid used in fireproofing — 2014-12-05
• Kind of acid — 2006-05-21
• Kind of acid — 1998-12-02
• Kind of acid — 1995-09-13
• Kind of acid — 1995-02-07