| 2026-01-07 | They have pH's below 7 |
| 2025-03-13 | Complements to salts and fats in the kitchen |
| 2023-12-02 | One side of a chemistry scale |
| 2023-01-21 | They're far from basic |
| 2022-12-12 | Low-pH liquids |
| 2022-08-02 | Lemon juice and vinegar, for two |
| 2021-06-03 | Things that are far from basic? |
| 2021-03-31 | They turn litmus paper red |
| 2020-11-17 | Lemon juice and vinegar, e.g. |
| 2020-08-29 | They're not basic |
| 2018-06-01 | Counterparts of tannins, in wine tasting |
| 2017-12-02 | Vinegar and lime juice |
| 2017-09-22 | One end of the pH scale |
| 2017-04-21 | Eating things |
| 2016-08-09 | They turn litmus paper red |
| 2015-12-04 | Vinegar and others |
| 2015-06-22 | Lemon juice and coffee, on the pH scale |
| 2014-11-20 | Etching supplies |
| 2014-08-10 | One side of the pH scale |
| 2013-09-04 | Fatty ___ |
| 2013-06-17 | Tums targets |
| 2013-03-16 | They're not basic things |
| 2012-12-06 | Substances low on the 49-Across |
| 2010-09-23 | See 27-Across |
| 2010-08-31 | They turn litmus paper red |
| 2009-11-15 | Aminos, e.g. |
| 2008-03-04 | Gastric juices, e.g. |
| 2007-12-27 | Stomach contents |
| 2006-09-07 | Causes of breakdowns |
| 2006-04-20 | Etching fluids |
| 2005-10-05 | Tums' targets |
| 2003-09-29 | Citric and others |
| 2003-05-27 | Corrosive liquids |
| 2002-10-07 | They have pH's of less than 7 |
| 2002-02-27 | HCl and others |
| 2001-10-13 | Chem lab collection |
| 2001-06-19 | H2SO4 and such |
| 2000-11-29 | Litmus reddeners |
| 1999-10-08 | Niacin and vitamin C |
| 1999-09-09 | Tummy troublers |
| 1997-06-27 | They have low pH's |
| 1997-06-26 | Stomach ___ |
| 1997-03-16 | Fatty ___ |
| 1997-02-20 | Litmus reddeners |
| 1997-02-08 | Litmus reddeners |
| 1996-12-25 | These can be citric |
| 1995-07-30 | Niacin and others |
| 1995-03-17 | Base neutralizers |
| 1995-02-16 | Substances with low pH |
| 1994-12-17 | Stomach _____ |