| Clue | Source | Date |
|---|---|---|
| Sweet-smelling liquid formerly used as a general anaesthetic | The Times Specialist Sunday | 07 Sep 2025 |
| Old anaesthetic compound | ||
| Knockout stuff from loch or ground | ||
| Brief task framing '50', old model number | ||
| Volatile liquid from Switzerland left room for being refined | The Telegraph Toughie | 02 Mar 2017 |