I have a family history with why mercaptan in added to Natural gas ASAP. My great uncle was superintendent of the New London School in 1937 when the school exploded after field gas (unodorized) collected under the new school. He and his two brothers lost children in that explosion.
https://www.texasmonthly.com/articles/the-new-london-school-explosion/
It was the story that brought Walter Cronkite to the attention of the big shots.
When I was young, they tried using silver iodide crystals.